Is now a good time to invest in solar?

Artman

I'll run the numbers again and let you know. I think with a decent SREC rate, it should be around 5-7 years, worst case about 10 years.

My original question wasn't really so much about the payback as it was the technology. I wanted to know if anyone here knew of any breakthrough technology that would make the old panels obsolete and very much more expensive. If the world was on the cusp of a breakthrough that would drive solar array prices way down or solar efficiency so good that fewer panels could do the same job. If the cost comes too far down, the market will become flooded and SREC prices will drop. Then payback would become an issue. Payback from electricity savings +rebate and tax credit, but with no SRECs is about 20 years.

My honest answer is "no." I wish I had done it sooner (when rebates were higher).

I attended an energy symposium where I had to answer questions about residential solar. there were several others there who had solar arrays as well and, from what they have said, all of them are very pleased with their investments. I'll post more about this later, some issues to be aware of came up out of that day.

OmCheeto

Not to politicize the engineering forum, , but with the gulf spill going on, I'd say your timing was impeccable.

Artman

One of the questions asked of the residential panel made up of home owners with solar arrays was: "Knowing what you know now, what would you do differently?"

A man with a huge 28 kw ground mounted array said he would have had it set slightly higher. His is only 6" above the ground at the low end (mine is about 30"). He said snow bunched up around the bottom and he had to clear it.

A man with a 9.5 kw array mounted on the roof of a pole barn said he would ride past mine (he lives close by me) during those days following the heavy snows and see my solar array was clear of snow while his went for weeks with snow on it because the angle was too small (30 deg over horizontal, mine is 40 deg) and the roof was too high for him to clear them. He said If he had it to do over, he would put it on the ground at a steeper angle, similar to mine.

I said I would have done it sooner.

I can understand their answers, my best days were days with snow on the ground and a clear solar array.

Artman

Wow, yes that could have an impact.

mheslep

Not sure how solar PV will help Artman to use any less oil in his next truck/car/airplane/train trip.

mheslep

Really? More kWh on snow days than the Spring months? How do your sky facing arrays get ray line from the snow?

Artman

I'd have to draw that out myself, but they did. One of our highest instantaneous outputs that I saw on our monitor was 10.15 kw at 1:20 on Feb 18th a day with snow on the ground. Other snow days also did over 9 and 10 kw peak instantaneous outputs. On no-snow-sunny days the highest it goes is about design 8 to 9 kw. Today was a screaming sunny day and the best I saw was about 7.6 kw, but it held that longer and will probably end up around 50 kwh today. March did have one of our highest daily outputs of 57 kwh and earlier that week it had a peak day over 10 kw. But the snow on the ground days do appear to be good performers.

mheslep

Part of that is because of the 30-40 degree C temperature difference between then and now, but that still doesn't explain a nearly ~30% power swing, from a lower in the sky sun (then) to a higher one (now). Perhaps the panels have gotten a little dirty? A little banged up (from ice, blown debris)?

OmCheeto

Might be the fact that fresh snow has an albedo of almost 90%.



Leaf, Volt, Tesla Roadster or Model S.

Airplanes will have to wait for Ivan and his green slime fuel.

blimkie.k

Artman,

First off, congrats on the successful installation of your system, sounds like its running great!

I am looking into building a 10 kilowatt system. We have submitted an application to the Ontario Power Authority to get a contract in there microfit program. They pay 82 cents a kilowatt over a 20 year period. Still doing the research but submitted the application because it takes about 3 months to be processed.

So are you saying on days were its pretty much overcast all days and really no direct sunlight you get about 25 to 30 khw per day with your 8.8 kilowatt system? Have you ever got anything lower then 20 khw in a day?

I have been doing some calculations using declination and determining the the max and minimum angles of the suns position at noon. (with a little help from in another thread on this forum). I'm trying to work out a good angle to have them tilted at.

You say yours is about 40 degrees. Does it ever change or is it always angled at 40 degrees?

Artman

We had 3 days below 30 kWh in June the lowest of those was 7.64 kWh, probably raining. The other 2 low days were above 20 kWh. In May we had 7 days below 30 kWh, the lowest of those was 8.16 kWh, one was 11.59 kWh the rest of the low days were above 20 kWh.


Ours has a fixed position. Always due south, always 40 deg tilt.

Good luck with it if you decide to go ahead. Ours has worked out well so far.

Thanks for the comments all.

mheslep

Of course, but the panels are not pointed at the snow. Is there significant flux in atmospheric scatter? I dunno.

Not yet
Not yet
$109k
Not yet

E-planes are certainly years away, but I think they're coming. Maybe fuel cells for awhile, but definitely e-motors. Just too many advantages.


DS-94 Fan, about 4KW per Kg power density.

http://www.electraflyer.com/gallery/...e_electric.swf

Of course Artman's panels would have to put in some overtime to charge the full size version.

OmCheeto

At 40 degrees from horizontal, the panels will be 140 degrees from the plane of snow. They would still catch light at that angle.
Also, as I noted back in February:


x axis is 'C, y axis is watts, ignore T < 30'C per the author.

The temperature of the panels changes their output significantly. I know that when I set mine up in the summer to water the volley ball courts at the beach, you could fry eggs on them.

450 watts/750 watts = 60%

I'd say Artman's panels must be better than my old Kyoceras with only a 30% reduction in output.

Ah ha! You could almost interpolate the panel temperatures from his panel's data sheet:
30%/0.45% + 25'C = 92'C

Yup. Probably could have fried eggs on them.
My laptop sounded like a pachinko machine the day they started taking reservations:

All were announcing they'd put in reservations.
True, but there are plenty of hybrids out.Good timing:



With a little cash on hand, maybe they can ramp up production = economies of scale <> $109k/vehicle

I want one of those.

mheslep

Yes, but only diffuse light. Nothing normal to the plane of the panel. So the question is what is the impact of diffuse light. I dunno. Per Artman's results there likely is some impact.

Not Plug In Hybrids. Solar panels don't help regular hybrids at all, can't plug them in.

The cost is in the very large, custom cooled battery pack they're using (220 miles worth at full charge). The li ion laptop style batteries used by Tesla are already made in very large quantity.

Me too

OmCheeto

Two words: Skiers Tan:


Hymotion can convert a Prius into a plug in hybrid in two hours. Why can't auto manufacturers do that? Is there a patent?
Good observation. Why are we powering cars with batteries designed for laptops?

mheslep

I always thought that was from being above 2/3 of the atmosphere at high elevation and loosing UV protection. I don't see skiers tans close to sea level no matter how much or how long the snow's on the ground, but maybe I'm not looking.

Expensive toy I expect ($10k for the conversion?) Small battery, takes up the cargo room, etc.
http://www.popularmechanics.com/cars/news/4215681

Tesla was the first out of the gate 5-6 years ago. That's all that was available then.

mheslep

Another price update:

i.e. $2.6 per peak Watt installed, with incentives. About 15 years payback given average US electric rates, even without SRECs.


Compared to last year's cost for a 8.8KW system in NJ:

Or $4.7 / peak Watt installed. That's a 44% cost decline in 2 years. I smell some kind of Moore's law effect here.