Author Topic: How do you deal with freezing rain and solar panels?  (Read 6852 times)

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Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #25 on: January 04, 2019, 01:26:54 pm »
yo there is the concern here that you can blow your roof up if there is a spark while you pour gallons of highly flammable solvent on the roof. this is a bad idea.



it also might end up as a pool of ethanol in front of your house on top of a ice sheet and remain flammable.

an idea for a snow sensor might be two photodiodes on a sloped trough that looks for a optical break, tested to resist heavy rainfall, with a mesh on top to keep out leaves. 
 

Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #26 on: January 04, 2019, 01:30:06 pm »
ethylene glycol is plenty toxic but the thing is it has a low vapor pressure so your not likely to get a dose from inhalation as you would from methanol. it also probably does not absorb well through the skin like very small methanol molecules.

iirc it turns into oxalic acid inside of your body.
https://en.wikipedia.org/wiki/Ethylene_glycol_poisoning

i hate the look of sloped solar panels too, i think it looks terribly unsightly and industrial for a home.
« Last Edit: January 04, 2019, 01:41:08 pm by coppercone2 »
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #27 on: January 04, 2019, 01:55:20 pm »
Yeah don't really want to start using chemicals as it will go on the roof shingles (might react weirdly?) and then on the lawn.  That stuff is basically poison.  Going to kill birds etc.

One thing I've been thinking of, would only really work in an off grid setup where there's not tons of litigation about wood burning, but I could glue pex lines under the panels like a floor heating system, then encapsulate it with rigid foam to insulate it in, and then connect it up to a wood fired boiler system.  Would use glycol as the liquid in a closed loop.   It would not require a huge battery pack like an electric heater or backfeeding would, and still be carbon neutral.   I imagine if I ran the boiler for like an hour or two it might be enough.  Would be a manual process though.
 

Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #28 on: January 04, 2019, 01:59:23 pm »
if you insulate the panels then they will run less efficiently when they are hot. i think you actually want to put heat sinks on them ideally to keep the silicon cooler as it works.

maybe if you run cooling through it during the summer, but that is a pump and alot of hydraulics to worry about, and you need some kind of chiller or heat exchanger. all insulation penalizes your heat exchanger because less is radiated.

https://www.civicsolar.com/support/installer/articles/how-does-heat-affect-solar-panel-efficiencies

the equation between visual look, ease of use, safety and efficiency is giving me a headache.

i would want it flat, fluidically temperature regulated, drained and low voltage.

don't forget all the work the pump has to do, in regards to tubing thickness for such an installation. it might be a hidden design nightmare.

and non closed cooling systems i.e. if you decide to mist it in the summer, may come with big concerns in terms of microbiological activity due to the humidity. talk about roof fungus.
« Last Edit: January 04, 2019, 02:11:37 pm by coppercone2 »
 

Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #29 on: January 04, 2019, 02:13:01 pm »
interesting discussion
https://www.solarpaneltalk.com/forum/solar/solar-energy-facts/18035-water-cooled-solar-panels-for-significant-output-boost

and if you never worked with heat exchangers before, their a complete psychotic bitch in terms of corrosion. believers in plating beware. you want it big and smooth and unfortunatly laminar for corrosions sake. think impedance matching so you don't have abrasive particles that bombard flat surfaces used for fluid direction changes.

and keep in mind of visosity of antifreeze agents etc. and poor thermal performance of room temperature freons. and how they leak all over the place where water would be fine.
« Last Edit: January 04, 2019, 02:17:19 pm by coppercone2 »
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #30 on: January 04, 2019, 05:24:20 pm »
Heat would be the least of my worries here, and for a few months of the year when it is really hot, the days are super long (like 4am sun rise and 10pm sun set) so I would have more than enough energy to run a chiller if I had to.   Which would be an interesting thing, as there might be a specific point where running a chiller gets more power than if you didn't run it, but have to find that sweet spot.

Another option might be to air heat them.  Just have  air blast under the panels from the bottom and as the heat rises along the panels it would heat them.  Not exactly that efficient though but in an off grid setting if I'm already using a wood stove to heat the house anyway, I could just pipe some heat to the solar installation or something and just have a damper that opens and pumps air then the return would come back and hit up the wood stove to be reheated again.

For my shed I think any solution might simply not be worth it so think I'll just leave them as is.  Went out again to see if I can skim some snow off but the broom just glides right on top, it's too icy and crusty.  I might eventually get it if I keep going every day though.  I am getting a voltage reading so they are producing a tad, but under 0.1 amps.
 

Offline Berni

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Re: How do you deal with freezing rain and solar panels?
« Reply #31 on: January 04, 2019, 05:55:28 pm »
Yea there is the issue of ethanol being pretty damn flammable.

If you really want you can always go up there with a heat gun and a scraper to clean the ice off manually, depends on how many panels you actually have, pretty doable for 3 to 5 panels. for 50 panels not so much.

And yes solar panels do loose efficiency when running too hot in the summer, but cooling them is not so easy so its a question if its actually worth it. You have to remember that a pump circulating liquid around the loop does need a fair bit of power to run.
 

Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #32 on: January 04, 2019, 06:01:42 pm »
how are you gonna cool your water   ?

keep in mind aerosols and legioneers disease.

and i think they are sealed with some kind of gasket, so be careful not to heat them too quickly or that might effect their moisture seal.
« Last Edit: January 04, 2019, 06:05:46 pm by coppercone2 »
 

Offline CatalinaWOW

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Re: How do you deal with freezing rain and solar panels?
« Reply #33 on: January 04, 2019, 06:18:37 pm »
How about a really old school solution that was used in my youth to stretch the growing season in the garden.

Freezing rain, freezing fog and other similar weather conditions seldom happen without warning.  When the weather report calls for it, put a tarp over the panels.  It can be relatively easily removed when conditions improve. 

This solution works really well for small, ground mounted arrays.  Gets less appealing as array size grows and for arrays mounted high in the air.

If you are so inclined there are a number of ways to automate this process.  Not cheap, but straightforward.
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #34 on: January 04, 2019, 06:44:47 pm »
With climate change I find we get way more unpredictable weather here.  Like this freezing rain I  never saw coming.  It was -30's but for maybe an hour it went up to positives enough for it to rain, then back to -30's. 

But yeah maybe I could have an automated system that covers them at night, since night makes up a good chunk of a 24h period here anyway, so statisticly, it should have a good chance at keeping them clear. 

More I think about it, for the shed I won't worry about any solution as they all seem quite complex, not worth it for 400w.   But if I do the house I will want to keep solutions in mind.  Especially because it will be too high to reach manually so even for just regular snow removal it will need to be automated. 
« Last Edit: January 04, 2019, 06:46:25 pm by Red Squirrel »
 

Offline apis

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Re: How do you deal with freezing rain and solar panels?
« Reply #35 on: January 04, 2019, 07:13:19 pm »
It was -30's but for maybe an hour it went up to positives enough for it to rain, then back to -30's.
Is that Celsius degrees or Freedom degrees?
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #36 on: January 04, 2019, 08:37:23 pm »
It was -30's but for maybe an hour it went up to positives enough for it to rain, then back to -30's.
Is that Celsius degrees or Freedom degrees?

Celcius
 
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Offline ahbushnell

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Re: How do you deal with freezing rain and solar panels?
« Reply #37 on: January 05, 2019, 01:20:23 am »
Well i just squirted a bunch of it all over my windshield and shed it all over the road behind me on my way to work since there was melting snow on the highway and that made the windshield get dirty as heck every few minutes.

According to Wikipedia its illegal to use Methanol in windshield washer fluid in the EU. Probably due to how toxic it is. So the popular alternative has become Ethylene Glycol or Ethanol. Im guessing then Glycol is not as toxic then.

So i suppose if you want to be safe you could dump some 90% Ethanol over the panels. This is essentially concentrated Vodka so if its safe to drink them i'm sure its also safe to pour on the ground. Tho don't actually drink >90% Ethanol as drinking this concentrated alcohol is not safe and the this sort of industrial alcohol has other crap in it that is not safe to drink (Like methanol) or they mix in a chemical that tastes incredibly badly to discourage people from drinking it (Tax for drinkable alcohol is much higher, so they rather have you buy that instead)
Ethylene Glycol can kill dogs.

https://healthypets.mercola.com/sites/healthypets/archive/2014/11/23/antifreeze-poisoning.aspx
 
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Offline Berni

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Re: How do you deal with freezing rain and solar panels?
« Reply #38 on: January 05, 2019, 10:00:53 am »
Well its very toxic to humans too but we tend to be smart enough to not drink antifreeze since its only really toxic when you eat it.

Tho that has not stopped some rather shady people adding it to wine because it made it taste better. Not sure how many people died from it before they found out whats in the wine, but id imagine it was quite a bit more than zero.
 

Offline Ian.M

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Re: How do you deal with freezing rain and solar panels?
« Reply #39 on: January 05, 2019, 10:47:40 am »
Oh for <expletive>'s sake, if you care in the slightest about the environment, small kids, your neighbour's pets, etc, get RV (Propylene glycol) antifreeze, if there's going to be any significant amount intentionally lost to the environment.  Its far far less toxic, and wont turn your yard into a superfund site.
 
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Offline Berni

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Re: How do you deal with freezing rain and solar panels?
« Reply #40 on: January 05, 2019, 01:48:10 pm »
Oh for <expletive>'s sake, if you care in the slightest about the environment, small kids, your neighbour's pets, etc, get RV (Propylene glycol) antifreeze, if there's going to be any significant amount intentionally lost to the environment.  Its far far less toxic, and wont turn your yard into a superfund site.

Ah i had no idea that stuff is actually safe enough to eat. So why is it not so widely used as the popular ethylene glycol? Does it not work as well? Or is it simply more expensive.
 

Offline coppercone2

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Re: How do you deal with freezing rain and solar panels?
« Reply #41 on: January 05, 2019, 04:13:55 pm »
you can get propelyne glycol cooling fluid mixtures. not sure why its not used in cars, most likely cost. its also possible it might be some what more prone to sustaining some kind of growth.
 

Offline edpalmer42

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Re: How do you deal with freezing rain and solar panels?
« Reply #42 on: January 05, 2019, 05:37:44 pm »
Why not use the ice melting cable that you put on the eaves to melt ice dams?  It would cover a small percentage of the panel, but if ice is a big problem, you would come out ahead.  You might have to space the cable more closely than usual since you're trying to clear the entire panel rather than just opening up channels for the water to run off.  Experimentation would be required.

https://www.canadiantire.ca/en/pdp/roof-de-icing-cable-0522580p.html

Ed
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #43 on: January 06, 2019, 12:50:03 am »
Yeah was thinking about that.  Issue is the amount of heat required would use more power than I would generate for days.    But I guess it's better than not generating at all for more than half the season. Just need a much bigger battery bank.  80ah won't cut it. Worse case scenario I use grid power, in an off grid setting with more land then I would have room for a better system like wood fired boiler etc.  That  and a better tilt angle.  Probably do two vertical arrays, east and west, and then south that is at around 45 degrees.  I need to optimize the system for winter as that is the majority of the season so even if tilt is not optimal in summer the days are longer I'd still get lot of power.

I managed to chip away at it from the ladder with a snow shovel while being careful not to damage them.  This is not just snow it's crusty/icy snow so it does not come off very easily.  It's hard to tell from the pic as it just looks like normal snow.




 
Managed to get some cells exposed at least.

What I'm thinking is either trying those heat cables on top of the panels as suggested, or come up with some custom heat pads of sort using nichrome wire driven to a certain temperature (would put temp probe in it) and stick them under the panels.    I wonder if I could get away with just heating the bottom part of the panel at a high enough temp like 30C and that might naturally gravitate towards the top through the cell material.  Guess I'll have to experiment.

I'd have to upgrade my inverter and battery bank though to run stuff like this.  At least if I get something like this to work I know it will be semi viable if I do the house as I would have a much larger battery bank and inverter.  Though looking at what I'm dealing with now I'm a little worried ice damming may be an issue, so don't even know if I want to do the house anymore.  Better off waiting till I can get a bigger property then do a proper ground mount system.
 

Offline apis

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Re: How do you deal with freezing rain and solar panels?
« Reply #44 on: January 06, 2019, 01:14:50 am »
I did some googling to see if someone had a solution here where we also have a lot of snow. Most people recommend you don't remove snow in the winter since walking around on an icy roof is not exactly safe and the power from the solar panels are so low that it is not worth the risk anyway. If you live in southern Canada that is further south than Sweden so you might have more daylight during winter. The recommended way to minimise the problem is to mount them at a steeper angle, while there is snow on the ground it can even be beneficial to keep them vertically since the snow will then reflect light onto the panels.
« Last Edit: January 06, 2019, 01:18:46 am by apis »
 

Offline edpalmer42

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Re: How do you deal with freezing rain and solar panels?
« Reply #45 on: January 06, 2019, 01:23:22 am »
Just remember that you don't have to run the heating cable at full power - use a light dimmer to control the power.  Also, it might help if you turn the cable on when the storm starts to prevent the kind of buildup that you're dealing with now.

Are you in an area where you deal with the 'Lake Effect'?  For those who don't know, near the Great Lakes the wind picks up huge amounts of water off the lakes and then dumps it as snow or freezing rain.  One storm can easily drop a meter of snow or a centimeter or two of solid ice on things like streets, power lines, or solar panels.  Kind of means that the entire area is 'off grid' for days after a bad storm!  :(

Ed
 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #46 on: January 06, 2019, 01:29:40 am »
Yeah I had googled this too I'm surprised there really isin't any real solutions.  Business idea perhaps if I come up with something...  At very least I do want to come up with something for normal snow.  Thinking some kind of brush that rides on a rail and it just sweeps the whole array. It would be manually operated remotely by looking at the array through a web cam.  Though it could be automated, just best to watch it do it's thing in case it gets caught up or something.  Once I finally build out my shop and add hvac, I'll be able to actually have a place to organize and setup all my tools etc and experiment with projects like this.

I'm thinking a better tilt is the best way though.  Could pretty much do a west/east vertical mount, and a south 45 degree mount.  The south one would just be a write off in winter, in summer it would add extra power to run A/C.  Though could possibly use power from the west/east one to try to melt snow off the south one. 

 

Offline Red Squirrel

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Re: How do you deal with freezing rain and solar panels?
« Reply #47 on: January 06, 2019, 01:31:42 am »
Just remember that you don't have to run the heating cable at full power - use a light dimmer to control the power.  Also, it might help if you turn the cable on when the storm starts to prevent the kind of buildup that you're dealing with now.

Are you in an area where you deal with the 'Lake Effect'?  For those who don't know, near the Great Lakes the wind picks up huge amounts of water off the lakes and then dumps it as snow or freezing rain.  One storm can easily drop a meter of snow or a centimeter or two of solid ice on things like streets, power lines, or solar panels.  Kind of means that the entire area is 'off grid' for days after a bad storm!  :(

Ed

No lake effect as I'm further north from the great lakes, but we USED to get tons of snow here, now we get a few feet at most, but our weather is so sporadic.  More freezing rain and other crap like that.  The normal snow is not too much of an issue I just use a long broom, like this:



(first few seconds of the video shows it quickly in action)
 

Offline duak

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Re: How do you deal with freezing rain and solar panels?
« Reply #48 on: January 06, 2019, 02:38:00 am »
I'm in Vancouver, and a couple of years ago we got a bunch of snow then rain that soon became heavy ice.  I usually sweep the snow off a fiberglass canopy over the deck but I was under the weather so I didn't.  The canopy has an access hatch but because of the ice I couldn't open it.  I rigged up a shower head on the end of a pipe and set it to spray hot water to at least free the access hatch.  It worked but it was slow.  The forecast was for sun but not all that much warmth so I spread some black poly film on the ice.  It actually worked quite well as the white snow and ice are much more reflective than the black poly.

Best o' luck
 

Offline richard.cs

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Re: How do you deal with freezing rain and solar panels?
« Reply #49 on: January 06, 2019, 11:59:23 am »
In the UK I'm pretty sure all screenwash is ethanol with non-methanol denaturing. I think methanol is legally out because it's toxic by inhalation and generally we don't like throwing ethelyne glycol everywhere. Propylene glycol could be used in screenwash but I don't think it's common.

In terms of deicing, I would probably be inclined to try heating the panels directly with a current source. If the cells are just in series then putting their rated current in should be completely fine. In fact putting 10x their rated current in is unlikely to damage the *cells* because the heat generated will be similar to the sun shing on them (assuming 10% efficiency or so). That's not really reccomend however because the interconnects between cells and the metalisation on the cell surfaces will not be designed for it.

In an ideal world I'd try it on a non iced panel in the summer and keep an eye on it with a thermal camera to determine what current is safe, then use that current the following winter. As that's not possible then sticking to ratings is better.

With parallel strings of cells the temperature coefficient means they won't share well. If you put the rated current for a single string in to the whole array it will be safe however, but most likely only a single string will deice. I initially thought that sun shining on that one string with the inverter off would shunt current into the others, but I don't think it will actually as it is the lowest voltage string (and lower still as it will be hotter from the sun) so that current will just circulate locally.
 


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