A PV module is mainly a unit which is made up of several different PV cells with the aim of generating power by making use of un-concentrated sunlight. They are often used to supply electricity in both commercial and residential units.
So, when designing PV modules, the heat generation dynamics is something which you need to be thoroughly acquainted with. Let us get down to the specifics.
The sunlight absorption
For any PV module to work efficiently, it needs to absorb the maximum amount of sunlight. Mostly, it is only 10 to 15% of the incident sunlight which gets converted into electric power by the PV module and the rest of it gets dissipated as heat.
So, what are the key factors which lead to such a massive loss? Let us take a look.
Heat loss factors
The top surface of the PV module holds a crucial role as light tends to get reflected from there.
Temperature rise (max) = incident power X reflection.
This shows that the reflected light doesn’t even heat up the module effectively. It simply leads to a loss of energy.
There are parts of PV module which aren't covered by solar cells. These parts too absorb sunlight which fails to get converted to electricity. The colour and material used for the back layer of the PV module at the rear end assumes massive importance. To minimize energy loss, one has to be careful in these aspects of designing.
The density with which solar cells is packed is also important for heat generation in a PV module. A very high packing factor tends to increase the overall heat generated per unit area simply because the solar cells are known to be one of the best absorbers of solar radiation. The heat generated could be much more than the module encapsulation which is already present.
Electrical operating point
One has to be mindful of having the right electrical operating point in the unit for optimum energy utilization.
Some of the solar cells may end up absorbing the infrared part of the light. They are of lower energy and thereby impact the output.
At the back side of the solar cells, aluminium is present. This is responsible for absorbing infrared light. If you make solar cells which lack the aluminium coverage at the back end, the infrared will be able to easily exit from the module and thereby the heat generated could be lessened.
So, these are the key factors which contribute to heat generation in PV module. By making note of it, one can maximize the energy generated and reduce the heat loss as well.