leaf-plus-solareditors-blog-entry3Solar-charged driving can, and does, save money.

I’ll use our own example.

We’re not solar-charged yet, but we’re hoping to be within the next two years.

In June 2010, REC Solar will install a 5.5 kW solar system on our Colorado home. It will produce 8,000 kWh per year.

After the 30-percent Federal Tax Credit and an Xcel Energy Rebate, our out-of-pocket costs for the system will = $8,500.

Yes, this is a great deal, not one everyone will be able to get. But those in solar friendly states like Colorado, California, New Jersey, Massachusetts, etc. certainly can get a deal approaching something like ours.

Our annual home electric use = 5,000 kWh per year (though we’re upping that this year by shifting some of our heat from gas to electric so that we can put up the size solar system we need; see ‘What comes first – the EV or the solar system’ for more on this ). That leaves 3,000 kWh per year for an EV, or about 12,000 miles.

Let’s assume 30 mpg for a gas car (a generous assumption; most people’s cars don’t get this mileage) and $2.80 per gallon of gasoline. In this case,12,000 miles of driving per year = $1,120.

Let also take $800 per month for our electric bill, and add in a 5% utility rate hike (a modest assumption) for each year.

Doing the math
Here’s a projection in our situation, one in which we can put up a solar system that powers 100-percent of our home electric plus about 12,000 miles per year in an EV. Let’s take four years as a sample time period, because, in our case, that’s about the point when we hit pay-off:

  • 4 years x $1,120 (offset gas costs, assuming no rise in cost of gas) = $4,480
  • 4 years x $800 (offset home electric, with 5% annual increase in rates) = $3,448
  • $5,600 + $4,420 = $7,928 (vs. $8,500 out of pocket for our 5.5 kW solar system)

So, at about 4 1/2 years, in our situation, we’ll hit payback. And, if gas prices spike, certainly a reasonable possibility, we hit payback earlier!

After that, we will save money, a lot of money, on our combined household electric + offset gasoline costs.

Even assuming no increases in the price of gas — an absurd assumption — and calculating out 10 years beyond payback, we will save, on gasoline costs alone — $11,200.

In terms of home electric, and without accounting for any utility rate increases whatsoever (again, an absurd assumption), we’re at $19,200 in total savings — with plenty more savings to come.

In short, when you look at the big picture — home electric costs + gas costs offset annually — solar-charging an EV saves money.

To be fair, your savings potential is dependent on:

No one’s done the numbers on how many Americans could power 100-percent of home electric use + 10,000 to 12,000 miles a year in an EV off electricity generated by a home solar system.

It’s reasonable to assume that in the sunny Southwest (including California), where about one-third of the total American population lives, there are likely millions of people who could power 100-percent of their home electric + 100 percent of 10,000 to 12,000 EV miles per year off of a home solar system on their home’s roof.

Howevever, it’s reasonable to assume that in the sunny Southwest (including California), where about one-third of the total American population lives, there are likely millions of people who could power 100-percent of their home electric + 100 percent of 10,000 to 12,000 EV miles per year off of a home solar system on their home’s roof.

Additionally, there are millions more who could cover 100-percent of home electric and some of the EV miles they travel. While we haven’t done the math here, those who partially cover their home electric and EV miles can, and do, also save money.

For example, check out, our feature story on Darell Dickey, of Davis, Calif., whose solar system doesn’t cover 100-percent of his home electric and 100-percent of his EV miles, but who estimates he’s saved $20,000 in seven years of solar-charging.

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