There was about a centimetre of snow outside this morning, making the ground crisp and clear beneath the blue sky. I postulated that there would be a coating on the roof too. This postulation, at least, was correct.
I also postulated that clearing this snow off the roof would increase the generation, and sure enough it did. Before I cleared the snow, it was generating 1.5 kW, which is not bad for 8 o'clock on a winter morning. I cleared the bottom row of panels of its thin covering of snow, and it went up to 1.8 kW, an increase of 300 watts. The array is 8 x 6, so I'd cleared 1/6, which presumably had been generating 250 watts before, more than doubling when I removed the snow. Another way of looking at it is that the panels generate a little less than half as much electricity when covered with a thin layer of snow.
They will also be absorbing half as much heat, so, as before, clearing these bottom panels speeds up the clearing of the whole roof. Ten minutes later, we were generating over 5 kW.
One interesting thing was that the cosmetic panels, which run up and down each side of the roof to make up the difference between the width of the roof and the dimensions of the panels, were already completely clear of snow from the melting effect of the sun.
I should probably warn you not to try clearing snow off your solar panels yourself. The only reason it's easy and relatively safe in our house is that we have a balcony running along the south side of the house, so I can step onto it from upstairs and easily reach the roof from there with a brush. The biggest danger is bits of snow falling down my neck.
