Solar energy guidelines

The efficiency of a Solar Panel

The efficiency of the cells and the module

  • The efficiency of the module
  • The efficiency of the cell  
  • The efficiency of the Panel
  • Impact of shading on solar panels 

In the Behind of every solar panel, you can see some instructions and numbers, the essential information you should look for before you buy any solar panel is efficiency.


what is the efficiency of the module?

The efficiency of the panel( ηis the portion of energy received as radiations that are capable of transforming into  electricity 



η=electricity produced / radiation received 

The efficiency of the cell  

the efficiency of each photovoltaic cell is:

ηcell = electrical energy produced / [ radiative energy (w/m2) *Acell (m2)]

with: Acell is the area of one cell 


 The efficiency of the Panel

ηcell = electrical energy produced / [ radiative energy (w/m2) *Apanel (m2)]

the surface of the panel exposed to the sun’s rays is not equal to the sum of the surfaces of the cells composing it: A Panel ≠ Σ A cells. Because of the empty space between the cells of the Panel, the surface of the module is larger than the surface of all the cells: 
A Panel > Σ A cells. 
The empty surface between cells can not convert the rays into electricity.


Impact of shading on solar panels 

The shade is the first enemy of the solar systems, many workers in this field never realize the consequences on the efficiency of the system, after making a solar system for a  customer he comes to the installer asking him about the output power of his system  You made for him a  3 kilowatts system but he gets only 2.6 kilowatts and he never knew What is the reason cuz he is not an engineer.

Basically, the two main  damages causing by the shade are :   


First: the so-called Hot spots 

 Shade forme hot spots on the panel, the shaded part of the panel will warm-up, as a result of that, it dissipates the heat as a result of it becoming a load relative to the other shaded cells. With time and a lot of working in this area, watch this and know that well.

Second: loss of power

 is the quantity of energy lost from the system, especially in the case of connecting the panels in serials.

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