Snow Build up Modifications

peakbagger · January 2014

Observing my new shallow roof mounted rack, its obvious that the snow build up has an aerodynamic component to it. The snow tends to build up about 1/4 past the leading edge of the panel and then the wind scours the rest of the panel. I am considering what sort of modifications could be made upwind of the panels to increase wind scouring. I envision the sort of deflector used on station wagons to clean the rear windows off. As long as the foil does not shade the panel it would be an interesting experiment. Alternatively I am curious if having the panels butted up tight to each other is a plus or minus.

Obviously mounting them at a proper angle (like vertical) is the best option but it would be interesting to see how a shallow angle could be improved.

westbranch · January 2014

Re: Snow Build up Modifications

A pic will be worth a 1000 + words.

Ralph Day · January 2014

Re: Snow Build up Modifications

Just depends on where the wind is blowing from. I had a storm from the southwest, the panels are clear and there''s a 5 foot tall drift behind them. Wind from the north would have deposited some of the snow on the panels.

If you can get at them a pool cleaning brush on a telescoping pole gives you the ability to brush snow off panels 12 feet off the ground (like mine).

Ralph

niel · January 2014

Re: Snow Build up Modifications

i'm having trouble picturing what you have in mind as well for the foil. in general with small gaps between pvs some lighter snows are free to fall off and not onto the next pv below it, but with a foil arrangement you might then need it for the bottoms of each pv row.

i haven't been utilizing my solar much lately due to many reasons, but the nasty cloudy and snowy days are the primary reason. i did use it the other day with temps near zero on my old us 64s and i was surprised to see a voc of 25v and the nominal rating is 21v or 21.5v as i forget offhand. i have never seen it this high before in all the years i had them (11). it was frigid with lots of snow and very clear strong sunshine. temps are far below normal with higher than normal snowfalls for the entire season. i'm over it.

vtmaps · January 2014

Re: Snow Build up Modifications

peakbagger wrote: »

Observing my new shallow roof mounted rack, its obvious that the snow build up has an aerodynamic component to it. The snow tends to build up about 1/4 past the leading edge of the panel and then the wind scours the rest of the panel. I am considering what sort of modifications could be made upwind of the panels to increase wind scouring.

After I read the OP, my first thought was "snow fence". Around here folks with windy sites put snow fences parallel to their driveways to prevent snow from drifting onto their driveway. The height of the fence and distance form the driveway are critical.

I tried to read up a little on the aerodynamics of snow fences to see if I could come up with something intelligent to advise you, but the stuff is too complicated for me to figure out how it would work on a roof.

--vtMaps

northerner · January 2014

Re: Snow Build up Modifications

I use a broom to clean off the snow from my panels which are on my roof. I made a long extension handle that allows me to do this from the ground. My panels are tilted up at a steep angle in winter (15 deg off vertical) to allow most of the snow to slide off. This works well here in northern Alberta, as temps in winter are usually well below freezing, and the snow is powdery.

peakbagger · January 2014

Re: Snow Build up Modifications

I had some heavy wind and the panels cleared off, thus no way of taking a picture of the buildup. Next time it builds up I will take a photo.

The panels are on a second story on a shallow pitch, no good way to clean them from the ground. I have used an extension ladder but not something I plan to do frequently. These were "bonus" panels, bought cheap and installed on roof as I didn't want to build another pole mount. I figured they would build up in the winter but would make up for it the times when I don't have snow.

niel · February 2014

Re: Snow Build up Modifications

northerner,
where you are i'd bet that 15 degrees is probably pretty close to the ideal for winter solar production and not just for snow removal. not sure of your latitude though. i'll bet your solar window is a very short time period in winter.:grr

zozomike · February 2014

Re: Snow Build up Modifications

You might take a look at this idea http://rimstar.org/renewnrg/venturi_solar_panel_cleaner.htm

northerner · February 2014

Re: Snow Build up Modifications

niel wrote: »

northerner,
where you are i'd bet that 15 degrees is probably pretty close to the ideal for winter solar production and not just for snow removal. not sure of your latitude though. i'll bet your solar window is a very short time period in winter.:grr

15 degrees off vertical is ideal for both snow removal and solar production here in winter. I'm located just north of 56 degrees latitude, so yes the solar window in December is very short. I just happened to have a clear sunny day on the winter solstice this past December and produced 8.7 kwh from a 2.8 kw array. Just over a month later (on January 27) I produced 13.7 kwh on another clear sunny day. Quite a big difference in just over a month away from solstice!

On December 21st, sunrise is at 9:20 and sunset at 16:14 at my location. That's a fairly short day of sun! The other issue is that the sun doesn't get high enough around noon to maximize production. Also December here is usually cloudy and snowy, so plenty of generator run time can be expected then.

Snow Build up Modifications

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