The solar industry and marketplace uses the word panel efficiency quite often when rating and comparing panels across the market. This can become confusing and difficult for consumers to understand when making the decision to purchase a solar panel from a manufacture. To make the concept of efficiency easier to understand, allow us to break it down to the basics.
Every panel from every manufacture will have a different rate of efficiency. This efficiency rating is the amount of energy the panel is capable of displacing per square inch of surface space. While efficiency is important to some degree it is not the single most import aspect when considering a panel manufacture.
All solar panels regardless of their efficiency will have an industry standard wattage assigned to them. The most common wattage is 250 watts. If we look at several 250 watt panels from different manufactures, all will have different efficiency ratings. This means that while each of the panels will produce the same 250 watts of energy, they will all be a different physical size. A higher efficiency will take up less space on the roof than a low efficiency panel. Essentially, efficiency is important, but only to those with limited roof space.
If almost all cases in Arizona due to our peak sun hours, roof space is not a primary concern. Because of this any Teir 1 manufacture will be adequate, as efficiency ranges are all very close to one another. There is no real need to increase the investment on a panel for a petty 1-5% efficiency increase when the costs could be nearly 40% higher. Efficiency ratings save a few feet of roof space, they don’t change the system size or annual savings.
Simply put, a 8kw system with a panel efficiency rating of 14% will produce the same amount of energy as a 8kw system with an efficiency of 15%, the only difference will be the overall size of the system on the roof. If your roof is big and open, don’t waste money getting caught up in the efficiency game.