New solar-cell efficiency record set

Scientific American ^ | Aug 27, 2009 | David Biello

[canuck_conservative]

Here's a seemingly simple solar power fact*: the sun bathes Earth with enough energy in one hour (4.3 x 1020 joules) to more than fill all of humanity's present energy use in a year (4.1 x 1020 joules). So how to convert it? In the world of solar energy harvesting, there's a constant battle between cost and efficiency. On the one hand, complex and expensive triple-junction photovoltaic cells can turn more than 40 percent of the (specially concentrated) sunlight that falls on them into electricity. On the other, cheap, plastic solar cells under development convert less than 5 percent.

In between, ubiquitous photovoltaics—the multicrystalline silicon solar panels cropping up on rooftops across the country and, indeed, the world—struggle to balance the need for (relatively) easy manufacturing and low cost with technology to get the most electrons for your solar buck.

Yesterday, Spectrolab announced that its newest triple-junction solar cells had achieved the world record in efficiency, converting 41.6 percent of specially concentrated sunlight into electricity. All told, a tiny cell just 0.3174 square centimeters turned the sunlight equivalent of nearly 364 suns into 4.805 watts. That kind of efficiency is why 60 percent of satellites in orbit today bear earlier iterations of the technology; that's a total of roughly 640 kilowatts of Spectrolab cells circling Earth.

Those cells cost 40 cents per watt, according to the manufacturer—if you happen to have the sunlight equivalent of 500 suns streaming down while enjoying a temperature of 25 degrees Celsius. In reality, only specialized applications like satellites (and government contractors or agencies like NASA) can afford the technology.

More Earth-bound photovoltaics, like Suntech's Pluto line of multicrystalline cells, which boasts 17.2 percent efficiency converting one sun's light into electricity, or Suniva's ARTisun single silicon crystal cells that can convert 18.5 percent of the sunshine into electricity, cost more than $2 per watt. Installation roughly doubles that price.

Bringing the cost of just the photovoltaic cells down to about $1 per watt is the magic number solar manufacturers are aiming for, figuring that will make them cost-competitive with electricity produced by burning natural gas. Some manufacturers of thin film cells (less efficient but cheaper), such as First Solar, claim to have reached that mark, with efficiencies around 10 percent. Finding a way to further boost the ability to convert sunlight into electricity while also lowering costs to this level would herald the true dawn for solar power—something anticipated since photovoltaics were discovered.

[wolf78]

Pricing for these technologies will not come down anytime in the foreseeable future -— nor should they.

That is simply incorrect. Prices for solar cells have halved over the last year. So they have come down quite a lot, however, not quite enough. If solar was 40c/KWh and now is 20c/KWh it still has some way to go to reach e.g. coal at 6c/KWh or nuclear at 8c/KWh.

[wolf78]

It’s always a true joy and delight to read someone who understands economics. So few conservatives these days do...

[the long march]

Solar cells for heating water not for concentrators that are used in solar thermal plants.

[Sparky1776]

Hi Only1, I actually just enrolled in a quick seminar next week provided by an inverter manufacturer, it about four hours long and will be a chance to tour their facility (I’m sure it is mainly a sales pitch) and collect a few CEUs for $30.

I’ve installed two commercial systems last year and the wiring was a couple days labor. The arrays were installed from out of state PV guys, hoping to have a one stop operation next spring.

As far as price goes - we’re being taxed right now to build a fund to subsidize the industry, so for me it’s a case of remaining unemployed (construction is dead - the 25 year building boom is dead) or tapping into the fund as a self employed installer. I actually think being a small local company competing with the larger national outfits will work in my favor.

[AFPhys]

It is a no brainer. It makes no economic sense at this point in time. There is no ROI - ever.

-—<>-—<>-—<>-—<>-—<>-—

I’ve done the same. I confirm your calculations.

[yefragetuwrabrumuy]

Don’t kid yourself. Almost nobody understands economics.

As a bonus, though, I like to put in a pitch for something new that everybody wants but isn’t in wide scale production yet. Thin sheet aerogel insulation.

Aerogel, or “frozen smoke”, has been around since the 1930s, but was brittle and very expensive, until recently, when a way has finally been discovered to make thin, flexible sheets of it at a much lower cost.

Its use as an insulator could save vast amounts of energy and money every year. Refrigerators, freezers, ovens, hot water heaters, and even homes can now have their energy bills slashed.

They have already tried putting it in garments and boots, but outside of Arctic conditions it is too efficient. A sauna in a blizzard.

First call for production sheet aerogel is going to NASA, as they want it to line satellites and space probes, and the demand is already huge once they can increase production volume. It can handle temperatures from -200°C to +635°C.

Aktarus Group is already producing the retail version.

http://www.aktarusgroup.com/content.asp?id=13&ln=eng#

[wolf78]

As a bonus, though, I like to put in a pitch for something new that everybody wants but isn’t in wide scale production yet. Thin sheet aerogel insulation.

I've been reading everything on aerogels for years now, they're just fascinating. They'd also be a perfect fit for PASSIVE HOUSE retrofits.

[Wonder Warthog]

And my point is that it is POSSIBLE for solar to do the whole job, without need for fossil fuel backup. Is it the BEST alternative, probably not. My own preference would be full bore nuclear fission, including spend fuel reprocessing and breeder reactors. But if we are NOT allowed to do that, solar CAN pick up the whole ball of wax. It won't be cheap, but it CAN be done, and with technology available today.

The real "missing ingredient" for solar thermal is a market size sufficient to justify the capital investment in a fully automated mass production facility for mirrors/concentrators. Once that point is reached, the price of the total system will drop significantly. The rest of the package is pretty much "off the shelf". A pot of thermal mass is NOT rocket science.