Solar Photovoltaic vs. Solar Thermal — Understanding the Differences
The transition to renewable energy is gaining momentum as concerns about climate change and energy security escalate, and solar power is leading the way. Solar photovoltaic (PV) and solar thermal are both leading sustainable solutions. Read this guide to learn the differences and decide which best suits your purposes.
Solar PV vs. Solar Thermal — What’s the Difference?
Quick Answer: Solar PV and solar thermal both harness energy from the sun but for different purposes. Photovoltaic (PV) systems convert sunlight directly into electricity, while thermal systems produce thermal energy for residential heating systems such as hot water or space heaters.
The differences also come down to how they capture energy from sunlight. PV systems generate electricity when photovoltaic panels capture solar energy and convert it into DC electricity. Thermal systems capture the sun’s heat through thermal panels that absorb the sun’s thermal energy and transmit it to a heat-transfer fluid.
In this article, you’ll learn:
- The differences between solar photovoltaics and thermal energy systems;
- How a photovoltaic panel converts sunlight into electricity;
- The different types of solar thermal systems, including flat-plate collectors and evacuated-tube collectors;
- Which system is best for your energy needs.
Solar Photovoltaic
Solar photovoltaic (PV) technology is a renewable energy system that converts sunlight into electricity via solar panels. A PV panel contains photovoltaic cells, also called solar cells, which convert light photons (light) into voltage (electricity). This phenomenon is known as the photovoltaic effect.
How Does Solar Photovoltaic Work?
Photovoltaic panels consist of semiconductor materials (usually silicon). When sunlight strikes the surface of a PV panel, the semiconductor absorbs energy from the photons. That reaction releases electrons from their atomic bonds. It creates a flow of electrons, resulting in an electric current.
The generated electric current is in the form of a direct current (DC). An inverter converts the DC power into alternating current (AC) to make this electricity usable for most household appliances and the electrical grid.
Components of Solar Photovoltaic (PV) System
PV systems have various interconnected components that work together to provide electricity to your home. These components include:
- Photovoltaic Panels
- Charge Controller
- Solar Battery Bank
- Inverter
- Utility Meter
- Electric Grid
Off-grid systems only use the first four components, as they do not utilize utility meters or electric grids.
The solar panels are your system’s first (and most important!) component. They interface directly with the sun’s rays, converting the photons into electricity.
An inverter converts direct current (DC) electricity into alternating current (AC) electricity. The inverter is crucial since PV panels produce DC electricity, while most household appliances and electrical systems operate on AC. Common types of inverters include string inverters, microinverters, and hybrid inverters.
The charge controller comes next in a PV system. This device sits between the photovoltaic panels and batteries to regulate the electricity that passes between them. The charge controller prevents overcharging and transmits an electrical current to the battery bank.
A battery bank stores electricity for later use. Also called a solar battery, it is handy for cloudy days or wintertime when your PV array produces less power.
Utility meters are an essential part of any grid-tied system. These devices measure the flow of electricity between the electric grid and your home’s solar system. A utility meter will track the electricity produced and consumed by a home.
The electric grid is the final component of a grid-tied system. The power produced from a residential solar array is sent through a utility meter and out into the electric grid. When a home draws power, it also pulls from the electric grid (unless the system has an energy storage system like a battery).
Net metering programs allow homeowners to receive payment for any excess energy produced during a billing period.
Advantages
- Whole-Home Power — provides electricity to an entire house, including appliances, lights, water heating, HVAC, and more.
- Renewable Energy — PV systems are a renewable energy source, reducing the user’s reliance on fossil fuels and utility companies.
- Lower Electricity Bills — photovoltaics can drastically reduce or eliminate your monthly electricity bill.
Disadvantages
- Upfront Cost — upfront costs for a PV system can be in the tens of thousands. However, this cost is easily recoupable over the system’s lifetime.
- Aesthetics — some home and business owners may find a solar array visually unappealing.
- Space Requirements — whole-home PV systems require around 480 sq ft (45 M2 on average.)
Solar Thermal
Solar thermal panels perform a similar function to PV panels by converting sunlight into usable energy. However, thermal panels differ in that they use a heat-transfer fluid — either water or air — to capture the energy, as opposed to the semiconductors of PV panels.
Thermal systems are an efficient and environmentally friendly method for residential or commercial heating. They reduce the user’s dependency on fossil fuels and lower greenhouse gas emissions.
How Does Solar Thermal Work?
Depending on the intended usage, there are a few different types of thermal systems. In all solar thermal systems, a heat-transfer fluid (water or air) collects energy from the sun. The hot fluid is then used directly in the space for heating, or it can produce steam for mechanical energy.
Most residential systems use flat-plate collectors. The thermal panel consists of a dark, flat surface encased in a thermally-insulated box. The dark color of the panel allows more energy absorption.
Another common type of thermal system is the evacuated tube collector. This type of panel features a series of glass tubes containing a vacuum, which reduces energy loss.
Either of these panel types can work for hot water heating, space heating, or electricity generation.
For home heating, the heat-transfer fluid can circulate through pipes in a floor through radiant heating. A radiant floor system radiates the heat from the liquid into the room.
Solar thermal systems can also operate on a commercial scale for energy production. The heat-transfer fluid produces steam that, when passed through a turbine, powers a generator that produces electricity.
Components Used in a Solar Thermal System
While individual systems will vary, a few components are common to most thermal systems.
Solar thermal collectors are the “panels” in a thermal system. They are usually installed on a home’s roof and convert the sun’s energy into heat.
The heat transfer fluid flows through a thermal collector and transfers the heat to the rest of the system.
The pump station distributes the heat transfer fluid throughout the system.
A controller monitors and regulates the transfer process. It controls the other system components, ensuring safe and reliable operation.
A hot water tank will likely be integrated into the design if the thermal system is for heating household water. For radiant heating systems, pipes installed in the floor allow the heat transfer fluid to flow throughout the home.
Advantages
- Efficiency — thermal systems are an efficient way to convert sunlight into heat for your home.
- Renewable Energy — a thermal system utilizes renewable energy to reduce environmental impact.
- Reduced Heating Bills —a thermal system may reduce your monthly water, gas, or electricity bill.
Disadvantages
- Limited Use — thermal systems are not practical for whole home electricity generation. A photovoltaic system is more efficient for this purpose.
- Incompatibility — radiant heating systems are part of the construction process, installed before pouring the concrete foundation for a home. It is often impractical to retrofit a home with radiant heating.
- Intermittent Energy Generation — a thermal system will only function while sunlight is available, so your energy production may decrease depending on the weather, season, or time of day.
Conclusion
Solar PV and solar thermal both utilize renewable energy. PV systems harness sunlight to generate electricity to use throughout your home, while solar thermal systems use sunlight to heat water or residential spaces. Either system can be liberating, freeing you from monthly electric bills and reliance on fossil fuels.
A solar thermal system may work for you if you just need to heat your home. Otherwise, photovoltaic systems are much more versatile — you can heat your home and water while also powering your home’s electrical system.
If you’re ready to install a PV system for your home, check out EcoFlow’s innovative solar solutions.
Frequently Asked Questions
No, solar PV systems and solar thermal systems are not the same. PV systems convert sunlight into electricity using photovoltaic cells, while thermal systems capture the sun’s heat using a heat-transfer fluid. Both harness solar energy but serve different purposes and use different technologies.
Yes, thermal systems can work in colder climates with less sunlight. While their efficiency may decrease in cold conditions, they can still provide heat by absorbing diffused sunlight. Evacuated tube collectors are particularly effective in cold climates due to their vacuum insulation, which minimizes heat loss.
Solar photovoltaic systems typically have a lifespan of 25-30 years, with panel efficiency gradually decreasing over time. Thermal systems can last around 20-25 years. Both systems require periodic maintenance to ensure optimal performance, and some individual components may need replacement within the lifetime of a system.
Photovoltaics are versatile technology that can generate electricity for various residential uses, including lighting, appliances, and heating. Solar thermal is a more specialized technology best suited for water and space heating. Combining both technologies can give you the best of both worlds and maximize energy savings.
EcoFlow is a portable power and renewable energy solutions company. Since its founding in 2017, EcoFlow has provided peace-of-mind power to customers in over 85 markets through its DELTA and RIVER product lines of portable power stations and eco-friendly accessories.
How do solar panels work?
What makes these alternative energy sources function?
Solar panels crown rooftops and roadside signs, and help keep spacecraft powered. But how do solar panels work?
Simply put, a solar panel works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity, according to the University of Minnesota Duluth. Solar panels actually comprise many, smaller units called photovoltaic cells — this means they convert sunlight into electricity. Many cells linked together make up a solar panel.
Each photovoltaic cell is basically a sandwich made up of two slices of semi-conducting material. According to the Proceedings National Graduate Conference 2012, photovoltaic cells are usually made of silicon — the same stuff used in microelectronics.
To work, photovoltaic cells need to establish an electric field. Much like a magnetic field, which occurs due to opposite poles, an electric field occurs when opposite charges are separated. To get this field, manufacturers dope silicon with other materials, giving each slice of the sandwich a positive or negative electrical charge.
Specifically, they seed phosphorous into the top layer of silicon, according to the American Chemical Society, which adds extra electrons, with a negative charge, to that layer. Meanwhile, the bottom layer gets a dose of boron, which results in fewer electrons, or a positive charge. This all adds up to an electric field at the junction between the silicon layers. Then, when a photon of sunlight knocks an electron free, the electric field will push that electron out of the silicon junction.
A couple of other components of the cell turn these electrons into usable power. Metal conductive plates on the sides of the cell collect the electrons and transfer them to wires, according to the Office of Energy Efficiency and Renewable Energy (EERE). At that point, the electrons can flow like any other source of electricity.
Researchers have produced ultrathin, flexible solar cells that are only 1.3 microns thick — about 1/100th the width of a human hair — and are 20 times lighter than a sheet of office paper. In fact, the cells are so light that they can sit on top of a soap bubble, and yet they produce energy with about as much efficiency as glass-based solar cells, scientists reported in a study published in 2016 in the journal Organic Electronics. Lighter, more flexible solar cells such as these could be integrated into architecture, aerospace technology, or even wearable electronics.
There are other types of solar power technology — including solar thermal and concentrated solar power (CSP) — that operate in a different fashion than photovoltaic solar panels, but all harness the power of sunlight to either create electricity or to heat water or air.
Additional resources
To learn more about solar energy, you can watch this video by NASA. Additionally, you can read the article Top 6 Things You Didn’t Know About Solar Energy by America’s Energy Department.
Bibliography
“Solar Power: A Feasible Future”. Sustainability, University of Minnesota Duluth (2020). https://conservancy.umn.edu/bitstream
“A Review on Comparison between Traditional Silicon Solar Cells and Thin- Film CdTe Solar Cells”. Proceedings National Graduate Conference (2012). https://www.researchgate.net
“How Solar Cells Work”. The American Chemical Society. https://www.acs.org
“Solar Photovoltaic Cell Basics”. Office of Energy Efficiency and Renewable Energy. https://www.energy.gov/eere/solar/solar-photovoltaic-cell-basics
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Mathematical modeling of photovoltaic cell/module/arrays with tags in Matlab/Simulink
Photovoltaic (PV) array which is composed of modules is considered as the fundamental power conversion unit of a PV generator system. The PV array has nonlinear characteristics and it is quite expensive and takes much time to get the operating curves of PV array under varying operating conditions. In order to overcome these obstacles, common and simple models of solar panel have been developed and integrated to many engineering software including Matlab/Simulink. However, these models are not adequate for application involving hybrid energy system since they need a flexible tuning of some parameters in the system and not easily understandable for readers to use by themselves. Therefore, this paper presents a step-by-step procedure for the simulation of PV cells/modules/arrays with Tag tools in Matlab/Simulink. A DS-100M solar panel is used as reference model. The operation characteristics of PV array are also investigated at a wide range of operating conditions and physical parameters.
Result
The output characteristics curves of the model match the characteristics of DS-100M solar panel. The output power, current and voltage decreases when the solar irradiation reduces from 1000 to 100 W/m 2. When the temperature decreases, the output power and voltage increases marginally whereas the output current almost keeps constant. Shunt resistance has significant effect on the operating curves of solar PV array as low power output is recorded if the value of shunt resistance varies from 1000 ohms to 0.1 ohms.
Conclusion
The proposed procedure provides an accurate, reliable and easy-to-tune model of photovoltaic array. Furthermore, it also robust advantageous in investigating the solar PV array operation from different physical parameters (series, shunt resistance, ideality factor, etc.) and working condition ( varying temperature, irradiation and especially partial shadow effect) aspects.
Background
Mathematical modeling of PV module is being continuously updated to enable researchers to have a better understanding of its working. The models differ depending on the types of software researchers used such as C-programming, Excel, Matlab, Simulink or the toolboxes they developed.
A function in Matlab environment has been developed to calculate the current output from data of voltage, solar irradiation and temperature in the study of (Walker 2001) and (Gonzalez-Longatt 2005). Here, the effect of temperature, solar irradiation, and diode quality factor and series resistance is evaluated. A difficulty of this method is to require readers programming skills so it is not easy to follow. Another method which is the combination between Matlab m-file and C-language programming is even more difficult to clarify (Gow and Manning 1999).
Among other authors, a proposed model is based on solar cell and array’s mathematical equations and built with common blocks in Simulink environment in (Salmi et al. 2012), (Panwar and Saini 2012), (Savita Nema and Agnihotri 2010), and (Sudeepika and Khan 2014). In these studies, the effect of environmental conditions (solar insolation and temperature), and physical parameters (diode’s quality factor, series resistance Rs, shunt resistance Rsh, and saturation current, etc.) is investigated. One disadvantage of these papers is lack of presenting simulation procedure so it causes difficulties for readers to follow and simulate by themselves later. This disadvantage is filled in by (Jena et al. 2014), (Pandiarajan and Muthu 2011). A step-by-step procedure for simulating PV module with subsystem blocks with user-friendly icons and dialog in the same approach with Tarak Salmi and Savita Nema is developed by Jena, Pandiarajan and Muthu et al. However, the biggest gap of the studies mentioned above is shortage of considering the effect of partially shading condition on solar PV panel’s operation.
In other researches, authors used empirical data and Lookup Table or Curve Fitting Tool (CFtool) to build P–V and I–V characteristics of solar module (Banu and Istrate 2012). The disadvantage of this method is that it is quite challenging or even unable to collect sufficient data if no experimental system be available so that modeling curves cannot be built and modeled.
From the work of (Ibbini et al. 2014) and (Venkateswarlu and Raju 2013), a solar cell block which has already been built in Simscape/Simulink environment is employed. With this block, the input parameters such as short circuit current, open circuit voltage, etc. is provided by manufacturers. The negative point of this approach is that some parameters including saturation current, temperature, and so on cannot be evaluated.
Solar model developed with Tag tools in Simulink environment is recorded in the research of (Varshney and Tariq 2014), (Mohammed 2011), etc. In these papers, only two aspects (solar irradiation and temperature) are investigated without providing step-by-step simulation procedure.
In overall, although having advantages and disadvantages, different methods have similar gaps as follows:
- The proposed models are not totally sufficient to study all parameters which can significantly affect to I–V and P–V characteristics of solar PV array, including physical parameters such as saturation current, ideality factor, series and shunt resistance, etc. and environmental working conditions (solar insolation, temperature and especially shading effect).
- Lack of presenting step-by-step simulation procedure and this causes difficulties for readers and researchers to follow and do simulation by themselves.
Therefore, the study proposes a robust model built with Tag tools in Simulink environment. The proposed model shows strength in investigating all parameters’ influence on solar PV array’s operation. In addition, a unique step-by-step modeling procedure shown allows readers to follow and simulate by themselves to do research.
Methods
Mathematical equivalent circuit for photovoltaic array
The equivalent circuit of a PV cell is shown in Fig. 1. The current source Iph represents the cell photocurrent. Rsh and Rs are the intrinsic shunt and series resistances of the cell, respectively. Usually the value of Rsh is very large and that of Rs is very small, hence they may be neglected to simplify the analysis (Pandiarajan and Muthu 2011). Practically, PV cells are grouped in larger units called PV modules and these modules are connected in series or parallel to create PV arrays which are used to generate electricity in PV generation systems. The equivalent circuit for PV array is shown in Fig. 2.
The voltage–current characteristic equation of a solar cell is provided as (Tu and Su 2008; Salmi et al. 2012): Module photo-current Iph:
I_ = [I_ K_ (T. 298)] \times Ir/1000
Here, Iph: photo-current (A); Isc: short circuit current (A) ; Ki: short-circuit current of cell at 25 °C and 1000 W/m 2 ; T: operating temperature (K); Ir: solar irradiation (W/m 2 ).
Module reverse saturation current Irs:
Here, q: electron charge, = 1.6 × 10 −19 C; Voc: open circuit voltage (V); Ns: number of cells connected in series; n: the ideality factor of the diode; k: Boltzmann’s constant, = 1.3805 × 10 −23 J/K.
The module saturation current I0 varies with the cell temperature, which is given by:
Here, Tr: nominal temperature = 298.15 K; Eg0: Band gap energy of the semiconductor, = 1.1 eV; The current output of PV module is:
Here: Np: number of PV modules connected in parallel; Rs: series resistance (Ω); Rsh: shunt resistance (Ω); Vt: diode thermal voltage (V).
Reference model
The 100 W solar power module is taken as the reference module for simulation and the detailed parameters of module is given in Table 1.
Module photon-current is given in Eq. (1) and modeled as Fig. 4 (Ir0 = 1000 W/m 2 ).
I_ = [I_ K_ (T. 298)] \times Ir/1000
Module reverse saturation current is given in Eq. (2) and modeled as Fig. 5.
Module saturation current I0 is given in Eq. (3) and modeled as Fig. 6.
Modeled circuit for Eq. (6) (Fig. 7).
Modeled circuit for Eq. (4) (Fig. 8).
The solar module simulation procedure is shown from Fig. 3 to Fig. 8b. The solar PV array includes six modules and each module has six solar cells connected in series. Therefore, the proposed model of solar PV array is given in Fig. 9.
Experimental test
In order to validate the Matlab/Simulink model, the PV test system of Fig. 10 is installed. It consists of a rheostat, a solar irradiation meter, two digital multi-meters and a solar system of two DS-100M panels connected in series, each panel has the key specifications listed in Table 1.
Result and discussion
Simulation scenario
With the developed model, the PV array characteristics are estimated as follows.
-
(i) I–V and P–V characteristics under varying irradiation with constant temperature are given in Fig. 11a and b. Here, the solar irradiation changes with values of 100, 500 and 1000 W/m 2 while temperature keeps constant at 25 °C.
- With two modules connected in series (Ns = 72, Np = 1), the value of current output is similar to that of it in case of one module (Ns = 36, Np = 1) but the voltage output doubles so the power output doubles.
- In term of two modules connected in parallel (Ns = 36, Np = 2), the value of voltage output is similar to that of it in case of one module (Ns = 36, Np = 1) but the current output doubles so the power output doubles. Similar value of power output is experienced in both cases of two modules despite different ways in module connection (parallel or series).
The proposed model has advantages not only in studying effect of physical parameters such as series resistance Rs, shunt resistance Rsh, etc. but also in investigating impact of environmental condition like varying temperature, solar irradiation and especially shading effect. In this study, the evaluation of shading effect on solar PV array’s operation is carried out through following cases. The simulation results are given in Fig. 15a and b.
No shaded PV module (full irradiation on solar PV array): 1000 W/m 2
One shaded module (receives irradiation of 500 W/m 2 ), others receive full irradiation of 1000 W/m 2
Two shaded modules (receive irradiation of 500 W/m 2 ), others receive full irradiation of 1000 W/m 2
Two shaded modules (receive irradiation of 500 and 250 W/m 2 ), others receive irradiation of 1000 W/m 2
- The power output of PV array reduces noticeably when it works under partial shading condition.
- The I–V curve experiences multiple steps whereas the P–V curve gives many local peaks along with the maximum power point (the global peak). In addition, more shaded modules are higher number of power output peaks is shown.
Experimental results and validation
The Matlab/Simulink model is evaluated for the experimental test system (two DS-100M panels are connected in series). The results are shown in Fig. 16. On the other hand, the empirical results with a solar irradiation of 520 W/m 2 and operating temperature of 40 °C are given in Fig. 17. The I–V and P–V simulation and experimental results show a good agreement in terms of short circuit current, open circuit voltage and maximum power output.
Conclusion
A step-by-step procedure for simulating a PV array with Tag tools, with user-friendly icons and dialogs in Matlab/Simulink block libraries is shown. This modeling procedure serves as an aid to help people to closer understand of I–V and P–V operating curves of PV module. In addition, it can be considered as a robust tool to predict the behavior of any solar PV cells, modules and arrays under varying environmental conditions (temperature, irradiation and partially shading condition) and physical parameters (series resistance, shunt resistance, ideality factor and so on). This research is the first step to study a hybrid system where a PV power generation connecting to other renewable energy production sources like wind or biomass energy systems.
Authors’ contributions
XHN initiated, proposed model developed in Matlab/Simulink and analyzed. He also prepared a draft manuscript for publication. MPN assisted in designing, data collection, analysis and reviewed the manuscript and edited many times and added his inputs. Finally, XHN decided finally the content of the research revised final manuscript. All authors read and approved the final manuscript.
Authors’ information
Xuan Hieu Nguyen is a lecturer in Department of Electric Power System, Faculty of Engineering, Vietnam National University of Agriculture, Hanoi, Vietnam. He had bachelor degree in electric power system, Hanoi University of Science and Technology, Vietnam in 2008. He received master degree in electrical engineering in University of Wollongong, Australia in 2012. Minh Phuong Nguyen is graduate student in Faculty of Engineering, Vietnam National University of Agriculture.
Acknowledgements
The authors are grateful to the support by this work through the project “Study, design and manufacture a solar PV system using SPV technology served for chicken farms in Faculty of Animal Science, Vietnam National University of Agriculture”, Vietnam (2014–2017).
Competing interests
The authors declare that they have no competing interests.
Author information
Authors and Affiliations
- Department of Electric Power System, Faculty of Engineering, Vietnam National University of Agriculture, Trau Quy town, Gia Lam district, Hanoi, 10000, Vietnam Xuan Hieu Nguyen
- Faculty of Engineering, Vietnam National University of Agriculture, Trau Quy town, Gia Lam district, Hanoi, 10000, Vietnam Minh Phuong Nguyen
The Ultimate Guide to Solar Cell with Jackery
Whether the source is sunshine or artificial light, solar cells are referred to as photovoltaic. They serve as photodetector devices, such as infrared detectors, that can detect light or other electromagnetic radiation close to the visible range or measure light intensity. Solar cells are frequently grouped to create solar modules, which are then connected to solar panels, which are even larger units.
Some solar-powered gadgets don’t even have an off button and never require batteries. They operate indefinitely as long as there is sufficient sunlight. But how does solar energy use? Of course, the solar cell plays a part. You will discover what a solar cell is, how it functions, how it was developed, and how to choose the best solar panel with Jackery in this post.
What is A Solar Cell
The solar cell is a crucial component of photovoltaic energy conversion, which transforms light energy into electrical energy. Semiconductors are typically utilized as the material for solar cells. Converting energy entails charge carrier separation and the production of electron-hole pairs in a semiconductor from light’s photon energy absorption.
French scientist Edmond Becquerel initially showed the photovoltaic phenomenon in 1839. Based on fabrication methods, solar or photovoltaic technology can be divided into three generations. First-generation solar cells are constructed using silicon, which is both efficient and profitable. The original generation of silicon-based solar cells still accounts for 80% of today’s solar cell production. The first generation consists of monocrystalline silicon solar cells, polycrystalline, amorphous, and hybrid.
Source: Anthony Fernandez
What is Solar Photovoltaic Cell?
A photovoltaic (PV) cell, also known as a solar cell, can either reflect, absorb, or pass through a light that strikes it. The semiconductor material that makes up the PVPV cell can conduct electricity more effectively than an insulator but is less effective than a good conductor like a metal. In PVPV cells, a variety of semiconductor materials are employed.
When a semiconductor is exposed to light, the light’s energy is absorbed and transferred to the semiconductor’s negatively charged electrons. The additional energy enables the electrons to conduct an electrical current through the material. This current can be used to power your home and the rest of the electric grid by extracting it through conductive metal contacts, which are the grid-like lines on solar cells.
How is The Solar Cell Market Today?
The efficiency of solar cells has increased dramatically in recent years, going from reports of roughly 3% in 2009 to over 25% presently. Although solar cells have rapidly increased their efficiency, several obstacles must be overcome before they can be considered viable commercial technology.
Wafer-based PV and thin-film cell PVsPVs are the two primary divisions of photovoltaic technologies. The wafer-based PVsPVs include conventional crystalline silicon cells and gallium arsenide cells, with c-Si cells currently controlling the PVPV market with a market share of roughly 90% and GaAs having the highest efficiency.
What Are Solar Cells Made of
A layer of p-type silicon is sandwiched between a layer of n-type silicon to form a solar cell. There are too many electrons in the n-type layer and too many positively charged holes in the p-type layer. The electrons on one side of the junction (n-type layer) migrate into the holes on the opposite side, which is close to the intersection of the two layers (p-type layer). As a result, a region known as the depletion zone is formed surrounding the connection, where the electrons fill the holes.
The p-type side of the depletion zone now contains negatively charged ions, and the n-type side of the depletion zone now includes positively charged ions when all the holes in the depletion zone have been filled with electrons. These ions’ opposite charges provide an internal electric field that inhibits the n-type layer’s electrons from filling the p-type layer’s holes.
- Purify the Silicon:Silicon dioxide is put in an electric arc furnace, where oxygen is released using a carbon arc. Carbon dioxide and molten silicon are left, but even this is not pure enough to be used in solar cells. This silicon will produce one with just 1% impurities.
- Create Single Crystal Silicon:The Czochralski Method, in which a seed silicon crystal is dipped into molten polycrystalline silicon, is the most used technique for producing single-crystal silicon.
- Cut the Wafers:A circular saw is used to slice the second-stage boule into silicon wafers. The best raw material for this task is diamond, which produces silicon slices that can then be further cut to create squares or hexagons that are simpler to slot together into the surface of a solar cell.
- Doping:This technique, also known as doping, often entails firing phosphorous ions into the ingot using a particle accelerator.
- Add Electrical Contacts:Electrical contacts serve as a conduit for the current generated by solar cells and connect them. These connections, made of metals like palladium or copper, are thin so as not to prevent sunlight from reaching the cell.
- Add Anti-Reflective Coating:To lessen the quantity of sunlight lost through reflection, an anti-reflective coating is put on the silicon.
- Encapsulate the Cell:To complete the process, the solar cells are sealed in silicon rubber or ethylene vinyl acetate and mounted in an aluminum frame with a glass or plastic cover for added protection and a back sheet.
Source: US Energy Information Administration
How Does A Solar Cell Work
The solar cell is a technological innovation that directly converts light energy into electricity through the photovoltaic effect, creating electrical charges free to travel through semiconductors. All solar cells share a similar fundamental design. An optical coating or antireflection layer that reduces the quantity of light lost through reflection allows light to enter the system. As a result, the light is trapped and is more likely to reach the layers below that do energy conversion. Spin-coating or vacuum deposition creates this top antireflection layer, commonly an oxide of silicon, tantalum, or titanium.
Below the top antireflection layer are three energy conversion layers. These are the top junction layer, the absorber layer, and the back junction layer. Two additional electrical contact layers carry the electric current to an external load and then back to the cell to complete the electric circuit. A solar cell is a sandwich of n-type silicon and p-type silicon. It generates electricity by using sunlight to make electrons hop across the junction between the different flavors of silicon:
- Photons (light particles) pelt the cell’s upper surface when sunlight shines.
- The photons (yellow blobs) transport energy through the cell at a downward angle.
- In the lower p-type layer, photons transfer their energy to electrons (green blobs).
- With the help of this energy, the electrons can penetrate the barrier into the top n-type layer and break out into the circuit.
- As the electrons move across the circuit, the lamp begins to glow.
Source: Advanced Renewable Energy Systems
The Types of Solar Cells
The three main categories of solar cells are crystalline silicon-based, thin-film solar cells, and a more recent innovation that combines the other two. P-type and n-type silicon are two types of semiconductors used to make solar cells. Atoms with one fewer electron in their outer energy level than silicon, like boron or gallium, are added to create p-type silicon.
Crystalline Silicon Cells
Crystalline silicon (c-Si) wafers, cut from massive ingots manufactured in laboratories, make about 90% of solar cells. These nuggets can develop into single or numerous crystals and can take up to a month to grow. Monocrystalline solar panels are made from a single crystal, whereas polycrystalline are made from multiple crystals.
Thin Film Solar Cells
While thin-film solar cells, also known as thin-film photovoltaics, are around 100 times thinner than crystalline silicon cells, they are still produced from wafers that are only a tiny fraction of a millimeter deep (about 200 micrometers, or 200m). Amorphous silicon (a-Si), in which the atoms are randomly organized rather than in an ordered crystalline structure, is the material used to create these thin film solar panels and cells. These films can also be produced using organic photovoltaic (PVPV) materials, copper indium gallium diselenide (CIGS), and cadmium-telluride (Cd-Te).
Third Generation of Solar Cells
The most recent solar cell technologies combine the best aspects of thin-film and crystalline silicon solar cells to deliver high efficiency and enhanced usability. They frequently have several junctions made up of various semiconducting materials’ layers. Also, they are typically made of amorphous silicon, organic polymers, or perovskite crystals.
Solar Cell Development
Solar energy already offers consumers many advantages while reducing the harmful environmental effects of fossil fuel power generation. Switching to solar energy has benefits on a more local level and reduces air pollution and carbon dioxide emissions because it locates power generation at the point of use.
Smaller devices like watches and calculators may now operate without batteries, and road and train maintenance signs can now be powered by the sun so that they can be used in even the most remote regions. In some nations, solar energy is used to power telephone booths, water pumps, and even refrigeration systems in medical facilities. As the supply of fossil fuels declines, there will be a greater need to turn to renewable energy sources, such as solar.
Best Portable Solar Panels with Jackery
Jackery portable solar panels can be folded and strapped for easy carrying and use. One of the highest efficiency rates in the industry makes it possible to maximize the sun’s energy and transform it into clean energy. Use solar power and the Jackery rechargeable portable power stations to keep your equipment charged. For better backup power, it is the advanced off-grid solar generating system.
With mono crystalline solar cells and adjustable supports, Jackery portable solar panels have a charging efficiency of up to 25%. Make the most of solar energy’s potential. The solar panel can be easily connected to your power source. Connect the DCDC input of your portable power source to the DCDC interface.
Jackery SolarSaga 200W Solar Panel
The Jackery SolarSaga 200W solar panels are your best option if you want a solution that can power your entire home. Solar panels can generate more power under similar circumstances with a higher conversion rate of 24.3%. A Jackery Portable Power Station Explorer 2000 Pro can be fully charged in 2.5 hours using 6 SolarSaga 200. Additionally compatible with various Jackery power stations is the portable solar panel.
Compatible With
Recharging Time
Conversion Efficiency
Explorer 2000 Pro 6SolarSaga 200