The Process

On November 15, 1996, we applied to become the first home PV system in Nevada County, California to have our PV system connected to Pacific Gas and Electric (PG&E) under California's recently passed net metering law. From everything we had read in Home Power and elsewhere, we were ready for a long, hard battle with the huge utility.

We contacted Clay Schmidt and Mike Bryant from our local PG&E office in Auburn and informed them that we were ready to sign up for net metering. In a few days, the two PG&E representatives came out to our home and inspected our system. At that time we supplied them with the documentation requested regarding our Trace SW4024 sine wave inverter. Fortunately, this inverter had already been tested and approved in May 1994 by PG&E for use with their power distribution system.

It was several months since the initial visit from PG&E, and we had not heard back from them. I contacted them and found that they really did not know how to proceed on this case, as their office had never processed a net metering application before. Mr. Schmidt honestly admitted that they didn't even know which forms to use. After a few more weeks, he called us back and said that they were ready to proceed.

On January 23, Clay Schmidt came back to our house with David Lee and Leo Starns, PG&E substation specialists to inspect the system once again. David and Lee usually deal with transmission voltages in excess of 60,000 volts, so needless to say, they found our system to be interesting. They found that it lacked only a visible, lockable disconnect to comply with the utility's fairly strict requirements. Within a few days, the appropriate disconnect was installed. On February 4, Clay Schmidt returned and gave final approval to our system. Immediately, we threw the switch and were treated to a rare and truly beautiful sight; a utility meter spinning backwards!

Schmidt admitted it may take a while for PG&E to get used to buying, rather than selling, electricity. "It's bizarre for us because we usually prosecute people whose meter runs backward," he said with a laugh. But seriously, it was a pleasant surprise to this writer how helpful and cooperative the PG&E employees were throughout the whole process.

The System

Our system is not large by today's standards. The heart of the system is a Trace Power Panel with a single SW4024 sine wave inverter. The power panel includes a Trace C-40 charge controller, which is generally not required in a line tie system of this type. The only scenario where the C-40 would serve a useful function would be if the power grid was down and we were producing a surplus, with full batteries. As most power outages in our area occur during the winter months, this is somewhat unlikely.

While a line-tie system does not really need a battery (assuming the appropriate inverter is used), a high priority for us was to be able to have power for our home in the event of a utility power outage. For this reason, we installed two sets of Pacific Chloride 6-85-21 industrial forklift batteries, with a total capacity of 1055 amp-hours at the 20 hour rate. At our average daily power usage of about 5 kwh/day, this battery bank would get us by for about four days with an 80% depth of discharge. While draining batteries this deep is ordinarily not recommended practice, we don't expect this to happen on a regular basis.

Our PV array currently consists of 16 ten year old ARCO Solar 16-2000 modules, rated at 35 watts each. This modest array provides for about half of our power requirement during the summer. As it is our goal to produce all of our power in most situations, we will be adding to our array in the next few months. We will soon be installing 12 British Petroleum BP-275 75 watt single crystal modules mounted on a Zomeworks TRPM12 passive Trackrack. This additional 900 watts of PV should provide more power than we need for most of the year.

Net Metering- How it works

Whenever we are producing extra power over and above our momentary needs (this happens most sunny days when we are at work), this surplus power is sold to the utility grid at the retail rate. During the evening, we buy the power back, at the same rate. According to state law, as long as we don't show a surplus in any month, we are paid the same rate as we are charged. If we have a surplus for the month, we are only paid for the surplus at the 'wholesale avoided rate," which of course is a small fraction of the retail rate.

One of the wonderful things about net metering is that we get to use the grid as a battery. Not just any battery, mind you. Normally, a penalty is paid for storing energy in a battery. When a battery is charged, electrical energy is converted to chemical energy. This is not a 100% efficient process. Later, when power is drawn from the battery, the chemical energy is converted back into electrical energy, incurring a loss once again. Because of California's net metering law, we can now use the power grid as a 100% efficient battery. Not only is it 100% efficient, but our "utility grid battery" will not wear out, unlike a normal battery which has a very finite life. In fact, the battery is the only part of a PV system which needs to be replaced on a regular basis. Also, using the grid as our battery saves a great amount of wear and tear on our forklift batteries, since they will be kept full for 99% of their life. This should give us approximately twice the life on these very costly (and very heavy!) components.

The House

Our house is a 1750 square foot passive solar home at the 3000 foot elevation in the Sierra Nevada foothills, just outside of Nevada City, California. It has three bedrooms, two baths, an office, a two car garage, a screened porch, a 900 square foot deck. In short, your average medium sized American home. All lighting is compact fluorescent, and we have a Sunfrost RF-16 refrigerator, which we love. Other than these items, everything else is pretty normal. We have a washer, a gas dryer, a dishwasher and a one horsepower submersible pump in our 500 foot well. The backup to our passive solar heating is a hydronic loop below the first floor, with gas direct vent room heaters upstairs (which almost never get used). Largely due to the compact fluorescents and the Sunfrost, our power use is quite modest. Before the PV, we were averaging utility bills in the $16 - $20 range.

What's the Big Idea?

The big idea is to demonstrate that it is entirely possible to live comfortably without using any more of the Earth's scarce resources than absolutely necessary. After our PV system is completed in early Summer, we'll continue to make refinements in the way we make and use energy. One important consideration in building our new home has been to test new ideas in energy production and conservation.

Even though we live in an area where it's not usually windy, it blows pretty well during storms. We see winds in excess of 50 mph now and then. With the advent of small inexpensive wind generators like the AIR 303 from Southwest Windpower, why not use the wind for power when the Sun is somewhere else? Future plans also include a Harris Hydro for our seasonal creek, which of course also runs best when the Sun don't shine.

Our water is still heated with propane, a fact that I'm almost embarrassed to admit. This will change soon. There are several really effective passive solar hot water systems available. Solahart and Progressive Tube are two types that we are considering that require no electricity and have no moving parts.

Conclusions

Net metering is not for everyone. But then, neither is solar, or even energy conservation in general. They all take an extra amount of involvement, and sometimes extra investment in the short run. To use any of these, one must live in a more conscious fashion than the average human being. They all require that we take an active part in how we use and produce power. If we'd prefer to let someone else i.e. "the power company" make these energy decisions for us, so be it. Rather than feeling powerless, some of us would rather take responsibility for where our power comes from and how it is used. It's just a part of reclaiming our personal power from the powers that be.

Access

Author: Jonathan Hill, Sierra Solar Systems
109-E Argall Way, Nevada City, CA 95959
phone: (530)265-8441, fax: (530)265-6151
email: solarjon@sierrasolar.com