Hot spot (photovoltaics)

The hot spot effect (literally translated: hot spot effect) describes in photovoltaics the overheating of an area of ​​a solar cell module due to uneven incidence of light, which in extreme cases can cause a fire.

root cause

The hot spot effect occurs when individual solar cells within the series connection in the solar module are in the shade. These shaded cells cannot generate any electrical voltage themselves and instead act like an electrical resistor , since they are operated in the blocking range of their current-voltage characteristic. The other cells connected in series continue to generate an electrical voltage. If this voltage exceeds the reverse voltage of the shaded cells, the reverse voltage is broken and the full current flows. The voltage then drops as in an electrical resistance and is converted into heat, the cell can overheat until it is destroyed.

In order to avoid or reduce shading , a shading analysis is carried out before installation . In order to avoid the hot spot effect in the solar cell, free-wheeling diodes are connected in anti-parallel to a certain number of the solar cells connected in series.