Solar panels cut my costs

Before I bought the electric car, the small solar-electric system on my roof would produce about $15 of excess electricity each year.  At the rates I pay with my solar panels, that amounts to about 135kwh, or enough electricity to drive over 500 miles.  Considering that I have been driving about 10,500 miles a year, that excess amount falls far short of my electric-driving needs.  Of course, I knew I would need more solar capacity.  So, I arranged to have four more 240-watt panels installed on my roof, with an emphasis on collecting energy from the west.  This means the panels will generate the most electricity during the afternoon hours when the summer generation rates are highest.  And, I have the flexibility to charge at night when the rates are the lowest, so I can multiply the kilowatts that my system generates to meet my needs.

My expansion solar panels that cover the extra cost of my 10,000 miles of driving.

The new panels on my roof have generated just shy of a megawatt hour (1,000kwh) of power per year.  Without the peak-hour generation benefit, that would be enough power to propel my purple car about 4,200 miles.  More than 75% of the energy produced by my new system is generated during the peak season, so I get a big benefit from the summer generating schedule.  I also charged about 130kwh on the ChargePoint network, which offsets about another 550 miles of driving.  This year, I over produced enough electricity to result in a $20 credit due to me (which PG&E drops because there was no over-production of electricity in my case).  So, the new solar panels produced enough energy (using time-of-use metering) for me to drive about 10,300 miles. 

So, the bottom line is that I spent nothing to drive 10,500 miles.  Of course, I had to invest $5,500 in the solar panel upgrade to eliminate my driving costs, otherwise my electric costs would have been closer to $260 for the year.  If electric rates remain constant, it would take over 21 years to recover the costs of the solar panels from a strictly financial perspective, but knowing that my car gets much of its energy from solar power provides an intangible benefit akin to the “value” of gambling in Las Vegas.  (If energy rates jump by 25% in the next 10 years, I can break even in fewer than 18 years.)  Now, if you factor in the savings over gasoline propulsion, the break-even time gets much shorter (to about four years).

Back up the mountain to Ridge Winery

After driving up successfully once, I was comfortable to drive up the mountain to Ridge Winery again.  This time, without the range-anxiety gnawing away at my mind every mile I drove, I was able to drive more relaxed knowing well what to expect.  Sure enough, on the way up to Ridge Winery, I used up four bars (about 25%) of the charge, and coming back down I regenerated about a bar and a half.  If nothing else, watching the bars reappear makes the whole trip worth it.  (That, and the fantastic wine at the top of the mountain.  … and the views.) 

The only oddity that I noticed was that towards the bottom of the hill, the regenerative brakes would fade momentarily and I’d be using the friction brakes.  My guess is that this is due to overheating, but it happened only once.  The other thing I noticed is that you have to get the car going about 25 MPH (or so) downhill before trying to use the regenerative brakes.  If you don’t get going this fast, the car will try to maintain the slower speed and you won’t generate as much electricity.  At the faster speed, more electricity is generated while you coast downhill.  It would seem that when going downhill at about 35 MPH, the car generates nearly the maximum electricity to keep the car from going any faster, but this speed is often too fast for many of the tight curves on this road.  So, it is better to maintain a somewhat slower pace.

1,800 feet up at Ridge Winery in Cupertino

Driving slowly

The thrill of driving a powerful gasoline powered car hard is sensational, from the forces exerted upon you to the sound effects emitting from the engine.  I should know, having owned a number of performance cars over the past three decades.  From my 1982 Mercury Capri with its powerful 5.0 liter V8, to the 1987 BMW 325i with its five-speed gearbox, to the 2001 Dodge Dakota Quad Cab with its pavement shredding V8 (coupled with trailer gearing), to my 2005 VW GTI turbo.  All of these cars are great fun to drive up hills, roar down the interstate, and pull away from a traffic light with great aplomb.  They also share the same drawback: trying to move slowly is a painful mix of lurching and clutch wearing strain.  Switching to an automatic transmission does little to resolve this either, as I have experienced in a Passat, an Audi A4, and a Toyota Corolla.  The fact is, gasoline powered cars were never designed to be driven slowly.

My (former) 1982 Mercury Capri in its new garage

Who needs to drive slowly?  Consider these situations …  You are stuck on I-405 approaching Century Blvd.  Finally, the traffic inches forward (literally, about 8 feet).  Or, you need to back into a gently sloping driveway.  Or, while visiting San Francisco, you have to stop at a stop sign on a 25% grade.  Or, you need to back your car into your underground parking space around the concrete pillar.  Too much gas, and you could slam your car into something not-soft.  Too little, and you could stall, changing your direction of travel unexpectedly.  Of all of these, the most annoying is trying to follow slow-moving traffic on the freeway that seems to lurch along.

I never expected that the electric motor would solve these issues.  The instant-on torque of the electric motor and the ability to deliver very precise amounts of current allow the electric car to thrive in these slow-motion environments.  In my Mitsubishi, the (software) engineers who programmed the motor controller were able to simulate the gasoline engine’s inability to stand still while in gear by allowing a small amount of current to flow to the motor while at “idle”.  The software does a spectacular job.  While backing into a gently upward sloping driveway, I was able to remove my foot from the “gas pedal” and the car backed itself up the driveway at about two to three MPH, allowing me to position the car deftly.  Another (software) engineering feat is just how smoothly the car transitions from standing still to a full run.  There is no jerk at all, and you can control the speed as slowly as you need, down to one or two MPH.  This came in very handy while inching into the parking lot for the electric car rally and parade recently, as the backup was over ½ a mile just to enter the parking lot.  (It takes a while to get 500 cars into a parking lot at the same time.)  While my electric car may be no faster than a cheap economy car on the highway, it more than makes up for it with its slow driving manners.