In the Sun Belt regions, the high irradiation leads to a high ambient temperature, and therewith a high module temperature. Due to an intrinsic property of the silicon, the module power decreases linearly with increasing temperature, which is a well known fact in the PV industry.
The parameter that describes this behaviour is the socalled temperature coefficient. The J.v.G. Thoma DESERT cell has a very low temperature coefficient compared to standard solar cells.
Another approach how to meet the problem of decreasing power at higher temperatures is the cooling of PV modules. Here J.v.G. Thoma offers a DESERT Hybrid module