Last Friday night (1/20/12) we had a couple of inches of snow in a short time. The next morning was very sunny & bright. I was interested to see how fast the sun would penetrate the snow and begin heating up the panels. About two hours after sunrise, several of the panels started shedding their snow. You can see here in this snapshot of a portion of our solar array the difference in performance by the snow covered vs cleared off panels.
One of the panels is generating 260 watts while the snow covered panel right next to it is only at 59 watts. Within about one hour, all of the snow had completely melted and all the panels were at full strength.
Check out the solar tab on the blog to see real time updates.