[This post is part of a series about our net-zero residential solar project - see a list of links to the full series here, a list of frequently asked questions here or click here to bring up all Green-related posts. Previous Post in Series.]
This week marked the first anniversary of our solar conversion. A year ago we flipped the switch to begin powering our house with a solar panel array. So how did we do our first year?
Before the stats, what is it like to live in a solar house? In a word, awesome. Day to day it is no different at all. You are still connected to the grid, and everything still works like normal. But beneath the surface, it is pretty cool.
Each morning at sunrise, a glow spreads across the East, the day begins to warm and the first rays of light begin to clear the horizon. You begin to see the sun, and its first rays hit your panels. At that moment, down in a dark closet in your cellar, some LEDs start to blink, the inverters wake up, and your house silently begins to generate some of its own power. With each minute, the trickle of power grows stronger until, at some point, maybe an hour or so after sunrise, your net meter slows to a crawl, then stops, and a moment later starts going backwards. You are now making more power than you are using, and you begin the process of selling the day’s surplus to your utility.
All day long the sun climbs higher, the flow of power increases, and the meter spins backwards faster and faster. At some point in the morning all of the power you borrowed during the night has been paid back. By noon you are generating a huge surplus and selling thousands of watts an hour to the power company. As the day progresses, you build a bigger and bigger surplus for the night. As the light fades in the late afternoon, the process reverses, and the meter slows down. An hour or so before sunset, the net meter slows and finally stops turning in reverse because your panels can no longer collect enough of the twilight to fully power your house.
Despite all the technology involved, all the silicon on the roof, all the meters and inverters and wires and lights, in an odd way it really takes you back to nature. You think about the weather more than you used to. You are more aware of the time of sunrise and the time of sunset. On a cold day you comfort yourself with the geeky knowledge of increased efficiency of panels in cooler ambient temperatures. On a muggy day in July you smile as you walk across a scorching parking lot thinking about how much energy your roof is collecting right that moment. You grump around more than usual on snowy or cloudy days. And you throw open the windows and experience the sounds and smells of summer instead of switching on the A/C.
Some months the amount you generate massively exceeds the amount you use, and some months you use more than you generate (see figure one for a graph of our actuals for the last year). Over the course of our first year we ended up generating 11,026 kilowatt hours. And our rather efficient household consumed a total of 9,675 kWh. Which means our net meter, which was installed brand new with the solar system at a reading of 0000 kWh, ended the year with a reading of -1,350 kWh. That’s right; we generated 1,350 kWh more electricity this year than we used, or a surplus of about 14%. Since the system and the meter were installed in the Fall, it crept into the positive consumption territory in the first few months, but as soon as February rolled around we started to break even and never looked back. We cranked the cumulative reading back a bit each month until it finally returned to 0000 kWh on July 3, and then it headed solidly into negative territory. Even though these last few weeks in October and November were close to break-even for us, we still had a surplus reading of -1,350 kWh by the time the first anniversary rolled around.
At our fully loaded electricity rate of $0.15 per kWh, that translates into $1,451 worth of electricity consumed, but $1,653 produced, or a current electric company balance of -$202.50. (It also means we generated 11 SRECs to sell; for a discussion of the economics, see here.) In environmental terms, our first year of solar works out to roughly 13,593 lbs of CO2 saved, which is equivalent to driving the average car 16,312 miles, or about what 158 trees would absorb in a year. Sparing that amount of fossil fuel also works out to 15.24 lbs of NOx emissions saved. In solid waste terms, this amount of green power is roughly equivalent to recycling 4,531 lbs of solid waste or avoiding the greenhouse gas produced by landfilling 2,047 lbs of solid waste. Overall, not bad work for 52 weeks of sunshine.
So as I head into my second year, what does all this mean? Well for starters, it means that my lifelong dream of living in a totally solar-powered house has finally come true. But it also means my second life-long dream of having a solar powered car is within reach…
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