More Power from Rooftop Solar (8 cent/kwh possible now?)

[kristopher]

More Power from Rooftop Solar

A startup says technology inspired by RAID hard drives can boost power output by up to 50 percent.
Friday, April 29, 2011
By Kevin Bullis


A startup called TenKsolar, based in Minneapolis, says it can increase the amount of solar power generated on rooftops by 25 to 50 percent, and also reduce the overall cost of solar power by changing the way solar cells are wired together and adding inexpensive reflectors to gather more light.

TenKsolar says its systems can produce power for as little as eight cents a kilowatt-hour in sunny locations. That's significantly more expensive than electricity from typical coal or natural-gas power plants, but it is less than the average price of electricity in the United States.

Solar cells have become more efficient in recent years, but much of the improvement has gone to waste because of the way solar cells are put together in solar panels, the way the panels are wired together, and the way the electricity is converted into AC power for use in homes or on the grid. Typically, the power output from a string of solar cells is limited by the lowest-performing cell. So if a shadow falls on just one cell in a panel, the power output of the whole system drops dramatically. And failure at any point in the string can shut down the whole system.

TenKsolar has opted for a more complex wiring system—inspired by a reliable type of computer memory known as RAID (for "redundant array of independent disks"), in which hard disks are connected in ways that maintain performance even if some fail. TenKsolar's design allows current to take many different paths through a solar-panel array, thus avoiding bottlenecks at low-performing cells and making it possible to extract far more of the electricity that the cells produce.

The wiring also makes ...

http://www.technologyreview.com/energy/37481/?p1=MstRcnt

8 cents a kwh for peaking power in the summer is a steal. - K

[TheWraith]

1. Uh huh. Call me when this has been independently tested.

Startup companies make all kinds of claims, in large part to help attract financing from venture capitalists. Only a tiny fraction of them ever even come close to doing what they claim, and most are out of business within a few years.

[kristopher]

2. There doesn't appear to be much to test here, and TechReview is a good first cut source.

Interesting though, you feel compelled to pointlessly criticize this information yet you jump on immediate adoption of any cockamamy fission scheme instantly.

Another case of nuclear supporters trying to disrupt discussion of renewable energy technologies and planning. Why are you doing that? You must know that your remark is virtually meaningless except that it is a negative thought you want to associate with this bit of positive news about solar, which begs the question of why you and your other fission acolytes are ALWAYS doing it?

[TheWraith]

7. Really? Can you provide evidence of me jumping on "adoption of any cockamamy fission scheme"?

Or are you just talking shit?

Would you like to dig through the archives here in E/E and find the number of "revolutionary advances" which have turned out to be not what they were billed as? Or do you simply take it on faith that everything works exactly the way the people who stand to profit from it claim it does?

[SpoonFed]

3. Solar power neophyte question...

Where does a value like 8c/kWh come from?
What sort of calculation?

I haven't spent a lot of time on the cost/benefit analysis but I'm considering buying some fairly large 295W panels, building (or buying) an efficient DC-DC converter, charging some LiFePo batteries, (supplemented by AC-DC conversion when needed) and then powering some DC equipment. I've been mostly thinking in terms of how much power and c/kWh the system uses now from conventional AC grid with AC-DC conversion loss and the length of time at which I consider the value proposition "worth it". Not really coming up with a c/kWh comparison to grid.

[kristopher]

4. It depends

It is always a similarly performed calculation, but the purpose for doing it (and therefore the "where" may vary) might affect the values assigned the specfic variables.
You'd considering the total cost of the system divided by the output. In this case that would be pegged to a specific system cost and performance and a generic estimation of the amount of energy per square meter in the sunlight of the "sunny" location. You'd have to be sure you have all the factors considered, however, which would include but not be limited to the cost of money and the financial payback lifetime of the panels . A utility might look at payback as being 15-20 years, while a homeowner might think 30 years is the right value.

I'd add that the cost of power from the grid is usually the determining factor about whether it is worth it or not. If you are assigning extra value to energy freedom, that is still going to start with the grid as a benchmark.

[AtheistCrusader]

6. Are there any samples/examples with specifics?

I don't know if that number includes a loan for the equipment, or cash out of pocket, etc.

[kristopher]

8. I don't understand your question. nt

[AtheistCrusader]

9. c/kilowatt hour implies something to me against the cost of the system to deploy/maintain.

How was it arrived at?

Basically, I'm the asshole math teacher demanding someone show their work. (This is relevant to my adoption of solar panels.)

[kristopher]

10. How was what arrived at? The claim in the OP?

If that is what you are referring to, I have no idea. The article isn't specific about the inputs, which is why I phrased it as a question in the header.

However, if the technology does what is claimed and allows the use of uneven lighting, then all the following assertions deserve to have the benefit of mildly suspended disbelief pending verification.


I'd suggest going to their website if you want more information. If it isn't there and you are interested in their product perhaps you could approach them directly as a prospective customer. Please let us know if you get more information.

[SpoonFed]

11. c/kWh cost calculations

If that is what you are referring to, I have no idea.

Alright. That answers my question. I was or am assuming or actually more hoping, that there must be some generally accepted or standardized way to make such calculations and claims. I have no idea and hence my question. I thought providing a few details of a specific use case might help.

Anyone?

[Name removed]

5. Deleted message

Message removed by moderator. Click here to review the message board rules.

[txlibdem]

12. Some things to consider during your comparison, hope this helps

It seems like you are trying to compare an on grid power backup system with a hybrid solar on+off grid system. There are a lot of variables to consider, such as:
1. Does your utility give a discount for power used during "off peak" hours?
2. Does your state/local gov't or your utility offer any rebates for solar?
3. How efficient is your charge controller (you call it DC-DC converter)?
4. How efficient is your DC-AC converter?
5. What percentage of your total load will be used to power DC equipment?
6. How many hours of peak sunlight do you get at your location?

In short, if #1 is yes then you would set the charge controller to charge your batteries during the lowest cost period. Use that cost per kWh (8c/kWh becomes .08) divided by the efficiency of your charge controller (95% becomes .95). In that example it works out to 8.4 cents per kWh.

For the purposes of your comparison (unless I totally missed your point) there is no need to factor in the cost or efficiency of the DC-AC converter because it would be needed in both systems. It only helps you understand your total costs, which would only help you determine if the whole thing is worth it or not. If you want to calculate this then first subtract the percentage of the total load that will run off pure DC because there would be no conversion losses for these items.

One thing about the solar panel setup: you are basically locking in the cost for the next 20 to 30 years. Historically, utility rates have gone up 3.78% per year. So, in other words, even if the solar panels are not the cheapest option this year they might be cheaper after year 5 or year 8 or whatever.

Here's a good site to start your solar panel cost per kWh:
http://greenecon.net/understanding-the-cost-of-solar-energy/energy_economics.html

Here's a solar map for PV (answers question #6):
http://www.nrel.gov/gis/solar.html

[SpoonFed]

14. Thanks for the effort and...

Thank you for a polite reply for a change that doesn't revolve around calling me an idiot anti-nuke.

No, the system I envision is only hybrid for emergency backup purposes. I'm quite sure that modern solar + modern battery technology is sufficient in all but exceptional circumstances. On a side notice, it is a very nice idea to sell juice to the power company at peak prices during the day if there was any excess capacity.

Here's a good site to start your solar panel cost per kWh:
http://greenecon.net/understanding-the-cost-of-solar-en...

Your greenecon.net link is one of the most horrible examples of blinkered economic theory and mathematics mixed together that I've read in a long time. The lack of comprehension of the English language by the author is striking. The conclusions might be correct but I doubt it and I can't be bothered to wade through the illogic.

From the "article"...

In comparison to conventional hydrocarbon fuels such as coal or oil in generating electricity, the cost of solar energy is significantly higher.

The article starts in it's first paragraph with a conclusion. The terminology and mathematics are faulty. It's no wonder that it references the K-12 Energy Education Program page for it's table of conversions. Hilarious.

One thing about the solar panel setup: you are basically locking in the cost for the next 20 to 30 years.

I'm not sure this is a correct assumption though one that immediately came to my mind. I'm starting to think that it's really nuclear/coal power company propaganda in my brain that makes me think it will take so long to pay for itself.

I've been doing not so tremendously complicated calculations that suggest 5-10 years with the added benefit of having power when the grid is down, which it was, for 3 days for basically no reason here recently. If I'm optimistic it's shorter than 5 years.

The new monopoly electric power company here is incompetent and I also assume corrupt. They took over from another company that almost never let the grid go out for more than 2 hours. I assume be cause they had a cheaper bid. The morning of day 3 of the recent outage, a service tech sat on the street out front and I heard the game of phone tag he played on his phone while talking with his own company while trying to report "oh, by the way, this is Bob, hi, yeah, I'm over here on this street and there is no power". I might add that I'm not located in the sticks.

[XemaSab]

15. No, no

You're only called an idiot if you're PRO-nuke.

That's how this forum rolls. :smoke:

[txlibdem]

16. Maybe I wasn't clear: you are basically locking in the cost for the next 20 to 30 years.

I meant that the major cost items will last for 30 years (for solar PV) and 20 years (for residential wind turbines). So your initial cost will, in effect, be locking in your electric rate at a set rate for the next 30 years. Meanwhile, your electric utility is going to keep raising its rates. Maybe not each year but it will stair step up and up and up. Historically, utility rates have increased by 3.78% annually.

That's why I said it may still make sense even if your electric rates today are less than the per kWh rate you'd be getting from your solar setup. The solar won't go higher; the electric company rates will continue going up and up and up. So I tend to take the long term view of which will end up being cheaper. One of these years, the electric rates from your utility are going to be higher than your all-in cost from the solar. Just a question of time.

PS, I came so close to editing my other post because the costs are definitely out of date. The most recent quote I got was $28,000 for 5.5 kWh installed. I didn't take a super close look at their method of calculating the cost per kWh.

[Kolesar]

13. "Microinverters" try to solve the same problem

Good article, :thumbsup:

[kristopher]

18. That is some improvement!

My browser is set to block images because of a slow connection, so I hadn't seen the graph you posted until now.

Thank you. Are there any advantages to microinverters in other areas?

[Kolesar]

19. If a buyer had to place PV panels facing different directions...

...because they had a complex roof geometry and were trying to fit in a lot of panels, then microinverters are necessary. One set of panels facing south and another set of panels facing west should not be placed on the same inverter.

Or so I have read

[kristopher]

17. Assuming this works as stated, the implications are huge...

Since it will work with any panel, it would mean global solar panel manufacturing capacity has just increased by 50%. As I read the article it describes the kind of improvement that would be difficult to hold exclusive rights to. Instead it looks to be one of those lightbulb moments when something that should have been obvious if finally done by someone. It isn't so much a specific patentable design that marks the improvement, but the concept of matching reflectors and circuitry itself. Now that it has been done, copying (and probably improving on) the results is only a matter of time.

I know that the fission-oughts will dismiss this, but the goal of the solar program is to get the price of solar electricity down to where it is competitive with coal by 2020. To do that will require a more manufacturing capacity - a LOT more. It this proves itself, this tech will drive investment in solar manufacturing by immediately expanding the potential market vastly.

1000GWp by 2020 is starting to seem possible even if it still feels improbable.