Measuring PV Efficiency – How Efficient Do Solar Panels Have to Be?
efficiency in photovoltaic solar panels is measured by the ability of a panel to convert sunlight into usable energy for human consumption. Knowing the efficiency of a panel is important to choose the right panels for photovoltaic system. For smaller roofs, more efficient panels required due to space limitations. How manufacturers can determine the maximum efficiency of a photovoltaic solar panel though? Read below to find out.
Let’s first start by saying that the maximum power, also known as Pmax, a 200W panel is 200W, regardless of the efficiency panel. It is to use the area of the solar panels to those 200W which determines how efficiently to obtain the panel. The efficiency panel determines the ability of a panel per unit area. The maximum efficiency of a photovoltaic cell is given by the following equation:
ηmax (maximum efficiency) = Pmax (maximum output) / (ES, γsw (incident radiation flux) * Ac (surface of collector))
The incident radiation flux can be better described as the amount of sunlight that hits the earth’s surface in W / m2. The supposed incident radiation flux under standard test conditions (STC) that manufacturers use is 1000 W / m2. Keep in mind though, that STC includes a number of assumptions and depending on your geographic location.
Now we are going a sample calculation to determine how the manufacturers charge up the maximum solar panel efficiency under STC.
Suppose you have set a 400W system with an area of 30 ft2 and you want the maximum performance from your solar panels under STC. Your first step would be the area of your panels’ to turn in units of square meters which is:
30 ft2 x 1 meter / (10.76 ft2) = 2.79 m2
(in determining the efficiency, I would personally also the dimensions of the frames in your calculations. While they are there for structural purposes, they are necessary components that do take areas)
Now that you have your Pmax (400W), ES, γsw (1000W / m2), and Ac (2.79 m2), you can plug your numbers into the efficiency equation where all units will raise and then multiply the value by 100% to you rate your efficiency give
ηmax (in percentage) = 400 W / (1000W / m2 x 2.79 m2) = 0.143 x 100% = 14.3%
This would be the maximum efficiency of be your solar panel not to be confused with the minimum that can be found on the product description of the panel.
So if you determine which solar panels are for you, think about how important the efficiency of the panels are in paying a premium price. Maybe you have a roof with a large area that would be ideal for the installation of solar panels, and therefore, would lower costs and less efficient panels work for you. If your roof area is limited but you can the efficiency you need for your panels to achieve the desired output over a limited area to determine.
Source: http://ezinearticles.com/?Measuring-PV-Efficiency—How-Efficient-Do-Solar-Panels-Have-to-Be?&id=3577736 by Bryan Accra