Modules come in a variety of sizes, types and ratings. The electrical performance of PV modules is given for Standard Test Conditions (STC). The common types of panel technologies used are mono-crystalline, multi-crystalline and thin film. The related cost of silicon-type panels depends on the layers used. The variation of temperature highly affects the efficiency of the module, for e.g. in Si-type, as temperature increases, the efficiency increases resulting in higher output and lower space site.
Traditionally, solar modules had 36 cells in series that could only be able to provide overvoltage to charge a 12V battery. With the advent of time, the number of cells in series has been increased to produce larger voltages such that there is compatibility with inverters for AC grid-tied systems.
Mounting components of a PV module:
Clear front cover (UV resistant plastic - watertight)
Cells in series
|Material base||Band gap, Eg (eV)||Direct, D or Indirect, I||Example of cell||Efficiency of commercial cell (%)|
|Multi-crystalline Si||-||-||Commonest commercial cell||13|
|Amorphous Si||-||-||Thin film or ribbon||~8|
|CdTe||1.4||D||Thin film (heterojunction with CdS)||~8|
|CdS||2.4||D||Only in heterojunctions||~8|