The efficiency of your solar roof is its ability to convert sunlight into usable electrical energy for consumption. It is important to know the efficiency of the solar panels so as to design an optimum solar power system. If you are having space constraints then you need more efficient solar panels and if you have ample space for your solar roof then you can trade off with less efficient solar panels.
Power under Standard Test Conditions
(More efficient solar panels produce more wattage per unit area and require less space while less efficient solar panels need more space to produce the same amount of wattage)
Let us calculate the efficiency with the help of an example:
The following table shows the Panel maximum power under STC and the area of the panel.
It is the area (length x breadth) of the solar panel which decides its efficiency.
Efficiency of the solar panel
The radiation flux is the amount of sunlight falling on the surface of the earth. It is measured in \(Watt / m^2\). The radiation flux under Standard Test Conditions is \(1000 W/m^2\)
Now, calculating the efficiency of the solar modules of different Pmax and the area:
Let us suppose that you want to install 3 KW roof top solar system to meet your daily energy needs, but you have a limited space at the top which is suitable for the installation. The total shadow free area available is \(23 m^2\), now you have to find out the best possible system which can be accommodated at your roof top and at the same time is the most efficient.
Let us calculate the number of solar panels required and the total area covered by them.
For 200 watts solar panels,
(I am not taking into consideration the gap in between the two panels which is generally provided for air to pass through to the keep the panels cool)
Therefore, 300 watt 10 solar panels having 15.46% efficiency are ideal to meet your desired demand and can be accommodated in the limited space at the roof top.
If you already have installed the solar roof at your house, then also you can calculate the efficiency of your solar roof as follows:
\(È max\) (Maximum efficiency of the solar roof) is as follows:
So whenever next time you decide to buy a panel, consider its efficiency before paying the price for it. You might have ample roof area which can accommodate less efficient panels. But when you are having a limited space, then efficiency plays a major role in designing the solar power system which can meet your electricity demand in a limited roof top area.