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.