Optical Concentrator To Make Solar Power Cheaper

Al writes "Researchers at a company called Morgan Solar have developed a simple solar concentrator that promises to cut the cost of solar energy. The Light-Guide Solar Optic (LSO) consists of a specially-molded acrylic optic that traps light and guides it toward its center using total internal reflection. At the middle of the concentrator another optic made of glass receives the incoming light, amplifies it and directs it toward a small solar cell at the very center of the device. Unlike other concentrators, the light doesn't leave the optic before striking a solar cell so there's no air gap, and there's no chance of fragile components being knocked out of alignment. This could significantly reduce the cost of manufacturing this type of solar cell."

Comments

Cool

[Hatta]

That's actually pretty cool. By concentrating the light, they need less photovoltaic material per square foot of land used for solar. I'm curious how the efficiency of photovoltaic cells varies with the concentration of light. Will 1 square foot of sunlight concentrated into a few square inches of photovoltaic cells produce as much power as 1 square foot of unconcentrated photovoltaic cells?

Re:Cool

[Skapare]

The efficiency actually goes up relative to PV material in straight unmagnified sunlight. I'm sure there's a saturation point where that stops. This is one reason concentrating light on PV is a plus. Of course, the other is that it involves less PV material cost.

Re:Cool

[M. Baranczak]

Won't work. This thing has to face the sun directly. Which means that it has to be a fixed installation, and it won't work when it's cloudy.

The article briefly mentions some other group at MIT that's developing a concentrator that works with diffuse light - so presumably that would take care of both those problems.

neat idea. What do they do with the heat though?

[Almost-Retired]

Neat idea, but how do they get rid of the heat of 1000 suns? Does the IR escape because it isn't reflected the same way?

It's just a fresnel lens

[Matt Perry]

From the picture, it looks a lot like a fresnel lens.

Re:It's just a fresnel lens

[Rowanyote]

There are some key differences. In a fresnel lense the ridges just bend the light passing through a small amount. It is basically the surface of a regular lense stepped into a flat surface. Thus it acts almost exactly like a standard lense and has a focal point somewhere behind that all the light is reflected to.

From the sound of it, this lens bends all the incoming light 90 degress or more, sending it towards the center through the lens itself to a secondary optic area which concentrates the light and reflects it all out of the center with a focal length of effectively zero.

transmission lines

[bcrowell]

I live in LA. To the east of us is the Mojave Desert, and there's already quite a bit of solar power out there right now. The big issue is transmission lines to get the energy from the Mojave to LA. Building transmission lines requires political action, and that's slow and uncertain because of NIMBY. I have photovoltaics on my roof, but objectively, if you look at the price of land where I live versus the price of land in the Mojave Desert, it's pretty clear where you should be building these things.

Re:neat idea. What do they do with the heat though

[Colonel Korn]

Neat idea, but how do they get rid of the heat of 1000 suns? Does the IR escape because it isn't reflected the same way?

About 80% of the energy is absorbed across the entire solar spectrum. Yes, it will radiate some heat away as IR, but mostly the heat is convected away by the surrounded air. You're right, though--this is a design concern for these devices, as temperature effects efficiency and lifetime.

Re:neat idea. What do they do with the heat though

[mh1997]

Neat idea, but how do they get rid of the heat of 1000 suns?

They keep them in the dark so they don't get hot.

or from wikipedia:

The solar cells require high-capacity heat sinks to prevent thermal destruction and to manage temperature related performance losses...In May 2008, IBM demonstrated a prototype CPV using computer chip cooling techniques to achieve an energy density of 2300 suns.

An unstated benefit

[vandelais]

of this particular solar advance means not only greater efficiency and lower cost, but also MUCH MUCH greater feasability for wider adoption by areas of higher latitudes. In addition, this particular advance would appear to reduce the detriment of partial occlusion by some factor.

This concentrator technology also reduces the manufacturing use of rare metals for these systems and that is another huge benefit also.

"Cheaper" Power Cells

[Mishotaki]

There has been so many news about breakthrough in power cells technology... making them cheaper and more efficient... but why the hell are they still so damned expensive?

Re:Shadow lines

[bcrowell]

That's the thing about alternatives. Storage.

Huh? My post, which you were replying to, didn't say anything about storage.

LA's problem with lack of capacity shows up on hot days in the summer, when everyone is running their air conditioner. That's exactly when the Mojave plants will be running at their maximum production. Because of this excellent match between peak production and peak demand, there isn't really an issue with storage. It's a perfect fit.

waste heat

[zogger]

Or use the waste heat to drive a stirling engine as a booster perhaps. I know just regular solar panels get wicked hot on the backs of them when sitting in full direct sun, I mean it is black stuff sitting behind a clear surface and stuck on a metal backing, it gets *hot*. Just doubling that heat would turn it into some sort of decent viable optional energy source.

And why PV? Instant electricity from it, solid state, no moving parts, pretty spiffy stuff. Big solar concentrators with turbines are cool too, we have those for giant megawatt scale production now, but we don't have them for joe homeowner yet or joe back packer, PV fits the bill for those purposes.

Re:Shadow lines

[WalksOnDirt]

Of course you don't want plants overgrowing your solar power plant anyway.

Which is why in actual practice the land under the solar collectors is made as sterile as they can afford to make it. We need to accept that getting most of our energy from desert solar will probably require destroying the ecology of several percent of the deserts of the southwest. I think that's an acceptable trade off, but for those who insist on a "greener" solution I suggest they push for nuclear power.