For our Grandchildren...

Solar panels work REALLY well as heating elements too... I bet <1kWh could make all the snow slide off; they only need to be ~40F then the thin film of water lets it all slide off. Not everyone has your level of devotion. Here's a FLIR image of a reverse biased cell. The dark spot in the lower right is a chunk of snow that was blocking some of the light to that cell causing it to consume instead of generate power. That's why bypass diodes are so important.





I keep waiting for someone smarter than me to build something that can reverse bias the array to get the snow off automagically.

tezco said:

Combined solar hot water/PV panels might do the trick since you could easily run hot water through them when needed.

Click to expand...

I had considered that as a fluid system could also be used to cool the panels in the summer. You get ~0.5% more power for every C. The trick is making it cost effective. For a 10kW system probably needs to run <$500... that rules out a liquid system. IMO a 200w DC source should work and cost <$200...

This is likely to become a significantly larger issue as PV becomes a larger percentage of generation. At some point utilities are either going to need a SIGNIFICANT amount of idle generation (very expensive) or rely on a certain amount of PV generation. You can see how even ~1" of snow could become a MAJOR concern. An overcast day reduces production by ~70% but 0.5" of snow reduces production >95%.

Fluid cooled / heated would be ideal, but hard to cost justify, especially as the cost of the solar continues to fall.

We built the house with a 9/12 slope on the south facing roof and ran the cap strips vertically to help the panels to clear themselves of snow. On the odd occasion when the snow is particularly heavy and a broom assist is required, you need to move smartly to avoid getting caught in the resulting avalanche!

on a side note, i think the overemphasis on reducing 'CO2" or "carbon footprint" has made the conversation far too simplistic.

i'd much rather we understand environmentalism in terms of the sum of resources that we use , and the sum of waste we produce. CO2 is just a minor distraction in the great , great diversity of wastes we produce....kinda like the simplistic belief taht recycling will save the earth (hint: it wont).

I like to take the approach of 'add your light to the sum of light' (favorite quote from a loved movie). Recycling, solar panels, reducing my use of fossil fuels, keeping bees, large organic garden, helping others ... no, none of those will save the earth. But if we each take responsibility for our own part of the world, perhaps we can make some progress.

My approach. Everyone lives their life in their own way.

bluenation said:

on a side note, i think the overemphasis on reducing 'CO2" or "carbon footprint" has made the conversation far too simplistic.

i'd much rather we understand environmentalism in terms of the sum of resources that we use , and the sum of waste we produce. CO2 is just a minor distraction in the great , great diversity of wastes we produce....kinda like the simplistic belief taht recycling will save the earth (hint: it wont).

Click to expand...

CO2 is an effective keystone... it's really difficult/impossible to lower CO2 emissions without using resources more effectively. Do you have any specific examples?

tezco said:

Of course, the elephant in the room is over population.

Click to expand...

The earth has sufficient resources to support ~100B people if those resources are used wisely.

But if the average human were as wasteful and frivolous as the average American with energy it would likely struggle to support 2 Billion. The first objective must be to stop using minerals as a fuel source... they need to stay where they are... in the ground.

Some problems are difficult... this one isn't.

This company proposes solar panels which can use some of the energy to melt the snow: Valsoltronic
In Switzerland, but maybe there are links to solutions in other countries.

tezco said:

I can't read the specifics, but when my panels are covered, I don't get enough current to even run a light bulb. It would require backfeeding from the grid to start the process. The wiring sizes would also have to be increased to get enough heat to the panels to do some good. I suspect you might need 1500 watts per panel to do any significant melting within a reasonable time frame. But once part of the array was clear, then you might be able to use array power to finish the job. I suspect the circuitry and controllers to do this and interface with the string inverters would cost a pretty penny, though.

Click to expand...

The trick would be to keep the panel warm enough so that the snow wouldn't build up in the first place. You'd need a sensor to determine if it was snowing (no need to keep the panel warm in cold temperatures without precipitation), and a battery system to keep it warm during the snow (assumes night time or low light level). My guess is that this would take less energy than trying to clear a snow accumulation.

jerry33 said:

The trick would be to keep the panel warm enough so that the snow wouldn't build up in the first place. You'd need a sensor to determine if it was snowing (no need to keep the panel warm in cold temperatures without precipitation), and a battery system to keep it warm during the snow (assumes night time or low light level). My guess is that this would take less energy than trying to clear a snow accumulation.

Click to expand...

Any system designed to melt all the snow either all at once or as it falls would likely be prohibitive in terms of energy consumption... As long as the panels are >20 degrees the snow should slide off if there is a thin film of water. Snow is an excellent insulator so it shouldn't require that much energy to melt the bottom layer; Hmmm... not sure how much resistance the frame edges would offer though, the snow could freeze fast to them. I have to think I'm oversimplifying this... if it was this easy someone probably would have done it already... I have a cheap laminate panel that could catch fire and burn for all I care when I get my FLIR back I'll try doing some experiments.... outside... just in case :wink:

Ah snow... the mortal enemy of solar panels... how ironic.