How do you deal with freezing rain, or crusty snow that can't be brushed off?

[JeepHammer]

I am warming up to this idea. (sorry, I could not resist the pun).

An interesting side point to this is that in normal operation, they are generating heat when they are producing current to charge the battery.

Almost all charge controllers stop the current once the batteries are full. If a way to keep the current flowing through a dump load is implimented it will allow the panel to stay warmer.

The side that REALLY sucks is after dark, or in heavy clouds (Like snow storms) The panels are warm enough to melt snow... For a while...
Then the water freezes into ice and the snow sticks to it.
Over night, there is NO current moving either way, so anything and everything sticks when freezing.

When you have low power panels (100 Watts) scratch one panel off on the negative end of the string, and it might take all day, but the power produced in first panel hits resistance in the next panel and is converted to heat, until that panel melts off, and so on down the string.
I've watched this happen a hundred times, the more panels in cleared, the faster the next one will melt off.

In series, they melt off in series.
In parallel, the charge controller is usually less resistance, so the rest of the panels melt very slowly, if at all...

When you allow reversion to happen, Series melts positive to negative, Parallel all melt at once, but takes a LOT more amperage.

It's not hard to follow, and as far as I know it doesn't harm panels, I have panels I've been doing it to for 20 Years.

 

[TheDroidsYouAreLookingFor]

No I was refering to the case in which the panels cear and send possibly too high of Voltage to your battery bank. In a lead acid situation you might off gas a little more and have no damage at all but with lithium you may exceed the voltage recommended for charging.

I was just stating that one does voltage one amperage. I think its a great idea to heat the panels the way you stated if you have the reserve capacity to make it work.

 

[JeepHammer]

I guess I signed on for this when I introduced a new idea...

I've never needed anti-reversion diodes in my bypass, and I've never needed a time, I simply drink coffee and watch panels melt off.
Since I get up before daylight during snow/ice season, it's not a big issue, I see snow, I flip switches and drink the first cup of the day, which always goes fast... (about 10-15 minutes).

Since I'm working BEFORE daylight, dealing with production FROM panels is impossible.
*IF* I were to lave the Rheostat turned on, it's serious resistance and would limit what could get from Panels to Batteries.
In the 20+ years since I discovered this on little panels charging a trailer winch battery without a blocking diode,
I've never, not once 'Forgot' to turn the Reversion Rheostat back off since I'm using it to clean panels, I don't 'Forget' the root task at hand.

==================

So now the topic of someone LEAVING the Rheostat or Resistors turned ON, it's solved with blocking diodes, just like the blocking diodes in the charge controller.

A TIMER solves the problem of the forgetful.

Rheostats are inefficient by design, and they are from a time when LARGE amperage was used, they won't break down nearly as quick as the mentioned tiny voltage/amperage units from 'Radios' and such.



I *GUESS* I could way over complicate things with MOSFETs and the like, but the question is 'WHY?'
Rheostats are cheap, can be used in parallel or a bigger unit used if you need serious amps, and diodes are 50 cents each, stupid simple to use, and common as nails.
While the timer drives up price about double, but if it makes someone feel better about brain farts, I guess it's worth the $20.
An 'Idiot' light can be added easily enough, or beeper, but how far do you want to go?

 

[FilterGuy]

Sounds like it would work except that a rheostat deals with current like really inexpensive and inefficient dimmers or motor controls and a potentiometer deals with voltage for example for use in volume control knobs. Not sure which one would work better in this situation but voltage could still come through if it is usong a rheostat.

In this case there is really no difference between a rheostat or a potentiometer. whatever you call it you are putting a variable resistor in series with the panel. I have always wondered why there is two different names in the first place. They are fundimentally the same thing that is used in different ways. It is kinda like the difference between a relay, a contactor and a solinoid.

 

[JeepHammer]

In this case there is really no difference between a rheostat or a potentiometer. whatever you call it you are putting a variable resistor in series with the panel. I have always wondered why there is two different names in the first place. They are fundimentally the same thing that is used in different ways. It is kinda like the difference between a relay, a contactor and a solinoid.

Semantics:
Relays do electrical work only.
Solenoids do mechanical work, like air or hydraulic solenoids, or starter motor solenoids that move the starter drive gear into place before closing the electrical circuit.
Contactors are make/break, they *Shouldn't* have Normally Open/Normally closed circuits.

Rheostats are for higher amperage, and have gone mostly away with scaling power semi-conductors that can do the same job without the issues of corrosion from heat.
Before semi-conductors Rheostats handled several thousand amps.

Variable resistors are mostly used for micro volt control of the mentioned semi-conductors.

I use them for small power panel strings because I don't have to design & build the semi-conductor circuit, just plug one in and run it.
It's used so infrequently it doesn't smoke itself, and for under $20 it's stupid cheap & simple to use.

There is something to be said for hitting the 'Easy Button', or the 'Cheap Button' when you are fooling around and have no idea if it's going to work or not...

I didn't do the 'Classical' education, so I didn't know things like this weren't *Supposed* to work, and the 'Classical' trained guys have issues grasping it when they see it working, it's just the training.
I got the text books, but instead of being taught current flows in this *One* way only, and *That* way is the *Only* way to do it, I try a little bit of everything.
Some works, some doesn't...

I've just had more time to screw things up than a bunch of the guys here, and I did everything myself, so I hit a LOT of obstacles that had to be delt with.
Some guys just have to learn the hard way, which is why I've burned my eyebrows off so many times!

 

[FilterGuy]

I guess I would fall into the 'classicaly trained' bucket, but I have paid a lot of tuition to the school of hard knocks too. The interesting thing about tuition is this: Whether you pay it for classical education or to the school of hard knocks does not matter. What matters if if you take the opportunity to learn from the experience. (I am sure we have both seen people that don't)

As far as the semantics goes, you are right, it is good to know the common usage(s) of a term because it helps me understand what others are trying to say. It is also good when I am searching for a particular part... if I know multiple names for it, I am more likely to find something that works for what I need.

However, 1) not everyone uses the same definitions and 2) I find terms like these are interchanged sooo much they loose their specific definition.

Take a look at this search result for rheostat



Notice the center picture calls it both potentiometer and Rheostat (and trimmer).

I don't care if it is called a Trimmer, Potentiometer, rheostat or twisty-turny thingy.... I go to the spec sheet. Can it do what I need (Voltage, amperage, resistance, or whatever)?

 

[JeepHammer]

I guess I would fall into the 'classicaly trained' bucket, but I have paid a lot of tuition to the school of hard knocks too. The interesting thing about tuition is this: Whether you pay it for classical education or to the school of hard knocks does not matter. What matters if if you take the opportunity to learn from the experience. (I am sure we have both seen people that don't)

As far as the semantics goes, you are right, it is good to know the common usage(s) of a term because it helps me understand what others are trying to say. It is also good when I am searching for a particular part... if I know multiple names for it, I am more likely to find something that works for what I need.

However, 1) not everyone uses the same definitions and 2) I find terms like these are interchanged sooo much they loose their specific definition.

Take a look at this search result for rheostat

View attachment 4497

Notice the center picture calls it both potentiometer and Rheostat (and trimmer).

I don't care if it is called a Trimmer, Potentiometer, rheostat or twisty-turny thingy.... I go to the spec sheet. Can it do what I need (Voltage, amperage, resistance, or whatever)?

I'm the same way, I don't much care if someone uses 'Common Usage' or not.

It wasn't an insult to the guys with formal educations either, it's just the way they are trained to think collides with what I do some of the time...
They can always work whatever out a different way, with safety in mind, I'm more of a small scale test, and if I still have my eyebrows I scale up...

While the line blurs with me on Rheostat, since a proper Rheostat is wire wound with a Load contactor arm, And the rest are carbon strip that handle virtually no amperage but do micro voltage really well.

With the one I use, from the local auto parts store, ceramic pot to handle 30-40 amps worth of heat from resistance.
Under $20, on the shelf most times, and with these small systems using MC4 connectors (20 Amps Limit) it works fine.
Like I said, balance in the system pays off in different ways... this just happens to be one of them.
$20 per panel string/charge controller to NOT chisel ice off the panels is worth it for me...

If I have to extend to jump Isolation Diodes between panel strings, I normally don't do it,
So when I say 'Small System', I'm talking REALLY SMALL, like 1-4 panels small...

The surplus sites are showing 500 watts of Rheostat for $120. When used on 400 Watts of panels pretty much means you can start at zero and work up to what it takes to melt the panels.
Like I said, it works for SMALL PANEL STRINGS.
(Big panel strings are usually in series, so you just clean off the first panel...)

If you want to use Semi-Conductors that's up to you...
Or not use one at all and chisel/chemical soak the panels, it's up to everyone what they want to do, like I said, I'm not trying to sell it as a home game, just something you can try if you want to, or not...
I would think a healthy PWM for bigger DC motors would work also, but I haven't tried them.

Just like the $5 worth of propane to melt off the patio instead of shoveling.
Keep in mind, my back was broke in 5 places, neck in two, missing more than half a lung, so I don't do shovels in sub freezing weather if I don't have to...
I was so hard on aircraft the Marine Corps sent me home, I was costing them too much!

I'd rather stay in the Moose Cave & Martini Bunker where it's warm and let things melt on their own!

 

[PHoganDive]

You could also swap out the rheostat with one of the cheap motor speed controllers/LED light dimmers they sell for DC systems. They use a PWM system to control the duty cycle of the ON time sent to the load. They are dirt cheap online, and are much more efficient than a rheostat, nearly all the power used from the batteries goes to the panels.
Here's one good from 10-55 volts at up to 100 amps of current...it can control over 5 kilowatts of power.

10-55V 100A Reversible DC Motor Speed Controller PWM Control Soft Start US Stock | eBay

Find many great new & used options and get the best deals for 10-55V 100A Reversible DC Motor Speed Controller PWM Control Soft Start US Stock at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[JeepHammer]

{SNIP} If you want to use Semi-Conductors that's up to you...
Or not use one at all and chisel/chemical soak the panels, it's up to everyone what they want to do, like I said, I'm not trying to sell it as a home game, just something you can try if you want to, or not...
I would think a healthy PWM for bigger DC motors would work also, but I haven't tried them.{SNIP}

You could also swap out the rheostat with one of the cheap motor speed controllers/LED light dimmers they sell for DC systems. They use a PWM system to control the duty cycle of the ON time sent to the load. They are dirt cheap online, and are much more efficient than a rheostat, nearly all the power used from the batteries goes to the panels.
Here's one good from 10-55 volts at up to 100 amps of current...it can control over 5 kilowatts of power.

10-55V 100A Reversible DC Motor Speed Controller PWM Control Soft Start US Stock | eBay

Find many great new & used options and get the best deals for 10-55V 100A Reversible DC Motor Speed Controller PWM Control Soft Start US Stock at the best online prices at eBay! Free shipping for many products!

www.ebay.com

So the idea has seated with PHogan,
AND, from that idea/suggestion he located the digital equivalent of a Rheostat for a VERY reasonable price!

That's Excellent!

I believe for that price I'll order one myself and try it, see if it works!

I've NOT used a PWM for this application, I don't foresee any problems, but I can't tell you it works with first hand knowledge.
I can't tell you if it will live under the conditions, or if an unforseen issue using one will present itself.
Even if I get one or two, I have to wait for snow/ice, which has been in short supply this year (and I'm happy about that!)

$20, 20 year old panels, what have I got to loose?
I have new panels on order anyway, just have to wait for a freezing night and wet the panels down, see how it works...

Now that I've said that, we'll probably get freezing rain, ice and snow for the next month...

 

[Steve_S]

Hmmm, I guess I'm "simple" but luckily mine is ground mount and only 3.5' up off the ground. I go out and use a Foam Scraper to get the snow off which is pretty easy. IT IS NOT A HARD SCRAPER ! and never ever bang on frozen rack or panels, micro fractures can become breaks very quickly.

These come with very strong extendable handles in 2 different lengths and not crazy expensive.

Garant Telescopic Scratch Free Snow Brush, 52-in | Canadian Tire

Garant Telescopic Scratch Free Snow Brush features EVA foam pivoting head | Canadian Tire

www.canadiantire.ca

Made by Garant

 

[JeepHammer]

Hmmm, I guess I'm "simple" but luckily mine is ground mount and only 3.5' up off the ground. I go out and use a Foam Scraper to get the snow off which is pretty easy. IT IS NOT A HARD SCRAPER ! and never ever bang on frozen rack or panels, micro fractures can become breaks very quickly.

These come with very strong extendable handles in 2 different lengths and not crazy expensive.

Garant Telescopic Scratch Free Snow Brush, 52-in | Canadian Tire

Garant Telescopic Scratch Free Snow Brush features EVA foam pivoting head | Canadian Tire

www.canadiantire.ca

Made by Garant

That's true, if you can reach the panels easily you have more options.
That's one thing I didn't specify, I use reversion heating on the stacked panels that I can't reach the most.
I'm pretty stoved up, and climbing in icy weather is a good way for me to wind up in traction, I don't even take small falls very well.

Like I said, not selling it as a home game, just an idea that worked for me...
I'm sure the collective brain power or someone that just got tired of ice have it figured out different ways, the thread was on how do WE deal with ice/snow, it's just what I do...

 

[JeepHammer]

One way I casually detect bad panels or bad cells in a panel is see which ones the frost/snow melts off of slowest.
It has to be casual, since I don't sit around staring at panels, but if the frost/snow melts quicker in one spot, it's a 'Hot' spot, resistance is higher, if it melts slower, it's a dead cell/panel.

--------------------------------------------

I you try the above PWM, scroll down the the bottom of the page and check prices & shipping locations.
I got stupid and paid more than I should have...

Lots of MOSFETs in these so if you are the 'EOTW' type probably not something you want (Even though your charge controller and inverter are full of this stuff).



Still waiting on mine to get here to see if the Negatives are common.
If the PWM pulses Negative, this won't work or the Negative to panels will need a Diode gang which will be a fight to keep isolation alive...

 

[Prefersdirt]

I wonder if RainX would help? Not now, but in a warm spell.

 

[kernel]

We just brush them off if it will not come off reasonably quick by itself and even then only if i need the power.

If i can just wait it out im not climbing up there, but its a simple task to brush them off with a push broom and let the sun do the rest. The steeper the better.

 

[Red Squirrel]

You can't brush off freezing rain though. It makes this nasty hard crust that the brush just glides over. Could maybe try adding a weight on the brush to make it heavier but that will make it harder to bring it up without potentially bending the pole too much.

Considered trying out RainX and other similar chemicals but I'm a bit worried they may react weirdly with the resins used in solar panels, given they're not made for that. Would need to get up there in summer and apply some to just one panel to see.

I may have to experiment with the backfeeding and see though. If I can get them warm enough to melt the crust from under, then the brush might be able to work. Too late to try anything this year though as I haven't been staying on top of clearing them off so there's a good couple feet of snow now. I should probably still go do it at some point since I don't know how much weight they can handle.

 

[iceledoar]

has anyone considered using Rainx?

 

[upnorthandpersonal]

Considering that RainX is essentially a type of silicone (it's active ingredient is hydroxy-terminated polydimethylsiloxane), it should work. As I mentioned in an earlier post, I spray silicone on my panels and that works great in preventing ice for forming on the panels.

 

[JeepHammer]

Considering that RainX is essentially a type of silicone (it's active ingredient is hydroxy-terminated polydimethylsiloxane), it should work. As I mentioned in an earlier post, I spray silicone on my panels and that works great in preventing ice for forming on the panels.

I don't have issue with silicone, it shouldn't attack panels.
Most have some form of silicone sealer between frame and PV hardware, so plain old silicone shouldn't speed up the decay process.

The issue I have is timing...
When the silicone is thick enough to stay in place, dirt sticks to it.
When I wait until there is ice in the forecast, the weather man is wrong about 90% of the time, so I'm out there spraying for nothing, and I get to wash it off with the dirt/crud it collects.

Some of the stuff intended for 'Ice' removal will attack sealer between panel layers, edge sealer, ect.
Just plain water freezing in the cracks will de-laminate panels over time, that creeping corrosion you see edging in on older panels, and I don't care to speed it up, so I'm particular about what I put on the panels...

The stippled (slightly pitted) looking glass used on commercial panels in 'Rough Service' enviorments drops production efficiency a little, but it does make ice come off MUCH easier, kind of like that no fingerprint coating on eyeglasses they have now.

 

[davissd]

Back when I had satellite TV, I would put a oil pan heater on the back of the dish and just plug it in when it got snow on it or, if I knew ahead of time, before it started. This looks like it might work as well: https://tinyurl.com/wmrp4u2 . Could just tape it to the back of the panel.

 

[TheDroidsYouAreLookingFor]

So to be clear some silicone lubricants can hurt silicone because of the other ingredients in the lubricant to keep the silicone vicious... Those other ingredients attack solid silicone and break it down. There is an alternative called Trico View, more costly but it actually bonds to the glass to make a waterproof barrier rather than turning into a hazy residue in a few weeks as rainx can sometimes do in some weather conditions. I honestly dont think rainx will hurt your panels I just wanted to point out that silicone lube WILL hurt silicone products. side note, you can never paint anything lubricated by silicone. I use silicone lube for sliding glass doors, tent trailer sliders, door hinges, old fans that stopped turning and anything that needs to move but is stiff or not working optimally. A quick squirt each time you put your chain on a chainsaw bar will last a long long time for a little extra protection on your bar chain as well. I had some silicone wrapped workout weights and the overspray from squirting a rusty equipment pully's bearings hit one. Within 2 minutes i went to wipe off the dot and the silicone wrapping came off with the consistency of really thick honey. Most car windows are made of a thick urethane glue and not silicone and I have no idea what they use in windows and solar panels. Just a word of caution, test a small spot and repair if it messes with anything.