Solar panel efficiency refers to the output of a solar panel relative to the space occupied. Although the primary determinant of a solar panel system performance is its type, there are other determinants. The most common types of solar panels have an efficiency of around 17% to 23%. However, some brands have efficiencies of more than 40%, but they are not economically viable.
Unless you have limited roof space, the solar panel’s efficiency should not be a big issue. There is no need to pay premium prices for high-performance solar panels. Apart from that, some solar types like solar shingles have low efficiency but highly aesthetic.
Efficiency determines the size and number of solar panels in a system. Solar panels should maintain a capacity of around 25% during cloudy days. However, this might not be the case because of low maintenance, shading, roof orientation, or roofing materials. Let’s look at how each of these factors affects solar panel efficiency.
Determinants of the Efficiency of Your Solar Panel System
1. Shading
Are you having objects or trees casting shadows on your solar panels? Shading can reduce the efficiency of solar panels by more than half. If the shadow blocks sunlight throughout the year, this can affect your solar panels’ return on investment.
You should cut any branches or remove any objects encroaching your roof. Professional solar installers should guide you on the best placement of solar panels to avoid blockage by shadows.
2. Weather & Climate
Extreme weather conditions can impact the performance of solar panels considerably. The solar cells work optimally under specific temperatures. There is a misconception that high temperatures increase the efficiency of solar panels. On the contrary, this can damage and even reduce the performance of your system.
Snow can also bury the system and reduce the total output. However, snow can improve efficiency as long as it does not block the panels. Because of its bright appearance, the snow has high irradiance, which increases the amount of sunlight that strikes the system.
3. Roof Orientation & Angle
For maximum performance, the roof should face south so that the panels are exposed to the sun maximally. However, this might not be the case because of the design of your house or shading. The solar company should identify the ideal placement of the system after assessing your roof.
The ideal slant of the solar panel is 30 and 40 degrees. For flat roofs, the installer can adjust the brackets to fit this angle and optimize efficiency. Under rare circumstances, redesigning your roof can be the best option because solar panel installation is a long term investment.
4. Type of Solar Panels
Monocrystalline solar panels have the best efficiency, with a performance of up to 23%. On the other hand, thin-film solar panels are the least efficient. There is no better choice than the other, though. It all depends on the size of your roof and your preference.
Some homeowners detest the blue crystalline appearance of polycrystalline solar panels, although they have better performance than thin-film. If you have enough mounting space, you can consider any of the two options. However, if your house’s roof is limited, monocrystalline solar panels are the best because of the high efficiency. Therefore, you will require a few solar panels.
5. Solar Accessories Efficiency
Solar inverters, energy controls, and cables affect the performance of your solar system. You should go for quality accessories that are compatible with the solar panels. Avoid compromise of the gadgets because this can reduce the output. Consequently, this will prolong the project’s payback period.
You should consider the cable sizes of your appliances to avoid excessive resistance, which can reduce efficiency. For example, a 220V device will reduce the performance of a 48V solar panel system.
6. Solar Tracking
Unlike fixed solar panels, single and dual-axis solar panels tilt with the movement of sunlight. For example, dual-axis solar panels can increase the number of sun peak hours in Texas from 5 to 6. The system helps adjust the solar panels’ position to face the direction where they have maximum sunlight exposure. Tracking can reduce shadowing and optimize the solar angles to expose the cells optimally.
7. Roofing Material
Solar panels work best under maximum exposure to sunlight. Some materials like iron sheets have higher irradiance than tiles. Another factor that can affect solar panel efficiency is the color of the material. Dark colors can increase the temperatures, thus reducing the performance of the solar panels.
8. Maintenance Practice
Clean solar panels regularly, especially in areas where it takes months before it rains or near roads, to avoid any fast deterioration in performance. You should also ensure there is no blockage from the snow. Low solar system maintenance can reduce the lifespan of the panels.
The efficiency of solar panels impacts the payback period and energy independence. Therefore, you should ensure the system is in top condition to avoid any unnecessary disruptions. On efficiency of solar panels during cloudy days, if in good condition, you should get around 25% of the total capacity. For example, an 8 kW solar system should produce approximately 2 kW during cloudy days.
