Utility Intertie Systems

I mentioned in a previous chapter the term utility intertie. This is not a functional piece of neckwear but rather a way of connecting renewable energy power systems to the utility grid.

"But why would I want to do that?" you might ask, "Especially since the idea of renewable energy is to get away from the grid." That's a darn good question (you folks are a smart bunch), but there are a lot of people who want to do just that. Maybe it has to do with some kind of residual grid-envy or a reluctance to sever the ties completely. Whatever the reason, I remain unconvinced that it is a good idea.

Some states (not Colorado, however) have enacted laws or regulations that require the utility companies to buy power from RE producers at the same rate they sell it. This is called net metering. This means that a homeowner who has connected his renewable energy system to the grid gets credit for every kilowatt hour of electricity that flows from his system into the utility grid. These states are the exception rather than the rule, however.

While this might sound like a good idea the reality is quite different. Very few, if any, utility intertied systems produce a profit for homeowners. Even in net metering states, utilities are allowed to charge a basic connection fee which often eats up any profit that might be made. Also, it is the rare homeowner who is wealthy enough to buy more charging capacity (in either PV or wind) than they might reasonably need for their own use. This means that there is little excess power available to "sell" back to the utility company.

It is even worse in Colorado. Here, the power companies can charge avoided cost, which means that they sell you power at, for example 8 cents per KWH but buy it back at less than 2 cents per KWH, or the price they pay for it wholesale. It is hard to see how anyone could justify grid-intertie in Colorado on economic grounds.

The result is, at best, a barely break even situation for the homeowner or a smaller monthly bill from the utility. So why do some people opt for utility intertie systems?

A lot of the people, especially in California, which has one of the stronger buy- back laws, can't wean themselves from the habits that use a lot of electricity. For these folks, who want the cachet of independence without having to actually make the leap, it means having what they consider the best of both worlds.

Systems like these will have relatively small battery banks, for those times when utility power fails, but rely primarily on the utility to "store" their power. These systems most often have large PV arrays or wind generators. They use inverters like the Trace 4024, which allows utility intertie, and will use utility power to keep the batteries fully charged. When the batteries are fully charged, either by the utility or the PV panels, the inverter will "sell" the excess power produced back to the utility. The power will be fed into the grid through a separate utility meter that monitors the power output from the house.

When the meter reader comes to a utility-intertied home she will read both meters and the homeowner is charged the difference in electricity usage, usually with a small fee added on. A home in Maine which uses this principle can be seen HERE. This home, built by the William Lord family, has a very large system with no battery bank, that feeds power into the Central Maine Power grid.

Interestingly, they don't say how much it cost, but I would suspect that it cost in excess of $30,000. And they still get a bill from CMP. I don't think they have made money on it even after 3 years of operation.

Time to get on my soapbox. One of the major reasons that Maggie and I decided to go solar was to get away from the corporate controlled grid and to take responsibility for our own power production. Another big reason, in this particular region, was the unreliability of the power grid when it comes to providing clean, consistent power. Let's face it, the grid power fails just when you need it most, in bad weather or at night. Tying a renewable energy system to such a grid, in effect maintaining a level of dependence on the grid, defeats a prime purpose for having a renewable energy system. A well designed renewable energy system and home will not need a grid connection. Regardless of the perception that our grid power system is getting better and more reliable, there is ample evidence that even in urban areas grid power is becoming less reliable as the 21st century approaches. Witness the massive power outages that occurred twice last year in the Western U.S.

There have been many days here in Guffey when I have been darn glad I have a renewable energy system. As I pointed out in my first column, I would not want to put up with the irritation of constant small power outages and occasional big ones that occur in this area. In my opinion a grid intertie, even one with a battery backup, is a false step on the road to energy independence.

All Contents © 1997
Wagonmaker Press
Thomas W. Elliot


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