Rooftop Solar Panels Energize Home and Mini E at Low Cost and With No Emissions

California couple finds EV and PV as natural together as chocolate and wine.

By Scott Doggett, Contributing Editor

"We live and drive on sunshine."

If you have the good fortune to spend a day with Peder and Julie Norby at their home in the Southern California town of Carlsbad, you'll not only hear Peder say that, you'll see it.

The Norbys are among a growing group of Americans who rely on photovoltaic (PV) panels on their roofs to meet or supplement their electrical needs.

In the Norbys' case, those electrical needs extend to a zero-emissions, 100-percent electric Mini E the couple is leasing from BMW.

Their PV array generates 12,000 kilowatt-hours of electricity each year, of which their home - think lights, appliances, air-conditioner - consumes 9,000 kWh and the Mini E 3,000 kWh. That makes theirs a zero-energy home.

Do the Norbys have batteries that store energy during the day for use at night, when the sun's tucked away and the photovoltaics are resting?

No. As long as you have a reliable grid, there is no need for batteries, Peder explained in the comfort of his great room. If you produce excess electricity during the day, the energy is not lost. In fact, it goes to the grid when the grid needs it most - during peak, afternoon hours.

When that happens, the Norbys' electric meter actually spins backward, generating credit for them.

Twice the Investment

But wait, there's more. If like the Norbys you work regular hours and plug in an electric vehicle late at night during off-peak hours, you're charged only half as much as the grid gave you credit for when it took energy from you during peak hours. That's true in San Diego County, where the Norbys live, and others across the nation.

That arrangement is like depositing $50 at a bank during the afternoon - when most people make withdraws - and having the bank give you a hundred bucks in the middle of the night. Double the return in only a matter of hours!

Sweet. But that's not all. While it's true that plenty of gas stations exist, you always have to go to them. Gas stations never come to your home. They never fill your car in your garage while you sleep.

Not so with an EV, Peder said as we peered through a window and into the Norbys' thriving backyard vineyard, which is way more cool than a swimming pool and produces a beverage that tastes a whole lot better.

The Mini E charger in the Norbys' garage has a timer. Peder, who drives the car more often than Julie, has it set so that the charger starts charging the Mini E at midnight, when the rates are very low.

When it's time for Peder to go to work, the EV is completely charged. Waking up to a full tank is a daily occurrence at the Norby residence, which they call Herons' House on account of the blue herons that occasionally visit.

As far as driving range per charge, there's no getting around the fact that you can't drive 200 miles nonstop if your car needs to be recharged after 100. But Peder, a county planning commissioner and entrepreneur who has been driving the Mini-E for nine months, says range anxiety has proven to be way overblown.

He says he knows he can drive 90 miles at 80 miles an hour on a single charge, for example. Like Dirty Harry said in Magnum Force, a man's got to know his limitations, and Peder says he's learned exactly how far he can go in the Mini-E given his driving habits and the road conditions.

When he needs to go farther on one haul than the Mini-E can go on a single charge, he must use another vehicle, such as Julie's Ford Explorer. The range issue does exist - I experienced it firsthand soon after my visit with the Norbys - but it's not nearly as problematic as most people think, Peder says.

Cable Be Gone

Indeed, he says he no longer feels the need to travel with the portable charging cable that came with the car. And, he reminds, it's not as if there's no one to turn to if he did find himself without enough juice to get home. BMW dealerships are equipped with rapid chargers Mini E lessees are welcome to use free of charge, and there's no shortage of BMW dealerships in So Cal.

Beyond that, Peder said there's a long list of people just like himself - Mini E lessees with home chargers - who are generally willing to let other Mini-E lessees borrow some of their juice when the need arises.

OK, so this all living on sunshine sounds pretty darn good, you say, like maybe too good. Heck, I thought it at one time. But it's not. Let's consider some numbers.

The average car in the U.S. these days gets 20.5 mpg. The average American motorist drives 12,000 miles a year. The average price for a gallon of gasoline in the U.S. these days is $3. Rounding down to 20 mpg for simplicity's sake, at 12,000 miles and $3 a gallon the average American these days spends $600 a year on gasoline.

Twenty-five years ago, the average price for a gallon of gas was $1.11. To reach $3 a gallon today, the cost of gas rose 7.5 cents a year. Because a gallon of gas costs $3 today, if it increases in price 7.5 cents a year for the next 25 years just as it did the last 25 years, we can expect to pay $4.87 a gallon for gasoline in 2035.

Experts expect the price to be greater, given the fact the cost to extract oil is expected to go way up. But even if the price of gasoline only increases at the rate it has the past 25 years, we can expect to pay ($3.075 x 600) $1,845 for our 600 gallons next year, ($3.15 x 600) $1,890 the year after and so on until we're paying $2,922 for our 600 gallons in 2035. If we add up the total for all 25 years, we can expect to pay $59,630 for the gasoline we use during the next quarter-century.

Cheap, cheap, cheap

The Mini E gets about 4 miles per kilowatt-hour, Peder said, which means 12,000 miles in one year will require 3,000 kWh - which, as noted before, is what the Norbys are experiencing. To generate 3,000 kWh, you'd need a 2-kilowatt photovoltaic system. Each kilowatt PV system generates about 1,600 kWh per year. That 2-kilowatt solar system is typically running right now between $3.25 and $4 a kilowatt-hour. So, on the high side, it's costing $8,000.

That $8,000 is the cost of the system, not an annual cost, and includes the cost of an inverter. After a dozen or so years, you'd need to replace the inverter. They cost about $2,000 now. So, the total cost of the system for 25 years is $10,000. And that is what you can expect to pay to run your Mini E on sunshine for the next 25 years. Ten grand versus the $59,630 you'd expect to pay in gasoline for a comparable gas-powered car.

But wait - you got it - there's more. Given what the Norbys are saving every month in electricity, they should have their solar system paid off in four in a half years. That's four and a half years since purchase.

After that, if they continued to drive the Mini E, the energy cost to them would be essentially free. As would the energy cost to run their lights, their appliances, their air-conditioner and other electrically powered items in their lovely home.

And as for those emissions that contribute to global warming and deadly illnesses? There aren't any from the Mini E or the zero-energy home just described to you and in use at a house in Carlsbad that enjoys the approval of the local blue heron population.

Posted by

Scott Doggett March 29, 2010