Ashburton action 3

COHO. Just over the hill from the logs, we came across a field full of solar panels, with this snap capturing rather more of the damp and the cold than action 1 below.

How much power were they getting out of them in the absence of sun? How much UV was making it down to ground level? How much did they lose by being on a north facing hill side, rather than south facing? Or perhaps northwest at a pinch; maybe they just catch the sunset.