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Community and Q&A

Backup power–generator vs. ???

davidmeiland | Posted in General Questions on

Working on a project where the owner would like a 20-kilowatt whole-house propane generator. Due to a variety of factors, it’s difficult to locate a unit of this size on their site, so I’m wondering now about other options for backup power. The primary issues they’ve raised are lack of water (they’re on a well, so no power = no water), loss of refrigerated and frozen foods, loss of communications, and lastly, loss of heating. Their house has a propane boiler and electric circulators, so only minimal power is needed to keep the heat on.

The two things that come to mind here are a whole-house battery, or perhaps an electric car that can be switched over to feed the house. I don’t know anyone using either of these strategies right now, but I know they exist. What is available and feasible right now, and if we fast-forward a few years, what might we see then?

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  1. GBA Editor
    Martin Holladay | | #1

    I think a fossil-fuel powered generator is the way to go.

    Here's my advice:
    1. Make a careful list of the appliances that have to be on the emergency circuit, and add up the total watts (taking surge power for start-up into consideration). You may need fewer watts than you think.

    2. Make a concerted effort to whittle this down by choosing very efficient freezers, refrigerators, and circulators. If you can end up with a smaller generator, you may save enough money on the generator to pay for a more efficient freezer and refrigerator.

  2. gusfhb | | #2

    20 kW?

    sounds huge

    I use a big box 3kw for fridge.

    Well pump is probably biggest load, but still not that big

    As a side note, I have a fairly large well tank [size of trash barrel] and can run best part of a day with judicious use

  3. GBA Editor
    Martin Holladay | | #3

    I thought the same thing -- but there is always the possibility that the family has two refrigerators and three freezers.

  4. STEPHEN SHEEHY | | #4

    My old house was 4200 square feet. The load: boiler, furnace, electric oven, well pump, lots of lighting circuits, fridge, freezer, etc. A 10K Generac propane generator ran everything we needed, even the oven if we didn't also iron clothes and dry hair at the same time. As you may already have noticed, a bigger generator doesn't cost all that much more, but can use a lot of propane. Sizing the tank is important, so look into what the realistic worst case scenario for power outages are. My 10K generator used about 1 gallon per hour.

    In my new house we are still mulling over what to do for emergency power. Everything is electric, we have grid tied PV, but no battery or anything that would allow us to use PV power when the grid is out. We'll probably end up with another propane generator. My electrician likes Kohler, as he says they have a better system for reducing power (and fuel use) when the draw is low.

    There's a lot happening on the storage/PV front. I suspect that a few years from now, systems with battery backup (maybe in your Tesla 3) will be widely available and easy to install. If nothing else, if you install PV, speak to the solar contractor about what sort of inverter will be best for any future changes.

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