By: Bryan Accra - PVPower.com Contributor - January 14, 2009
The most efficient solar panels are the panels that give you the most power while using the least area. A simple way to determine the efficiency of a panel is to divide the panel’s maximum power rating (Pmax) by its area (A) to find out which panels give you the most power per unit of area, or energy density . Several manufacturers also list the panel’s minimum or maximum efficiency in their specification sheets. If you have two 100W panels and one takes up an area of 9 square feet while the other has an area of 8 square feet, by a simple calculation of Pmax / A, you can easily see that the 100 W panel with an area of 8 square feet is the more efficient panel.
Solar panel efficiency is important for those who have limited rooftop space, but desire a greater power output than panels with average efficiency can offer. Assume you have a rooftop area of 50 square feet available for placing panels, and want a 700W system. The less efficient panels would not be able to deliver the power needed for this area. Therefore, you would have to invest into more efficient panels to meet your power needs.
What efficiency can you expect when setting out to buy the most efficient solar panel available? Typically, crystalline silicon based panels average about 12% efficiency up to 20% for the best commercially available. However, the most efficient panels are used for more advanced applications. Expectations in efficiency should be tempered to a difference of a few percentage points from the average of 12%. While seeming like a small difference, it could be the difference between a 300 W system and a 400 W system when roof space is limited.
While there are several solar panels to choose from in the market place and finding the most efficient panel can be a tedious task, I have narrowed down my comparison of solar panels to those offered by PVPower.com. I have found from comparing solar panels offered by PVPower, that the most efficient panels on a W/area basis are:
1. Sharp 245W Solar Panel, Monocrystalline, Clear, NU-U245P1 with an energy density of 13.97 W/ft2
2. Sharp 240W Solar Panel, Monocrystalline, Clear, NU-U240F1 with an energy density of 13.68 W/ft2
3. Suntech Polycrystalline 280W Solar Panel (STP280-24/Vb1) at 13.39 W/ft2
4. BP 230W Solar Panel, SX3230T at 12.81 W/ft2
Although the efficiency of a panel may be important in making your decision, there are many other factors to consider beforehand, when purchasing solar panels. We will discuss these factors in the next article.
Download full article on how to Measure PV (Solar Panel) Efficiency
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