World record solar cell with 44.7% efficiency • Hacker News Board

Re: World record solar cell with 44.7% efficiency

#111

Post by dredmorbius » Thu, Sep 26, 2013, 3:16 AM UTC

robertskmiles wrote: post #98

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

Regarding storage, I've read some interesting things about the potential of electric vehicles here. If every car were electric, that's a massive array of large efficient batteries connected to the grid. If utility companies charge varying amounts at different times, depending on supply, you could imagine a smart charger for your car whereby you buy electricity when it's cheap, store it in the battery, and sell it bac…

There's some opportunity for this, and I've seen discussions of it. The capability is real and is being seriously considered, though with existing EV fleets the effects are too small to consider.

Given the variability of renewables supply, this is a good way to allow for surplus daytime supply (of solar) and possibly overnight supply of wind (though in many areas winds tend to peak during the afternoon/evening due to land heating effects).

The challenge though is that you're still ultimately limited by battery materials. Known lithium reserves would be exhausted within a century even with recycling (about 90% efficient) providing only a fraction of the world's population with a Tesla-sized battery. Other electrolytes, improved recycling, or sourcing lithium from much poorer sources (potentially seawater) might work around this, but it's still a constrained resource.

Re: World record solar cell with 44.7% efficiency

#112

Post by dredmorbius » Thu, Sep 26, 2013, 3:18 AM UTC

kken wrote: post #103

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

Solar power has something that has been proven to be an universial law for all manufacturing: The manufacturing cost decreases is a power function of cumulative production, also known as wright's law. This is a very interesting paper about this concept: http://arxiv.org/abs/1207.1463 Moore's law is special because it relies on physical scaling (See Dennard Scaling) of the product. The transistors get smaller with eac…

I've been very interested in finding out what lies behind Swanson's law. I suspect that chip fabrication technologies and methods have much to do with this, and to that extend there would be some carry-over from IC silicon fabs.

Thanks for the reference.

Re: World record solar cell with 44.7% efficiency

#113

Post by dredmorbius » Thu, Sep 26, 2013, 3:19 AM UTC

pcowans wrote: post #75

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

I think the total energy available at ground level is something closer to 250W/m^2.

It's 1kW/m^2, which, given cell efficiencies of ~25% gives you your 250W/m^2 value. I goofed saying 1W/m^2.

Re: World record solar cell with 44.7% efficiency

#114

Post by dredmorbius » Thu, Sep 26, 2013, 3:24 AM UTC

mentos wrote: post #93

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

Is long term storage necessary? Couldn't a coal powered plant be fitted with solar to create a hybrid solution where coal burning kicks in when the clouds come out? edit: The idea being that you can piggy back on the infrastructure already in place at power plants?

First off, you're going to want to be getting away from coal by and by, for both availability reasons (turns out Peak Coal may well hit us sooner than expected) and for greenhouse gas (CO2) emissions. An alternative would be to have biomass plants available for weak-supply periods, and some solar plants (the solar thermal plant in Spain for example) use this method.

Second, solid-fuel plants don't ramp quickly. If you're keeping them in standby, you're burning a lot of fuel just to keep your boilers hot. Most peaking plants today are either hydroelectric (which can literally spin up in seconds) or natural gas (not quite as quick, but still capable of demand-matching in a few minutes). Natural gas is also subject to depletion and CO2 concerns.

For base-load power, nuclear and geothermal would be good options. Geothermal also doesn't ramp particularly quickly in most cases, though it's very reliable. Enhanced geothermal (ground holes dug into which water is injected) has proven to be much more expensive and accident prone, and less productive, than hoped.

Re: World record solar cell with 44.7% efficiency

#115

Post by dredmorbius » Thu, Sep 26, 2013, 3:34 AM UTC

kelvin0 wrote: post #83

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

I wonder if electrolysis and storage of Hydrogen would be a viable 'storage' method? Of course, the problem then might be the hazards associated with containing such a 'bomb'.

If you've got sufficient excess energy, a supply of water, and the means to store it, it's a possibility.

It competes with alternatives such as compressed air storage, where you literally compress air and pump it into the ground, filling reservoirs from which natural gas was extracted. These rely on suitable geological structures, but it seems to be a real consideration.

For hydrogen, the main challenge is that you'd need to compress or liquify it for long-term storage. It's also possible to convert it to other fuels (electricity-to-fuel conversion) though that's complicated, fairly inefficient, and not something I've looked at in depth.

Re: World record solar cell with 44.7% efficiency

#116

Post by dredmorbius » Thu, Sep 26, 2013, 3:38 AM UTC

X4 wrote: post #108

dredmorbius wrote: post #73

For those wondering about the significance of this announcement: As several people have noted, what matters for solar PV isn't efficiency but cost per Watt . The maximum available energy is 1W/meter^2 at ground. Single-layer PV efficiency is on the order of about 40%. Mutliple-layer cells can reach a maximum of around 80%. Even with existing efficiencies, the land space necessary to dedicate to solar power for all el…

Bill Gates invested in at least 5 Battery Startups who could revolutionize the capacity problems of the large power-grids worldwide: http://gigaom.com/2013/04/02/bill-gates-investors-back-sodiu... Soon replaced by graphene super capacitors.. How conservative do you sound when you promote Thorium reactors in a solar cell thread? ..some people have heard enough "positive" things about nuclear power now. There are cheap…

Gates has looked at a number of power options, including Sadoway's liquid metal batteries and the TerraPower "nuclear candle" breeder reactor.

I'm not convinced that nuclear's the way to go, but we know how to create working plants based on both uranium and plutonium fuel cycles, with thorium looking pretty viable. How economically feasible and long-term safe they are remains an open question, though I'd consider them as at least bridge technologies to whatever human's next stable-stage energy mix is.

The best fusion reactor design I've seen is a third-generation design that's been in long-term field trials with wide deployment, and can be found in an operational model 8 light minutes away. The primary challenge is figuring out how to plug it into human power grids.

Re: World record solar cell with 44.7% efficiency

#117

Post by dredmorbius » Thu, Sep 26, 2013, 3:42 AM UTC

mchannon wrote: post #89

kelvin0 wrote: post #83

Earlier quoted context omitted.

I wonder if electrolysis and storage of Hydrogen would be a viable 'storage' method? Of course, the problem then might be the hazards associated with containing such a 'bomb'.

In practice it's pretty bad; Hydrogen, even compressed, takes up a large amount of volume. A 10 gallon tank stores about 1.5 gge of compressed H2. The energy to compress H2 is again as much as it takes to create H2, and you don't get that energy back when you burn it (combustion perhaps 30% efficient). An electric battery returns a far higher percentage of the power in, and is far simpler and safer. H2's dangers are…

I don't see H2 as a highly efficient storage option, but if the alternative is simply wasting the electricity generated, it's a choice worth considering. Compression or liquification will address some of the storage density issues, combustion is straightforward. If it's being used on-site or nearby then transport and handling are reasonably minor issues -- wider-scale distribution is a thorny problem.

In an oil-scarce world, hydrogen (or hydrogen-derived gaseous or liquid fuels) are probably the only real bet we've got for heavier-than-air aircraft fuels where passengers, significant freight, or military performance are required.

Re: World record solar cell with 44.7% efficiency

#118

Post by dredmorbius » Thu, Sep 26, 2013, 3:43 AM UTC

Roboprog wrote: post #90

forgottenpaswrd wrote: post #78

Earlier quoted context omitted.

"The maximum available energy is 1W/meter^2 at ground" Where are you from, Britain? http://en.wikipedia.org/wiki/Sunlight ""sunshine duration" to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per meter" "The total amount of energy received at ground level from the sun at the zenith is 1004 watts per square meter" This depends on altitude of course, the max…

I assumed he meant "1 kW" and missed the k.

Quite.

Re: World record solar cell with 44.7% efficiency

#119

Post by anovikov » Thu, Sep 26, 2013, 10:27 AM UTC

dredmorbius wrote: post #110

anovikov wrote: post #74

Earlier quoted context omitted.

Not true at all. Your statement about available land is correct of course, but the important part of picture is that the soft costs for construction of solar electric power plants are already much higher than hard costs. And, improving efficiency is a great way to cut them. Imagine a 10 MW power plant built out of panels with 10% efficiency. If you replace them with 20% efficient panels, you increase output 2x withou…

Sure, you can increase your efficiency, but: There's a hard upper limit. 1 kW/meter^2 (mis-typed as 1W above). And you've got diminishing marginal returns of more efficient cells. The truth is that the land requirements are likely to go down by a factor of 2-4 maximum. Other cost factors (transmission, but especially storage) will dwarf these. Once you've provisioned land for solar, the key costs are in replacing the…

Correct, i agree to all these. I just meant that there are hardly many ways to decrease costs for large-scale solar available now except cell efficiency (not for U.S. where majority of costs are red tape and scarcity of installers, i mean countries where markets are established like Germany or Italy). Also, there is not much NEED to decrease costs below those achievable with efficiency increases (especially if efficiencies ca. 30% are achieved, which is possible like, 10 years down the road). A solar power plant with fully installed system cost of $1.5 per watt will be cheaper that high-voltage grid in majority of places, at $1 per watt in nearly every place.

>We've got cost reductions built in to PV production for the foreseable future.

In which way? Production capacity-related economy of scale? Current production capacity is already close (well, at least half of) what can be sustainably loaded worldwide. Maybe, another 2x growth is possible because factory builders don't care much if their business is sustainble long-term, they will work until worldwide demand is filled. But i will be very surprised to see over 300 GW/y production capacity worldwide anywhere in the coming 10 years. Apart from economy of scale, there is little way to reduce price.

Re: World record solar cell with 44.7% efficiency

#120

Post by anovikov » Thu, Sep 26, 2013, 1:25 PM UTC

dredmorbius wrote: post #110

anovikov wrote: post #74

Earlier quoted context omitted.

Not true at all. Your statement about available land is correct of course, but the important part of picture is that the soft costs for construction of solar electric power plants are already much higher than hard costs. And, improving efficiency is a great way to cut them. Imagine a 10 MW power plant built out of panels with 10% efficiency. If you replace them with 20% efficient panels, you increase output 2x withou…

Sure, you can increase your efficiency, but: There's a hard upper limit. 1 kW/meter^2 (mis-typed as 1W above). And you've got diminishing marginal returns of more efficient cells. The truth is that the land requirements are likely to go down by a factor of 2-4 maximum. Other cost factors (transmission, but especially storage) will dwarf these. Once you've provisioned land for solar, the key costs are in replacing the…

Germans in their Kombikraftwerk study back in 2007, figured out that you need 5x the capacity (compared to the average usage) to cover entire annual (and daily) fluctuations of the grid with renewables, without storage (more exactly, with that little storage they already have - in the form of a few pumped hydro plants). I tend to still trust this study, there are no counter-arguments to speak of.