Solar panel efficiency is based upon the amount of power produced in one square meter during peak irradiation. A one square meter solar panel would produce 1,000 watts of power at 100% efficiency. Most solar panel efficiencies range from approximately 12-19%, depending on, among other things, the materials used to produce the solar panel. The name plate capacity of a solar panel takes the panel’s efficiency into consideration, so a 270 watt solar panel will produce 270 watts of power at peak irradiation regardless of the efficiency of the panel. A 270 watt solar panel that is 12% efficient would be larger than a 270 watt solar panel that is 19% efficient, but both solar panels would be capable of producing 270 watts of power under standard test conditions at peak irradiation. Efficiencies are also affected by environmental impacts such as temperature or soiling. As solar experts, we coach you on how to keep your system running at its peak efficiency.