Solar Panel Efficiency

Most commercially available solar panels have efficiencies around 12-17%. Thin film panels mostly are at the lower end, with crystalline panels at the mid to high end. But what does a high efficiency rating actually mean? Does a high efficiency panel mean that your solar system is going to generate you more kWhs? Not necessarily, here’s why.

Polycrystaline solar cells

Polycrystaline solar cells

The panel’s efficiency rating is based on the amount of the sun’s energy that it can convert into electricity. On a clear day the sun dumps about 1000 Watts of energy per/m2 at sea level. If a panel has a 15% efficiency rating, it means that 15% of that energy is turned into electricity. So if the panel was 1m x 1m it would be 15% of 1000W or a 150W panel. These days, most panels are around 250W and have a larger surface area, more like 1.7m2.

So what happens if we have a high efficiency 250W panel of 20%? Basically the surface area gets smaller; a 250W panel at 20% efficiency has a surface area of 1.25m2. Both panels have the same output – 250W, but are different sizes. So in terms of the way a system with high efficiency panels performs, compared to one with lower efficiency panels, if all things considered are the same the output will be the same. In a 3kW system with 12 x 250W panels, the lower efficiency panels will just take up a larger area – 20.4m2 compared to 15m2.

When you are deciding on which solar panel to choose, there are a number of things to consider. A high efficiency panel can be a good option if you have a restricted roof area, but if you are looking at system performance there are other factors to take into account.

Green Energy Options offer a range of different solar panels including the Sunpower E20/327, which at 20% efficiency, has the highest efficiency of any commercially available panel. If you would like to advice on solar options for your property please give us a call on 1300 929 931 for a free consultation.