The problem with snow is that being white, it doesn't absorb much solar energy, so despite the gloriously sunny days that usually follow a fall of snow, you get zero kWh out of your PV until it eventually starts to melt - which can take several days even if there is no more snowfall.
Angle seems to help - if air temperatures go above freezing, the snow will slowly melt and if the panels are steep, the snow will slide off the panels, at least to some extent. But low-angle or flat panels don't benefit from this.
What I've found is that if you can clear some snow from the panel, the dark coloured PV cells start absorbing heat, and this quickly melts any residual snow. Even if you just clear half of the panel, this heat will start to melt the snow on the uncleared section, and I think if the voltage is high enough to start some power flow, the resistance of the PV cells still covered in snow will turn them into heaters, accelerating the melting of the snow above them.
I usually clear my panels with a window rubber blade - freshly fallen snow clears very easily, but if it has thawed slightly and refrozen (ie sat there for 24hours or more), it tends to stick quite tenaciously to the panel.
I have wondered whether a rod full of small holes blowing compressed air might clear panels effecctively. Or even, possibly, sprinkling the snow with some dark powder to make it absorb heat.
In the pictures below:
Snow from yesterday has slid down the panel and frozen on the lower half, then fresh snow covered the whole panel this morning - I've crudely scraped the easy snow off the top half of the panel
within about 15minutes, the snow on the lower half had unstuck itself, and easily slid off with a bit of help, any residual snow quickly melts, so you don't have to be too thorough. You can see the difference between the ones I haven't touched - still completely covered in snow.
repeating the process for the last 5panels.
