Recently, we experienced complete outages for around 8 hours, due to construction on a nearby road. We have decided to install a backup battery and solar array to prevent this from happening in the future.

Question One:

Is this feasible? Would a gas generator be better? Would a battery be able to power a house with average power consumption in the US for one day, which would be about 33 kWh?

Question Two:

Where would I be able to purchase such a battery, and a solar array that would fit the specifications above?


  1. The battery must be at least 33 kWh in capacity
  2. This array, with zero outside power supply, should power an average US home for one day (24 hr) at average usage.
  3. This battery should be able to charge by solar panels, perhaps installed on the roof or on another place (location is not relevant).
  • $\begingroup$ A rough estimate for information: a typical car battery (say here in the UK) is 12V and 45-50 Ah. Say 600 watt-hours. 33 kWh is fifty or sixty of those batteries... A generator as EnergyNumbers has suggested would be much cheaper. $\endgroup$ – Andy Aug 10 '16 at 13:14
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    $\begingroup$ You should start by reading up on commercially available systems: cost, peak & continuous wattage capability, etc. Then realize that there's no such thing as "average home" or "average usage" . $\endgroup$ – Carl Witthoft Aug 10 '16 at 13:57

It sounds like what you are after is increased energy security. You want a backup which would have a very low load factor - it wouldn't get much use each year. You want fast response, times of high power, and a decent amount of storage. But it sounds like you don't need absolute continuity of power - it's ok if power goes out for a few seconds.

Almost all entities in your position that I'm acquainted with, use a diesel generator. It would meet your needs, be very cheap to buy and own, and be fairly easy to maintain (you might need to run it for a few hours each month to keep it in decent shape). It will be smelly, noisy and environmentally damaging in operation; but if you barely use it, that's much less of an issue.

You just need to spec it to be able to comfortably produce the maximum power draw you need - that might for example involve an electric shower, a kettle and a bunch of appliances on all at once.

If you wanted absolute continuity of power, then a battery-powered UPS (uninterruptible power supply; it's charged from the mains power) for the critical kit would be an appropriate addition to the diesel genset. It would not be cost-effective to have it for all your kit: only for the kit that you absolutely need continuity of power.

PV is a completely different issue, tangential to your requirements. You might want it, for all sorts of reasons; but not for the use-case in your question.

  • $\begingroup$ Propane-powered Generacs work just as well as diesel-based generators. And they don't smell :-) . $\endgroup$ – Carl Witthoft Aug 10 '16 at 13:58
  • $\begingroup$ My neighbor's generator will power his entire house and is connected to the natural gas line. It switches on every Thursday at 1300h and runs for 5 minutes to keep things lubricated. $\endgroup$ – DLS3141 Aug 10 '16 at 16:52

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