How important is the efficiency of the solar panels when comparing solar panels?

Invariably when a customer is considering going solar they will have two or more companies pitching for their business with different solar panels.

Often the solar contractor with a higher efficiency panel will cite it as a good reason why you should purchase their system, it sounds reasonable that a solar panel with a higher efficiency should be more expensive than a system using less efficient solar panels but is it really worth paying more for panels with higher efficiency?

Efficiencies range from as low as 10% for cheaper thin-film panels to 14-15% for most polycrystalline panels and up as high as 20% for some panels that use more advanced technologies (or combinations of technologies). But does this mean that a consumer buying a 5kw system with a panel that is 18% efficient will get more kwh’s of solar electricity than a person buying a solar power system with panels that are 14% efficient?

The answer is no! They will both get the same amount of power produced because the efficiency of the solar panel is already taken into account when rating a panel. This will mean that if two panels are both 300 Watt panels then they both produce 300 watts of power at standard test conditions (25C).

The only difference may be that the more efficient panel may have physically smaller dimensions because it needs less irradiation (and therefore less surface area), to produce its solar electricity, compared to a less efficient panel.

This is not to say that it is never worth paying a premium for a more efficient panel. The obvious case would be a situation where you have limited roof space and want to generate the maximum amount of power. There is an argument, in this case, to pay for a premium panel.................READ MORE