House Project: Backup Generator Worked, But There's Some Minor Issues

We lost power last night about 10:30 PM--and so did everyone in Horseshoe Bend. From our commanding position on the mountain, we can see every house. We were watching something on History Channel about Caribbean pirate technology, and sudden darkness. My wife says, "Okay, where's the backup generator?" Sure enough, it started, but as I think I have mentioned in the past, there wasn't enough capacity to run every circuit in the house from it, because it is only seven kilowatts, so only the kitchen appliances, the furnace/air conditioning system, and the well and pressurization pumps remained powered. The rest of the house was dark.

Now, at any given time, I'm sure that we are not using seven kilowatts in the whole house. The problem, at least as the electrician who wired the house and installed the generator explained it, is that the backup generator is set up to power circuits based on their maximum capacity.

When I went out today and counted up the capacity of all the circuits that the backup generator protects, I counted 145 amps--which at 120 volts, would be 17.4 kilowatts--quite a bit above the seven kilowatt capacity of the generator. So why can't it spread its capacity across more circuits? I've called the electrician to ask what we can do about this.

I have an idea--and that's to buy a large storage battery and inverter such as would be used with a photovoltaic system or wind generator that can feed all the circuits in the house, and have both the backup generator and the grid keep it fully charged. If we lose grid power, the battery feeds the house, and the backup generator recharges the battery. That way, we have full power for the house, and it would take a very long outage to discharge the battery sufficiently that we would have to start shutting off unnecessary circuits. It also makes it easier to add a wind generator to feed the battery.

Alternatively, we might use the storage battery and inverter to feed all the other circuits, figuring that these are less essential, and only a long outage would cause us to lose the luxuries of computers, televisions, and lights.

If I understand the math on this unit, it supplies 258 amp-hours at 12 volts, which would be 3.096 kilowatt-hours. There's some loss from running it through an inverter to get it back to 110 VAC, but still, that would run at 20 to 25 100 watt light bulbs for an hour. It's about $447 (plus shipping, which might be expensive for something this heavy). Unfortunately, the inverters end up well above $1000, so it turns into an expensive investment.

Last house project entry.