Wednesday, May 24, 2006

Some Solar & Wind details

Beo asked about what kind of alternative power setup we were looking at. I started to reply via comment, but it got big enough that I decided to move it here.

First, a little background. There are several different ways to set up a solar or wind power system, and each choice seems to bring with it more options. Which configuration makes the most sense depends on your circumstances. I got most of this information from the company we asked to come out and do a site evaluation. Hopefully this won't be too confusing for anyone who's interested...

You can set up your system to be connected to the power company's infrastructure (a.k.a. "the grid"), and feed any energy you generate back into the grid, or you can be off-grid. If you are off-grid, you'll most likely need a battery storage system. This is usually used in remote locations, where there is no power company.

If you are interconnecting to the grid, the power company generally has to give you credit on your electric bill for any energy you feed back into the system. You can decide to have a battery system, or just use the electric grid as "storage". If you do not have a battery system, and the power company has an outage, you have no power.

If you are grid-connected and you have battery storage also, you have two choices. You can feed your power back to the power company first, and only use your batteries if the power is out, or you can feed your power to the batteries first, and use that power before taking anything from the power company.

This last scenario is the one we were looking at. I don't know about other states, but here in Ohio, if you get your electricity from a for-profit power company, they basically have to pay you the same rate you pay them for electricity. If they charge you 6 cents per killowatt-hour, they pay you 6 cents per killowatt-hour that you generate. Rural co-ops though, don't have to pay you full price. They only have to pay you something called "avioded costs," which is typically 1/3 to 1/4 of what they charge you for power.

So it would be silly for us to generate power and sell it to the co-op for 2 cents, and then buy it back for 6 cents. We're better off using it directly, and then buying the rest for 6 cents. Then, only if we have more than we can use and/or store, do we sell it back to the power company.

In a setup like this, we would actually be taking specific circuits out of our circuit box in the basement, and running them into the battery bank and inverter, and then back to the circuit box. So only some parts of our house would be able to use the alternative power directly. That makes sense though, because we wouldn't have the capacity to run everything in the house anyway.

If there isn't sufficient sunlight, or wind, the batteries are kept fully charged by the power company, so that if the power does go out, you're always starting with a full charge.

Our objective is to keep the bare essentials up and running during an emergency - the well pump, the sump pump, the corn stove (it requires a small amount of power to turn the auger and the firepot stirrer), and, depending on the how the numbers work out, possibly the fridge, the ceiling fan (for heat distribution or for cooling), maybe the gas range and/or the microwave... we'll have to work all that out. I've got a little device called the "Kill-A-Watt" that you plug something into, and it plugs into the wall. It will then tell you the power consumption for that item. It doesn't work for hard-wired items, but it'll still be pretty useful, if we decide to do this.

We haven't worked out whether we're taking the plunge or not. It may have to wait. From a money standpoint, it's like taking a percentage out of your electric bill, and paying for that electricity in advance. For that pie slice, you're buying the next 20 years' worth, all at once. It should be a bit cheaper in the long run, but hard to pull off in the short term.

I'll keep you posted...


At 5/25/2006 9:06 PM, Blogger Beo said...

This is the first I have come across he selected circuts idea-though it has some very intriguing aspects-like leaving an outlet or two in the garage to run the tablesaw instead of spending an extra $2k on a huge inverter to handle a rarely used high power tool.

Just to clarify-would your coop have two meters-one for what you use and one for what you give back to the 'grid'? As I understand it (you are much further along on this than I am) here in WI the meter would just spin backwards when the wind blows and forwards when it calm and cloudy-effectively giving us $.085/kwh credit for what we produce.

At 5/26/2006 8:22 AM, Blogger e4 said...

Great question on the backward metering. I'll see if I can find out and update here.

At 5/27/2006 5:47 AM, Blogger Morgan said...

sentences to long hurts my eyes must look away


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