So far, the "advancements" require more manufacturing accuracy, and higher cost materials (real silver is far more costly than aluminum).

I would rather see slightly larger but much cheaper mirrors with lower "efficiency" but delivering the same net energy. Sunlight is free.

In short, the push should be to make a cost effective system, not a technological record breaking wonder that is impractical to produce.

Is this 31% efficiency about the same as the most recent solar panels developed for NASA's space projects?

Which approach is cheaper to build and maintain?

Hold it. Who really believes this? An American lab? This is just more image PR from the collapsing free-enterprise empire.

It looks like the Sandia Sterling engine solar power system is more efficient in producing useful energy than using the same land to grow corn for processing to ethanol.

If that's the case, since a high percentage of our electric power comes from fossil fuels, we might keep more carbon dioxide out of our atmosphere with solar electric power than mindlessly persecuting the auto industry with demands for more biofuel use.

Harvey,

This is 31% to the grid AND likely to be much cheaper than the high tech solar cells used by NASA. With a solar cell you still need a DC to AC conversion and power management which lowers the efficiency slightly (and I think the most advanced solar cells are somewhere in the neighborhood of the mid 40% for conversion from sunlight to electricity...it would be easy to look up to verify).

"Spectrolab and the National Renewable Energy Laboratory (NREL) demonstrated a world-record concentrator triple-junction cell of 34.2% conversion efficiency."

These are the most efficient commercially available concentrator cells that I know of.

http://spectrolab.com/prd/terres/cell-main.htm

The challenge solar cells have is that they miss some wavelengths of light, so they don't harvest as much energy as an ideal thermal system could. That said, solar cells have no moving parts compared to the sterling engine.

I think these excercises are good because they show a better way, and engineers can always give up a few percentage points of conversion efficiency to bring down the costs and time to market.

I think at some point you consider land-use efficiency. Large concave dishes leave more spaces in between than photovoltaic, and probably troughs. Troughs in particular can store molten salt for later use, to extend the portion of the day they provide power.

http://www.renewableenergyworld.com/rea/news/story?id=49483

42.8% looks like the current record holder so low 30's is probably appropriate for the cells actually used on space projects.

I want to know what it takes to clean the mirrors on a 1 GW power output array of these things...job for coal miners?

Anyone knows which one produces cheaper electricity:
this Stirling System, or Australian Solar Systems ?

http://www.greencarcongress.com/2006/10/solar_systems_t.html

"31.25% efficiency" meaningless BS! Since the "fuel" is free, efficiency make little difference. What is the $/watt???

system produced 26.75Kw in 2 hours, maybe 13kw per hour?.. probably not enough to run one house.

The cost of the silver coating is minimal, it is extremely thin.. but it will tarnish if not carefully coated.. is the silver coating in front of the glass mirror or in the back?.. if it is in front it will deteriorate in a year or so to below the performance of aluminum coatings.

@ Herm

During the 2.5 hours test, it produced an average POWER of 26.75 kW. This means about 66.87 kW-hour of ENERGY during the two and a half hours.
I think the most expensive component of this system is the Stirling engine.

The system produced 26.75 kW in 2.5 hours. Meaning it produced 10.7 kW/hr or 10700 Watts/hr or the ability to light 107-100 watt light bulbs for an hour. Seems to be more than enough power for a single house in that time period.

This is bleeding edge technology. Breaking efficiency records makes yesterday's bleeding edge more affordable today.

What would be interesting would be if the stirling engine would be coupled with a fluid to further cool the cooling chamber and if that fluid could be used for further purposes. ie industrial/residential heating or such. This efficiency was achieved in relatively cold 0C temperatures. If the heat could be further used it would be even better.

According to the DOE, these solar heating systems are in the 10-12c/kwhr range, last time I looked it up. But those were trough systems and not these focusing systems.

You have to wonder at the modularity of the system. Without a huge reservoir system, they have the advantage over trough systems in that they could be put nearer residential areas as single enclosed stations. This would allow buildup without adding huge infrastructure costs especially in sunny climes. Of course it would look pretty weird with the things just sitting there among regular buildings but that is another question.

Here's a great recent article on what it would theoretically take to create a solar infrastructure and the basic scientific hurdles necessary to complete it. Has a discussion board and the author/scientist is actually in the blog answering questions.

http://www.sciam.com/article.cfm?id=a-solar-grand-plan

http://www.solarplan.org/

my house has a 125amp 220v service, to feed the electric stove, AC, water heater etc.. that is 27.5kw.. granted it will never use all that at one time, and I could easily have a gas stove and water heater to reduce it even further.

@aym:

Jorge already explained the difference between power and energy; at an average power level of X, you don't divide, but multiply by the time to come up with the the energy produced (are SI units really that hard to grasp by people educated in the US)?

@DS:

I agree with you, efficiency is of less importance - cost related to power/energy is what prevents the widespread use of one form or the other of solar power. For example, if someone building a house could get roof tiles which have the ability to convert solar radiation into electricity at marginally more cost than ordenary tiles, we'd see widespread use; Current thin-film solar cells with 7-10% efficiency cost at around 1,30 USD/Wp.

Another note: if peak efficiency was what they were after, why didn't they use real high-reflectivity, wide-band dielectric mirrors?

http://web.mit.edu/newsoffice/1998/mirror.html

Anyway, SciAm has a cover story about using solar energy in the (US) southwest to provide nearly all required electricity for NA (including energy for transport -> EV, PHEV...). This type of plant has the potential for using less land (~50%) and be more cost effective then (thin film) solar cells...

If you can get down to $3 per watt installed, you can get to a 15 year payback at 10 cents per kwh with 2000 solar hours per year. If this is a 25kw dish, then it should cost $75,000 installed and I think they are much more expensive than that.

You also have to maintain the Stirling engine, dish and tracking mechanism, so the costs go up. We may be getting to a point where electricity costs more per kwh from here on out, so this might be cost effective in the future. They may be doing this because some states will require 20% renewable energy from utilities in the future.

You could put a 10 foot dish with the Spectolab triple junction cells in your back yard and produce enough energy to drive your EV 80 miles per day....not bad.

It was not generating at 10.7 kw per hour. It was generating 27.5 kw for 2.5 hours for a total of 68.75 kwh of electrical energy.

Sorry bout that. I did get my electrical computations out of wack there. No need to get snarky. Also I did grow up with SI units, i only got a little confused there for a sec and holy bejesus multiple people jump down my throat. I would've thought that after the one post about my mistake that that would've been enough. Also if I saw Jorge's post, I would've better checked my own calcs but he posted in just before me and I didn't see it until too late and the page refreshed.

Anyway 26.75 kW over a 2.5 hr period means that it generated 66.88 kWh. Which is still a heck of a lot more than a single house would use in a day. I think the lowest monthly reading for me was in 180-220 kwhr range.

Anyway thought a picture would be nice. Hears what part of the installation looks like. Only problem is, you can't tell the scale of the things.

http://www.sandia.gov/news/resources/releases/2008/images/sandiadishsirling.jpg

@realarms, I've already linked to the sciam article above, with a secondary link to the author's non profit project to support it.