Snow on my panels is killing me

[Deej]

hammick,
I am curious as to what you decided to doing relating to this topic.

I have a similar situation. I am planning to install panels in parallel on my SE wall and also on SW wall of my house. I am not planning to not tilt them due to the potential for high winds.

 

[nonoceb]

Hi, for heating solar panel i suggest to see this video for the principe of physics

I think you can supply a solar panel with the normal current flow with a negative supply (and current regulation to not damage cell) it's will emit infrared light perfect to heat.
the main issue is bypass diodes, dam!

"The diodes’ main task is to protect the solar cells from overheating when partial shading occurs." ?

Checking bypass diodes on solar panels: Part 1 - pvBuero

Almost all solar panels include integrated bypass diodes. Crystalline panels generally have three of them, which are located in the junction box and can each bypass a third of the panel when necessary. The diodes’ main task is to protect the solar cells from overheating when partial shading...

photovoltaikbuero.de

 

[rin67630]

Hi, for heating solar panel i suggest to see this video for the principe of physics

I think you can supply a solar panel with the normal current flow with a negative supply (and current regulation to not damage cell) it's will emit infrared light perfect to heat.
the main issue is bypass diodes, dam!

"The diodes’ main task is to protect the solar cells from overheating when partial shading occurs." ?

This is full of wrong information:
to get your panel heating, you must supply a FORWARD current to the panel. This current will only flow to a usable value if you exceed Voc by some percent. (e.g. for a 40Voc Panel inject 43v or more limited in current.
The bypass diodes are not interfering since they a not fed forward.

"The bypass diodes’ main task is to protect the solar cells from overheating when partial shading occurs."
Yes, but not like you think.
When a panel is partially shaded a half string gets a reverse polarity. Cells are not designed to cope with a reverse polarity of more than 20V and will begin to avalanche like a Zener.
That is the very reason why bypass diodes are there to prevent this reverse voltage.

So to heat a panel, feed it forward with more than Voc. The bypass diodes will not prevent that.

 

[Hedges]

So to heat a panel, feed it forward with more than Voc. The bypass diodes will not prevent that.

Doesn't need to be more than Voc.

At Voc (and panel at 25 degrees C), it will conduct Isc, dissipating power W = Voc x Isc which is greater than nameplate wattage.
At Vmp, it will conduct (Isc - Imp), which is considerably less than nameplate wattage.

At cold temperatures, current will be lower for a given voltage.

If you have two PV strings in parallel, one on the roof covered with snow and the other in a protected location such as under the eaves exposed to sun, then if SCC isn't drawing power from the array it will warm the covered panels. Difference in temperature will affect how much current/power is dissipated in each string.

Having the strings on separate MPPT charge controllers wouldn't help, but if paralleled on one it could.

 

[nonoceb]

So to heat a panel, feed it forward with more than Voc. The bypass diodes will not prevent that.

In the link : For 24 cells, the “breaking point” voltage is about 336 volts"
this is a lot of high voltage to feed a 76cell panel!

edit : i just made a real test on small 150w panel voc = 20V, isc = 9A
At 21V with the solar panel under sun i was able to inject > 1A (current limited mode)
At 20V, injection is 0A

 

[rin67630]

Doesn't need to be more than Voc.

In fact it does not matter: feed it with constant current ~Isc (here it runs at 105% of Voc.)
There are a bench of good boost converters able to do that even from battery voltage.

 

[nonoceb]

Yes it's very clear now, shaded cell see negative voltage and positive current and when we inject power cell voltage is positive, function of iradiance and current is negative.

 

[Deej]

Having the solar panels being able to de-ice themselves is very interesting clever idea. However, I don't believe that I am comfortable enough to try this myself until I have had a chance learned more about it.

At this point I am planning to install some panels (since I already have the extra panels) wired in parallel on my SW and SE walls. Does anyone have any pointers regarding installing panels on a wall in a windy area. I am planning to have them parallel to the wall a few inches off. I am far enough north that the angle is not as much a concern (compared to the wind). Any suggestions are appreciated.

thanks

 

[pollenface]

Where I'm located. It's best to have panels tilted around 50-60 degrees during the winter months (although it doesn't snow here).

I'm sure vertical panels facing the right direction would give you more output than you are receiving currently. Worth a try!

 

[willh]

Any updates on this system? Have you wall mounted a few panels for winter charging? Would be interested to know what you have determined to work or not work.

 

[Tomthumb62]

Panels can be had for $0.15 to $0.50 per watt, plus shipping.

Where do you buy your used panels from? And what age starts becoming too old to buy them used to justify shipping expense?

 

[Hedges]

Santan solar is a vendor many are happy with.
There are other liquidators like them.
You'll also find local vendors on Craigslist and eBay.

Good panels should have lots of life left even when 20 years old.
Some panels, and some environments, have rapid degradation.
I would look up the brand and year/model in test reports.

Is there a reliable resource to compare panel makes/models

Well that sounds like a heck of a deal! Glad you placed your order and can't wait to see how it all works. That is a very good price, and I should not be surprised but that confirms they get a great deal when they upgrade. I wonder if they went with Trina on the replacement units? Any idea?

diysolarforum.com

I think used panels can be a better deal, more kWh/$ over lifetime than new.
Relatively new panels (past 5 to 8 years?) are likely to have 50% greater efficiency, 50% more kW/m^2, than panels from 20 years ago.

 

[fromport]

Santan solar is a vendor many are happy with.
There are other liquidators like them.
You'll also find local vendors on Craigslist and eBay.

Good panels should have lots of life left even when 20 years old.
Some panels, and some environments, have rapid degradation.
I would look up the brand and year/model in test reports.

Is there a reliable resource to compare panel makes/models

Well that sounds like a heck of a deal! Glad you placed your order and can't wait to see how it all works. That is a very good price, and I should not be surprised but that confirms they get a great deal when they upgrade. I wonder if they went with Trina on the replacement units? Any idea?

diysolarforum.com

I think used panels can be a better deal, more kWh/$ over lifetime than new.
Relatively new panels (past 5 to 8 years?) are likely to have 50% greater efficiency, 50% more kW/m^2, than panels from 20 years ago.

I just looked at santan and would you advise anyone to buy these?

Blemished SanTan 250W Solar Panel | SanTan Solar

www.santansolar.com

“These panels have developed cell-side vinyl cracking, which is cracking in the vinyl layering beneath the cells. This has allowed for water intrusion, which has caused discoloration on the vinyl and busbars. They may contain other blemishes such as snail trails or minor surface scratches. Please see pictures for more details. The panels still output approx. 75% of the listed specifications.”

bargain at $0.14/watt ?!
WCPGW, right?

[/sarcasm] I would want those even if they would give me money. imo pure chemical waste

 

[Hedges]

I wouldn't advise that, but some people here have bought because they're cheap (the people, also the panels) and are happy.
Given the labor, shipping, support components, I've decided to stick with relatively premium parts.
I happen to be well paid and in an expensive market. For those on a shoestring budget, and living where property taxes are $50/year not $12,000/year, prices are looked at differently.

Santan has something for everybody, new and used (but large stocks only of used.)

 

[hammick]

OP here. Guys I apologize that I have been absent from this thread for so long. Things have changed for us. On June 15th, 2021 we had a massive forest fire that completely burned our 40 acres and the entire area. All the trees are gone ? (Robertson Draw fire outside Red Lodge, MT). Our building was spared because we had a good perimeter. Others weren't so lucky. We didn't get out in time (stupidly trying to save vehicles) and rode it out with the Hotshot crew. They saved our lives and are unsung heroes to us.

Then on November 16th, 2021 we had category 4 winds that did a ton of damage to our place. These winds lasted for over two hours. Our insurance claim is more than it cost to build our place. These are the kind of winds that completely destroyed some structures and vehicles.

Three of our panels were shattered and the rest all sandblasted. Insurance has paid us for the panels so we are installing 12 260w Q-cell panels on an Iron Ridge Ground mount. This mount will have the proper angle for our area and should solve our issue with snow covering the panels. The damaged array on the roof is operating at about 70% and will not be replaced when we get the new roof.

Putting the panels on the roof was a mistake that we will not repeat.

Thanks for all the advice and help on this.

 

[curiouscarbon]

oh my gosh, so sorry to hear of these misfortunes.

hoping repairs can proceed smoothly and safely !

 

[Checkthisout]

You need a wind turbine.

 

[Alkaline]

Last winter and now this winter so far have been crazy for snow. I'm on day three of generator charging because my panels are covered with crusty icy snow. The roof is too slick to get up there and even if I had a roof rake I think it's too crunchy to remove. It's too cold to spray them with water. My 9 roof mounted panels work great year round when there is no snow.

So I'm think of installing three or six panels vertical on the wall of my building. One wall faces due South and another wall due East. Maybe three of the panels on the East wall to catch the morning, winter sun. The Hughesnet satellite dish is going away in a couple weeks so I should have plenty of room for 3 or 6 panels.

Anyone ever install vertical panels for winter charging?

South facing wall: (the two 100w panels are for trickle charging vehicles, toys, tractors, etc. and work very well for that).

View attachment 25740
View attachment 25741
East facing wall:

View attachment 25742

Hammik... after seeing your pictures I have no sympathy for you at all, in fact I hope you get more snow that is until I read the rest of the thread, sorry about the bad luck, hope you get it fixed up soon.

 

[curiouscarbon]

seems a little rough eh!

the angle seems a bit gentle for passive snow shed. i do not envy that design detail.

hoping for a positive outcome

random inane thought, do people in situations with a tall structure in a relatively open plain with occasional high wind load, ever construct wind breaks around the structure? aesthetically unpleasing and ineffective are my main gut thoughts.

kind regards and best of luck dealing with mother nature

 

[Karmagl]

I don't have my big system up and running yet, but I have 3 panels at an angle on top of a shed. I purchased an extended feather duster wand and go out every hour or so when its snowing so the ice doesn't build up. Not a great solution but its working for now. Defenantly doing ground mount when my 20 panels get here as icy ladders are no fun.