Snow removal

[Sharich]

iced panels

If the snow slides off a ground array, you may need to bring around a snow blower, to
keep the pile from blocking the sun by winters end. However that isn't as big a problem,
easily mechanized.

Seems like, tilting the panels ought to be an option. Either get them vertical enough to
keep snow from sticking, or turn them so the sun warms the clear backside and snow
falls off the other side.

But how about more on thermal? Panels only need to get above freezing, but with
enough power to get it done quickly instead of just bleeding the heat away. If it is
to be done electrically, how will the power be delivered, and will it be automatically
controlled? And will half an hour of heating be justified by several days of subsequent
PV production? Bruce Roe

I thought about heat tape around the panels, but haven't heard of anyone suggesting this.

[maple flats]

Reading this thread reminds me why I set my array on a ground mount. I use a extendable handle push broom (it's dedicated use) to clean my panels and when the pile builds too much on the ground I clear it using the tractor/loader.

[russ]

They are not after cooling the panels, cooling the panels is just a side effect, sort of.
What they are doing is this. They generate electricity and this is a no-brainer, but they also use the heat that the solar panel provides to heat water in a tank/reservoir to be used for the a water heater or to help to heat a living space.

I have seen concentrator systems tha do this - Solar 8 from Sweden for one.

Not cost effective - in this case they are building a product with such a small market they are out of business before starting.

[russ]

Holy smokes!

This is a copy-and-paste from an article I wrote on my personal blog last December: http://www.frozennorth.org/?q=content/snowblind

Moderator, can I at least get attribution in a footnote?

I banned him the same day - some kid from India posting. Five posts and all blather.

Russ

[Johann]

I live near Philadelphia and we received a lot of snow this year. Sometimes my panels are covered for up to 5 days with minimal power production. Thinking of a way to get that snow off my roof. Came across these guys http://roofrake.com/Productpages/snowpro2.asp looking at the 30' extension pole the the rubber device they claim made for solar panels. $150 seems like a hefty cost. Anyone here have this model and if so is it effective in removing snow from your panels?

John

Since this is posted in the grid tie section, a heat tape could be use which is using about 3 watts a foot.
Heat tape could be mounted on the underside of the panel at the lowest point since heat is rising upwards.

If you only have snow laying on the panels and temperature is not to much below the freezing point, a water hose connected to cold water could be used to wash-melt the snow.

[bcroe]

I seen a house in Main that used them and middle in the winter, those hybrid
panels produced 140 F water in a very little time.
Those panels are made according to your needs. If you want more electric power then they make it where they produce more electric power and if you want more thermal heat for heating water they make them that way too. It all depend on your needs and wants.

They sound custom made, which translates to VERY EXPENSIVE. Need more information,
meanwhile working on the electric defrost idea. Bruce Roe

[Johann]

An expensive hybrid that doesn't make much sense. The cooling you get is the same as a couple of more panels with a lot less complication plus you are not potentially mixing electricity and water.

They are not after cooling the panels, cooling the panels is just a side effect, sort of.
What they are doing is this. They generate electricity and this is a no-brainer, but they also use the heat that the solar panel provides to heat water in a tank/reservoir to be used for the a water heater or to help to heat a living space.

I seen a house in Main that used them and middle in the winter, those hybrid panels produced 140 F water in a very little time.
Those panels are made according to your needs. If you want more electric power then they make it where they produce more electric power and if you want more thermal heat for heating water they make them that way too. It all depend on your needs and wants.

[pleppik]

There are three basic approaches to removing snow and ice from Solar Panel: mechanical, chemical, and thermal. It's not necessary to completely clean the solar panels, just get enough snow off so the dark surface can start absorbing light. The heat of the sun will do the rest.

Mechanical: You can physically removing the snow from the panels is the simplest method, and could be as easy as brushing it off with a roof rake. That could work for the part of our system over the garage, which is relatively close to the ground. Climbing up on a snow- and ice-covered roof is dangerous.

Chemical: Spraying some sort of deicing fluid on the solar panels should break the bond between the snow and the glass and allow the snow to fall off. The problem here is finding an effective antifreeze which will be safe for both the solar panels and the environment. Sugar water should be safe for the equipment and the environment, but isn't that great as an antifreeze. Propylene glycol should be safe for the equipment, but maybe not the environment.

Thermal: Heating the solar modules would certainly work and be environmentally safe. The problem is that it takes a lot of energy to melt snow and ice, and it's possible that it could take more energy to shed the snow than you would generate. Partly it comes down to whether you need to melt all the snow, or just a little bit to make it slide off.

Holy smokes!

This is a copy-and-paste from an article I wrote on my personal blog last December: http://www.frozennorth.org/?q=content/snowblind

Moderator, can I at least get attribution in a footnote?

[bcroe]

Probability a very niche market for people in snow prone areas or maybe for people who do not want to brush snow say for physical reasons or climbing on roofs, etc.

That includes nearly, approximately, almost, 100% of people who gets snow on their panels.

Still looking at electrically heating the elements here to get the snow to
slide off. It needs enough power to quickly get the surface above freezing,
so the heat isn't just bled away. The bypass diodes need to be disabled.
Probably don't need them anyway, when shade comes the string is about
done compared to 4 in parallel maintaing full voltage. I see the terminal
box on my 250W panels has a couple clips on each edge holding the cover on.

I suppose this will kill the warrantees.

Instead of an experimental setup, might just go after one of the 10 regular
strings. Disconnect a 3 KW string of 12 panels and reverse feed it about
300 VDC at 9 A, shouldn't do any damage. First disconnect it, maybe a blocking
diode will avoid an arc. Then heat it, will only be able to do one string at
a time. When the snow is gone, turn off the DC. The now exposed string
will be generating its own power now with the supply in bypass mode, so
there will be 400V and up to 8A to disconnect, nice arc. With a blocking
diode it should then immediately connect to the inverters. Bruce Roe

[russ]

love all of your ideas !

Mike - Your first day here and all you can do is blather?

[DanS26]

That ought to be a good product. However it doesn't say where the heat reserve comes
from, guess you need to have it..........

It appears you have to connect the thermal to a hot water system that has the capability of generating heat of itself, such as a self fired gas water heater. Then when there is insufficient thermal to melt snow or ice you temporarily pump internal generated heat to melt the ice or snow.

Probability a very niche market for people in snow prone areas or maybe for people who do not want to brush snow say for physical reasons or climbing on roofs, etc.

[russ]

Bruce, have you seen this product?

Made right here in Osgood Indiana by a German company.

http://www.szna-usa.com/pv-thermal.html

Combines PV and Thermal. Reverse the thermal and "walla", snow be gone........

An expensive hybrid that doesn't make much sense. The cooling you get is the same as a couple of more panels with a lot less complication plus you are not potentially mixing electricity and water.

[bcroe]

Bruce, have you seen this product?
Made right here in Osgood Indiana by a German company.

http://www.szna-usa.com/pv-thermal.html

Combines PV and Thermal. Reverse the thermal and "walla", snow be gone........

That ought to be a good product. However it doesn't say where the heat reserve comes
from, guess you need to have it. It won't work for me, because I have no thermal
solar, my panels are 600' from my house. I am still thinking along the lines of back
feeding panels electrically for the heat (which means defeating the bypass diodes).
I wonder what they cost?

I probably don't need the bypass diodes anyway. When one of 5 parallel strings is
shadowed, it is out of business. I have already sorted out any "weak" panels that
can't keep up. thanks, Bruce Roe

[DanS26]

If the snow slides off a ground array, you may need to bring around a snow blower, to
keep the pile from blocking the sun by winters end. However that isn't as big a problem,
easily mechanized.

Seems like, tilting the panels ought to be an option. Either get them vertical enough to
keep snow from sticking, or turn them so the sun warms the clear backside and snow
falls off the other side.

But how about more on thermal? Panels only need to get above freezing, but with
enough power to get it done quickly instead of just bleeding the heat away. If it is
to be done electrically, how will the power be delivered, and will it be automatically
controlled? And will half an hour of heating be justified by several days of subsequent
PV production? Bruce Roe

Bruce, have you seen this product?

Made right here in Osgood Indiana by a German company.

http://www.szna-usa.com/pv-thermal.html

Combines PV and Thermal. Reverse the thermal and "walla", snow be gone........

[bcroe]

Snow removal

There are three basic approaches to removing snow and ice from Solar Panel: mechanical, chemical, and thermal. It's not necessary to completely clean the solar panels, just get enough snow off so the dark surface can start absorbing light. The heat of the sun will do the rest.

If the snow slides off a ground array, you may need to bring around a snow blower, to
keep the pile from blocking the sun by winters end. However that isn't as big a problem,
easily mechanized.

Seems like, tilting the panels ought to be an option. Either get them vertical enough to
keep snow from sticking, or turn them so the sun warms the clear backside and snow
falls off the other side.

But how about more on thermal? Panels only need to get above freezing, but with
enough power to get it done quickly instead of just bleeding the heat away. If it is
to be done electrically, how will the power be delivered, and will it be automatically
controlled? And will half an hour of heating be justified by several days of subsequent
PV production? Bruce Roe