Friday, July 20, 2007

Solar Cells

It is my hope that continued innovation along these lines will someday help reduce the strain on our power grid here in California.

Researchers at New Jersey Institute of Technology (NJIT) have developed an inexpensive solar cell that can be painted or printed on flexible plastic sheets. "The process is simple," said lead researcher and author Somenath Mitra, PhD, professor and acting chair of NJIT's Department of Chemistry and Environmental Sciences. "Someday homeowners will even be able to print sheets of these solar cells with inexpensive home-based inkjet printers. Consumers can then slap the finished product on a wall, roof or billboard to create their own power stations"...

"Developing organic solar cells from polymers, however, is a cheap and potentially simpler alternative," said Mitra. "We foresee a great deal of interest in our work because solar cells can be inexpensively printed or simply painted on exterior building walls and/or roof tops. Imagine some day driving in your hybrid car with a solar panel painted on the roof, which is producing electricity to drive the engine. The opportunities are endless. "


KauaiMark said...

Now if they can only make it work with house paint, you could turn your whole house into a giant battery charger!!

Darren said...

I saw an episode of NOVA a couple weeks ago where people are working on exactly that.

steph said...

Nice! And the rest of the world says that Americans only pollute our environment... tsk, tsk.

allenm said...

I wish being a party pooper paid better. I suppose I'll have to be satisfied with the alliteration.

I'm no mathematician but arithmetic seems to be quite enough to let the air out of various tires.

I poked around to find some commercial solar cells. I found one that gets you eight watts out of forty-three square inches. That works out to .065 watts per square inch. I don't represent that to be average, above or below. It's just the first solar cell I ran into on a google search that had both area and power output.

According to the Union of Concerned Scientists, not my idea of a credible source but they popped to the top of the Google list, the US had, as of 1990, 690 giga-watts of electrical generating capacity. It's significantly higher then that now, a bit over 1,000 giga-watts according to the Energy Information Administration but I don't feel like redoing by arithmetic.

If you shovel some coal into the boiler of the spreadsheet engine you get a figure of a bit over 2.6 million square miles of solar cells to equal the generating capacity of the US in 1990. The surface area of the U.S. is 3.5 million square miles.

That 2.6 million square miles isn't to replace the generating capacity of the US, just to equal it at high noon. To replace that generating capacity you'd have to increase the area by somewhere between two and three times and construct energy storage capacity of truly gargantuan proportions.

Bottom line? You won't be driving a solar-powered car any time soon.

Darren said...

I don't expect a completely solar powered country. Like a stock portfolio, I want diversification.

There are a lot of roofs in areas that get 300+ days of sun a year. That's not an insignificant number.

Ellen K said...

This has been in the technology pipeline since the 80's. There's more readily available solar technology out there. If the gov. would reinstate the tax credit for installing solar water heaters, you would see a boom of them. We used to have one and they were great. It's already out there, why not use it rather than spending millions on something that may not be as efficient.

David Foster said...

A couple of things make me wonder about these guys:

1)How could printing solar cells on a home printer be more economical than producing them with purpose-built equipment in an industrial environment?

2)Solar cells on a car roof would produce such a small fraction of the car's energy demand that it wouldn't be worth the trouble.

Allen...there's something wrong with your math. 8 watts divided by 43 square inches has to give a result very close to 1/5, or .2

allenm said...

I don't expect a completely solar powered country. Like a stock portfolio, I want diversification.

I wasn't inferring that it's an all or nothing proposition, either everything is solar or nothing. What I was getting at is that solar power is inherently a limited solution in any practical sense.

As a sole source of power it's a niche solution. If you want to live in the boonies then solar's better then nothing. If you live in town and insist on being as green as the Jolly Green Giant then solar's a statement and if you, or anyone else, feels inclined to make statements, by all means, go ahead. But as a mainstream power source, as a replacement for any significant percentage of electrical generating capacity, solar just doesn't make it.

Even with the unrealistically generous assumptions about costs and land area made by proponents there's inevitably "obvious" requirements for energy conservation presented as if energy conservation's a noble goal that all right thinking people naturally pursue.

The only way I see photo-voltaics hitting the mainstream is if they show up as a roofing material with characteristics similar or superior to conventional roofing materials with the additional benefit of generating some electricity. Even then you have to add the additional cost of storage capacity since the setting of the sun means that all the centralized base generating capacity still has to exist.

Without your own storage capacity you pay for your solar cells and pay more for your electrical-company generated electricity. The demand for electricity doesn't stop with the setting of the sun but the power company is selling half the electricity so there's a smaller sales volume to spread fixed costs over.


Yeah, you're probably right. It was late. I was frightened. I was alone....Oh, sorry. That's Rodney Dangerfield's recounting of his first sexual experience.

I just redid the first "calculation" and it comes out to .15 watt/inch which sounds a little more reasonable. Still, the amount of surface area necessary is simply immense and that's under the most unrealistically optimistic assumptions. I don't feel like redoing the arithmetic again but the last time I went through the exercise I believe the result was an area the size of North and South Carolina or thereabouts.

I don't have anything against solar power I'm just not ready to sign on with the religion of solar power. If it makes my life better in some way I value, cool. If it doesn't then the only reason to "go solar" is because the proponents are in a position to impose their opinions on me.

Anonymous said...


I'm a staunch SUV-driving conservative, yet back in 2004 I tapped my HELOC to put a (nominal) 3KW PV array on my roof.

The actual output of the array varies with the weather and the season, but on the average it outputs about 1KW/h, so recently we've seen some 20KWh days.

Let me explain why a hard-core right-wing NRA member would drop $17K plus interest for a PV array.

The short version is that I am effectively locking in my electrical energy costs for the next 30+ years. It's hard to forecast exactly when I'll break even on the cost-- no one can predict what Southern California Edison will be charging for electricity in five or ten years-- but conservatively, I'm predicting that break-even will occur in ten years or less.

Edison uses a multi-tier, quasi-progressive billing rate, which makes it hard to peg the actual rate of increase experienced by customers (it depends on consumption levels). But when I pulled three years worth of bills (2003-2006), I calculated the annualized rates of increase as follows:

The first tier, baseline summer, increased by 14.7%;

The second tier, 100-130% of baseline, increased by 13.5%;

The third tier, 131-200% of baseline, increased by 9.0%;

The fourth tier, above 200% of baseline, increased by 26.7%.

I have not dug in to find the rates of increase for other baseline periods, but I would expect that the rate of increase would be highest for the summer period.

When I compare my pre-PV array electric bills with my current bills, our average consumption has decreased by 40%, as have our costs (and this, as Edison has been raising rates).

Anonymous said...

I think in the developing world, LEDs paired with solar panels could provide a cheap, sustainable light source that doesn't need a traditional power grid. And combined with other technology, solar power could be used for small but important jobs. In reality, solar power may not provide enough energy for ALL of our energy needs. But it could provide be a large percentage energy source. Coupled with nuclear power, wind power and water power, we could stop global warming.

Darren said...

I don't think so. Global warming is a naturally occurring, cyclical phenomenon.

But having a diversity of energy inputs like you described will cut down on pollution, which is always a good thing.

I'm not too crazy about wind power at all, though.