I have quite a bit of experience with solar systems in terms of remote telecommunications facilities where utility power isn’t practical. These involve large battery banks and over-engineering to ensure reliable power for radio, microwave, and telephone relay stations that need to be up 24/7.
So, the idea of a solar system in a suburban area with plentiful utility power didn’t make sense to me at first. Electricity is readily available at reasonable rates. It would be satisfying but not practical to pull the plug on Edison.
Then, I stumbled across a mention of solar “co-generation” on Southern California Edison’s website. Co-generation is when a customer connects a source of power such as solar or wind into the electric grid. With solar, California supplies a rebate to pay part of the cost, and the federal government provides an additional tax credit.
On further research I found the idea of co-generation kind of exciting. I can use the entire utility grid as my energy storage. I don’t need a battery and I don’t need to design the system any bigger than my load.
I was also considering my electric vehicle (Chevy Volt). I decided the convenience of the 240-volt charger was worth it. Rebates cover half the cost of the charger and installation. If I came home from a day trip with a depleted battery I could plug in for a couple of hours and then go out to dinner on electricity. However, the Volt would be away from home when my solar panels would be generating power from the sun.
With co-generation, I just produce more power than I need when the sun shines, feed it to Edison, and then pull power from Edison at night to run my home and charge the car. I also switched to a rate plan that gives me much lower electric rates at night and credits me at higher rates in the daytime when the sun is shining and I’m producing electricity. Some friends were predicting that the Volt would cause my electric bill to skyrocket –ha![Click image to see more…]
As luck would have it, I have a great roof for solar. It is south-facing and doesn’t have any vents or obstructions. I had enough area to install panels that could generate about 4kW peak power. I’m good with my hands and have a lot of experience with wiring and electrical things. My initial plan was to install the solar as well as the level 2 car charger myself.
I quickly changed my mind about installing the solar because I’m not comfortable with the permit process and roof penetrations kind of scare me. I shopped around and chose Coastal Constructors to provide the hardware, do the mechanical work and take care of the permit paperwork. They did the wiring at the same time as they wired the charger, and everything passed inspection. Modern panels are a lot better looking than the earlier ones. I’m very happy with the appearance as well as the performance.
Another modification I considered was the inverter systems. Most grid-tied systems connect a number of panels in a series string to produce high-voltage DC, and then put in a large wall-mounted inverter to convert this to conventional AC power. I was not excited about this design. A fault in one panel can bring down a whole string. Due to the high DC voltages, the wiring is complicated.
I discovered a company in the Bay Area, Enphase, that does things differently. They manufacture micro-inverters. Each micro-inverter handles the output from one solar panel. One mounts underneath each panel and they connect in parallel. If one panel or inverter goes bad, the rest of the array keeps going. The DC wiring is low-voltage and needs no conduit.
In addition, my solar system has its own website that not only shows real-time and historical data for every panel, but can also alert me if there’s ever a problem. If there’s debris such as bird droppings on or an electrical problem affecting one panel, the other panels are not affected, and I get an email describing the issue and showing me which panel is in trouble.
It’s now been in service for almost 10 months. I’ve ”banked” a bit over 6 megawatt-hours of electricity with Edison. Carbon offset a bit over 4 tons. Every month since installation I’ve produced more electricity than I’ve consumed. Not only am I driving on daylight, I’m powering my house with it and even providing solar energy to my neighbors via the grid-tie.
Kermit was wrong. It’s easy being green. Take a look at my solar production >