Solar to power heated roof and gutter tape?

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
I know little about solar electric power but I'm very interested to know if it is feasible to power a single run of 120v heat tape such as THIS.

This is for a condo and I'd need to do six separate arrays that will need to run at night. Is it possible and if so, what do I need to know or at least where can I start?

Thanks!!
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  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    #2
    Re: Solar to power heated roof and gutter tape?

    What's wrong with grid power?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: Solar to power heated roof and gutter tape?

    Do you have a reason that you want to use solar panels + a battery bank to supply power to the deicers?

    Normally, solar power costs you about 10x what grid power will cost per kWH (upwards of $1-$2 per watt)...

    And for many climates where you have icing problems, there may be little sun during the winter anyway--Making pure off-grid battery backed solar either near impossible, or even more ridiculously expensive.

    Say you have 6x 50' of deicer at 5 watts per foot and need to run it 10 hours a night:
    • 6x 50' x 5 watts * 10 hours * 30 days per month = 450,000 WH per month = 450 kWH per month
    Say your power costs ~$0.12 per kWH and your winter solar PV array costs you $2.00 per kWH (all hardware, 20 year life, replacing batteries every 4-8 years, etc.):
    • $0.12 per kWH * 450 kWH per month = $54 per month
    • $2.00 per kWH * 450 kWH per month =$900 per month over all solar system costs
    Hmmm... I may be completely over estimating the amount of power used by a deicer heater--I don't live near snow... But anyway, you can see where I am heading with the questions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #4
    Re: Solar to power heated roof and gutter tape?

    The condos are not well built for utilizing grid power. The HOA needs to pay for the operation of the cables but the only way to power them with grid is to do so by choosing one tenant's fuse boxes and that introduces a number of challenges. One being that we won't know how much of the tenant's monthly power bills are due to cable use. I was hoping that solar might be a good long term solution but perhaps that's not the case.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #5
    Re: Solar to power heated roof and gutter tape?
    9gturns wrote: »
    The condos are not well built for utilizing grid power. The HOA needs to pay for the operation of the cables but the only way to power them with grid is to do so by choosing one tenant's fuse boxes and that introduces a number of challenges. One being that we won't know how much of the tenant's monthly power bills are due to cable use. I was hoping that solar might be a good long term solution but perhaps that's not the case.

    Why not place a meter on the heat tape line separately and assess each condo from those numbers.

    I assume this is for ice dam issues, those are usually caused by a problem with the insulation in the attic. perhaps you should look to fix those problems and talk to a roofer about the ice daming.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Solar to power heated roof and gutter tape?

    A good long-term solution would be to hire a reputable contractor to fix the problem with the building, as eaves should not ice up in any climate.

    Right now there's snow on my roof and it's warm as toast inside; nothing melting down the edges, no ice forming on the eaves. As it should be.

    Running heat tape off solar would be a huge waste of money and the wrong solution, in my opinion.

    Just price out the cost of panels to supply 150 Watts (with derating) at 120 Volts. Plus, the thermostatic switches on this stuff are not rated for DC and would probably weld themselves shut.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #7
    Re: Solar to power heated roof and gutter tape?

    Almost every apartment / condo / townhouse building I've seen has a "house" panel and meter - generally used for things like hallway lighting and electric gates and sprinkler systems and whatnot.

    If your building doesn't have a house panel, you can hire an electrician to install one and split off some circuits to it, and have the bill sent to the HOA.
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