Recent data from the National Renewable Energy Laboratory (NREL) shows solar arrays can reach temperatures up to 65°C (149°F) – that's hotter than your morning coffee and roughly equivalent to frying an egg on your rooftop!Recent data from the National Renewable Energy Laboratory (NREL) shows solar arrays can reach temperatures up to 65°C (149°F) – that's hotter than your morning coffee and roughly equivalent to frying an egg on your rooftop!.