Life span of solar panel is statistical measure of percentage of power generated over years against the rated power of the panel. Usually it is measured in years. General rule is solar panel will degrade at rate 0.5 to 1 percent a year. To work efficiently it has to produce at least 80% of the rated power. Hence, one can consider life span to be above 20 years considering the degradation percentage.
Example: Consider a solar panel of rated power 100 Watt. Hence, to work efficiently it needs to generate at least 80 Watt. Below we shall calculate with various degradation percentage.
Formula for calculation: Efficiency = Watt – Watt * Degradation Percentage / 100
Life Span for Solar Panel with degradation rate of 0.5 %, 0.8% and 1 % considering solar panel Watt = 100
Above Table indicates, with 0.5 and 0.8 % efficiency if over 80%. Hence Solar Panel Life Span in 25 Years. However, with 1 % efficiency it is over 80% for 20 years, solar panel life is 20 Years.
Degradation rate means accurate quantification of power decline over time. Solar panel degradation is caused by caused by thermal stress and mechanical influences that will impact the components of the solar panels.
Geographical Location: Rate depends of climatic condition. There will be high degradation in extreme temperature (Cold, Hot, Snow Fall, Windy). Moderate climatic condition such as in India, degradation rate us very low.
Physical Damage: When there is damage to solar panel, efficiency is decreased considerably with dust, water seepage and blocking of sunlight due to scratches.
Life Span for Different Types of Solar Panel.
Mono crystalline and Poly crystalline panels have almost similar life span. However, degradation rate of poly crystalline is higher (0.6) than Mono crystalline (0.4). This does not make much difference as both can last up to 25 years easily.