Keeping snow off solar panels

Hi All!

I have a small PV array on my roof in northern Michigan. I've fixed the panels at 55 degrees wrt horizontal for better late fall/early spring/winter collection. However, I didn't design a way to remove snow from the panels. Sure, a lot of it will fall off... but a good couple inches remain sometimes for weeks at a time and that reduces collection efficiency to almost nothing.

Does anyone have a solution to remove snow from panels that are inaccessible with a broom or other handheld device? I don't want to climb on the roof in the winter. I can't reach the panels from a ladder.

Some attempts at/thoughts about solutions:
I've successfully sprayed off the snow using a garden hose, but this is cumbersome and, depending on the depth of snow on the panels, can take up to an hour to complete.
I've thought of buying a cheap drone to blow off light fluffy snow... but that won't remove the heavier snow.
I've also thought of placing something like pipe heating tape below the panels, but I don't want to introduce thermal stress and cause the panels to crack.
I've thought about running a reverse current through the panels... but I don't want to damage them.
I've considered attaching "drip lines" to the tops of the panels and then designing the tubing to fully drain after each usage.

But certainly someone else has faced this problem before and has a solution! What are all of your thoughts?

Thanks,
HJG

Will a leaf blower reach?

No problem with snow, just coatings of dust reducing efficiency.  We bought a brush for washing a truck (Semi?) not oversized car type.  Handle extends, brush has a soft-ish bristle and a hose can be attached - good for us, but perhaps not for icy conditions.

This is somewhat out of my specific experience, but when we get snow, there a many things that *have* to get cleared, as our snow is usually very wet and heavy and often rained on while falling!

Hjg Werdna wrote: Does anyone have a solution to remove snow from panels that are inaccessible with a broom or other handheld device? I don't want to climb on the roof in the winter. I can't reach the panels from a ladder.

I'll back the not climbing on the roof part - but maybe long term planning could involve installing a platform so that you can safely access the panels for cleaning? A concept for everyone contemplating roof panels to consider?

"Can't reach" can mean many things. My first idea reading this, is that possibly when the snow is light, you could stand on a ladder and point a leaf blower at the panels? If you don't have a leaf blower, I would suggest you find one you could borrow for the first try?

I've successfully sprayed off the snow using a garden hose, but this is cumbersome and, depending on the depth of snow on the panels, can take up to an hour to complete.

We have a power washer. That may or may not work faster than the hose. However, power washers have to be stored where they won't freeze, so that needs to be kept in mind. Again, if you don't have one, I'd try to borrow one for a trial.

I've also thought of placing something like pipe heating tape below the panels, but I don't want to introduce thermal stress and cause the panels to crack.

I don't know the difference between pipe heating tape, and the specific roof/eves trough heating tape that my parents had. They had a section of north facing roof where some of the snow would melt and back up under the shingles because ice would form in the eves trough and not melt fast enough. Personally, I still would hesitate using it on solar panels without discussing it with the manufacturer.

It might help if you could attach a few photos, and certainly help if we had more of an idea of the closest distance you can get to the panels. As Hubby got older, he found accessing the chimney for sweeping harder and harder. He decided to splurge on scaffolding that is now permanently installed beside the chimney. Luckily it's mostly out of sight.

You can get heating cables (and tapes, I think) that are self-limiting to a specified maximum temperature, so this is pretty easy to manage. Ideally, you'd only turn it on when there was snow.

I used to have the same problem when I was in Indiana...

Solution,   move to Florida ;-)      I get far more sunny days here.

Other options  increase the angle higher helps, but you don't get as much out of the panel....

Curtis Stone on youtube offgrid sweeps his panels on a regular basis up in Cananda.

This is probably more work up front to save you time in the long run...
Could you reposition the array for easy access?  You mentioned it is a  small size

I have the same problems, and no good solution.
If even a patch of panel is cleared the solar heating of the dark panel patch will spread melting and sometimes cause snow to slide off; panels only achieve ~~20% PV conversion, so ~~80% of the incident solar energy is potentially available as heat, once the snow reflection is broken.

Panel makers could include circuitry to run the panel backwards to dump some heat, but snow cover is a niche market; I suspect a cunning engineer could set up such a system, but it might void warranties.
I wonder about melting tape; depending upon temperature it might create ice pack that is more problematic than snow.
Brushing can damage or scratch the panels.
Even 60 degree angle does not reliably shed snow in my climate.
I did a little googling on silicone 'RainEx', but worry it could dissolve silicone sealants or cause a buildup of film.

Solar panels are getting cheap enough these days, you might think about another array if you have room for it. Vertical south facing panels do very well in winter here in Montana, as they don't collect snow, and the reflected light off the snow on the ground + the higher efficiency on cold days = a lot of power generation.

Hindsight and all that….

Ground mount with bifacial panels. They will create enough heat from the backside to melt the snow, usually.

Working with what you have….

I have seen powered sweeps for the panels, I’m sure you could come up with a rope powered version, but you would need nice conditions to get it installed.

What about one of those super long snow rakes like they use on roofs?  

I don't know how far out of reach the panel is. Would a 20 foot joint of PVC pipe with a broom head on it reach? Someone above said you only have to get a little bit cleared to make it do the rest on it's own. Even a clumsy long pipe with a head of any sort might be adequate to clear it enough.

Just a possibility depending on how much PV surface area we are talking about here and I realize this does not solve your problem of accessibility.  I have a single panel for charging an electric utility vehicle for the farmstead.  For the most part that vehicle in winter is charged in the garage using a standard plug-in charger.  But I've aldready determined that a good sunny day will drive pretty decent power through that panel in midwinter for recharging the vehicle.....**IF** it is clear of snow.  Just now not doing that since there is a few inches of crusted snow/ice covering ~40% of the panel.  This would melt off relatively quickly if we had some sun and the temps stayed above 10F for a long enough stretch, but the time of year is working against us.  Nevertheless, if I really needed that panel cleared, I probably would use a tarp draped over the panel and a space heater running underneath the tarp so the heat rose upward across and underneath the panel.  I've found that this usually loosens ice and snow to the point where you can remove it in chunks manually or teasing the pieces off with a long 2X4....the wood being more gentle on the PV surface.  Hoping this may offer some ideas.

Hey Everyone!

I want to thank everyone for all of the great ideas!

When I'm on a ladder facing the panels, the farthest one is about 15 feet away. The array is small enough where I could move it to the ground, but the best unobstructed solar exposure is on the roof. While bifacial panels likely would receive sufficient light from the rear of the panels, alas, they're not bifacial. A leaf blower would definitely work for very light, fluffy snow (I've heard of people using them to clear a dusting of snow from walkways, etc.), but probably not the wet, warm stuff or the really cold grainy stuff. (I tried removing inches of snow from a shed roof with a leaf blower and the results were mixed.) I'd suspect that a power washer wouldn't be very effective at 15 feet, but up close it probably would be great! I agree that direct solar exposure will melt everything off in short order, but many days where I live are overcast. On overcast days, I can get 5 - 20% nameplate capacity without snow, but the diffuse light isn't intense enough to noticeably warm the surface of the panels. Warming tape or electric heaters from behind would be effective, but it would be a hassle for me to add the additional circuitry for that... unless I run DC power through them directly from the panels... which wouldn't work when they don't receive any light. Though I can see where this could work well had I planned ahead for it. Having a remote, rope-actuated sweeping rig seems really cool, but I don't know how I'd set that up.

I'm thinking that vertical panels facing south and a permanent structure to use to sweep off the panels are the ticket.

Thanks again,
HJG

To be clear, mine are not on the roof.  Before bad weather hits, I put a tarp over  them.

Well, now gee, that is just cheating!
Great idea though!

I use a 20 foot HD extension painters pole with a push broom head.

Has anyone tried heat tape/cable for this?

Anne Miller wrote:Has anyone tried heat tape/cable for this?

I use heat tape to keep my LifePO4 cells warm. Not sure it'd cover enough area on panels to work without burning a lot of power.

Snow is a problem here for sure. I don't like roof penetrations, screws whatever. Future trouble only in my mind.
My roof is well pitched and sheds snow after a bit. All the plumbing vents were cleaned off by sliding snow after a large storm in 2008.
My winter yard faces a frozen lake, our solar gain with snow on the ground is pretty good, so, to me, the idea of 'pitching' fixed panels to maximize gain is short sighted.
I built these to allow me to follow the sun during the day, the arc is quite large in the summer here at 55N. I also lose sun to the trees to the west for a good part of the year, maximizing what I do get makes good sense. They collect frost, but do not collect snow, typically, but our winter snow is powdery.
I used 1 1/2 inch sched40 pipe set in concrete to mount my setup. My plumbing house cuts the pipe and re-threads for free. 6' 6" sections make it easier to transport, and the -3ft. drop left from the 21ft. full length stick is pretty useful.
I use a pipe union at the bottom to allow me to both turn the panel and lock it in place. It is braced to the house at the eaves. The "merchant coupling" pictured is included with every length I buy and is strong enough for this application. Purchased couplings are typically much heavier.
The difference in gain following the sun is as much as 30%, way more than a few degrees of tilt will gain you on a panel whose direction is fixed south or wherever. Standing this assembly was an adventure, roof is too steep to stand on. Winch rope over the peak guiding it was the trick.
Each location here is it's own mini grid. I have another grid up at the garage. I used 2 in. pipe intending it to be freestanding. But with two panels, I eventually tied it back to the garage with a brace.
The other panel in the photo is part of my water system. Two 275g totes, a Trojan storage battery and a 12v RV pump for yard watering and burn pile tending.

Tommy Bolin wrote:....
My winter yard faces a frozen lake, our solar gain with snow on the ground is pretty good, so, to me, the idea of 'pitching' fixed panels to maximize gain is short sighted.
....

Interesting!... May consider this approach for upcoming install.  Our roof definitely holds snow, even with a ~45 degree pitch and metal surface.  With roof snow and your design, I'm assuming bifacial panels would make good sense?  It also seems like slightly tilted brackets on top of a sturdy pole would allow some gain back in summer, yes?  Liking this approach!...

Personally I am not thrilled with the garden hose idea—I just foresee too many problems with ice buildup.

I do like the idea of some type of leaf blower.

Is there any chance that you could heat the solar panels just enough to melt the snow as it fell?  Being on top of the house, one would think that heat is already working in your favor.  Is there some way to raise the temperature to between 32 and 35 degrees?

These are just the ideas that come to mind.

Good luck!!


Eric

I have an extendable ‘roof rake’ which I use on my single story house to get snow off the panels. It’s basically a snow shovel on a really long colapsable handle that you pull towards you. I think I got it at Home Depot but I don’t remember. If you can reach it maybe put a tarp over it before snowfall .

Just wanted to add some ideas to these entries based on a recent snowfall.  For sure, my situation is very scaled-down and reachable compared to that describe by the OP, but may be of use.  We had a fairly typical late winter storm move through that started out as sleet, then wet heavy snow, then a larger amount of colder, drier snow.....and then back to near zero F nights for several days with highs in the teens.  Still, the sun has gained some strength and is up for a longer stretch of the day now.  So I used a long-reach truck window brush and squee-gee to clear off the top layer of snow.  With the squee-gee side, I was able to get down to the ice layer across the surface, but this now rendered the panel dark in color versus the reflective white of the snow.  Figuring to use the panel later in the day, I went back into the house for a few hours to work on another project.  At some point less than 2 hr later, I looked out to see the panel completely cleared!  The black background of the panel combined with the design had provided enough heat from the sun not only to melt the ice, but to dry off the surface of he panel.  So **if** you were able to replace the metal scraper head of one of of those long roof rakes with a lightweight shop broom head, you might be able to remove sufficient snow to enable the sun to do the rest in short time.  Just a thought....

John Weiland wrote:

Tommy Bolin wrote:....
My winter yard faces a frozen lake, our solar gain with snow on the ground is pretty good, so, to me, the idea of 'pitching' fixed panels to maximize gain is short sighted.
....

Interesting!... May consider this approach for upcoming install.  Our roof definitely holds snow, even with a ~45 degree pitch and metal surface.  With roof snow and your design, I'm assuming bifacial panels would make good sense?  It also seems like slightly tilted brackets on top of a sturdy pole would allow some gain back in summer, yes?  Liking this approach!...

Bifacial, maybe, but was not in the budget.
I bought about half crate of 375W Canadian Solar panels from an installer downstate. Smokin' deal, paid cash.
I can track the sun directly all year from sunrise into the afternoon. Turn panels once a day, generally. Reset them facing sunrise after supper. The roof of my house as well as my windbreak of forest to the west limit my solar exposure.
Might get more tilted, but I doubt the difference would be worth the complication. This was very simple install method.
I don't get more than 16in of snow on the roof before a weather change sends it sliding.
Good luck.