PSA: Don't park your car below snow-covered PV!

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RegGuheert

Well-known member
Joined
Mar 19, 2012
Messages
6,419
Location
Northern VA
Just a note for those new to PV and snow. If you have a driveway below the edge of a PV-covered roof, be sure to never park a car there when there is snow coming or already on the PV panels. It can slide off and damage your car. (You can see pictures of the PV panels on our garage in the links in my signature.)

Sorry, I don't have any disaster pictures from our system (yet!), but apparently this can be a costly mistake. I was reminded of this today when I went outside to see that the 6.5" of snow + sleet + freezing rain we got yesterday is still up there and ready to let loose as soon as it warms up enough.
 
Nice warning. Fortunately my garage roof gable end faces the driveway, which was nice since then the garage roof is north/south :) I have a similarly full roof as you and think it's probably worth the effort of clearing the snow as it accumulates as I could see it all sliding off at once and taking out the gutters. The last time it snowed it slide off the panels hitting the roof/gutter and then stopped sliding but it wasn't very much snow.
 
QueenBee said:
I have a similarly full roof as you and think it's probably worth the effort of clearing the snow as it accumulates as I could see it all sliding off at once and taking out the gutters. The last time it snowed it slide off the panels hitting the roof/gutter and then stopped sliding but it wasn't very much snow.
I think there is essentially no chance of ice taking out the gutters on our garage since the top surface of the panels is about 6" directly above the gutters.

The gutters on the house may be another matter altogether. Sometimes the snow sheds off the panels and goes all the way to the ground and other times it creeps off onto the roof as yours did. But I suspect there is an in-between mode which includes gutter removal. This is our fourth winter with the array up there and we haven't lost it yet!

I did buy a roof rake a couple of winters ago when we had three feet of snow and my house looked like a small version of the winter palace in Dr. Zhivago. But that is quite a bit of work and I only get it out if there does not appear to be warm weather coming. Somehow, the snow has managed to stay put so far, in spite of rather comfortable temperatures today. I hope it doesn't hold on until this evening.

I now consider the sliding snow to be my annual PV cleaning regime, since I imagine it does a decent job of scrubbing the surface dirt off of the panels. Come to think of it, since this is the first decent snow this winter, perhaps that dirt is what is holding the snow on the panels today!
 
RegGuheert said:
I did buy a roof rake a couple of winters ago when we had three feet of snow and my house looked like a small version of the winter palace in Dr. Zhivago. But that is quite a bit of work and I only get it out if there does not appear to be warm weather coming. Somehow, the snow has managed to stay put so far, in spite of rather comfortable temperatures today. I hope it doesn't hold on until this evening.
Unfortunately, the snow DID manage to hold on until Sunday night and then another four inches got added on Tuesday. As a result, we had about three inches of snow from Sunday (after melting and compression) topped by about 1/4 inch of sleet and freezing rain which was then covered by four inches of wet snow on Tuesday. While this amount of snow is no threat to the integrity of the roof, it certainly eliminates any chance of producing electricity from the roof for the next few days with the cold setting in.

Here are some pictures:
PVRoofRakeGarage20131211.JPG
You can see the result of my roof raking of the garage PV panels. Those are clear now after the melting yesterday afternoon. You can see what the roof rake looks like sitting on the driveway and you can also spot the wovel sitting behind the Honda Civic Hybrid.

PVRoofRakeHouse20131211.JPG
It is much more difficult to rake the panels on the house due to their higher location on the roof and the fake gable there. Only three panels are fully exposed after melting and the rest will likely remain covered for the next few days.

SnowView20131211.JPG
This picture gives the view in the opposite direction so that you can see what the snow looked like yesterday. The driveway is a bit over 5000 square feet and I was able to clear four inches of wet snow in about 1.5 hours using the wovel! Love that thing!
 
RegGuheert said:
...and you can also spot the wovel sitting behind the Honda Civic Hybrid...

...I was able to clear four inches of wet snow in about 1.5 hours using the wovel! Love that thing!

OK, what the heck is a wovel? Never heard of it; made me google it.
Great idea! I sure could've used one of those last season.
 
eclecticflower said:
RegGuheert said:
...and you can also spot the wovel sitting behind the Honda Civic Hybrid...

...I was able to clear four inches of wet snow in about 1.5 hours using the wovel! Love that thing!

OK, what the heck is a wovel? Never heard of it; made me google it.
Great idea! I sure could've used one of those last season.
Yeah, that thing is amazing! I moved ~1650 cubic feet of wet snow and I didn't even get a backache! Coming from someone with a weak back, that is high praise indeed!
 
My garage roof also sheds in front of the garage door. I usually have to shovel the snow pile to get the cars out (although in recent days it has been so cold the snow didn't slide off the roof until today). If I had it to do over again I'd design the roof structure differently.

Had my first zero solar day in more than a year on December 4th — it snowed from dawn to dusk, which is unusual here in sunny Colorado. But yesterday was the best production day since October 23rd, despite the short days and low angle of the sun: cold + cloudless day = great solar!

5pfo.jpg

My solar panels on October 4th before pulling the snow off.
 
dgpcolorado said:
My garage roof also sheds in front of the garage door. I usually have to shovel the snow pile to get the cars out...
Yeah, I should have taken a picture of the big pile of snow behind the cars before I moved it off the driveway. Normally it arrives there without my assistance.
dgpcolorado said:
My solar panels on October 4th before pulling the snow off.
Is that a squeegee with an extension pole that you use for clearing the panels?
 
RegGuheert said:
dgpcolorado said:
My solar panels on October 4th before pulling the snow off.
Is that a squeegee with an extension pole that you use for clearing the panels?
Yes, a window squeegee on a long painter's pole. Works well and doesn't harm the glass. I use a snow cutter for the roof when I want to take the snow off in places, but the roof is metal so it usually sheds pretty well.
 
dgpcolorado said:
My garage roof also sheds in front of the garage door. I usually have to shovel the snow pile to get the cars out (although in recent days it has been so cold the snow didn't slide off the roof until today). If I had it to do over again I'd design the roof structure differently.
Seven Words:

Snow fence and a large everything pizza.

(Actually, just the snow fence, I just added the pizza to pad to seven words. ;) )

There are various types. We used a finer opening on steep roofs in Nrn Michigan, saw some in Germany as well.

0014.JPG


http://rockymountainsnowguards.com/
 
AndyH said:
Seven Words:

Snow fence and a large everything pizza.

(Actually, just the snow fence, I just added the pizza to pad to seven words. ;) )...
I prefer that the snow slides off the roof; I don't mind shoveling it from the garage entrance and everywhere else it isn't an issue. The big problem I have is the north facing roof valleys: the snow turns to ice and the glaciers + gravity have damaged my metal roof. I've considered heat tape but it would be awkward to install and is a waste of electricity, so I now use my snow cutter to pull the fresh snow away from those valleys. In retrospect I wish I had designed a shed roof profile that had no valleys for snow to build up and turn to ice. Live and learn.
 
The snow that has been lingering on my lower panels for days apparently cause the Enlighten website to flag 6 of the panels/inverters as broken. I guess I should get a really long squeegee...
 
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