Actually, I've done the math on it. One thing people forget to figure in is the cost of the vehicle. The only time this doesn't count is if they do not already have a car. But if they do, they will loose substantial amounts of money before regaining it back. Here's the indirect science: The average electric car might draw about 22,000 kW per charge (which is by far more then the average 2 bedroom house draws in one day) and the best monocrystaline roof-top solar panels take about 2 days to make that power even in direct sunlight all day. With Lithium Polymer batteries, the car can most likely go about 300 miles per charge and spend about 5-6 hours recharging a full 350V DC traction battery pack at 7-8 amps /115VAC. This is where you calculate the cost: if the 300 miles lasts you 4 days, then you're going to save money as the solar panels will spin your electric meter backwards for 2 days more then it needs to. (Solar panels only off-set the cost of charging.) However, if you drive about 150 miles a day, you do not save anything and you will break even. If you drive any more then 150 miles a day (average) then you will loose money in electricity (but not as much as the cost in gasoline.) However, you must add up the cost of the car (possibly $50K) and the solar panels (I've seen them as low as $7K) and the cost of charging (maybe $5 dollars every 150 miles - still nice). All together in 1 year, you might drive 15K miles. (15000/150x5=$500) So at this point, you're spending $57,500 in one year on an electric vehicle. If this cost does not out-weigh the amount you're spending on gas in 1 year, you're driving a M1 Abrams tank. But if you have to buy a car anyway, at least you can knock $50K off that figure and spend $7500 for the one year and make back some money on the next. I'm basing all my figures off of current costs. Average fuel spending last year was around $3700 anually. Current electric costs in my area aren't too bad. And solar panels are cheap right now as there is a city-sponsored discount for getting solar panels plus a good home owner's tax cut.
I have not done the detailed math. For starters I live in the Mojave Desert and drive 700 miles a week. My location is primo for solar power, sunshine all the time and my car fuel cost is on the high side. I was thinking of a ten year amortization because solar cells have a lifetime about that long. If the new technology batteries have a similar lifetime then the calculations are simplified. I would think that at the very least a solar roof would be a great ajunct to a hybrid and probably hit breakeven before ten years. I am ignoring the cost of the car, I will have to get a new car eventually no matter what kind of drive train.
Understood. To give you an idea of how long the batteries last, each battery has a Depth of Charge (DoC). The DoC is how much capacity the battery will hold after a certain amount of cycles (or equivalent full charges). In this case, the manufacturer will place certain limits and specifications, (weather conditions, temperature, strain, discharge limits, voltage limits, etc) that will determine a batteries life and DoC. On average, the DoC on most Lithium Polymer batteries are about 80% @ 800-1000 cycles. This means that after about 1000 charges, you only get 80% of the capacity of the batteries original capacity. A batteries capacity is measured in Amp-Hours (Ah), so if you have 200 Ah batteries and you cycle them about 1000 times, you might be down to 160 Ah. It's common to say that you get about 1.2 miles per Ah. So batteries that have about 240 Ah should get you about 290 Miles. But after 1000 cycles, you may only get 230. So really, the question is, how often will you charge your batteries?
there is a documentary out on GM killing the EV.........its called "who killed the electric car".......haven't seen it but it seems interesting.
I read of some experiments with cabs in Canada where they were varying the depth of discharge and the amount of charge, one guy running with 60% discharge [I think it was] had 300,000 miles on a set of batteries. I need to get some real cost figures for my area, and solar production figures and find out what the bottom line is for my situation.
WHOA! I'm impressed. I wonder what batteries. I've been looking into Thunder-Sky.com batteries and Kokam.com batteries. Kokam seems to have the best setup battery, accept the DoC sucks compared to the Thunder-Sky batteries.
I don't recall the details. I get these electronics trade magazines, read the articles and toss 'em all the time. I did some more math regarding solar power on the roof of my house, in the desert, and my 700 mile a week driving habit. Right now the fuel cost might hit breakeven at $3/ gallon amortized over ten years. Not quite enough to push the decision to the "let's do it" column. I have an amateur radio shack that I might use solar and wind power for just for fun and for emergency communications in case of disaster. I could get my feet wet with that and go to the hybrid car later on when the technology improves. If I made some hyperbolic tracking reflectors for some solar panels I probably could power the house and the car from the back yard but the investment would be huge.
Yeah. The investment is more then I'd put out for now. I've looked into hybrid technology. I did some research on Hydrogen Fuel Cells, and only found disappointment. The cells cost too much and hydrogen doesn't transport enough energy. At about 3.6Litters, it only generates about 42V @ 20amps. Even though that seems like a lot, the cell weighs ~60lbs and are quite big. You would need about 4-6 of these cells (each costing about $50K) plus enough hydrogen tanks to make it worth it. In the end, you have a heavy, expensive, short range car. By the way, these fuel cells are usually only 50% efficient. Why waste the electricity when electric cars are 93-97% efficient?