Solar Cell Efficiency vs Solar Panel Efficiency

by Shawn Roe | Be the first to comment

My prospective supplier states that the Schuco 210 watt SMAU-1 panel has a cell efficiency of 16.8%, whereas your table gives a panel efficiency of 14.93%. What is the difference between panel and cell efficiency and which should be my guide?

Great question.

Confusing chart of solar cell efficiencies
Confusing chart of solar cell efficiencies

Cell efficiency is measured as the percentage output of energy to the theoretical amount of energy supplied by the Sun (hitting the cell). So if 100 Watts hits the cell (under Standard Testing Conditions, STC, which is laboratory conditions), and it spits out 16.8 Watts, then the cell efficiency is 16.8%.

My table gives panel efficiency of how much output of energy (as measured by PTC, which is the realistic test conditions of a panel on a roof) to the amount of space that panel takes up in squarefoot area.

Your supplier is right, but if you want a point of comparison, ask him to give you the “cell efficiency” of all the competitor’s panels. What my table allows you to do, is compare all the panels (eligible for rebates in CA, which is more than 1,700 8,700) by the panel efficiency. Though our efficiency measurements are slightly different, mine are standardized across all panels using the data that CSI (California Solar Initiative) uses to pay rebates. So, you can easily see how Schuco 210′s compare to any other 210 panels (or 200, or 220, etc…)

Hope that answers your question. He’s not lying. My table just gives you a bit more information to allow you to compare solar panels more easily.


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