I am over in intern land, done on Friday though. We prefer the 10 to 10 kind of schedule, just like we're still in college.

Narmacil, what department are you in? I'm currently interning in Avionics for my second summer.

If you're in the LA area I can give you a tour of the SpaceX facility and show off awesome rockets and spaceships.

Arnold is from Austria, not Australia, get your own geography education.

Um, what?

Top of the line Lithium Ion batteries (they'll soon trickle down to automotive) are at about 240 Wh/kg, or 0.864 MJ/kg. Now, here's the cool thing about electric cars, you can get ~70%+ efficiency from battery to tire patch (aka, 70% of the power is used to move the car), and 80%+ fairly easily. Gasoline engines top out at around 25-35% efficient (Carnot efficiencies). Assuming a gasoline efficiency of 35% and electric car efficiency of 70%, you need half as much energy per kg storage capacity for electric cars.

The second cool thing about electric cars, regenerative breaking. You can recover around 70% of the energy from stopping as electricity and put it back into your battery. It is easily more efficient to use batteries/electric drive trains than gasoline in urban transportation. Why do you think hybrids get such great city mileage? This further reduces the storage density needed. Hybrid buses are awesome at city transportation, serial hybrids at any type of transportation are just epic. Electric drive train to maximize drive train efficiency, gasoline or other generator for range running at most efficient gearing.

I definitely agree with you there. Should simply be a meter that monitors and records power usage with remote viewing. No remote disconnect or any such.

There are undoubtedly a number of products you can install to do the same thing.

Touche. I think a small device that monitors your power usage and that the owner can connect to is a great idea. I don't know if smart meters in their current form are a good way to go about it. Why do you feel they are an exceedingly dumb idea?

I really don't know what to say to this other than wow. Seriously? Wow.

That's got to be the first time Australia got something first or at least before the States. Lucky bastard :)

What do you think we're stockpiling all our nuclear waste for? Refueling the Sun, of course!

Who would've imagined that knowing you'd get a huge bonus anyway would make you work less/not as hard? The rest of us in the real world already know this.

You touch on another of the ideas that people are working on alongside efforts to make a high efficiency cell. While concentrator systems up cell efficiencies, the convertible spectrum is still limited by the cell. Some researchers, such as those at MIT as published last year, are working with dyes and other materials to re-emit the sunlight at a more cell friendly frequency, although this method too has major losses.

A second method not often mentioned here is called thermophotovoltaics. The idea is that you use concentrated light to heat up an element that then emits light at a different spectrum. To me, the cool idea about this is that if you can emit at the right range and get really high efficiency cells, somewhere down the line you might be able to replace the steam part of current power plants. Although that goes outside my realm of knowledge.

The issue with most cells' spectrum is that you need to shift the light up in frequency, not down, which is harder/more expensive. However, it could be useful if you could target the frequency at which the cell is most efficient.

I don't know exactly what the absorption and conversion rates are with the 40% efficient cells, but its safe to say it's very high. One of the biggest hurdles with solar cells is simply getting the charge out, getting the electrons and holes that are knocked out out of the semiconductor. It plays a very large part as to why current efficiencies are so low.

To hit 25+% efficient cells, in essence 3 cells were combined to create a multijunction cell that has 3 layers in series. To get to 30+%, refined deposition methods and clever semiconductor tricks were used. To get to 40+%, you need concentrated light and, in some cells, more layers of different materials.

The journal paper describes a simulated cell with a 14.5% efficiency and that it will compete with crystalline silicon cells - the middle of the pack for silicon efficiency and cost. The big advantage here is that the amount of semiconductor used is very low, which could make these cells very cheap. Another thing to keep in mind is that this method can potentially be applied to other, more efficient technologies, although there will be a few more hurdles should they go that route.

I very much like the idea of cheap solar cells, but it needs to be clear that this is not an efficiency breakthrough. But let me tell you, as a solar car alum, the idea of even a 40+% efficient non-concentrator cell gets me excited, even though this is not that.

There are many different factors that go into making a high efficiency solar cell. You need a front material that has very high transmittance/low reflectance at incident angles, a high absorption semiconductor, a high photon to carrier generation rate, high/easy carrier collection from the semiconductor, and broad spectrum conversion. These silicon-wire arrays appear to have high absorption and high carrier generation, but thats only part of the story. The other issue is that silicon misses out on a fair chunk of the solar spectrum. Anything after 1100nm is not converted, its simply below the bandgap.

The title of this post and the article is incredibly misleading and very annoying/frustrating to someone who's been working on solar technologies for a while. Don't get me wrong, I think this is a very cool thing, sounds like they have to potential to make very cheap cells, but approach, let alone surpass, current multijunction cells (30-40% eff.) they will not.

Disclaimer: University of Michigan Solar Car Team alum

So solar cells take a lot of energy to make, no argument there. But why is it always assumed that you're not making your cells with energy from other solar cells? No, the first cells weren't made using renewable energy, but who says we can't do that now? Imagine that, a renewable loop. Oh, and don't forget that you can recycle the solar cells at the end of their lifetime to make new ones.