Home editor's blog on going solar Two years of solar = $5,400 in gasoline savings

Two years of solar = $5,400 in gasoline savings

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In 27 months, our 5.59 kW home solar system has produced 20,000 kWh -- and we've only used 10,000 of those, banking the other 10,000 kWh for future use.

editors-blog-entry3We recently hit 20,000 kWh (20 megawatts) of solar electricity produced with our 5.59 kW solar PV system here in Aurora, Colo. At around the same time, we hit 10,000 kWh of banked, extra electricity, meaning across the 27 months we’ve had home solar, we’ve produced 200 percent of the electricity we’ve used.

The main reason for our large excess solar production: Back in 2009 when we signed on the dotted line for our 5.59 kW system, for which, by the way, we paid just $8,000 out of pocket, we thought we’d have an electric car, maybe even two, by now.

Due to unusual, and, frankly, somewhat unanticipated personal circumstances, we have not yet bought an EV. So, for the past two years, we’ve been acting as a mini-neighborhood “utility”, producing enough electricity to power not only our own home, but enough to power our neighbor’s home as well.

Since we just hit two solar electricity production milestones at essentially the same time, I figured it would be interesting to reflect on 20,000 solar kWh and 10,000 banked solar kWh and what they mean, both environmentally and economically.

Slicing up our solar (over)production
Let’s slice up those solar kWh ;-) – keeping in mind that we’ve (over)produced these solar kWh in just 27 months.

20,000 solar kWh = Enough electricity to power two average American households for a year.

20,000 solar kWh = Enough electricity to power four energy efficient/energy conserving American households consuming electricity at our annual rate of about 370 kWh per month for a year.

20,000 solar kWh = About 38,000 pounds of CO2 saved, at least according to our SMA Sunny Boy 6000 solar inverter. That’s the approximate equivalent of taking one 21 mpg car off the road for more than five years, the approximate equivalent of flying 3,200 miles per month for a year, or the approximate equivalent of planting 93 trees per year.

coal-tracks

Coal litters the train tracks heading into the Valmont Power Plant in Boulder, Colo. Home solar reduces the amount of coal burned by plants such as this one.

20,000 solar kWh = About 20,000 pounds of coal not burned, or one train car full of coal not burned.

20,000 solar kWh = About $2,200 worth of electricity at the 11 cents per kWh rate Xcel Energy charges customers here on Colorado’s Front Range. At this per kWh rate – and not taking into account how adding an EV to the home solar equation radically changes the equation and also not taking into account rises in utility rates over time – we’ll hit solar payback in about another five and a half years, or about eight years after we purchased our system.

20,000 solar kWh = Approximately 70,000 miles of driving in an EV using the conversion rate of 3.5 miles per kWh. Of course, we could not have used all of 20,000 solar kWh we’ve produced for an EV, but we could have used the 10,000 we’ve banked to fuel an EV – which is a nice segue into focusing on our 10,000 banked solar kWh.

10,000 banked solar kWh = Enough electricity to power our energy efficient, energy conservation oriented household for more than two years!

10,000 banked solar kWh = About 19,000 pounds of CO2 prevented and temporarily donated to our neighbors ;-)

10,000 banked solar kWh = Approximately 10,000 pounds of coal not burned, or one half of a train car full of coal not burned.

10,000 banked solar kWh = A little over $1,000 worth of electricity at the Xcel Energy per kWh rate of 11 cents per kWh. Of course, Xcel pays solar customers just 3.5 cents per extra kWh of solar electricity produced, which means our 10,000 extra solar kWh are worth a measly $350 payout from Xcel. That’s why we chose Xcel’s lifetime kWh banking option for all extra solar kWh we produce when we signed on the dotted line about two and a half years ago.

Finally -- drum roll please – the grand finale: The solar + EV savings represented by 10,000 banked solar kWh.

Our 10,000 banked solar kWh = 35,000 miles of solar EV driving, or 35,000 of what I call Sun Miles® defined as “miles driven by an electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV) whose batteries have been charged using solar energy and/or using electricity from kWh credits amassed via solar offset generation.”

At 25 mpg and $3.80 per gallon, and 3.5 miles per kWh, our extra 10,000 banked solar kWh hours are worth $5,320 in gasoline replacement costs. If you add this to the $1,100 worth of home electric savings the other 10,000 solar kWh hours we’ve generated, and used, sans EV, you’re up to $6,420, or just $1,600 shy of solar payback for our $8,000 5.59 kW home solar system. In fact, if you include gasoline replacement costs, we’ll reach solar payback in about three years.

And they say home solar is “too expensive”. Say what?

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