The efficiency of solar panels can be affected by a number of factors such as types of solar panels, inverter efficiency, heat circulation, etc. Here are some factors to consider before purchasing a solar panel system:
Types of solar cells
When deciding which type of solar panel is right for your home, the first thing you should do is learn about each type, its structure and performance.
- Monocrystalline solar panels. The most popular and efficient type of solar panel, monocrystalline solar panels are popular among homes and businesses. They are made from a single crystal of pure silicon and each can generate 300 to 400 (sometimes more) energy.
- Polycrystalline solar panels. Polycrystalline solar panels are made up of several pieces of silicon that are split and fused together. They are slightly cheaper but also more efficient than monocrystalline solar panels.
- Thin film solar panels. Thin film solar panels can be made from three different materials: amorphous silicon (a-Si), cadmium telluride (CdTe) and copper indium galenide (CIGS). Each type of thin film solar panel is cheaper than crystalline solar panels, but also more efficient.
solar hours
Although solar panels can produce electricity in a variety of lighting conditions, even on cloudy days, their efficiency drops significantly during low light hours. As a rule of thumb, your solar panel needs about four hours of direct sunlight per day for optimal performance.
However, during the rest of the day, when sunlight is present but not direct, solar panels can produce large amounts of electricity. It is the same on cloudy days.
The number of hours of sunlight per day directly affects the overall performance of your panels in the short term. Solar panels that do not receive the optimal amount of sunlight each day have no long-term effects.
inverter efficiency
An inverter is what converts the regular direct current (DC) that powers your home. Most inverters have a conversion efficiency of 97% to 99%, so the energy loss is relatively low.
temperature coefficient
The efficiency of solar cells is measured and recorded under laboratory conditions called Standard Test Conditions or STC. Laboratory conditions include measurements at 25°C (77°F). The temperature coefficient of a solar panel measures the percentage loss in efficiency of the panel when its surface rises above this temperature.
For every degree Celsius that the panel temperature exceeds 25, the efficiency of the panel will decrease by its nominal factor.
For example, SunPower's most powerful solar panel, the M440, delivers a maximum output of 440W under ideal conditions of 25°C. Its efficiency at this temperature is 22.8%. The panel has a modified temperature coefficient of 0.29%.
When the temperature of the panel rises by 10°C (50°F), which usually happens in hot sun, its efficiency drops by 2.9%, meaning the overall efficiency drops below 20%. Basically, it produces less power when it's hot.
moist heat
Solar cell wet heat testing rigorously tests solar cells at 85°C and 85% humidity for 1000 hours. The purpose of the test is to recreate and accelerate the extreme conditions that a product can be subjected to over several years of direct exposure to the elements.
While wet heat testing does not directly measure the effect of weather conditions on the performance of the panel, the process checks the integrity of the unit for delamination and corrosion, which affects the overall performance of the panel.
thermal cycle
Thermal cycling tests your solar cells to see if they can withstand a wide range of temperatures. Solar cell components can expand and contract during thermal cycling, which can affect efficiency.
solar array orientation
South-facing roofs are ideal for generating solar energy. The next best choice is west facing roofs and the next best choice is east facing roofs. If you have a north-facing roof, you may want to reconsider your decision. West and east facing panels will produce 15% less energy than south facing panels, while north facing panels can lose up to 20%.
Determining the main angle of installation with respect to the sun is very important to optimize the performance of solar panels. The exact angle depends on the latitude, but is usually 30 to 45 degrees. The angle of installation affects the amount of time the panel receives direct sunlight.
The installation angle is most effective in winter when the sun is low on the horizon. In winter, the correct orientation and angle can produce 50% more energy than panels installed without the same care.
