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The deal as you describe it seems like a terrible deal for the electric company. I don't see how it makes economic sense for them, considering this solely from a purchased power point of view. A big, 5 ton capacity central air conditioner might draw 40 amps at 240 volts. A big electric water heater might draw 30 amps. Call the total 17000 watts. Let's suppose that they must pay a usurious $1.00 per kilowatt hour for wholesale peak electricity on the spot market. If they shut down your 70 amp load for 7 minutes, they save 17 * 7/60 = 2 kilowatt hours of electricity. That's $2.00 worth of electricity. You would have paid them ~10 cents per kwh retail rates for it anyway, so they save only $1.80 cents per shutdown. You pay $16.00 less per month, and they get savings of only $1.80 per month? What am I (or you) missing? (In the most abusive period of the Enron era, wholesale electricity was selling for $3.00 per kilowatt hour. Even if this situation repeats, that's $5.40 per month.) The elec company does get to preserve precious capital dollars in not having to contract for (or generate) more peak capacity. Plus air conditioner loads have an unfavorable power factor, and a high starting current, so there are side benefits to them I've not accounted for. But still, only 7 minutes per month for $16.00? I'd take it in a minute. Jump in the car and flip on the AC if the house is too hot. Pay for the gasoline with a small part of your savings. Are you sure its not 7 minutes per day? Or maybe 4 times 7 minutes per day? I wouldn't worry too much about big brother. If the electric company can't keep up, they can shed the load more crudley by creating rolling blackouts using that same computer. Your thermostat is still being controlled by them.
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