PV Gap

Tracey Said:

Am I the only one who thinks this would be a good idea?

We Answered:

I like it! The beauty is that the more you need it, the better it works!

The closest thing to a solar-powered a/c unit on a car is the solar-powered exhaust fan they had on the Mazda Millennia.

One problem is that the area of photovoltaics needed to power an a/c compressor is greater than you could conveniently fit on the surface of a car.

At maximum cooling, an a/c unit in a car uses about 4kw. Photovoltaics in the sun belt can deliver about 0.09 kw per square foot. That means you'd need about 43 square feet of photovoltaics. Most cars' roofs are pretty narrow, and unfortunately, cars are getting smaller. If the roof is 4.3 feet wide, it would have to be ten feet long, so it might work on a minivan or station wagon.

Of course, right now the limiting factor is cost. Photovoltaics in big installations are running about $4.00 per watt peak (Wp). That means your 43 sf, 4kw solar array would cost about $16,000!

As technology evolves, and more and more are made, that cost may come down, like everything else electronic.

Nice idea, but I don't think its time has come -- yet!

Ben Said:

Why is it impossible to have solar Air Conditioning?

We Answered:

"20k can run a whole on grid house... my electric bill a month is between 150-550 at peak times....it would not take 30 years to recoupe my money."

Assuming you can get the panels for $20k, at 10 cents a kWh from your utility, that would offset 200,000 kWh. If your on-grid house uses 1,000 kWh per month, that's 200 months which works out to just over 16 and a half years.

Nope, not 30 years, but longer than most people are willing to wait for a payback.

Also, $20k is typically about a 2 kW system, which might handle a single window AC system, but a central AC system will be more like 10 kW, which would put you in the $100k range for the solar system to run it. At the same 10 cents/kWh, that puts your payback just over 83 years.

And yes, people will tell you the next breakthough is just around the corner and solar will get a lot cheaper.

Just like they've been saying since the 70's. Someday they will actually be right. But, I wouldn't hold my breath!