Comments on: Solar PV’s 44% Efficiency Record, Thanks To NREL & Solar Junction

By: jburt56

jburt56 — Mon, 31 Dec 2012 20:08:00 +0000

Looks like quantum dots will be the next big step up.

By: James Van Damme

James Van Damme — Mon, 31 Dec 2012 16:06:00 +0000

Us folks with flat surfaces and no tracking concentrators are not going to be impressed with HE cells when we see the price tag. But keep at it, folks.

By: Pete Stiles

Pete Stiles — Mon, 31 Dec 2012 12:37:00 +0000

100% efficiency is 1Kw per M^2 (in perfect sun) a 2×2 meter panel is therefore 4 Kw. Average annual insolation (amount of sunshine) is about 4 hrs in the US (depending on location).
So 16 Kwhr per day which at 44% efficiency is 7Kwhr. We would need to deduct about 20% from this to compensate for losses in the batteries,wiring and controllers etc so 5 Kwhr per day is a nice round figure. A Chevy volt type battery bank is about 25 Kwhr so your answer is 5 days charging for 1 day driving, Mind you 4^m might be an ambitious area to find on a typical car.

By: dynamo.joe

dynamo.joe — Mon, 31 Dec 2012 05:52:00 +0000

I have been wondering for a couple of years now why none of the university teams that enter solar car competitions have attempted a CPV design. Maybe they did try it and it was less efficient? Instead you only see teams trying to make the lightest, most aerodynamic car they can and slap solar cells on it.

C’mon guys start thinking outside of that box.

By: dynamo.joe

dynamo.joe — Mon, 31 Dec 2012 05:41:00 +0000

That’s a good question. I’m sure if you asked Solar Junction they would say something like “that is a design decision that is made by each of our customers”.

Like you I would hope they are finding some use for all that energy but if the project is far out in the desert I’m not sure what use they would find.

If the project was on the roof/parking lot of a highschool or something you would think it would be easy to use the waste heat to heat and cool the school.

By: Bob_Wallace

Bob_Wallace — Mon, 31 Dec 2012 01:49:00 +0000

Everyone seems to love Stirling engines but I’ve never heard of one in actual use. So I googled. From the American Stirling Company page…
“The modern uses of Stirling engines are invisible to almost everyone. There have been many research engines built in recent years but there are only three areas where Stirling engines have made a dramatic impact.

There are Stirling engines in Submarines, stirling machines used as cryocoolers,
and Stirling engines in classrooms. ”

http://www.stirlingengine.com/faq/#5

Wiki tells me that –
“A *Cryocooler* is a standalone cooler, usually of table-top size. It is used to cool some particular application to cryogenic
temperatures.”

Further searching leads me to no current applications. Seems like Coleman made a small cooler for a while that sold for several hundred dollars.

By: Matthew Todd Peffly

Matthew Todd Peffly — Mon, 31 Dec 2012 01:29:00 +0000

So at the large CPV plants using these cells. What are they doing with the “waste” heat? Sounds like you could set up some stirling cycle engines and extra more power from the system. Please don’t say that they are setting up cooling towers.

By: Bob_Wallace

Bob_Wallace — Sun, 30 Dec 2012 22:11:00 +0000

It wouldn’t be an optimal use for the cells.

First, it’s best to point cells at the Sun, most of the surface area of a vehicle is flat.

Second, one would always need to park in the sunshine. Not under a tree, in a garage, in the shadow of a tall building.

Third, once the vehicle batteries were full then the rest of the potential electricity would be wasted.

Better to install them where they will get the most possible sunlight, at the best angle, and feed all the power to the grid. A plugged in vehicle can grab that power with little loss.

By: photosymbiont

photosymbiont — Sun, 30 Dec 2012 20:58:00 +0000

What about the potential for incorporating high-efficiency solar cells in the roof / hood / trunk panels of electric vehicles? The limited surface area available on an EV would point towards the use of high-efficiency panels – but how long would it take to charge a typical EV battery using a 44% efficient panel, perhaps two meters square?

By: dynamo.joe

dynamo.joe — Sun, 30 Dec 2012 19:34:00 +0000

Efficiency doesn’t seem to scale much with number of suns (~400 gives 43.5%, ~900 gives 44%). What will be a strong function of number of suns is cost/kWhr.

So at 1 sun efficiency will probably be ~42%, but the cost would be 100 times more expensive than going down to radio shack and buying whatever polycrystalline Si solar cell they have there and it will only supply 2-3 times as much electricity. So economically a bad plan to use these in a non-concentrating environment.

But at 900 suns you get 1800-2700 times the electricity that you would get from your 1 sun radio shack cell. You also have to supply a reflector, a tracking system, and an active cooling system. But as long as all of that costs less than 2700 times your radio shack cell, you still have a less expensive system on a $/kWhr basis.

By: DJ

DJ — Sun, 30 Dec 2012 18:31:00 +0000

what would be the efficiency in 1 SUN