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51 Uses of Solar Energy. Spherical solar panel

51 Uses of Solar Energy. Spherical solar panel

    Design and analysis of multi-layer silicon nanoparticle solar cells

    We investigate the concept of nanoparticle-based solar cells composed of a silicon nanoparticle stack as a light trapping absorber for ultrathin photovoltaics. We study the potential of using these inherently nanotextured structures in enhancing the light absorption. For this, a detailed optical analysis is performed on dependency of the cell response to parameters such as the number of particle layers, lattice structure and angle of incidence; Optical response of these cells are then compared with the results in conventional silicon solar cells. over, we propose various configurations to apply these submicron particles as a p–n junction solar cell. We also compute the electrical performance of selected configurations. In doing so, key issues including the effect of contact points between nanoparticles and impact of loss are addressed. In the end, we show how \(\mathrm_2\) nanoparticles on top of the cell structure can enhance the photocurrent. The appropriate range of \(\mathrm_2\) particle size is also obtained for the typical cell structures.


    Ultrathin solar cells are referred to a group of photovoltaic structures possessing light absorbers with a thickness of at least an order of magnitude smaller than conventional solar cells 1. These cells have drawn attentions for decreasing the raw material requirements, their flexibility and bendability 2,3. Despite their reduced thickness, optical path length is improved by engineering the cell structure so as to compensate their low absorption. Ultrathin solar cells are expected to be fabricated with low-cost techniques via increased fabrication throughput 4 ; for instance, they may be realized without protective glass layers 3 or their active layer can be deposited with lower deposition techniques 1. These cells can show robust performance in cell dislocations and low light-induced degradation 5,6. Besides, bulk recombination mechanisms such as Auger recombination—are limited, which result in higher open-circuit voltages, and carrier collection is facilitated on contacts 1. With these features, the concept of ultrathin photovoltaics has experienced a fascinating growth through the last decade and found applications in spacecrafts 3 due to their short carrier diffusion lengths, which brings immunity against radiation damages. In addition, thanks to their flexibility, these cells are candidates to supply energy for portable devices in remote areas.

    Attempts for design and realization of ultrathin solar cells have been concentrated on studying both the electrical and optical aspects; On the electrical side, common analysis include optimization of cell absorbers bandgap 7,8. together with studying photo-carrier drift, diffusion, generation and recombination using carrier transport equations 9,10. On the optical side, the absorption behavior of a cell is the key parameter that determines how efficient a cell architecture is in producing higher photocurrent. The main drawback against high cell efficiencies is insufficient light absorption in ultrathin structures. Due to this, researches on these cells are often directed toward finding light management architectures with practical values 6,11,12,13,14. For instance, using proper anti-reflection coatings and embedding back mirrors 15,16. using periodic nano-gratings on the front 17,18,19. or random pyramids on the front and back of ultrathin silicon layers to achieve omnidirectional reflectance 20. Optical confinement has also been explored through the excitation of edge states around the photonic topological insulator 21. Considering these, the attempt has therefore been focused on configuring the structure both optically and electrically to preserve high short circuit currents while decreasing the thickness.

    The efficiencies reported for ultrathin solar cells are also promising; in GaAs cells of thickness around 205 nm the conversion efficiency has reached 19.9% 3. For CIGSe cells with the thickness of 1.2 \(\upmu\) m, the efficiency of 11.27% is reported in 22. In ultrathin silicon solar cells, the efficiency of 8.6% is reported for a 1.1 \(\upmu\) m absorber, that although is lower than conventional cells, it shows a remarkable progress toward realizing a Lambertian model in ultrathin cells 1.

    Pattering an ultrathin structure can, however, complicates realization of these cells, and even contradicts with their principle benefits. Thus, simple cell configurations with reasonable efficiencies are most often preferred. Among various techniques to increase the short circuit current in ultrathin cells, using randomly roughened surfaces has shown promising results 6. In this regard, the beneficial effect of nanoparticles on absorption enhancement and broadening solar spectral Band for ever thinner solar cells has been extensively addressed 23,24,25,26 ; In terms of fabrication, in contrast to photonic crystal patterns, nanoparticles can be made and deposited via lower cost techniques 27. While attentions on ultrathin solar cells have been mainly drawn toward GaAs solar cells 28. the low cost silicon solar cells of this type possess commercially more chance to be employed in widespread terrestrial applications with low energy requirements.

    In this paper, we demonstrate multi-layer Silicon Nano-Particle (SNP) solar cells as a promising photon management technique in ultrathin photovoltaics. We show how this inherently textured architecture acts as a light absorber while having the potential to separate and transport photo-generated carriers. We compare the optical properties of a structure composed of these Mie scatterers with planar cells of the same thickness and provide a comprehensive analysis on the cell behavior for different number of particle layers when exposed to oblique incidence and also for various particle periodicity. Then, we study different scenarios to tailor the silicon nanoparticles as the active layer of a realizable cell. Next, we concentrate on an appropriate structure and optimize its geometrical and electrical parameters. In order to further improve the absorption, we examine the effect of distributing \(\mathrm_2\) nanoparticles on the cell front. Finally, we estimate the expected power conversion efficiency of the cell and compare it with the efficiencies reported in the literature.

    Electromagnetic properties of SNP absorbers with various parameters

    We here concentrate on the absorption properties of SNP layers and compare them with planar silicon layer. The two structures are shown in Fig. 1a,b. As shown in this figure, the silicon nanoparticles are densely stacked inside a dielectric medium. We also assume a metallic contact (silver) below, and an anti-reflection coating(ARC) above the absorbers to further resemble a real cell. We assume that particles have an identical size of the order of a few hundred nanometers; this dimension range ensures achieving a remarkable light trapping through the frequency spectrum that contributes in photo-generation (i.e. \(\lambda\) = 300–1100 nm). Assuming the spherical shape of silicon nanoparticles, by reducing the particle radius, a fewer number of Mie resonances are excited and this leads to a lower light absorption. In addition, we will see that as the particle radius increases above 500 nm, the absorption enhancement—in comparison to a conventional cell—becomes negligible. This is because the absorption for the silicon nanospheres with a radius of 500 nm or larger will be close to the unity in the bandwidth of the solar cells. Light trapping in this particle-based structure is enhanced due to the excitation of whispering gallery modes. over, from the ray optics viewpoint, the random path length of light beams inside the structure increases total absorption. With regard to the flat silicon layer shown in Fig. 1b, at \(\lambda 500\,\mathrm\). the absorption is due to the intrinsic loss of the crystalline silicon. In this range, the optical responses of both structures are very close together. At higher wavelengths, the Fabry–Perot resonance is the only mechanism for trapping light in the flat structure, and it happens only at limited number of wavelengths. In the following sections, we examine various aspects of distributed silicon nanoparticles in light absorption, if they are employed instead of the silicon layer.

    The number of NP layers

    We first study the impact of the number of particle layers in Fig. 1a on the absorption. The aim is to explore how many layer is beneficial in reaching higher absorption in comparison to a conventional cell in Fig. 1b. We assume that particles are spherical with a selected radius of 300 nm. Particles are assumed to be inside a carrier transport medium with the refractive index of 1.8, which is an average value for a number of materials such as PEDOT:PSS polymer and spiro-OMeTAD at the interested frequency spectrum of sunlight. The thickness of this medium above the upper layer is assumed to be 75 nm, which imitates the typical thickness of an ARC. Figure 2a,b show the absorption spectra of a multi-layer SNP absorber with two (N = 2) and five (N = 5) layers of silicon nanospheres when compared with that of a flat layer (by integrating the obtained graphs over the wavelength interval, we can compute the sunlight power density that is absorbed by the structure). As can be seen, a particle-based structure and a flat layer behave the same at short wavelengths in both figures. This was expected as the penetration depth is such small that the optical power is absorbed regardless of the considered configuration change. However, these particle-based structures provide improved absorption, at longer wavelengths. over, by comparing the two figures, higher absorption is achieved when N = 5. Note that, if we assumed that the two structures (i.e. the multi-layer SNP and a flat structure) should have identical absorber volume, we would reach even further discrepancy in their absorption at long wavelengths.

    Although the absorption is enhanced as the number of layers increases, the total absorption approaches that of a planar structure. This is shown in Fig. 2c where the total absorbed power density—at the interested wavelength interval—is computed for the particle-based structure and the planar one, as a function of the number of layers. We have also defined total absorption enhancement as the ratio between the total absorbed power density of the two structures. From the figure, increasing the number of SNP layers reduces the advantage of the SNP structure in comparison to a planar one. This indicates that the SNP cell is optically preferable only when a few layers are used.

    The lattice type

    Particles in each layer of the structure shown in Fig. 1a may be arranged in different forms. Considering a dense distribution, a random arrangement for particles is a cheaper choice and practically preferred for mass production. Despite this, in terms of numerical analysis, one often has to consider a sort of periodicity to reduce the simulation domain. Knowing the impact of various particle distributions on the absorption behavior helps in finding an average expected response of a random distribution. Before studying the impact of particle arrangements, we emphasize that dense distribution of SNPs are much more desirable than sparse ones for solar cell applications. This is because SNPs are assumed to be the main absorber in the cell. Thus, any distance between them reduces the absorption of incident photons. As SNPs become closer, a stronger coupling will be formed between the optical fields inside the cell absorber.

    We restrict our study to a lattice composed of two layers of identical silicon nanoparticles with the radius R. Figure 3 shows the cross-sectional top-view of three different arrangements of these layers. Figure 3a, is a Simple Cubic (SC) arrangement where we assume that the cross-sectional location of particle centers in the upper layer resides on the particle centers in the lower layer. Figure 3b, is a Body-Centered Cubic (BCC) arrangement where the upper layer—shown inside the dashed square has a rectangular cross-section and—is shifted with a lattice vector \(R\,\hat_x R\,\hat_y\) with respect to its below layer. Finally in Fig. 3c SNPs form a Hexagonal Close-Packed (HCP) array wherein SNPs in the upper layer have the same pattern and location as the below layer. In terms of the absorber density we have HCP BCC SC. The reflection from these structures are compared for \(R = 100\,\mathrm\) in Fig. 3d. As can be seen, the reflection from the first and third arrangements have very similar behavior at shorter wavelengths; at higher wavelengths, the HCP structure has an improved absorption due to its new resonances. The reflection corresponding to the BCC lattice presents a fairly fluctuating behavior; while the reflection is reduced in several wavelength intervals, between 680 and 780 nm, it is increased. The total reflection from these structures is also shown in the figure. over, the photocurrent produced by each one is obtained via 29

    \begin J_\mathrm = \frac\int ^\lambda = 1100 \mathrm_\lambda = 300 \mathrm S(\lambda )A(\lambda )\lambda d\lambda. \end

    where c is the speed of light, e is the electron charge, h is Planck’s constant, and \(S(\lambda )\) is AM 1.5G solar spectrum 30. The reflection values show that the second form of periodicity—that much more resembles a quasi-random distribution—can generate larger \(J_\mathrm\). Despite this, we consider the worst scenario (i.e. the first form of periodicity) when simulating the electrical behavior of these structures in the following sections.

    Solar cell performances with different cell configurations

    Various configurations of SNP structures can be considered to operate as a solar cell. These structures can be categorized according to the particle size, type of distribution (i.e. periodic or random) and the operating mechanism designed for the cell. In terms of dimensions, we concentrate on SNPs with submicron dimensions. Also, cells based on silicon quantum dots are not considered here because poor carrier conductivity is still a serious drawback toward using them in photovoltaics 31. Within this dimension interval (i.e. SNPs of a few hundreds of nanometer dimensions) the particle Band gap remains unchanged. In terms of cell mechanism, we FOCUS on configurations having p–n junctions. Depending on materials used as a host of nanoparticles there exist other quasi-p–n schemes that may be used to form a real SNP cell. They will be discussed in the next sections.

    Figure 5 shows the cross-section of three cell configurations where particles have formed several layers. We here assume that particles have spherical shape so as to propose our main ideas. Figure 5a shows a unit cell composed of several layers of doped silicon particles inside a dielectric medium. The p-type silicon (P-Si) particles are placed above a n-type silicon (N-Si) layer to form a p–n junction. In this sense, the carrier transport toward contacts occurs through particle interfaces with adjacent particles or with the N-SI layer. The medium surrounding the nanoparticles can be assumed air. However, for the stability reasons, this is not a practical idea. Instead, assuming P-Si particles, then their surrounding medium can be a hole transport layer (HTL). This structure, henceforth called Structure A is a generalized form of the ultrathin structure proposed in 32. The second structure (Structure B) shown in Fig. 5b is composed of merely multi-layers of SNPs that form a multi p–n junction cell inside a dielectric medium. Each layer has particles with a doping that is opposite to its adjacent layers. The main concern about this configuration is that particles in upper layers may diffuse into their below layers and hence, disrupt the expected carrier separation and transporting toward cell contacts. An alternative way to realize a structure with particles of various doping, is the configuration shown in Fig. 5c (Structure C). As seen, particle layers of different doping are separated with a thin interlayer medium. This layer can be of intrinsic silicon. In practice, this ultrathin layer may be realized using even smaller silicon nanoparticles. The P(N)-Si particles in this case are surrounded by a hole (electron) transport medium. A disadvantage of this structure is that particles below the intermediate layer do not effectively contribute in light confinement. However, the structure allows particles with various doping to form a cell structure. In the following, we first look at structure A and explore its optical and electrical parameters in a case study. Next, we look at the structure C and perform similar analysis to extract its electrical performance.

    Structure A

    In this section, we numerically study structure A shown in Fig. 6a. We will also compare the cell performances between the SNP cells with identical and non-identical P-Si NPs. As shown in Fig. 6a the simulated cell is composed of two identical P-Si nanoparticles immersed in a HTL. Regarding the top contact, a transparent conductive oxide (TCO) with the refractive index of 1.8 is considered. We have also assumed that there exists an identical contact area between the nanoparticles. The HTL is assumed to be the organic polymer PEDOT:PSS in this case study, and has covered the particles with the thickness \(\mathrm_\mathrm\). A very thin buffer layer—with similar index of refraction as the TCO—is also included between the HTL and TCO, to protect the HTL from parasitic absorption. We note that solutions composed of silicon nanocrystals in polymers have been recently demonstrated for cheap and flexible optoelectronic applications 33. Main material specifications and geometrical parameters of our case study are brought in Table 1.

    Considering the dimensions given in the table, Fig. 6b compares the photocurrent \(J_\mathrm\) generated by the cell as a function of particle dimensions (All particles have identical size). These results are compared with the produced current a conventional silicon cell having identical thickness to the particle-based structure (i.e. Thickness = \(\mathrm_\mathrm\mathrm_\mathrm\mathrm_\mathrm\) ). As can be seen, the proposed cell offers approximately 30% higher photocurrent in comparison to the flat cell. Thus, despite having less volume of absorber, the particle-based cell acts highly efficient for light trapping. As the particle dimension increases, the photocurrent takes naturally higher values. However, if we draw the ratio of photocurrent to the silicon volume used (see Fig. 6c), we observe a downward trend with increasing the particle dimension, that indicates cell is becoming less efficient in terms of the absorber material consumed. Figure 6d shows the distribution of the carrier generation rate—in a logarithmic scale—of the cell in its cross-section. The generation rate is higher in the upper silicon particle; it is also highly concentrated in the bulk of the particles rather than the their boundaries. The current/power-voltage characteristics of the cell is obtained for various dopings of silicon layer in Fig. 6e. As can be seen, by increasing the doping value, the open circuit voltage also improves.This is because the dark saturation current density is decreased by increasing doping. This improves the cell efficiency from 5.8% for \(\mathrm_\mathrm = 10^ \,\mathrm^\). to about 11% for \(\mathrm_\mathrm = 10^ \,\mathrm^\). Despite this, the short circuit current remains almost unchanged with doping variation. This is because that the structure is basically a diffusion device. That is, the dominant carrier transport is the diffusion current, in which minority carriers in the P-Si nanoparticles (i.e. photo-generated electrons) move down to the N-Si. By increasing the doping density of the N-Si layer, the depletion width becomes narrower. However, the drift current is not a dominant factor to influence the total current. That is, not only the doping concentration of the P-Si nanoparticles but the photo-generated electrons in particles are remained unchanged. Thus, the short circuit current does not change noticeably.

    Figure 6f shows the distribution of total current density at V = 0.41 v when \(\mathrm_\mathrm = 10^\, \mathrm^\). In addition, arrows show the direction of the normalized current density in the structure cross-section. As can be seen, in particle contacts, the current has critically high densities—up to 120 \(\,\mathrm \,\mathrm^-2\) ; at the top surface of the upper particle the current is much widely distributed with slightly higher values around highest point.

    The commercially produced nanoparticles are hardly pure spherical 34. often, they are characterized besed on their average physical size (APS). As a result, contacts between particles is an area rather than a single point. To consider this in modelings, we assume that the upper and below area of each particle are cropped. This forms a circular contact area as shown in Fig. 7. We note that in extracting the I–V characteristics we have assumed that the contact area on upper and lower part of the nanoparticles has the radius \(r_\mathrm = 60\,\mathrm\). As we reduce this interface, the cell efficiency will be reduced. Table 2 shows the variation of the efficiency, short circuit and open circuit voltage as a function of \(r_\mathrm\).

    Structure C

    The next structure in our studies is an example of Structure C shown in Fig. 5c wherein, two nanoparticles with various doping are deposited on the upper and lower sides of an intrinsic silicon layer. The cell is shown in Fig. 9a and the geometrical parameters together with the electron transport layer(ETL) used in simulations are listed in Table 3. Note that the HTL is similar to the structure illustrated in the previous section. Figure 9b shows the photocurrent generated in the cell structure as a function of silicon particle size; the results are also compared with a conventional cell of the same thickness. A similar behavior to the previous case study can be seen for both cell structures (i.e. particle-based cell and conventional one). In terms of current produced per volume of the unit cell, Fig. 9c shows that smaller particles are more efficient despite generating lower levels of photocurrent. The generation rate of the unit cell over the cross section in Fig. 9d shows that most carriers are generated at upper nanoparticle and the generation rate reaches \(10^\frac\mathrm^3\) around the particle center. We have also looked at the I–V characteristic of the structure in Fig. 9e; we assumed that doping of the P-Si particle is \(10^\, \mathrm^\). Then, for various doping concentration of the N-Si particle, I–V graphs are obtained. In contrast to the structure A in the previous section, here, the short circuit current is significantly influenced by doping; At higher dopings, the short circuit current is reduced to \(15.9 \;\;\text^\). In contrast to the structure A, here is only a single layer of P-Si nanoparticle. The below particle layer is N-Si, and an intrinsic layer is sandwiched between the particles. The device is therefore, like a PIN diode. The depletion region is now large and the drift current becomes a dominant mechanism. By increasing the doping in N-Si nanoparticle, the width of depletion region is reduced, hence fewer photo-carriers are generated inside that region. As a result, the drift current—which is the dominant one—is reduced by increasing the doping concentration. Although the open circuit voltage is increased by doping, the total power conversion efficiency is reduced and reaches 7%. Figure 9f shows the distribution of total current density at V = 0.41 v when \(\mathrm_\mathrm = 10^\, \mathrm^\). Likewise Fig. 6f, arrows show the direction of the normalized current density in the structure cross-section. As can be seen, the current density is strongly concentrated at the center of the below particle; this is because much weaker light hits to that particle and the carrier transport is limited to particle contacts; at the top surface of the upper particle, current is again much widely distributed over the particle surface.


    The cell configurations introduced in this study provide improved optical absorption in an inherently textured structure. Interestingly, these features even happen for configurations with random distributions of nanoparticles; this issue leads to a simplified way for fabrication of these ultrathin cells. The overall efficiencies determined for the multi-layer SNP cells show a competing results with those of a nanowire cell. Table 4 shows the reported electric parameters of several nanowire solar cells. The table indicates that despite a rather low open circuit voltage—which is also common in nanowire cells—the expected efficiency of the SNP cell is remarkable.

    While realizing a p–n junction was the basis for configuring and analysis of the described cells, by using hole transport polymers such PEDOT:PSS in contact with N-Si in Fig. 6a, a hybrid organic-inorganic junction is also formed. It is demonstrated that such these contacts act almost like a quasi p–n junction by Jäckle et al. 44. Based on the free carrier movement in a simple PEDOT:PSS/N-Si junction, the generated carriers in our case studies is expected to constructively contribute in the overall current density. Another issue is about the effect of crystallinity of the silicon nanoparticle. We only considered crystalline silicon particles in the simulations. Cells based on amorphous silicon nanoparticles present weak carrier mobilities despite having high absorption. Therefore, they provide poor conversion efficiencies 33.

    A critical challenge on proper functionality of the proposed structures is the impact of recombination. Although we have included the conventional loss mechanisms in the models, the effect of surface recombination was neglected. In the following, we separately investigate impact of this loss by adding a recombination rate on particles as well as the front side of the silicon layer in the structure A. Figure 11 shows the J–V plot of the cell assuming the dimensions and material properties listed in Table 1. The particles doping are assumed to be \(10^ \,\mathrm^\) and the silicon layer is assumed to have the doping \(10^ \,\mathrm^\). As can be seen, by increasing the recombination velocity up to \(10^\,\mathrm^\). the J–V graph remains almost unchanged. At higher recombination velocities, both open circuit voltage and short circuit current are reduced. Due to that, the cell efficiency drops to 5.6% for the surface recombination velocity \(\mathrm = 10^\,\mathrm^\). The graph shows that only at high surface recombination rates, efficiency is affected. This is because the carrier generation is mostly concentrated in the bulk of nanoparticles, away from the particle surface; the surface recombination is therefore effective on particle upper and lower areas where carrier transport happens.

    We assumed that the silicon bandgap is unchanged by doping. At high levels of doping, bandgap narrowing appears which limits the increment of open circuit voltage 45. In addition, we did not consider series resistance in the presented electrical calculations because the main purpose of this work was to propose the conceptual design of the structure without concentrating on a specific contact; Apparently, resistance—which is proportional to the contact material—slightly reduces the fill factor and hence, the cell efficiency. An inevitable consideration about the top contact is to choose materials which prevent diffusion of oxygen to the hole transport medium and silicon particles. This is because the emerging oxide layer around the nanoparticles can affect cell performance. Although thin oxide layers (say below 1 nm) can help in passivation of dangling bonds on the particle surface, further increase in the thickness prevents carrier transport between particles.


    In this paper, we proposed that multi-layer silicon nanoparticles of submicron dimensions can be deployed as the absorber of an ultrathin solar cell. We provided a parametric analysis to study the absorption behavior of the stack of these Mie scatterers and showed that the absorption efficiency of the structure is higher at lower number of layers and it approaches to absorption of a flat silicon layer for higher number of layers. We showed that in a dense distribution of silicon nanoparticles, their periodicity play a negligible role in absorption improvement. Several configurations were introduced to tailor these particles as a p–n junction cell. We finally investigated the electrical performance of selected case studies and found that the theoretical efficiency can reach about 11%, which is a promising value for such an ultrathin structure. over, we showed that by including silica nanoparticles of proper size on top of the cell structure, one can enhance the photocurrent up to around 10%.


    In this paper, we numerically investigated the optical performance of the proposed solar cell with multi-layer silicon nano-spheres via full-wave simulation in CST. Due to the resonant nature of a SNP solar cell, we used the FDFD solver to achieve appropriate response accuracy; this solver also allows choosing the number of simulated frequencies in the interested interval. We applied periodic boundary conditions under normally(or obliquely, if needed) propagation of plane wave. The absorbed power inside the silicon parts, together with the corresponding generation rate were calculated. For the electric analysis, we then simulate the 3D cell structures in the Charge module of Lumerical. For this, each sphere was modeled as a stack of 3D polygons having thin thicknesses. The obtained generation rate is imported in the simulation. In addition, the material properties including permittivities, dopings and losses found in the literature were considered for silicon, silver and polymer parts.

    Data availability

    The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.


    Authors acknowledge support from the University of Tehran, Science and Technology park.

    Uses of Solar Energy

    Our sun is the source of all life on Earth, making solar energy useful to us in many different ways.

    The sun creates two main types of energy — light and heat — that we can harness for numerous activities. These range from prompting photosynthesis in plants to creating electricity with photovoltaic (PV) cells to heating water and food.

    So, what are some uses of solar energy? Let’s explore 39 common uses of sunlight in our daily lives.

    Home Systems

    A rooftop solar installation can provide enough energy to power your home’s electricity and HVAC needs.

    Solar Electricity

    This solar energy application has gained a lot of momentum in recent years.

    As solar panel costs decline and more people become aware of solar energy’s financial and environmental benefits, solar electricity is becoming increasingly accessible. While it’s still a tiny percentage of the electricity generated in the U.S. (2.8% as of 2021), solar electricity is growing rapidly.

    Technicians usually install a distributed solar PV system on the rooftops of homes or businesses. These solar power systems generate electricity to offset the property owner’s usage and send any excess production to the electric grid.

    Solar Batteries

    A solar battery can connect to your solar power system. This setup lets you use solar after sundown and provides backup power during emergencies. Some homeowners may choose go more off-grid with a solar power and battery system, but whether this works for you depends on several factors:

    • How much energy you use daily
    • The amount of sunlight in your area
    • The efficiency of your panels
    • Your battery’s storage capacity

    Solar Generators

    A solar generator typically refers to a combination of portable solar panels, a battery, a battery charger and an inverter. These all make up one device — the generator. With it, you can absorb solar energy, then store and distribute it when needed.

    Solar generators are quite common on camping and boating trips. They also prove incredibly useful in emergency situations when you need backup power, like during a wide-scale, long-term power outage.

    What’s more, a large generator (around 20 KW of storage capacity) can power an entire house for two to eight hours. But this depends on how much energy your home uses in terms of lighting, appliances and more.

    Solar Ventilation

    Solar ventilation solutions such as solar attic fans can reduce the burden on your HVAC by helping cool your home during the summer. This may be a good option if you can’t install a solar PV system that offsets your home’s entire electricity use. One innovative product is the Solatube solar attic fan.

    Solar ventilation technologies also apply to commercial and industrial use applications. These technologies can preheat a building’s air in cold climates, which reduces energy costs.

    Solar Water Heating

    Homeowners can also use solar energy to power their water heaters. Two types of solar water heating systems exist:

    Active Solar Water Heater Systems

    Active solar water heaters use mechanical circulating pumps to move fluids between your rooftop solar panels and storage tank. In turn, these heaters have two different types:

    • In direct circulation systems, a pump moves regular water into your house through solar collectors. Because the water can freeze, direct circulation systems work best in climates that rarely see freezing temperatures.
    • Indirect circulation systems circulate nonfreezing liquids through solar collectors to a heat exchanger. From there, the energy transfers to water that circulates into your house. Climates with freezing temperatures can rely on indirect circulation systems.

    Passive Solar Water Heater Systems

    Unlike active solar water heater systems, passive systems lack mechanical pumps. Instead, they have simple physics to thank because heat naturally rises. Unsurprisingly, this makes them much cheaper (albeit less efficient) than their active counterparts.

    Passive solar water heaters also have two basic types:

    • Integral collector storage systems have a solar collector integrated directly into their water tanks, which allows the sun to heat the tank. These systems work well in homes with significant hot water needs and in climates where freezes are rare.
    • In thermosiphon systems, the solar collector sits lower than the storage tank, which allows the heated water to rise into the tank. Installing thermosiphon systems is slightly more complicated because they’re usually located on the roof.

    Solar House Heating

    Typical uses of solar space heating systems include powering radiant floors or pairing with a hot water or hot air system to heat homes.

    Hot Water Solar Systems

    Hot water solar systems use solar collectors to heat water (or another fluid, such as antifreeze). Circulating pumps move the water through the collector and into either a storage tank for later use or a heat exchanger to provide immediate warmth.

    Liquid-based solar systems are complex, large-scale systems, so industries more commonly use them for commercial applications. However, they’re a home heating option.

    Hot Air Solar Systems

    Hot air solar systems work by circulating air that the sun has heated — such as by striking a wall or roof — throughout your home.

    Technicians typically design homes that rely on these systems with siding or roofing materials that have excellent heat absorption properties. The systems also often use a circulating fan to distribute the heated air, which is where solar power comes in.

    Solar-Powered Pumps

    Some of the heating systems above rely on a pump to circulate water. Because your home’s electricity powers these pumps, they of course consume energy. And that’s energy you hoped to save by installing a solar-powered system in the first place.

    To avoid this problem and save even more energy, you can install a solar-powered pump instead. Installing a battery or generator means you can run your circulating pumps 24/7, regardless of sunlight.

    Solar Heating for Your Swimming Pool

    Another solar energy application, especially in the southern and southwestern U.S., is heating swimming pools. The systems circulate water to a collector, where sunlight heats it. The system then pumps the heated water back into the pool.

    With costs between 2,500 and 4,000 and a payback period of one to seven years, the U.S. Department of Energy says that “solar pool heating is the most cost-effective use of solar energy in many climates.”

    Solar Heating for Your Hot Tub

    Like with swimming pools, solar hot tubs work by using solar collectors.

    You may be surprised to hear that solar energy can provide enough power to heat a hot tub. However, solar vacuum tubes have become so efficient that they can actually overheat your tub in the summer! To avoid this, homeowners in warmer climates often opt for flat plate panels — they get the job done without generating too much heat.

    Of course, you may still need an auxiliary heater after sundown, so we recommend having your existing heater and solar heater work in tandem.

    Solar Lighting

    Solar can power just about any type of lighting you can imagine.

    Solar Landscape Lighting

    When you think of solar lighting, landscape lighting is probably the first thing to come to mind.

    Solar landscape lighting technologies are inexpensive and readily available. You can find basic to high-end designs everywhere from your local hardware store to online shopping websites like Amazon.

    These fixtures didn’t always provide the most light, but LED technology and enhanced batteries have changed that. Individual lighting fixtures now provide sufficient lighting with no wiring connections. Each lighting fixture has its own solar cell and rechargeable battery, which often generates enough energy to power your lights all night.

    Solar Security Lighting

    Solar lighting fixtures have become so reliable that they’re a great candidate for home security lighting as well.

    Like with landscape lighting, the batteries connected to solar security lights typically generate enough energy to last them through the night. This is especially true with motion-sensor options, which save stored energy for when you really need it.

    You can even find options with up to 3500 lumens. That’s enough light to illuminate your outdoor space and give your family peace of mind. Plus, water-resistant features mean you’ll never have to worry about product failure due to weather.

    Solar Holiday Lights

    That’s right — you can take advantage of solar during the holidays with solar-powered Christmas lights. After all, everyone’s budgets feel strained this time of year — don’t let electricity costs to power Christmas lights add to that!

    Good Housekeeping reviewed the seven best solar Christmas lights for 2022, with options ranging from simple white string lights to uniquely shaped options.

    Indoor Solar Lighting

    If you thought lighting had to be located outdoors for solar to power it, guess again.

    As with outdoor solar lights, these indoor fixtures have individual solar cells and rechargeable batteries. The difference is that you can often position the solar cells wherever they’ll get maximum sun exposure. And that means they’re not necessarily located in the same place as the lighting fixture itself.

    Options range from desk lamps to pendant lighting. One especially innovative use of indoor solar lighting, featured on Mashable, is the Solatube skylight. It adds natural light while reducing energy use.

    Solar Appliances

    Appliances with low energy requirements may be able to rely on solar alone for power. Many larger appliances, such as refrigerators and washers and dryers, come in energy-efficient models that make them ideal for solar-powered homes.

    Solar Ovens

    Solar ovens, aka solar cookers, are a great way to cook when the power goes out, while camping or when you simply want to save on electricity costs. They work by gathering and trapping the sun’s thermal energy.

    For example, think about your car with its Windows rolled up on a hot sunny day. The Windows let in and trap the sun’s thermal energy — and the air inside gets hot as a result. It’s no wonder we often say our cars feel like an oven on really hot days!

    Various types of solar ovens exist, and you can make most of them yourself with a handful of simple materials. However, if DIY isn’t for you, you can also purchase one.

    Solar Cooler

    If you’re still toting an ice-packed cooler when you head to the park or campground, it’s time to bring you up to speed.

    Solar-powered coolers are now the go-to product. They ensure your food stays cool for longer and eliminate the issue of melted ice (and soggy sandwiches). Portable power stations receive energy from solar panels and then transfer that energy to the cooler when it’s in use.

    Here are your six best options for solar-powered coolers in 2022, five of which function as both refrigerators and freezers.

    Solar Portable Bluetooth Speaker

    Solar-powered Bluetooth speakers work just like the wireless speakers you’re used to. The difference is that you can charge them without electricity because they have built-in solar panels.

    This makes solar speakers perfect for anyone who spends a lot of time outdoors or on the go, such as while camping or traveling.

    Solar Calculators

    Did you know that solar-powered calculators have been around since the 1960s? That’s right — you’ve probably used one before!

    Solar calculators have tiny solar cells mounted onto them, usually at the top of the device. Because calculators require so little energy to work, the solar cells mean you’ll likely never have to charge the battery.

    Solar Flashlights and Lanterns

    When the power goes out or the sun goes down and you’re out of batteries, you’ll be glad you opted for a solar-powered flashlight or lantern. Some of the best options last up to 30 hours when fully charged, making them lifesavers in an emergency.

    Wireless Solar Keyboard

    Wireless keyboards offer a much better typing experience because you can place your keyboard wherever it’s most comfortable. Plus, you don’t have to deal with cords.

    But when you’re in the middle of an important project and the batteries die, you’ll wish you’d gone for a solar-powered keyboard. Here are 10 excellent solar keyboards to explore.

    Solar Battery Chargers

    In our connected world, phones and tablets are always with us (and, let’s face it, often running low on battery). Portable solar PV chargers keep our personal electronic devices charged — no matter where we are.

    The technology to integrate solar cells into our phones already exists, and it’s been in watches since the 1970s. Researchers in Japan have even developed lightweight, water-resistant solar cells that we could someday sew into clothing to power devices.

    Solar Security Cameras

    Surprisingly, solar-powered security cameras don’t require any wires to function (unlike traditional ones). So rather than connecting to scrambled data cables, you can simply connect your solar security camera to Wi-Fi. And the cameras are also easy to install — you can put them virtually anywhere, whether an outlet is nearby or not.

    Batteries aren’t needed, so you don’t have to worry about replacing them every few months. With traditional cameras, you often have to take them down to recharge or switch out batteries. This process not only adds hassle but also interrupts your video footage.

    Lastly, solar-powered security cameras provide you with continuous recording. Compare that to traditional cameras, which often go into power-saving mode or record only if and when they detect motion. If you have a regular security camera, its motion detector must be on point — otherwise, you could have delays in your footage (or no footage at all).

    Solar Umbrellas

    Solar panels attach to the top of the umbrella and charge its built-in battery whenever sunlight shines. At night, the solar batteries power LED lights on the underside of the umbrella.

    Thanks to these solar-powered umbrella lights, you can play cards, read, write and do much more at night under an illuminated tabletop in your backyard.

    Solar-Powered Wi-Fi Garbage Bins

    Garbage bins that transmit Wi-Fi are becoming increasingly common in major U.S. cities. But they’re also picking up internationally in places like Stockholm, Amsterdam, Dublin and Hamburg.

    Bigbelly, a company that creates waste and recycling solutions for public spaces, founded the Smart bins. And they’ve made a big impact on the cleanliness and Wi-Fi availability of city life.

    These solar-powered trash bins have built-in solar panels that generate energy to enable Wi-Fi. Then, passersby can take advantage of Wi-Fi hotspots while commuting.

    Granted, it might not seem ideal to stand next to a heaping-full, steaming trash can in the midst of summer. But free Wi-Fi never hurts — especially when green energy fuels it.

    Home Beautification

    Solar landscape lighting already goes a long way toward beautifying your outdoor space, but you can do even more with solar energy.

    Solar Garden Decorations

    From solar-powered light-up wind chimes to colorful garden ornaments shaped like animals, insects, flowers and more — you’re sure to find solar garden decorations that suit your aesthetic.

    Solar Bird Feeders

    For such a straightforward product, solar-powered bird feeders come in a staggering range of options.

    On the simpler (and more affordable) end, you have bird feeders that are essentially solar-powered outdoor lights with integrated feeders. Their solar cells charge their batteries during the day, and at night they light up to provide ambience.

    On the higher end are products like the Bird Buddy. The Bird Buddy is a Smart bird feeder with an integrated camera that can notify you of your bird visitors via a smartphone app. It even captures and organizes photos for you to review and share, making it a bird lover’s dream.

    And of course, its detachable solar panel roof powers all these features.

    Solar Water Fountain

    What’s even more Zen than the calming sound of water trickling from your garden’s water fountain? That’d be knowing the fountain isn’t adding to your electricity bill because the sun’s energy powers it.

    And don’t worry — solar-powered fountains come in a broad array of styles and sizes, so you’re sure to find the perfect fit for your garden.

    Solar-Powered Irrigation Controllers

    We know what you’re thinking. Irrigation timers don’t sound particularly aesthetically pleasing, but they do help keep your yard lush, so we think they count.

    The beauty of solar-powered sprinkler controllers is that you can automate your irrigation without wiring — a standard garden hose and water source are all you need.

    Here are some of the best options out there to get you started.

    Solar-Powered Underwater Pool Lights

    Most people are familiar with standard pool-surrounding lighting. But other great features to add to your home pool are lights on its floor and sides — in other words, completely submerged lights.

    Throughout the day, the submerged lights absorb energy from the sun, which they then store in batteries. Once nighttime comes, the lights illuminate and add ambience to your pool. What better way to enjoy a night swim than with a fully lit pool?

    Solar Wearables

    Manufacturers can also integrate solar into some of the products you wear and use every day. As a result, you have power on the go.

    Solar Watches

    Charging batteries is always a chore, but that’s especially true with watches. Who has spare watch batteries lying around?

    Enter solar-powered watches. Both environmentally friendly and long-lasting, solar watches are becoming increasingly popular. And with more and more watch brands going solar, you have a plethora of styles to indulge in, ranging from casual to dressy to sporty.

    Solar Backpacks

    The idea behind solar backpacks is simple: We often need to charge our electronics — and lack access to charge them — when we’re out and about. So why not integrate a charger directly into an item we all use while we’re hard at it?

    With small built-in solar panels that store energy in a battery pack, solar backpacks are a nifty solar energy invention that can charge your electronic devices from anywhere. Whether you’re an avid hiker, camper, photographer or world traveler, they’re sure to come in handy.

    Solar Bluetooth Headphones

    Surprisingly, solar-powered Bluetooth headphones are relatively new to the market. Urbanista launched a pair in 2021, and Adidas followed suit in 2022. Both options are self-charging thanks to solar cells built into the headband, and both offer 80 hours of battery life.

    Solar Earbuds

    To boot, Urbanista launched solar-powered wireless earbuds using Powerfoyle technology in August 2022. Along with solar-powered charging, the earbuds have noise-canceling capabilities. But unlike solar-powered headphones, the solar cells aren’t in the actual earbuds — they’re in the charging case.

    Solar Headset

    A company called Blue Tiger also recently released the “world’s first solar-powered communications headset.” The headset uses Powerfoyle cell technology and has a noise-canceling boom mic. So in short, your solar-powered listening options abound.

    Solar Bike Helmet

    Solar power has made great strides in the outdoor industry, so it’s unsurprising that you can buy solar-powered bike helmets. But just what their batteries power might surprise you.

    Some options, like POC’s Omne Eternal, simply generate energy to power a rear light for safety. WertelOberfell’s ESUB Tracks helmet, however, goes much further:

    • It powers built-in “bone conduction speakers” that send sound (or vibrations) through the bones near your ears, rather than inside your ears. And that means you can listen to music safely without being unable to hear other sounds.
    • It powers the technology necessary to automatically fit the helmet to your head — you don’t have to adjust anything manually.

    Solar Textiles

    Solar textiles may not be on the market yet, but they’re in the works. And they certainly represent an innovative new use of solar.

    Scientists are working to weave solar cells into fabrics such as clothing, car seats, curtains and tents. In October of 2022, researchers at Nottingham Trent University proved these textiles can charge devices such as mobile phones and smartwatches. They believe electronic textiles “have the potential to change people’s relationship with technology,” and we agree.

    Solar Transportation

    From residential use to public and commercial uses, solar power is transforming the transportation sphere.

    Home Solar EV Charging

    Electric vehicles (EVs) are growing in popularity, with sales making up 5.6% of the total auto market at the end of 2022 — up from 2.7% at the end of 2021. And with EVs’ growing popularity, people need an eco-friendly way to charge them.

    That’s where home solar EV charging comes in. Installing solar panels to charge your EV means you can avoid sourcing energy from the grid — and thus save big on your electricity bill.

    Solar Carports

    You can power your EV with an existing rooftop solar installation, but some homeowners are constructing solar carports specifically to power their electric vehicles (EVs). As an added benefit, these structures protect your EV (and your investment) from the weather.

    Solar-Powered Mobile Homes and Tiny Homes

    Tiny homes are great candidates for solar power because they have lower energy needs. They have less space for — well — stuff that requires electricity.

    Similarly, some mobile homes are compatible with solar systems. However, if your mobile home is located in a community that uses its own septic system or runs off the grid, you’ll want to check with the owners association before moving forward.

    Public Solar EV Charging

    We already touched on residential solar EV charging, but there are also solar-powered public charging stations for EVs. These stations are ideal for quick charging when you’re on the move. You’ll often find them paired with parking lots so drivers can charge their vehicles while parked.

    Solar Panel Parking Lots

    As their name suggests, solar panel parking lots are essentially solar panel-covered parking lots. While parking lots can use ground-mounted systems, they typically use parking lot structures to free up ground space for vehicles.

    Parking lots covered with solar panels are growing in popularity thanks to the many benefits they provide. These perks include charging parked vehicles and even providing energy for surrounding buildings.

    Solar Bus Stop Shelters

    You can also find solar energy in public transportation via solar bus shelters.

    Solar bus shelters have solar panels installed either on the shelter’s roof or nearby. They generate power for advertising and lighting, and passengers can charge small devices. Options like that from EnGoPlanet even have a built-in bench and phone charging station.

    With those kinds of benefits, waiting for the bus doesn’t sound so bad.

    Solar Benches

    Solar benches take the same concept as solar bus shelters and apply it to benches used in parks, airports and just about anywhere people sit. Also like solar bus stops, solar benches provide a spot for people to relax and charge their phones, as well as illumination after sundown.

    Solar Street Lights

    Solar street lights play an important role in public transportation, particularly in areas without reliable access to the grid. These lights give such areas an alternative energy source. And that not only increases safety and peace of mind but also reduces the city’s electricity bills.

    Of course, you can also purchase a solar street light for your own driveway or street.

    Solar Energy for Industries

    Solar energy has practically limitless potential in industrial applications, especially in industries with high equipment requirements and electricity needs. Powering these needs with solar can play a significant role in reducing costs and improving bottom lines.

    Outdoor Tools, Products and Stations

    Solar-Powered Tents

    Solar tents are just like regular tents, with one key difference. You guessed it: They’re solar-powered. They have specially designed solar panels on the outside to generate power for devices.

    Whether you need to charge your phone, laptop, digital camera, portable speaker, tablet or other device, you can use the power your tent generates.

    However, if some of your items are already solar-powered (like the appliances and wearables we mentioned earlier), then you’ll have more solar power available for items needing external power sources!

    Solar-Powered Drinking Water

    Imagine being able to produce your own water — well, sort of. With Source Hydropanels, you can essentially generate your own water out of thin air (and sunlight).

    A professional can install this exciting-yet-expensive technology at residential homes, commercial worksites, schools and more. People have also used it as a bike attachment for professional and recreational athletes to use during workouts.

    The technology works by absorbing sunlight via solar cells in the panels. Then, the generated energy cools the air enough to transform it into water. With innovation like this, having clean, accessible drinking water on a whim is a not-so-distant reality!

    Solar Cinema

    Solar movie theaters are another great use of solar power. Because theaters are a bit energy-intensive, the fact that solar energy can fully power them is a big plus.

    For example, Sol Cinema (based in South Wales) is a fully solar-powered theater. However, it’s also the smallest movie theater in the world!

    It can hold an audience of eight adults, who enjoy usherette service, a red-carpet entrance and popcorn.

    Solar-Powered Internet Cafes

    Fortunately, solar-powered internet cafes are on the rise — and ZubaBox is a major part of that mix.

    uses, solar, energy, spherical, panel

    A ZubaBox is a fully solar-powered internet cafe constructed from shipping containers. It was brought to Kenya by its inventors, making its premiere in Kakuma.

    Now, ZubaBox cafes are making their way to locations across Africa, thanks to the partnership between AMREF and U.K.-registered charity Computer Aid International.

    Spherical Solar Power Generator

    Beta.ray, an invention from architect Andre Broesell, sheds light on a new way of generating solar power.

    The massive device includes a tall foundation with a crystal globe that functions as a hybrid collector. The globe tracks and moves with the sun, and it can concentrate both sunlight and moonlight at nearly 10,000 times more intensely than traditional solar devices.

    So whether it absorbs light during the sunniest time of day, early morning, late evening, during an overcast spell or on rainy days, it squeezes the most energy out of each ray.

    A Solar-Powered Future: Countless Uses of Solar Energy

    Renewable energy is already becoming a familiar part of our lives. Innovation will continue to drive new solar energy technologies that improve our daily lives and power a cleaner world.

    How many more uses of solar energy does the future hold? We’re excited to find out!

    Seven Uses of Solar Energy FAQs

    What are the main uses of solar energy?

    The main uses of solar energy are solar photovoltaics (PV) for electricity, solar heating and cooling (SHC) and concentrated solar power (CSP). People primarily use SHC systems for heating or cooling water and spaces (like your home). CSP systems use reflective devices to concentrate the sun’s energy and are mainly marketed to utilities.

    What are the five uses of solar energy?

    The five main uses of solar energy are solar electricity, solar water heating, solar heating, solar ventilation and solar lighting. There are more uses for solar energy, but home solar installation and businesses typically use solar energy for these purposes.

    What are the uses of solar energy?

    The uses of solar energy include solar electricity, solar water heating, solar heating, solar ventilation, solar lighting, portable solar (for personal electronic devices) and solar transportation (for electric vehicles).

    Where is solar energy used the most?

    China uses the most solar energy. The country has the largest solar fleet installation, which generates about 205 GW of power. By 2060, China aims to fully neutralize its carbon emissions.

    What is solar energy and examples of its use?

    The sun creates two main types of solar energy, light and heat, which people can harness in a variety of ways. For example, some electric vehicles (EVs) use solar photovoltaic (PV) energy to charge their batteries instead of relying on gasoline. Another example is using a solar water heater to heat the water in your swimming pool or the water you use in your house through a sink faucet or shower.

    Where is solar energy used in the U.S.?

    Solar energy is used across the U.S., but it’s most prominent in the states of California, Texas and North Carolina. California uses the most solar energy by far, with over 29,000 megawatts of electricity produced in 2020 alone. This is partly due to a 2018 California law requiring single- and multi-family homes, as well as commercial buildings, to install solar panels starting in 2020.

    What are the five advantages of solar energy?

    The five main advantages of solar energy include saving money on your monthly energy bill, improving local air quality, increasing your home’s resale value, making the electric grid more resilient and providing a path for you to be energy independent.

    Why is solar the best energy solution?

    Solar is the best energy solution because it’s fully renewable, unlike traditional power. This means it’s available every day, and people anywhere in the world can harness it. Solar energy is abundant, and it benefits the environment and public health by substantially reducing carbon emissions. Solar projects also make better use of underutilized land, such as through agrivoltaic farming.

    What are the four advantages of solar energy?

    The four main advantages of solar energy are that it reduces your monthly utility bill substantially, improves air quality thanks to zero carbon emissions, improves your home’s resale value and reduces reliance on local grids.

    What is solar energy and what are some of its benefits?

    Solar energy is radiant heat and light from the sun that people harness using a variety of technologies. The benefits of solar power include lower monthly electricity bills, improved local air quality and higher home resale values. It also makes the electric grid more resilient, provides a hedge on rising energy costs and offers energy independence.

    How does solar help the environment?

    Solar helps the environment by reducing carbon and methane emissions and decreasing ground and air pollution. Solar also helps decrease water usage and doesn’t pollute the ground, rivers or any natural waterbodies.

    What is a solar ventilation system?

    A solar ventilation system is a transpired solar collector or solar wall that heats air before it enters a building or other structure. Solar ventilation systems are a sustainable and efficient way of lowering a building’s energy consumption and costs through renewable sources.

    What are sources of solar energy?

    People source solar energy entirely from the sun. They can harness it in a variety of ways, using technologies such as solar photovoltaic (PV), solar thermal and solar heating.

    Why is solar power important?

    As of 2022, solar energy is the most abundant renewable energy source on the planet. It is inexhaustible, unlike traditional fossil fuel energy sources, which are harmful to the environment and public health.

    uses, solar, energy, spherical, panel

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    Solar Cells

    Solar cells are in fact large area semiconductor diodes. Due to photovoltaic effect energy of light (energy of photons) converts into electrical current. At p-n junction, an electric field is built up which leads to the separation of the charge carriers (electrons and holes). At incidence of photon stream onto semiconductor material the electrons are released, if the energy of photons is sufficient. Contact to a solar cell is realised due to metal contacts. If the circuit is closed, meaning an electrical load is connected, then direct current flows. The energy of photons comes in packages which are called quants. The energy of each quantum depends on the wavelength of the visible light or electromagnetic waves. The electrons are released, however, the electric current flows only if the energy of each quantum is greater than WL. WV (boundaries of valence and conductive bands). The relation between frequency and incident photon energy is as follows:

    h. Planck constant (6,626·10.34 Js), μ. frequency (Hz)

    Crystalline solar cells

    Among all kinds of solar cells we describe silicon solar cells only, for they are the most widely used. Their efficiency is limited due to several factors. The energy of photons decreases at higher wavelengths. The highest wavelength when the energy of photon is still big enough to produce free electrons is 1.15 μm (valid for silicon only). Radiation with higher wavelength causes only heating up of solar cell and does not produce any electrical current. Each photon can cause only production of one electron-hole pair. So even at lower wavelengths many photons do not produce any electron-hole pairs, yet they effect on increasing solar cell temperature. The highest efficiency of silicon solar cell is around 23 %, by some other semi-conductor materials up to 30 %, which is dependent on wavelength and semiconductor material. Self loses are caused by metal contacts on the upper side of a solar cell, solar cell resistance and due to solar radiation reflectance on the upper side (glass) of a solar cell. Crystalline solar cells are usually wafers, about 0.3 mm thick, sawn from Si ingot with diameter of 10 to 15 cm. They generate approximately 35 mA of current per cm 2 area (together up to 2 A/cell) at voltage of 550 mV at full illumination. Lab solar cells have the efficiency of up to 30 %, and classically produced solar cells up to 20 %.

    Wafers and crystalline solar cells (courtesy: SolarWorld)

    Amorphous solar cells

    The efficiency of amorphous solar cells is typically between 6 and 8 %. The Lifetime of amorphous cells is shorter than the lifetime of crystalline cells. Amorphous cells have current density of up to 15 mA/cm 2. and the voltage of the cell without connected load of 0.8 V, which is more compared to crystalline cells. Their spectral response reaches maximum at the wavelengths of blue light therefore, the ideal light source for amorphous solar cells is fluorescent lamp.

    Surface of different solar cells as seen through microscope (courtesy: Helmholtz-Zentrum Berlin)

    Solar Cell Models

    The simplest solar cell model consists of diode and current source connected parallelly. Current source current is directly proportional to the solar radiation. Diode represents PN junction of a solar cell. Equation of ideal solar cell, which represents the ideal solar cell model, is:

    IL. light-generated current [1] (A), Is. reverse saturation current [2] (A) (aproximate range 10.8 A/m 2 ) V. diode voltage (V), VT. thermal voltage (see equation below), VT = 25.7 mV at 25°C n. diode ideality factor = 1. 2 (n = 1 for ideal diode)

    Thermal voltage VT (V) can be calculated with the following equation:

    k. Boltzmann constant = 1.38·10.23 J/K, T. temperature (K) q. charge of electron = 1.6·10.19 As

    FIGURE 1: Ideal solar cell model

    FIGURE 2: Real Solar cell model with serial and parallel resistance [3] Rs and Rp, internal resistance results in voltage drop and parasitic currents

    The working point of the solar cell depends on load and solar irradiation. In the picture, I-V characteristics at short circuit and open circuit conditions can be seen. Very important point in I-U characteristics is Maximum Power Point, MPP. In practice we can seldom reach this point, because at higher solar irradition even the cell temperature increases, and consequently decreasing the output power. Series and paralell parasitic resistances have influence on I-V curve slope. As a measure for solar cell quality fill-factor, FF is used. It can be calculated with the following equation:

    IMPP. MPP current (A), VMPP. MPP voltage (V) Isc. short circuit current (A), Voc. open circuit voltage (V)

    In the case of ideal solar cell fill-factor is a function of open circuit parameters and can be calculated as follows:

    Where voc is normalised Voc voltage (V) calculated with equation below:

    k. Boltzmann constant = 1,38·10.23 J/K, T. temperature (K) q. charge of electron = 1,6·10.19 As, n. diode ideality factor (-) Voc. open circuit voltage (V)

    For detailed numerical simulations more accurate models, like two diode model, should be used. For additional explanations and further solar cell models description please see literature below.

    Solar Cell Characteristics

    Samples of solar cell I-V and power characteristics are presented on pictures below. Typical point on solar cell characteristics are open circuit (when no load is connected), short circuit and maximum power point. Presented characteristics were calculated for solar cell with following data: Voc = 0,595 mV, Isc = 4,6 A, IMPP = 4,25 A, VMPP = 0,51 V, and PMPP temperature coefficient γ =.0,005 %/K. Calculation algorithm presented in the book Photovoltaik Engineering (Wagner, see sources) was used.

    FIGURE 3: Solar cell I-V characteristics for different irradiation values

    FIGURE 4: Solar cell power characteristics for different irradiation values

    FIGURE 5: Solar cell I-V characteristics temperature dependency

    FIGURE 6: Solar cell power characteristics temperature dependency

    [1] Sometimes term photocurrent IPh is also used.
    [2] Sometimes term dark current Io is also used.
    [3] For paralell resistanse term shunt resistor Rsh is also used.

    Simulation Tools

    Open Photovoltaics Analysis Platform. Open Photovoltaics Analysis Platform (OPVAP) is a group of software used in the field of solar cells, which include analyzing experimental data, calculating optimum architecture based on your materials, and even some research assistant tools such as PicureProcess.

    Organic Photovoltaic Device Model. Organic Photovoltaic Device Model (OPVDM) is a free 1D drift diffusion model specifically designed to simulate bulk-heterojuncton organic solar cells, such as those based on the P3HT:PCBM material system. The model contains both an electrical and an optical solver, enabling both current/voltage characteristics to be simulated as well as the optical modal profile within the device. The model and it’s easy to use graphical interface is available for both Linux and Windows.

    Other Technologies. Links

    NanoFlex Power. flexible organic solar cells.

    sphelar power. spherical solar cells technology.

    The spherical solar power generator

    Spherical solar power generator: It is a prototype created by the “Rawlemon” which is called BETA RAY, Spherical sun power generator uses the dual-axis tracking system, the glass globe concentrates the diffused sunlight onto a small solar panel with a little surface.

    Before jumping into the spherical solar power generator, let us talk about Sun in general:

    Sun is vital for life on earth, it triggers the photosynthesis and plants grow. Later these plants suck carbon dioxide and produce oxygen for us and vice versa.

    Sun gives the necessary heath to our planet, it enables evaporation, hence, water cycle.

    Sun is a great energy source for our planet and humans know it.

    We tried to capture the sunlight to produce heat and electricity.

    For past 50 years, we are trying to utilize solar energy using PV panels.

    But the earth revolves around the sun and the rigid panels are losing most of its efficiency.

    The spherical solar power generator

    In order to follow the Sun’s path, we invented the tracking system (dual axis). A tracking system is useful but is expensive and vulnerable to a harsh atmosphere like the strong wind.

    Spherical Solar Power Generator invention by a German, architect Andre Broessel

    One day, a German Architect Andre Broessel had an idea of focusing Sun’ energy on a smaller surface with more efficiency using a glass sphere with dual tracking system using the diffused rays of the sun.

    It makes it more efficient because they are utilizing less surface, producing more energy and following the sun using a dual-axis tracking system. It is transparent, and it guarantees no weather impact because it has a strong base and body, it is fully building integrable.

    For more than two years of the hard world, Andre Broessel (inventor and founder of Rawlemon) found the perfect spherical sun power generator shape with its dual axis system.

    Working of the Spherical sun power generator

    The spherical sun power generator

    • Spherical solar power generator can work on both diffused or direct rays of the sun.
    • Diffused rays of the sun are directed towards ball lens and ball lens will FOCUS the diffused ray onto a collector plate.
    • This collector plate is small but as powerful as a larger PV panel.
    • Collected energy will be converted into electricity using that smaller PV panel and will be directed towards the battery.
    • The spherical sun power generator has a dual axis tracking system with a micro tracking system,
    • both the spherical solar power generator and tracking system are immune to weather or it will absorb a very little damage in the windy season.
    • Collected energy in the battery can be used in electric cars or any solar driven appliance.
    • Spherical sun power generator can easily supply its energy to the power grid in the future.
    • Heat is the additional benefit of the spherical solar power generator.

    Future for spherical sun power generator

    The spherical solar power generator is aiming to charge electric cars and fully integrate into the building and homes. Form small devices like mobile phones to the air conditioner, the spherical sun power generator can provide all of that with an additional heat to the homes.

    With the TESLA’s solar roof technology and electric cars inventions, the Spherical solar power generator is more than qualified to compete with Tesla which is one of the biggest energies and technology companies in the world.

    The spherical sun power generator is a transparent future of the world regarding global energy mix due to its efficiency.

    low carbon footprints, less surface space, sun tracking system and strong structure.

    Spherical solar power generator will be in the market in a few years and we are expecting it to be cheaper than the ordinary set of PV panels.

    The Beta Ray

    According to the data of inventor and founder of Rawlemon Andre Broessel:

    “The beta. Ray comes with a hybrid collector to convert daily electricity and thermal energy at the same time.

    While reducing the silicon cell area to 25% with the equivalent power output by using our ultra-transmission Ball Lens point focusing concentrator, it operates at efficiency levels of nearly 57% in hybrid mode. At nighttime, the Ball Lens can transform into a high-power lamp to illuminate your location, simply by using a few leds. The station is designed for off-grid conditions as well as to supplement buildings’ consumption of electricity and thermal circuits like hot water.”

    Applications of spherical sun power generator:

    There are many applications that spherical solar power generator can be used for, some of them are:

    • Electric car charging stations
    • Energy producing Windows
    • Autonomous power generators
    • Hybrid pow plants
    • Beta rays can charge cellphones as well.Spherical solar generator
    • Integration into the walls of buildings etc.


    The spherical solar power generator sounds like a futuristic technology and an amazing idea which has a great potential to help us to switch from dirty fuels (fossil fuels) to fully renewable energy.

    It still needs research and funds to study the BETA.RAY and sun’s behavior, we all can help or support ANDRE BROESSEL AND THE RAWLEMON to complete their study on the beta. Ray and spherical sun power generator for becoming a reality.

    The Spherical sun power generator can also operate in a night.

    Andre Broessel’s spherical sun power generator is in the nominations for the World technology award.


    [5] Founder and inventor of Rawlemon Andre Broessel

    The Real Answer to the Question, “How Long Do Solar Panels Last?”

    New technologies and production scale made high-performance solar panels more affordable than ever. But what determines the actual service life of your green power installation?

    If we could capture just one hour’s worth of solar energy that hits the Earth each year, every gallon of oil, every lump of coal, and every cubic foot of natural gas could be left in the ground.

    The cost of solar panels has fallen 99% since 1977, making solar energy more accessible to a lot of people. However, for many homeowners, a solar panel array is still a significant investment, even with net metering, and federal rebates.

    Which is why a question that I often hear is how long do solar panels last and what can be done to increase their service life.

    How Long Do Solar Panels Last?

    Solar panels last about 20 years, according to the Federal Trade Commission.

    But there’s much more to the answer than that.

    The exact number would depend on several factors, like the type of the panel, the way the system is installed, the climate where you live, and the maintenance.

    The great news is that, with proper maintenance, your panel may actually run for as long as 40-50 years. Read on to know how you can make your panel last as long as this.

    Basically we’ve learned to make [solar] modules cheaper a lot faster than we’ve learned how to install them cheaper. Now the module is only a small fraction of the total price.

    Zach Holman, Assistant Professor of Electrical Engineering, Arizona State University

    What is the Solar Panel Degradation Rate?

    The solar panel degradation rate on average is 0.5% per year.

    This is the rate at which your panel efficiency reduces over time.

    Basically, it shows the quality of your panel — the smaller the rate, the longer your panel will keep its properties.

    A degradation rate of 0.5% per year means that, after a standard 25-year long warranted service, your solar panel system will provide 87.5% of its factory output.

    However, manufacturers like SunPower have achieved degradation rates that are as low as 0.3% per year. This means that after 25 years, your panel will operate at 92.5% of its original output.

    Not too shabby for something that gives you free energy.

    Related Articles:

    Tips on How to Make Your Solar Panels Last Longer

    One of the things that friends and colleagues who are interested in solar energy almost always ask me is this: Is it possible to make solar panels last longer?

    And my answer is always yes, it’s definitely possible to make solar panels last longer. You can achieve this by doing these 5 things:

    Regularly Get Your Panels Checked and Maintained

    Broken glass, cracked panels, and loose connections are the top three issues that you can have with your panels over the years.

    Electrical faults are more difficult to discover, but if you suspect something is wrong with your solar system, have the company check your power output.

    If you see a large difference from the same month in previous years, you might be dealing with an electrical issue.

    Replace Inverters After 10 Years

    Faulty inverters cause system failures much more often than the panels themselves. A typical solar inverter has a lifespan of 10-15 years, with 5-10 years of warranty.

    This means that you’ll need to replace the inverter much sooner than your panels. These days, many homeowners choose microinverters, because they can last for 25 years — that’s almost as long as quality panels.

    Maintain and Replace Batteries

    If you have a large bank of batteries, rotate them periodically. This is so that each battery will receive an equal amount of charge, which will extend its service life.

    You can also improve their charging by using large battery cables, which have lower resistance.

    Lastly, never leave your batteries uncharged for longer periods of time, as this can reduce their capacity.

    Keep Your Panels Clear of Debris and Other Materials That May Damage It

    Although quality solar panels are built to endure high winds, heavy snow, and even inch-sized hail falling at about 50 miles per hour, you still need to keep them clean at all times. [1]

    It’s also always better to wash them off in the morning before they heat up, so they don’t crack.

    Your solar panels will last longer and operate at their peak efficiency if you also regularly remove dust, leaves, pollen, and bird droppings from them. Check out the video below to see how you can do this.

    Work With A Trustworthy Solar Panel Provider

    Probably one of the best things you can do to make your solar array last longer is to get a reliable provider at the very start. Two of the most popular and trustworthy ones in the industry are SunPower and Jackery.

    Which Type of Solar Panel Lasts Longest?

    Both monocrystalline and polycrystalline silicon solar panels last for a long time, with lifespans that go beyond their 25-year warranties. However, there are pros and cons to both.

    First, let’s see how you can tell them apart.

    Monocrystalline silicon panels are the most efficient type of panel for harvesting solar energy. [2] They are dark, with solar cells shaped like squares with cut-off corners.

    However, their high efficiency comes doesn’t come cheap, as they are typically more expensive than polycrystalline panels.

    Monocrystalline silicon panels

    Solar panels last about 20 years, according to the Federal Trade Commission. The great news is that, with proper maintenance, your panel may actually run for as long as 40-50 years.

    Polycrystalline silicon panels

    Polycrystalline silicon panels, on the other hand, are blue in color. They look as if they have shiny confetti inside, which are actually silicon crystals.

    Between these crystals, there are gaps that “trap” some of the electrons, which make these panels less efficient than their monocrystalline counterparts.

    What Makes Your Solar Panels Become Less Efficient?

    By now, you should know a thing or two about choosing a panel that will last long. Now let’s see how long do solar panels last when faced with things you can’t control.


    High heat can cause cracks that allow moisture to get inside. Moisture is a big issue because it doesn’t only reduce your panel’s energy output — it increases its degradation rates as well.

    In extreme cases, heat can discolor the panel, which makes your whole solar energy system less efficient.


    A strong wind can cause the entire structure to vibrate, loosening the fasteners that hold different parts of your solar system together. These wind vibrations are just as bad for your panels as the vibrations caused by any piece of machinery.


    If your solar array isn’t installed correctly, rain can cause corrosion which reduces your system’s efficiency and increases its degradation rates. Corrosion can also weaken its metal understructure and framing.


    Freezing temperatures can cause solar panels to warp, cells to crack, and frames to move apart. Now add a thick layer of snow on top of that, and guess how much extra weight do panels and the mount have to suffer.


    Do solar panels go bad?

    Yes, solar panels go bad because their energy output reduces over the years of operation. Materials used to convert solar energy into electric energy lose their properties over time, at a rate between 0.3% to 0.8% per year.

    What happens to solar panels after 25 years?

    Molar solar panels lose their manufacturer’s warranty after 25 years, which means that the owner is solely responsible for their repair and maintenance. Although you can easily find panels with 25-year warranties, most systems last much longer than that, but with reduced power output.

    Do solar panels need a lot of maintenance?

    No, solar panels don’t need a lot of maintenance. You should, however, have them periodically checked by your solar provider. Just one inspection can discover problems such as mechanical or electrical faults. Dirt and leaves make your panels less efficient, so you also need to wash them off from time to time.

    What do you do with old solar panels?

    You can sell old solar panels, give them away, or pay for them to be recycled. If you decide to sell them, don’t expect a good price, as there’s little demand for used solar equipment. Paying for them to be recycled or disposed of as e-waste is the best option from an environmental point of view.


    How long does a solar panel last depends on the panel type you choose, the local climate, your maintenance routine, and the brand you go for.

    You need to be careful with extreme temperatures, wind, and snow as they can damage your panel’s components. Keep an eye out on dirt and debris on the panel surface as well since they can reduce its efficiency.

    But the most effective way to make your solar panels last long is to choose a solar provider that offers a solid warranty.


    Nikola Gemeš

    Nikola uses his background in electrical engineering to break down complex sustainability topics for GreenCitizen’s readers. He is a firm believer in environmental conservation, which he practices daily through recycling and home-grown food. He enjoys hiking, engaging in white-water sports, and collecting knives.

    23 Комментарии и мнения владельцев on “ The Real Answer to the Question, “How Long Do Solar Panels Last?” ”

    I liked your blog post about solar panels and how they last. It was interesting to see how long they last and how they’re becoming cheaper. I also appreciate how you shared your thoughts on how long we’ll be able to use them.

    Nice article! informative article for reader…Appreciate your work on solar (Energy), Thanks for giving us a informative article connecticut solar panels

    A solar photovoltaic system, usually just called a solar PV system, is a power system that uses solar panels to convert sunlight into electricity. PV systems are often used to power homes, businesses, and other facilities.

    Solar panels offer a number of advantages to both homeowners and business owners. Some of the benefits include decreased energy costs, reduced greenhouse gas emissions, and improved property value. Additionally, solar panels can help businesses meet sustainability goals and compliance standards.

    If you live in a private home, installing panels is the best thing you can do!

    Thank you for your valuable comment.

    Great article beautifully described. Thanks for sharing it.

    Wow!! Amazing blog. you are really a great writer. your solar panel procedure is really great. Solar panel installation is important for saving money and the environment.

    Thank you very much for your inspiring comment. We really appreciate it!

    As technology develops, the lifespan of solar panels becomes more durable over time. Besides, periodic maintenance is essential for every electronic device. After that, the long-term warranty of 11-25 years will no longer be a problem to make you think

    Hey, Thanks for sharing the blog post! I was planning to buy a solar panel for my house to reduce my electricity bill where I was searching for the answer to this question how long do solar panels last. Finally, I found the right solution for my question. Also, the tips you have shared are very useful.

    Your tips on how to maintain solar panels to make them last as long as possible were extremely helpful, so I appreciate you putting them in your article. I’ve made the decision to invest as much as possible into our current house since none of us have any desire to move out of it, so having an energy system that can make up for itself in the future sounds perfect. Once I get a solar panel installer to help us out with this, I’ll make sure I use your tips to maintain it well.

    I have read many of your articles. They are really interesting and helpful. I will continue to follow up on your new posts. Thanks a lot

    Thanks for sharing this useful! I am also using SunPower solar panels. So far they are quite good and so is their service. Hope they work long term

    uses, solar, energy, spherical, panel

    The industry standard life span is about 25 to 30 years, and that means that some panels installed at the early end of the current boom aren’t long from being retired. And each passing year, more will be pulled from service — glass and metal photovoltaic modules that soon will start adding up to millions, and then tens of millions of metric tons of material.

    Great article. Most folks have to learn this the hard way.

    Solar panels can last long due to their sturdiness. Nevertheless, there are some things you can do to make them last longer. One is to find a trustworthy installer that has good customer service.

    Second, check the warranty. I’ve seen warranties that offer an equipment warranty of 10 to 12 years for environmental or physical defects. This deal is good enough since solar panels do last a long time.

    I’ve been wanting to know this information because I am planning to put solar panels on my home. Thanks for sharing this.

    It’s really amazing that some of these solar panels are going to last around 40 years if maintained properly. My brother is trying to get some solar panels soon so that he can save money on electricity. He wants to make sure he is being a lot more eco-friendly as well.

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