Understanding Efficiency of Solar Modules

Published by firstgreen on

Understanding the Efficiency of Solar Modules


Solar panels are usually able to process 15% to 22% of solar energy into usable energy, depending on factors like placement, orientation, weather conditions, and similar. The amount of sunlight that solar panel systems are able to convert into actual electricity is called performance, and the outcome determines the solar panel efficiency

Apart from the standard test conditions, solar panels are extensively tested for performance in extreme conditions.



Let us do an example calculation

Efficiency is the ratio of watts per square meter of output at STC to the irradiance at STC, which is 1000 watts per square meter.

For instance, if a PV module was making 200 watts per square meter, then 200 watts per square meter output / 1000 watts per square meter (STC) input = .20 or 20% efficiency.

Example  : 330W PV Module Dimensions 1698 × 1004 mm

1.69m × 1.0 m = 1.69 square meters

330W/1.69 square meters = 195 W/square meter

STC is 1000 watts per square meter

 195 W/1000W = 0.195

0.195 × 100% = 19.5% efficient PV

Important:  Do not use dissimilar PV modules in series. Here’s Why

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