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We’ve Blown Past Net-Zero! Now How Much Surplus Power Can We Produce?
Posted on June 23rd, 2014
By Eric and Alex
Exciting news! Despite the unseasonably cloudy summer we’ve been experiencing here in Seattle until recently, we achieved net-zero almost three months ahead of schedule.
Our net meter (the one that goes forward or backward depending on whether we’re using more power than we’re producing at any given moment) now reads 99,690. No, that doesn’t mean that we’re in for a whopping electricity bill. Rather, it means that the meter has been running backwards so much that we’ve actually gone past zero and into negative territory for the year.
What’s more, we still have many days of sun left before we reach the critical 12-month mark. Our meter hit zero on August 2, and in the last two weeks, we’ve already produced 310 kilowatt hours more than we’ve used. We have more than eight weeks until October 22, which will be exactly one year since the meter was first installed. If we keep going at this rate, we might be able to record a surplus of nearly 1,200 kWh for our first year!
What all this means is that the house is performing way better than expected. In fact, we couldn’t be happier!
Keeping Relatively Cool
In addition to producing a surplus of power, the house has also passed another test. We were a bit worried about how comfortable it would be in the summer given the passive solar heat gain from all the south-facing windows. Having sunlight and free heat streaming through our windows is great in the winter, but would we find ourselves baking in our personal greenhouse in the summer?
We were pleasantly surprised to find that Ted Clifton Sr. had designed the eaves to let in lots of light when the sun is lower in the sky in the winter but to block nearly all of it during hot summer afternoons, when the sun is higher in the sky.
While we could technically run our heat pump in reverse and chill our floors, we’ve kept the house pretty comfortable during the hottest days (not that we’ve had many this summer) using some common sense and a simple trick Ted taught us.
We leave the windows open to let in the cooler night air and turn on the exhaust fan in the kitchen (which also activates a powered HEPA ventilation system) for about 15 minutes first thing in the morning. When the outside temperature starts to rise past what it is inside, we simply close all the windows tight and lower our double-honeycomb cloth blinds, and the temperature stays low without any air conditioning.
Right now, for instance, the outside temp is 86 degrees, while inside it’s a comfortable 75. (I haven’t even bothered to turn on the ceiling fan in my office in the loft yet.)
Room for More
Even though we’ve gone past net-zero with our current solar panel array, we could be producing even more power. We currently have twenty-eight 230-watt Solar World panels covering about two-thirds of the roof. We still have room for about sixteen more. This would give us more than enough power to run an electric car.
While on a backpacking trip last weekend, I stopped in Skykomish and noticed a high-speed electric vehicle charging station in front of a deli. The woman who worked there said that lots of people use it and that it takes about half an hour to charge up a car like the Nissan Leaf. Best of all, it’s free for now.
I had kind of dismissed electric cars because most of the driving we’d do would be to get out of town for hiking trips and things like that, but knowing there are charging stations like this on the way to the Cascades changes things a bit. Suddenly, the idea of paying nothing for driving, even on longer regional trips, seems pretty attractive.
Ted L. Clifton has been a designer and builder for more than 45 years. Educated at Berkeley, California, Ted has worked in every phase of construction and knows first-hand what it takes to design and construct a quality home. Having built hundreds of homes as well as commercial and institutional buildings, Ted has the advantage of extensive knowledge of the means and methods used in all three. He has worked in three very different climate zones, from the foothills of California, to Ketchikan, Alaska, to Whidbey Island, Washington.