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Has anyone gone off the grid doing this?

Post in 'The Green Room' started by jaychino415, Oct 31, 2013.

  1. jaychino415

    jaychino415 Member

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    This might sound crazy. installing solar panels where it doesn't snow of course, connecting to deep cycle batteries, a power inverter to run your hearth fan?

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  2. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Moving to the Green Room where solar is a big topic.
  3. jaychino415

    jaychino415 Member

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    thanks BrotherBart, wasn't sure if it belonged here or there. wrote="BrotherBart, post: 1559911, member: 6"]Moving to the Green Room where solar is a big topic.[/quote]
    tha
  4. woodgeek

    woodgeek Minister of Fire

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    Can't size a system unless we know how many watts your fan needs, and how many hours a day you want to run it. Cali will help, out east the solar resource is pretty good, but not in the months you would want to run a blower--too cloudy.
    Last edited: Nov 2, 2013
  5. Redbone

    Redbone New Member

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    My entire house is solar powered, but I don't have a stove fan... A fan would not use much power. Find out the wattage, convert to amps, multiply by hrs per day of operation, multiply by days of reserve power you want the batteries to have on cloudy days, and figure the batteries shouldn't discharge more than 50 to 60%. You're there with the battery amp-hr calc. Size the panels similarily. I sized my system with a four day battery reserve, and assuming it would take two sunny days to fully recharge when its discharged to 60%. You can get lot's of system design info at www.backwoodssolar.com. Another great resource is http://www.amazon.com/Photovoltaics...=1-2&keywords=solar power system installation. I used that book extensively when designing and installing my system. Ended up with 2kW of panels on the roof, and 1400 amp-hrs in the batteries.
    jaychino415 likes this.
  6. peakbagger

    peakbagger Minister of Fire

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    Yes it can be done but typically off grid power is 5 to 6 times more expensive than on grid power. If your state has net metering you are far better off installing a couple of AC solar panels with micro-inverters and net metering. If you really want the "SHTF" scenario go with batteries but realize that odds are you are buying a new set every 10 to 12 years (if you buy true solar batteries, otherwise it could be 3 to 5 years for walmart deep cycles). Most folks go with a generator and a few cans of gas.
  7. KindredSpiritzz

    KindredSpiritzz Feeling the Heat

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    I was thinking about doing the same thing to run the fan on my wood furnace but i have no idea where to start. Harbor Freight sells 45 watt solar panels for $130 i have been thinking about trying but i don't know if that'd be enough to charge a battery bank to run the fans. Keep us posted if you do it.
  8. jebatty

    jebatty Minister of Fire

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    I kind of started doing what you want to do to prep me to know about solar before doing my 6.5kw solar system. I bought a 30 watt panel and a charge controller to charge a 35AH SLA battery. I use the battery as a back-up charger for 6 rechargeable solar lights I use in the house and also to charge my other rechargeable devices (cell phone, laptop, etc.). It works very well for this purpose, but a much larger battery/system I think would be needed for what you want to do. This was and remains part of my mission to reduce grid power usage.

    The 30 watt panel puts out a maximum of a little over 2 amps in full sunlight and less of course in lesser light. You can estimate the maximum output of a 45 watt panel to a 12v battery charge controller at a little over 3 amps. That is about a maintenance charge rate for a large capacity battery but not really enough to charge it. For a large battery follow the mfr instructions as to appropriate charge rates. I use a rule of thumb for an SLA battery of 1/10th the AH capacity. Be sure to use a charge controller.

    BTW, even with the 6.5kw solar system, so far I still am using this 30 watt panel system for the same purposes, but I'm thinking the hassel of doing this will likely change my mind in the future. I may consider selling it unless I can re-purpose its use.
  9. Where2

    Where2 Member

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    If you know where to look, you can find much better deals than the 45W Harbor Freight panels. The 4.4kW PV system on my roof is comprised of twenty 220W panels that were only $172 each when purchased in a quantity of 20 on a pallet. For single panels, best I have seen recently is around $1/W plus shipping for 60 cell panels. What do you do with a 60 cell panel that puts out around 24-30V, you use a 24V charge controller and dump it into two 12V batteries in series, and you step it down to 12V to run things. My 24V to 12V step down converter cost $15 with the following specifications: 5A continuous, 10A for 7 minutes, 15A for one minute.
  10. woodgeek

    woodgeek Minister of Fire

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    For small panels in a hobby system, the cost per Watt will be higher, and the fixed cost of the controller and wiring will up the cost/W further. The best prices I found on small modules were on FleaBay, IIRC closer to $2/W. I also think for a hobby system, he will want to run 12V and one batt. And if he wants to run a blower during a blackout, he should just get a HF genny on sale for $80.

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