Almost a PV catastrophe

 We recently has PV solar panels installed on the roof.The day we turned them on was cloudy, and they produced almost nothing. 18 cents worth of electricity. The next day was very sunny and resulted in about 75% of their designed power production midday and about $6 worth of energy, which is very good for a short day in December. 

Then we had two good sized snowstorms just before Christmas, and the resulting accumulation on the panels shut down production to almost nothing. Here's the week centred on Christmas Day. 

So what happened on December 27th to restore production? Mid-morning, the sun and warmth was finally uncovering the panels from their snowy blanket.

In the late morning after taking this picture, while I was checking the oil prior to our road trip, an angel came to me in a dream and suggested moving the car back from the house. 

Just before 2:00PM, while doomscrolling on the couch, I heard a loud rumble and felt the house shake a bit. Going outside, I saw this:

The pile was about knee high, and had this dense snowball of ~75-100Kg in the middle, I guess formed when the snow slid off the glassy smooth panels and fell 5 meters to the ground. If it had landed on our car, I think poor Sheila would be a write off. At least a new hood, windshield and some engine work.

It took 15 minutes to move the pile. 

Production immediately surged to a decent level, from 100 watts or so to about 3000 watts.

I'm not sure if we need to do anything to prevent these avalanches. We do need make sure to park away from the house, or in the garage. Would your standard metal roof snow breaks do anything useful?

The avalanche triggered a motion capture even on our security camera. You can see it come flying in from the upper left, mostly miss the small roof over top the garage, and plummet straight to the ground. Hopefully no damage to the roof.

In relating this story, I've heard some other ones. One friend of a relative had an avalanche like this into their backyard. Shortly afterwards, their dog went missing. They found it in the spring when the pile melted. 😧

The relative's sister had an avalanche fly off their roof across the deck and partially demolish a gazebo in the backyard.