Understanding Solar Photovoltaic (PV) Power Generation
Solar photovoltaic (PV) power generation is the process of converting energy from the sun into electricity using solar panels. Solar panels, also called PV panels, are combined into arrays in a PV system. PV systems can also be installed in grid-connected or off-grid (stand-alone) configurations. The basic components of these two configurations of PV systems include solar panels, combiner boxes, inverters, optimizers, and disconnects. Grid-connected PV systems also may include meters, batteries, charge controllers, and battery disconnects. There are several advantages and disadvantages to solar PV power generation (see Table 1).
Sunlight is free and readily available in many areas of the country.
PV systems have a high initial investment.
PV systems do not produce toxic gas emissions, greenhouse gases, or noise.
PV systems require large surface areas for electricity generation.
PV systems do not have moving parts.
The amount of sunlight can vary.
PV systems reduce dependence on oil.
PV systems require excess storage of energy or access to other sources, like the utility grid, when systems cannot provide full capacity.
PV systems have the ability to generate electricity in remote locations that are not linked to a grid.
Grid-connected PV systems can reduce electric bills.
Table 1. There are advantages and disadvantages to solar PV power generation.
Grid-Connected PV Systems
PV systems are most commonly in the grid-connected configuration because it is easier to design and typically less expensive compared to off-grid PV systems, which rely on batteries. Grid-connected PV systems allow homeowners to consume less power from the grid and supply unused or excess power back to the utility grid (see Figure 2). The application of the system will determine the system configuration and size. For example, residential grid-connected PV systems are rated less than 20 kW, commercial systems are rated from 20 kW to 1MW, and utility energy-storage systems are rated at more than 1MW.
Figure 2. A common configuration for a PV system is a grid-connected PV system without battery backup.
Off-Grid (Stand-Alone) PV Systems
Off-grid (stand-alone) PV systems use arrays of solar panels to charge banks of rechargeable batteries during the day for use at night when energy from the sun is not available. The reasons for using an off-grid PV system include reduced energy costs and power outages, production of clean energy, and energy independence. Off-grid PV systems include battery banks, inverters, charge controllers, battery disconnects, and optional generators.
Solar panels used in PV systems are assemblies of solar cells, typically composed of silicon and commonly mounted in a rigid flat frame. Solar panels are wired together in series to form strings, and strings of solar panels are wired in parallel to form arrays. Solar panels are rated by the amount of DC that they produce. Solar panels should be inspected periodically to remove dirt, debris, or snow, as well as to check electrical connections.
Since photovoltaics are adversely affected by shade, any shadow can significantly reduce the power output of a solar panel. The performance of a solar panel will vary, but in most cases, guaranteed power output life expectancy is between 10 years and 25 years. Solar panel power output is measured in watts. Power output ratings range from 200 W to 350 W under ideal sunlight and temperature conditions.
Series and Parallel Connections in Solar Modules
The basic ‘nerves’ of the solar module array which sends signals or currents to different parts of the system principally depends on the module circuits are designed in such a way that the multiple cells that make a module are connected to increase the power and voltage obtained from the device. The design is done under standard test conditions where maximum power is acquired at 0.5V at 25°C. Therefore, when it comes to circuit design of PV modules, there are 2 classifications which are:
Modules connected in series usually consist of wiring the positive terminal of one solar cell to the negative terminal of another solar cell such that voltage increases and current remain the same across the circuit.
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However, since wiring is involved, there’s a chance for mismatch losses to occur. These losses are caused by interconnection defects of solar cells or solar modules because of varying properties or conditions. For example, if a part of a solar cell or module is shaded, the overall power being generated will be lower than the expected system performance output because the power that’s being generated at the good side of the cell/module will be dissipated due to improper wiring. This, in turn, will lead to localized heating which may damage the cell or module irreversibly. Most of the PV modules are connected in series which leads to a higher chance of series wiring mismatch that occurs in the circuit. There are 2 types of series mismatches:
Open-circuit voltage mismatch: This is a mismatch that’s not significantly threatening to the module but its effects are pronounced when the overall power is being calculated. In series, current remains the same but the overall voltage is increased by adding voltages at various values of current.
Short-circuit current mismatch: A short circuit current mismatch has a drastic effect on the module because current passing through the solar cells is the same. The overall current depends on the ‘poor cell’ because it cannot exceed it. This leads to dissipation of power at the poor cell which can cause perpetual damage to the module
Modules connected in parallel involve connecting all the positive terminals together and all the negative terminals together in the module. This wiring increases the current flowing through the circuit and keeps the voltage same throughout.
Mismatch Effects in Solar Modules
Usually, in PV systems, we find a combination of series and parallel wiring. This is common in large systems used for residential or commercial purposes. The combination wiring is used for large PV arrays wherein a set of solar cells/modules connected in series is known as a ‘string’. Since a combination wiring design is used, there are chances for mismatch effects to occur at an array scale because of the series and parallel connections present in the circuit design.
These effects can significantly affect the entire array if by-pass diodes are not connected. By-pass diodes are connected in parallel. They help in reducing the effective resistance and are usually accompanied by another diode called a ‘blocking diode’ which prevents overloading in the module. They are wired in series.
Each string present in the array should be equipped with its own blocking diode because these diodes reduce mismatch losses that frequent in arrays having parallel connections by inhibiting the flow of current from parallel strings to strings of lower current. They prevent current from flowing into modules that are possibly shaded which if it did flow, can lead to overheating and solar cell damage
Fortunately, with current developments in loss management and encapsulation techniques, manufacturers can give a module lifetime guarantee for more than 20 years where for the first 10 years, the module will produce 90% of its total rated output and approximately 80% for the next 25 years which shows the robust nature of PV modules in the current market.
Market Trend of Solar PV Modules
When we consider the current market for solar PV technologies, there is an expected to grow to USD 345 billion by 2020. The main reasons for this projected growth are because of increasing demand for energy, a noticeable concern for sustainable practices and the Government’s support for the same.
Solar panels made from crystalline silicon are expected to hold the majority of the market share because of their semiconductor properties and competitive costs in the market. Photovoltaic technology made from inorganic materials such as Silicon, CdTe, CIGS, Amorphous silicon, etc. are the major contenders because of their potential to achieve high efficiencies. The utility applications have the highest demand for PV market primarily in defence, space utility, military applications and in power plants.
The Asia-Pacific (APAC) region had the largest share in the PV market because of Governmental initiatives to shift towards the Renewability sector. Therefore, the production costs are low and often supported by Government subsidies. The major contributors from these regions are India, South Korea, Japan, China and Thailand
In this course you will learn how to turn solar cells into full modules; and how to apply full modules to full photovoltaic systems.
The course will widely cover the design of photovoltaic systems, such as utility scale solar farms or residential scale systems (both on and off the grid). You will learn about the function and operation of various components including inverters, batteries, DC-DC converters and their interaction with both the modules and the grid.
After learning about the components, you will be able to correctly apply them during main design steps taken when planning a real PV installation with excellent performance and reliability.
Through modelling, you will gain a deeper understanding of PV systems performance for different solar energy applications, and proficiency in estimating the energy yield of a client’s potential system.
This course is part of the Solar Energy Engineering MicroMasters Program designed to cover all physics and engineering aspects of photovoltaics: photovoltaic energy conversion, technologies and systems.
At a glance
- Bachelor’s degree in Science or Engineering and/or the successful completion of PV1x and PV2x (or firm grasp of their content).
- In order to carry out the assignments in the course, you will need to install MATLAB (student license will be given). Please check the system requirements: https://nl.mathworks.com/support/requirements/matlab-system-requirements.html
- Language: English
- Video Transcript: English
- Associated programs:
- MicroMasters ® Program in Solar Energy Engineering
Build your own Photovoltaic Array
The amount of solar radiation received and the daily energy demand are the two controlling factors in the design of the photovoltaic array and solar power systems. The photovoltaic array must be sized to meet the load demand and account for any system losses while the shading of any part of the solar array will significantly reduce the output of the entire system.
If the solar panels are electrically connected together in series, the current will be the same in each panel and if panels are partially shaded, they cannot produce the same amount of current. Also shaded PV panels will dissipate power and waste as heat rather than generate it and the use of bypass diodes will help prevent such problems by providing an alternative current path.
Blocking diodes are not required in a fully series connected system but should be used to prevent a reverse current flow from the batteries back to the array during the night or when the solar irradiance is low. Other climatic conditions apart from sunlight must be considered in any design.
Since the output voltage of silicon solar cell is a temperature related parameter, the designer must be aware of the prevailing daily temperatures, both extremes (high and low) and seasonal variations. In addition, rain and snowfall must be considered in the design of the mounting structure. Wind loading is especially important in mountain top installations.
In our next tutorial about “Solar Power”, we will look at how we can use semiconductor photovoltaic arrays and solar panels as part of a Stand Alone PV System to generate power for off-grid applications.
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- Standard Test Conditions
- Temperature Coefficient of a PV Cell
- Bypass Diode
- Solar Cell I-V Characteristic
- Photovoltaics Turning Photons into Electrons
- How Many Solar Cells Do I Need
- Photovoltaic Panel
- Photovoltaic Types
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Hi there my name is Matt D’Agati. Solar technology has grown to become probably the most promising and sought-after sourced elements of clean, renewable energy in the past few years. This is due to its numerous benefits, including financial savings, energy efficiency, and also the positive impact this has from the environment. In this specific article, we are going to talk about the advantages of choosing solar energy in homes and businesses, the technology behind it, and just how it could be implemented to increase its benefits. One of many benefits of using solar power in homes may be the financial savings it gives. Solar energy panels can handle generating electricity for your house, reducing or eliminating the need for traditional sourced elements of energy. This will probably bring about significant savings on the monthly energy bill, particularly in areas with a high energy costs. 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Furthermore, companies that adopt solar power can benefit from increased profitability and competitiveness, since they are seen as environmentally conscious and energy-efficient. The technology behind solar technology is not at all hard, yet highly effective. Solar energy panels are made up of photovoltaic (PV) cells, which convert sunlight into electricity. This electricity are able to be kept in batteries or fed straight into the electrical grid, with respect to the specific system design. So that you can maximize the many benefits of solar power, it is critical to design a custom system this is certainly tailored to your unique energy needs and requirements. This may make sure that you have just the right components in position, including the appropriate amount of solar energy panels plus the right types of batteries, to increase your power efficiency and value savings. One of several important aspects in designing a custom solar technology system is knowing the various kinds of solar energy panels and their performance characteristics. There are 2 main kinds of solar power panels – monocrystalline and polycrystalline – each featuring its own benefits and drawbacks. Monocrystalline solar power panels are made of an individual, high-quality crystal, helping to make them more cost-effective and sturdy. However, they are more costly than polycrystalline panels, that are produced from multiple, lower-quality crystals. Along with solar energy panels, a custom solar power system will also include a battery system to keep excess energy, in addition to an inverter to convert the stored energy into usable electricity. It is essential to choose a battery system that is capable of storing the actual quantity of energy you want for the specific energy needs and requirements. This can make certain you have a trusted way to obtain power in the case of power outages or any other disruptions to your time supply. Another advantage of using solar power may be the positive impact this has from the environment. Solar power is on a clean and renewable power source, producing no emissions or pollutants. This makes it an ideal replacement for traditional resources of energy, such as for example fossil fuels, that are a major contributor to polluting of the environment and greenhouse gas emissions. By adopting solar power, homeowners and businesses can really help reduce their carbon footprint and play a role in a cleaner, more sustainable future. In closing, the advantages of using solar energy both in homes and companies are numerous and should not be overstated. From cost benefits, energy savings, and increased property value to environmental impact and technological advancements, solar technology provides a variety of advantages. By knowing the technology behind solar technology and designing a custom system tailored to specific energy needs, you’ll be able to maximize these benefits and then make a positive effect on both personal finances while the environment. Overall, the adoption of solar energy is an intelligent investment for a sustainable and bright future. Should you want to learn about more info on this fact matter take a look at a blog:
How photovoltaic technology is made possible
In order to consistently generate photovoltaic solar energy year after year, photovoltaic solar panels have to withstand the outdoors. The ability to perform depends a lot on the photovoltaic materials, which must be durable and robust. We’ve already mentioned that the cells of a solar photovoltaic module consist of a silicon semiconductor. This semiconductor is enclosed by a protective material in a metal frame. The protective material is an encapsulant which consists of transparent silicon or a butyryl plastic and bonded around the cells. The cells are then embedded in ethylene vinyl acetate (EVA).
A polyester film – mylar is one example – is used for the backing. A glass cover or sometimes lightweight plastic encases the array, while the frame is steel or aluminium. Silicon bonds everything together. The bulk of the electronic parts are usually made from copper.
Solar cell to solar array
A solar cell module array is part of a photovoltaic solar panel system. What is an array in solar PV systems? It’s a collection of solar photovoltaic PV panels. The panels are wired together to form one large-scale solar energy photovoltaic PV system. A solar PV array is usually associated with solar farms, but really, it’s any grouping of connected modules.
Solar photovoltaic conversion of sunlight into usable solar energy is typically 20%. This means the photovoltaic panel output can, in theory, exceed 400 watts of power. The more efficient the panel is at converting sunlight into energy, the higher the output.
Most solar panels with 60 cells generate between 270 and 300 watts. Let’s say your panels will be in direct sunlight for five hours a day. Now let’s use an example wattage from one solar panel with 60 cells at 290 watts of power. The calculation for estimating your energy output would be:
5 hours x 290 watts = 1,450 watts-hours, or 1.5 kilowatt-hours (kwh)
This translates to around 500—550 kWh of energy a year for each of your panels.
Applications of photovoltaic systems
Photovoltaic power is used for a variety of applications, either as a way to reduce one’s carbon footprint, save energy costs or because an area is not served by power lines. Examples of how and where solar photovoltaic energy conversion systems are used include:
- Space satellites
- Water pumps
- Parks in remote regions
- Remote residences
- Telecommunication repeater stations
- Navigational aids
- Home appliances
- Office equipment
- Laptop computers
- Supply of occasional power
- Calculators and watches
- Military uses, e.g., lightweight PV for charging electronic equipment in the field
No matter what your application is, you can also learn more from our Quick guide: components for your solar PV system.
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