Solar Cell Efficiency

Posted on 01/12/2018 at 12:00 by Daniel Stieler Phd

Solar Cell Efficiency Blog Post Title Graphic


What exactly does solar cell efficiency mean?

If you’ve spent any time in the solar industry you understand that one of the first questions out of a person’s mouth when it comes to solar technology is, “how efficient is it?”

While the measurement of solar cell efficiency is standardized and relatively easy to understand, it can often be misleading in real world applications.

Solar cell efficiency is not comparable to the energy efficiency of your furnace or water heater. If your furnace is higher efficiency that leads to a decrease in your utility bills and more money in your pocket.

That is not what solar module efficiency is. 


The efficiency of a solar cell is actually the amount of power the module will produce divided by the area of the module (Watts/Square Meter).

So efficiency only comes into play when you are determining the amount of area required to produce a given amount of power. Whether a module is 5% efficient or 20% efficient, if it will produce 10W that is what you will get.

Also, efficiency is only applicable to modules that are used outdoors. This is due to the fact that the light spectrum of the sun is very different from indoor light sources.

For example an amorphous silicon cell that is 6% efficient outdoors will produce more power per square meter under an LED light indoors than a 20% efficient mono crystalline silicon module.

This happens because LED lights produce light primarily in the visible spectrum where the amorphous silicon is absorbing light to generate power.

The mono-crystalline silicon cells are higher efficiency outdoors because they convert much of the infrared light from the sun into power, but LED lights produce little infrared light.

So the next time you have a project that requires a specific amount of power you might be surprised what technology best meets your needs.

While efficiency is undoubtedly important it is only one aspect of what will create the best solution for you.

Do you have a project that we can help power? We would love to speak with you. 


Contact us or leave a comment below.



Categories: Solar Education