The Electric Slide

I’m two weeks into my my photovoltaic design class, and while there’s alot to learn about proper placement, sizing, physics, wiring, etc., it’s becoming clear that the most important thing about using solar power is knowing your usage patterns (and then figuring out how to reduce them).

The above graph represents my energy usage over the last couple of years, in Kilowatt/hours and Gas Therms.   It’s usually easy to spot the trends- higher gas use in the winter, higher electric usage in the summer- though there are some odd spikes, like in June of 2009.

My lowest electricity usage in this time range is 5.8 kilowatt/hours.  That’s quite a bit in my opinion.  According to some vague statistics from Ameren, my power utility, my home’s usage is about half the average home.  That’s encouraging, but hardly cause for celebration.  The highest monthly usage is a whopping 15.2 kilowatt/hours- God only knows what we were doing that month. If I’m gonna get serious about using photovoltaics to supplement my power usage, my habits will have to change, too.

The reason is pretty simple- solar electricity is considerably more expensive to produce than fossil fuel electricity, if you just look at dollars and cents.  However, I try to be a little more circumspect and take into consideration the cost of pollution and the uncomfortable reality of being heavily dependent on foreign oil, and all the nasty side effects that dependence brings.  So I embark on the solar path knowing full well that it will cost more in the short term.

The important lesson is this: it costs less to reduce your energy usage than it does to produce solar electricty.  For a quick example, let’s look at the fridge.  My $400 GE uses about a kilowatt of electricty per day.  If I spend $1500 on a SunFrost fridge that uses half as much electricty, that’s 500 watts less electricity per day.  If the cost of a 100 watt solar panel is $500, that’s $2500 off the up-front cost of a solar array, not to mention reduced complexity and installation costs.

The fridge is an easy target for being an electricity hog, and rightfully so- it chills the beer that helps me make it through the week.  However, the real shock is how much small electronic devices use.  My DSL modem, for example, uses 10 watts/hour.  Not much by most standards, but it runs 24 hours per day, so 240 watts daily.  Then there’s my router, another 10 watts, and we’re up to 480 watts per day.  My portable phone system is a cool 8 watts, 192 watts per day, up to 672.  Toss in the TV, microwave, stove, at 5 watts/hour each, and I find that I’m using 1072 watthours per day before I flip a single light switch.  Ouch!

Those 1072 watthours would cost an arm and a leg to power with solar, so the onus is on me to figure out how to reduce my usage as much as I can.  Which will be fun, for someone who’s already mental about electricity usage.

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