Is solar panel efficiency important?


Solar panel efficiency measured by how much of the sunlight that falls on it is turned into electricity. Solar panels efficiency ratings range from 15% to 23% depending on the manufacturer. You would think it makes sense that the better the efficiency of a solar panel the better the product and the more energy you get?  Well, no….. we will explain why below. 

Solar panels are sold on by their peak power rating in kW, not there physical size.

This means a 6 kW solar power system with 15% efficient panels will require 24 of them, while with 20% efficient panels only 18 will be needed. Both systems will give you the same amount of energy, but the lower-efficiency system will take up more space on your roof because you’ll need more panels. It’s often cheaper to install 24 less efficient than 18 more efficient. You will generate the same amount of power. Higher efficiency panels are more expensive as they use the latest technology.

Unless your roof isn’t big enough (and most domestic roofs are) it’s not economical to pay more for a higher-efficiency system.

So in most cases efficiency, is not important.

There is an exception, that in the near future, roof space is going to become more valuable. As batteries become cheaper, people will install more home batteries and electric cars, all of which need charging. Therefore in theory the best way to prepare for this is to have the most efficient solar panels you can, leaving space for even more as you need them. It’s a big if, and something we currently think is not worth the extra investment.


If you are interested in installing solar panels then fill out the form below and one of our team will get in touch with you to see how we can help.