There has been a huge rush over the last few years to build PV plants in Gujarat & Rajasthan based on the solar irradiation received. Little attention is paid to how modules perform at 40 deg C in dusty conditions. Contrary to expectations, plant operators may find better performance in the winter.

I met an experienced installer who said that he measured a 150Wp poly-crystalline panel (manufacturer will remain un-named) putting out 3A @ 19V at mid-day in 40 deg heat. Most module manufacturers will list the loss in power per degree above 25 deg C in their data sheets but what most won't tell you is that the loss isn't linear - the hotter it gets the greater the losses are. So the data sheet will state 0.5% power loss per deg C - so a 7.5% loss if you're at 40 deg. But this 0.5% is per deg above 25 deg C near 25 deg. What's the loss per degree at 35 deg C ? I don't have data but if I were to guess it's closer to 2%.