40% Efficiency Solar Cells Developed

gtada writes "A story published at Physorg.com discusses recently published research into the fabrication of solar cells that surpass the 40% efficiency milestone. Such devices would be the high water-mark to date, and hint at the possibility of even more effective technology. 'In the design, multijunction cells divide the broad solar spectrum into three smaller sections by using three subcell band gaps. Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.'"

Comments

Is efficiency the problem?

[timeOday]

There is really no shortage of sunlight anyways. If only solar cells could be made cheaply. I suppose this will be great for satellites though.

Re:Is efficiency the problem?

[SnowZero]

While space will eventually be a problem, I think cost is still the limiting factor right now. How many houses can afford to cover their entire south-facing roof with panels right now? If you see panels on a house, its usually only covering a fraction of the available area, which implies the limit is cost.

Right now, we've got ~40% efficiency panels which are very expensive, and 1-2% panels which are cheap to make. I think the real breakthrough will be when we can make 20% efficiency panels that are inexpensive enough to cover a roof. So, in the long run, you are right that space will be the overriding factor, but right now it's cost-per-watt that is the biggest problem.

Re:Is efficiency the problem?

[Anonymous Coward]

One of the difficulties that may prevent this as that some of the materials required for these systems have undergone quite considerable asset inflation - rare earths, copper, etc. This is partly because reserves of these elements are dwindling, partly because the machinery to mine them relies on machinery powered by oil derivaties which are more expensive, and partly because high global liquidity and low interest rates has led to a possible asset bubble in a number of assets. If cost drops to that of a car in 2008 then increased demand will then cause those raw materials to increase a lot in price, in which case the cost will then go up meaning a price of more than a car in 2009.

This is one of the big challenges facing us - a combination of some raw materials being in short supply (and thus high cost) at the same time, coupled with asset inflation due to other reasons. In some instances the high price will bring in investment to create new mines to create new supply, but this will take a decade or more (assuming new supply is possible). The problems at hand of energy security and of reducing climate change is one that needs to be invested in heavily on a more urgent timescale. If demand drives above supplies of the raw materials and the cost of the raw materials becomes 'real' (i.e. the element due to global liquidity asset price inflation vanishes) and this feeds into general inflation, then interest rates might be stubbornly high which makes long term investment in these technologies more expensive.

In other words the time to have really pushed forward on implementing many of these technologies would have been a decade ago, even with less mature technologies, as the economic conditions were more benign between then and now than they are likely to be between now and 2017. The technologies are still needed, but things will be tougher. The lowest hanging fruit need to be identified and identified quickly.

Re:Studebaker Nuclear Reactors

[thisissilly]

Solar, at 40% efficiency would still require covering something like 8% of the land surface area of Earth to meet current-day demands.

You might want to re-check your calculations. Total world energy usage is ~15 TW. Light at surface averages ~342 W/m.

Land surface is 148,939,100 km

(1.5*10^13 TW / [0.4 *342 W/m]) / 148939100000000 m = ~ 0.07%. Let's double it for extra capacity (and because half the planet is in night), and we're still under 0.15% of the land surface area. Your 8% estimate is large by a factor of 50 or so.

Of course, putting the whole thing in space might make more sense. If you really want pie-in-the-sky thinking, covering the moon with 10% efficient solar cells would provide about 86 times the power the world uses now. Getting it all back to Earth would be the tricky part.

Though I also agree we should be using better nuclear reactors.