The question you asked comes under a very broad area; however, I am giving you the answer covering some of them. I hope other researchers can give (or add) more points to these.
Here's why efficiency tends to increase with temperature and what factors can boost the efficiency of a solar cell:
1. Increase in Efficiency with Temperature:
Why It Happens: Solar cells are typically made of semiconductor materials (like silicon, CIGS, CdTe, CZTS, Perovskite etc.) that generate electricity when exposed to sunlight. When the temperature rises:
More Energy: Sunlight carries energy, and when it heats up the solar cell, it provides extra energy to the electrons in the semiconductor.
Reduced Resistance: Higher temperatures can reduce the electrical resistance in the material, making it easier for the electrons to move through the solar cell.
Improved Performance: As a result, the solar cell can generate more electricity for the same amount of sunlight, which increases its efficiency.
However, there's a limit to this effect. At extremely high temperatures, solar cell efficiency can start to decrease due to other factors like increased electron recombination.
2. Factors That Increase Solar Cell Efficiency:
a. High-Quality Materials: Using high-quality semiconductor materials in the solar cell can boost efficiency. These materials are designed to capture more sunlight and convert it into electricity effectively.
b. Multiple Layers: Some advanced solar cells have multiple layers of semiconductor materials. Each layer absorbs different parts of the sunlight spectrum, allowing for more efficient energy conversion.
c. Anti-Reflective Coatings: Coatings on the surface of the solar cell reduce light reflection, ensuring that more light is absorbed and converted into electricity.
d. Tracking Systems: Solar tracking systems that follow the sun's path throughout the day can maximize the amount of sunlight falling on the solar cell, improving efficiency.
e. Concentrated Solar Power: Concentrating sunlight onto a small area of solar cells with mirrors or lenses can increase the intensity of sunlight, leading to higher efficiency.
f. Advanced Technologies: Ongoing research and development in solar cell technology leads to more efficient designs and materials. Basically, we need cells with high shunt resistance and low series resistance.
In summary, higher temperatures can initially increase the efficiency of solar cells due to improved electron movement and energy absorption. However, many factors influence solar cell efficiency, including the quality of materials, design, and technology advancements. Researchers are continually working to develop more efficient solar cells to harness more clean energy from the sun.
In addition to these, the thin film, quantum dot-based solar cell can give better performance at a low cost (however, some of them are toxic materials).
I hope these points gave to an overview, but if you want a more technical answer, please let us know, and we will be happy to answer.
Increase in temperature affects the semiconductor material parameters by increasing the energy of bound electrons. This means that the energy difference to achieve the exited state is smaller, which results in reduced power output and efficiency of solar panels.Photovoltaic modules are tested at a temperature of 25 degrees C (STC) – about 77 degrees F., and depending on their installed location, heat can reduce output efficiency by 10-25%. As the temperature of the solar panel increases, its output current increases exponentially, while the voltage output is reduced linearly.Reflection—A cell's efficiency can be increased by minimizing the amount of light reflected away from the cell's surface. For example, untreated silicon reflects more than 30% of incident light. Anti-reflection coatings and textured surfaces help decrease reflection. Increase in temperature affects the semiconductor material parameters by increasing the energy of bound electrons. This means that the energy difference to achieve the exited state is smaller, which results in reduced power output and efficiency of solar panels. Current is the rate at which electricity flows through the system. Temperature affects solar panel voltage and current. As temperature increases, it reduces the amount of energy a panel produces. This is due to an increase in resistance high temperatures slow the speed of the electrical current. As of 2022, the world record for solar cell efficiency is 47.1%, set in 2019 by multi-junction concentrator solar cells developed at National Renewable Energy Laboratory (NREL), Golden, Colorado, USA. This record was set in lab conditions, under extremely concentrated light. UV light-induced degradation (UVID). Initial exposure to sunlight causes the crystalline silicon oxide on the surface of the panel to form a layer of boron dioxide that reduces its efficiency. The highest output power of PV panel will be produced by a combination of high solar irradiance and low temperature. As illustrated in this figure, the most efficient power production by PV panel was 15.43 % when PV panel temperature was 25 °C at 1000 Wm-2. Most solar panels perform optimally in the laboratory at the Standard Test Condition (STC) temperature of 77°F. Their efficiency degrades significantly once they reach 149°F. The decline in solar panel performance past 77°F is easy to calculate, allowing you to create projections of their output at summer temperatures.
Efficiency of the solar PV panel increase upto the standard operating temperature given by the manufacturer, after beyond the temperature the efficiency automatically decreases.
Reducing the temperature during its operation by active or passive cooling will automatically increase the efficiency and electrical power of the PV panel.
Solar cell efficiency decreases with temperature, not increases.
Why does solar cell efficiency decrease with temperature?
There are two main reasons why solar cell efficiency decreases with temperature:
Increased band gap energy: As the temperature of a solar cell increases, the band gap energy decreases. This means that less energy is required to excite an electron from the valence band to the conduction band. As a result, more electrons are excited, which increases the number of carriers that can recombine. Recombination reduces the number of carriers that can generate current, which reduces the efficiency of the solar cell.
Increased carrier mobility: As the temperature of a solar cell increases, the mobility of the charge carriers increases. This means that the carriers can move through the solar cell more quickly, which reduces the time that they have to interact with photons and generate current. As a result, the efficiency of the solar cell is reduced.
Which increases the efficiency of a photovoltaic or solar cell?
The following factors can increase the efficiency of a photovoltaic or solar cell:
Higher quality semiconductor materials: Higher quality semiconductor materials have fewer defects, which reduces recombination and increases the efficiency of the solar cell.
Better anti-reflective coatings: Anti-reflective coatings help to reduce the amount of light that is reflected away from the solar cell, which increases the amount of light that is absorbed and converted into electricity.
More efficient cell designs: More efficient cell designs can help to reduce recombination and increase the efficiency of the solar cell.
Conclusion
Solar cell efficiency decreases with temperature. The factors that can increase the efficiency of a photovoltaic or solar cell are the quality of semiconductor materials, anti-reflective coatings, and cell design.
Higher temperatures can initially increase the efficiency of solar cells due to improved electron movement and energy absorption. However, many factors influence solar cell efficiency, including the quality of materials, design, and technology advancements. Efficiency will also increase if the initial temperature is increased. That is why in thermal power plants, efforts are being made to increase the steam turbine inlet parameters. The efficiency of a heat engine is directly related to the temperature difference between the high and low temperature reservoirs. The larger the temperature difference, the more efficiently the heat engine will operate, and the higher the internal efficiency will be. Additionally, improved efficiency increases real incomes and accelerates economic growth, further increasing the demand for resources. The Jevons paradox occurs when the effect from increased demand predominates, and the improved efficiency results in a faster rate of resource utilization. The energy for work comes from a decrease in the total energy of the fluid used in the system. Therefore the greater the temperature change, the greater this decrease in the fluid and thus the greater energy available to do work is. Hence, the heat engine is a system of converting heat energy into mechanical work. The efficiency of a heat engine is the ratio of difference between the hot source and sink to the temperature of the hot source. The efficiency of the heat engine depends on the difference between a hot reservoir and a cold reservoir. An increase in engine speed reduces engine load requirements and thus, turbocharger loads. Lower turbocharger requirements reduce ACT and, consequently, reduce knocking. This process allows an advanced ignition timing, enabling more chamber pressure and improving fuel conversion efficiency.Reflection—A cell's efficiency can be increased by minimizing the amount of light reflected away from the cell's surface. As, untreated silicon reflects more than 30% of incident light. Anti-reflection coatings and textured surfaces help decrease reflection. The metal nanoparticles are utilized to provide extra scattering in order to increase the efficiency of the photovoltaic cells or for the enhancement of photovoltaic devices by using the surface plasmon resonance within the visible and near-visible spectral range. Solar photovoltaic systems may be less efficient than solar thermal systems, but these are more multi-purpose. That's because they're made for electricity generation meaning you can use them for all your appliances. Thanks to that, you can cut your electricity bills by a lot.Though most commercial panels have efficiencies from 15% to 20%, researchers have developed PV cells with efficiencies approaching 50%. As of 2022, the world record for solar cell efficiency is 47.1%, set in 2019 by multi-junction concentrator solar cells developed at National Renewable Energy Laboratory (NREL), Golden, Colorado, USA. This record was set in lab conditions, under extremely concentrated light.Monocrystalline (mono) panels offer the highest efficiency rates and power output. Although they have the highest price tag, their long-term benefits are worth the investment. Mono panels are more compact, making them ideal for homes with limited roof space. The optimal temperature for solar panels is around 25°C (77°F). Solar panels perform best under moderate temperatures, as higher or lower temperatures can reduce efficiency. For every degree above 25°C, a solar panel's output can decrease by around 0.3% to 0.5%, affecting overall energy production.