7 Dec 2010 Snow on Panels

Snow does fall and stick to solar PV panels! Contrary to what solar salesmen say, it doesn't "just slide off", nor do the panels generate enough heat to melt the snow all the time. The sun must be bright and providing significant direct radiated heat onto the panel surface for snow to melt. This should come as now supprise when you think about it, but it is not the same message an aspiring solar system owner hears from the solar sales people. Quite often they may not have experienced seeing their systems installed long enough to provide an accurate picture of snow duration on panels.
What I found was:
- the panels are largely the same temperature as ambient under heavy overcast conditions
- snow drifts and remains on panels much like it did on the roof prior to panels
- snow will not slide off unless the panel surface is above freezing temperature.
- partial snow coverage (see photo) significantly decreases power generation, not much above generation of full snow coverage
- power generation may not be a substantial less during snow-covered days as production can be very low during heavy overcast days
Now that December 2010 is over I shall publish the month's results and my observations.