The holy trinity of energy management - conservation, efficiency and renewables - can be illustrated in terms of a common household lamp: Conservation means shutting it off; efficiency means fitting it with a compact fluorescent light bulb; and renewables means installing a solar panel to power it. Off-grid houses usually combine all three methods.

Charlotte residents Brian Thompson and Katherine Knox live with their two daughters in an off-grid home they built in 2003. For them, going off the grid made good economic sense: Their lot is located half a mile from the road, and running subterranean wire that distance would have cost $30,000 - the same amount as installing a renewable-energy system.

The house includes roof-mounted solar panels, a 100-foot windmill and a propane-powered backup generator. The solar panels work well when it's sunny; the wind generator can provide an extra power boost in a breeze, and doesn't stop at night or when it's cloudy. The propane generator is a failsafe, especially for November and December when both sun and wind are scarce. This system generates about 140 to 150 kilowatts each month, more than enough to cover the household's power needs.

Thompson and Knox were happy to conserve energy, but they wanted to have a "normal" house - and they do. It has running water, a propane water heater and stove, and an energy-efficient electric fridge. Their dryer uses electricity to turn the tumbler, but the heat comes from propane. Because their house is designed to let in natural light, they usually only need to turn on lamps after sundown. One thing they don't own is a coffeemaker - they just pour hot water through the grounds. "Those things suck a lot of power when they're keeping coffee warm," says Thompson.

Situated near the top of a hill overlooking Mt. Philo, the spacious house stands a short distance from the wind tower, which is supported by guide wires. When Seven Days caught up with Thompson on a recent sunny day, clean laundry was flapping in the breeze, and chickens were roaming a nearby grassy field.

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SEVEN DAYS: How much propane do you go through in a year?

BRIAN THOMPSON: We use about 500 to 600 gallons a year, but that's mostly for cooking, it's not really for the generator. The backup generator runs between 50 and 100 hours a year, so far. So I think if you were to compare propane usage for normal houses, it would be twice or three times [as much], because we use it for heat as well. But we also heat with wood - that's our primary heat source . . . This year, it was such a mild winter that the furnace hardly ever came on. The wood stove kept the house really nice and toasty.

SD: Why did you choose the combination of wind and solar?

BT: Mostly to have two sources to charge my batteries. It's not a real big wind generator. It's only a one-kilowatt wind turbine. It only weighs 80 pounds, and the blades are only 4 or 4-and-a-half feet each, so it's got, like, a 9-foot swept area where the blades spin. When you're driving by on the road you can hardly see it.

SD: How much wind does it take to make the turbine spin?

BT: About, I don't know, 2 or 3 miles an hour . . . It doesn't take much. And it has a cutout speed. If the wind speed gets over 29 miles an hour, the tail turns. The wind pushes the tail over this way, and then the wind generator turns itself out of the wind and slows down. It'll eventually tilt back, and then it'll start speeding up again.

SD: What kind of batteries do you have?

BT: They're called marine batteries. They're like, 200 ampere, so if you think of a normal car battery, they're probably like three times the size.

SD: Chemically, are they the same composition as car batteries?

BT: Yeah, they're a lead-acid battery. And that's actually the one thing I have to maintain on my system: Every four or five months, I have to go down in the basement and open up my battery box, take the caps off all my batteries, and add distilled water to each one.

SD: If you wanted to go away on vacation for a couple of weeks, would that be a problem?

BT: No. We go away for weeks in the summer. It's pretty much self-sustainable. I don't know if I'd want to do it in November and December . . . The backup generator comes on by itself, but I prefer to be monitoring it.

SD: Did you receive any tax credits or incentives for your home's energy system?

BT: No, I didn't. When we installed the system in 2003, there weren't any . . . They started in 2004, I think.

SD: So that's a one-time thing, when you build, not something you could get every year for having it.

BT: Right. I know there's a guy in Colchester who just put his 10-kilowatt wind turbine up, and got half of it covered, federal and state.

SD: Are those credits related to being tied to the grid?

BT: No, just for putting up renewable energy, for using it. It made a big difference in the cost. It would have cost him $30,000 to put it up, but it only cost him $14,000.

SD: Could you say, annually, what percentage of your power comes from wind and what percentage from solar?

BT: It's probably about 70 percent sun and 30 percent wind, on average.

SD: Is there a way to turn solar panels off?

BT: They regulate themselves. When they see that the batteries are full, there's a dump load, and they just start dumping power into a big resistor.

SD: Do you have a solar hot water system?

BT: No, we didn't invest in solar hot water, primarily because of the cost . . . It was as much as the wind generator to do all of the plumbing and put the tanks in.

SD: Do you think you'd ever want to be connected to the grid?

BT: At this point, I don't see a reason to, because it's just not something that we need. I've never had an outage since we've been online, and we're going on three years now, come November.

SD: Where was the wind turbine manufactured, and how did you decide on that particular turbine?

BT: The person who recommended it was the person who installed the whole system, a professional . . . It's a Bergey XL-1 - I'm pretty sure they're made in Oklahoma.

SD: If you were to separate out the cost of having just wind power, how much would it cost to put up a turbine like yours?

BT: Oh, that was only $5000, for that wind generator and tower.

SD: What kind of permits did you have to get to install the turbine?

BT: I had to get a height variance from the town. That's a zoning deal. You're not technically supposed to have anything higher than 30 feet. When you ask for something like that, you have to involve your neighbors, because they all need to know about it. And then I also had to get an actual Act 250 permit amendment.

SD: Has the wind generator ever been a concern for your neighbors?

BT: Well, there were two neighbors that didn't really like the idea, because they didn't really know what it was going to be like. They would come to meetings and offer resistance of some sort. They wanted me to make the wind generator smaller, not so high in the air . . . Today [the neighbors] have changed their minds. They understand that it's a good thing.

SD: If there's freezing rain or really drastic weather, would you have to worry about the wind generator?

BT: No, when you get ice on the blades, it doesn't hurt it any. It still keeps running in bad storms. Typically when you have a good storm, when it turns itself out of the wind, it makes a pretty loud howl.

SD: Did you have any background with renewables before you looked at doing this, or were you a blank slate?

BT: Blank slate.

SD: Apart from having chosen energy-efficient appliances, are there certain things you do to try to conserve energy?

BT: Oh, yeah. We don't have any plug-in clocks. All our clocks run off batteries. I made all my outlets switched, so I can switch an outlet off and there's no power running to it. For example, we have a TV and a DVD player, and a VCR, but I turn the power off on that when we're done with it.

SD: Those appliances would drain power?

BT: They're called "phantom loads" - things that are in your house that are using power all the time, even when they're not on. A clock in your stove? That's using power. The same thing with your TV and your VCR, all that stuff that's set on a timer . . . All of our lighting is compact fluorescent, as well. And when we built the house, we had it facing south with all of these big windows, so we get a lot of light.

SD: If you had to do it over again, is there anything you'd change?

BT: No, I don't think so. I guess I'd like a bigger house. [He chuckles.] You know, you always want more space.