Solar Cell Efficiency VS Solar Panel Efficiency

When trying to decide on the best panels for your system, you might find yourself seeing two types of efficiency indicators on a datasheet. What is the difference between cell efficiency and module efficiency? 

Let’s start with how efficiency is calculated in the first place:

Let’s take for example the PEIMAR SG300M 300W solar panelto compare cell and module efficiency:

Cell efficiency is quite higher at 21.65% versus module efficiency at 18.33%. The reason for this difference is that cell efficiency is calculated as the energy hitting the individual cell, while module efficiency is the whole panel. Since solar panels often have spacing in between cells, some energy is lost. Solaria solar panels avoid that by having cells tightly together, thereby maximizing the solar panel’s space.


Why is efficiency not 100%?

100% efficiency means that a solar panel would be able to output the same amount that the sun gives off to the panel. The reality is that solar panels currently can only capture a small percentage of that energy to convert into usable energy.
This goes for other methods of producing energy as well, such as traditional fossil fuel energy generators. For example, when burning fuel, more than half of the energy is lost due to heat in the environment.
While capturing 100% of the imputed energy may not be possible, solar panel manufacturers are constantly improving efficiency.

What does that mean for you?

A high efficiency is an indicator of an overall high quality solar panel and thereby a longer lasting panel. On the other hand efficiency should never be your only consideration factor; the solar panel’s cost, size (such as 60 vs 72 cell), wattage and warranty are also key figures to consider.


“GCSE Bitesize: Efficiency of Power Stations.” BBC, BBC, www.bbc.co.uk/schools/gcsebitesize/science/21c_pre_2011/energy/generatingelectricityrev4.shtml.