wildleg

later on this year I'm thinking about playin around with some solar on my house, maybe building some panels from 6x6 poly. anyone done this ? comments, suggestions, advice ? (I haven't done any solar or wind stuff, so I have to get up to speed on the grid tie)

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backstay

PV panels are under $2 a watt now. Why would you try to build your own?

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wildleg

for fun. I am still conducting experiments to determine the detrimental effects of alcohol on common work and production tasks (since it is no longer politically correct to do this at work)

__________________
As President Roosevelt said: "We have nothing to fear but fear itself. And Chuck Norris. And 滿口胡言. And Grabthar's hammer. And Gort. and 江南 Style. and rotting in the street and Zombies . . . and Wayne Griffen "

BBQ

Step it up a bit, http://www.popsci.com/diy/article/20...uclear-reactor

backstay

I wonder how many ideas like this produced positive power output, but then was buried by big business? I'm thinking along the line of "free energy would destroy the world economy" BS.

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When "deleted" called the Seals, they killed Bin Laden. When the Seals called "deleted", he denied them.

wildleg

that's a good idea, but in reality a reactor that small doesn't produce sustainable fusion - it is just to show that fusion takes place. you need a reactor the size of a large rec room for a decent reactor, and when you add the "chernobyl" component (I can just see my wife turning off, say, the cooling system because it is too noisy), I'm gonna stick with playing around with some PV. I'm serious about the original post, tho, if anyone has any helpful hints or links they want to share.

__________________
As President Roosevelt said: "We have nothing to fear but fear itself. And Chuck Norris. And 滿口胡言. And Grabthar's hammer. And Gort. and 江南 Style. and rotting in the street and Zombies . . . and Wayne Griffen "

Big John

LMAO.

-John

Electric_Light

$2 for realistic watt or per ideal condition watt that you'll never get in real life?

backstay

Do you really know anything about solar?

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When "deleted" called the Seals, they killed Bin Laden. When the Seals called "deleted", he denied them.

BBQ

I am pretty sure he is a photographer.

backstay

Panels are rated under standard test conditions (STC) at 25 C. So a panel at a lower temperature will produce more than the name plate. Where I'm at they almost always produce more. I've only had digital readouts on my system for the last 3 years, so I can't speak for the 15 years before that. But I don't think the laws of physics changed.

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When "deleted" called the Seals, they killed Bin Laden. When the Seals called "deleted", he denied them.

Electric_Light

Not really. If I did, I wouldn't be asking the question.
I know that a PV won't give the same output on a cloudy day as it does on a sunny day.

What I don't know is if 1000W panel can make 1,000W real life or only in laboratory conditions.

Hmmm... is it a flash reading where the panel is maintained at 25C, then taken into a bright output for a measurement before it has the chance to get hot or is it able to sustain the rated output in 25C ambient temperature?

raw performance specs for LEDs are measured like that. The chip is given a short burst, then the light output is measured.

s.kelly

I will be interested to hear your results. I made a solar air heater in 2010. It is far less than ideally located for visual constraints, but I still get about a 10 deg temp rise on a 100cfm fan (if I remember right) for about 4 hrs a day.

Might have 300 in it and alot of that was the fan. Fun build.


Room is discharges in is noticibly warmer than adjacent rooms when it runs.

I have seen guys run data loggers and get real data, but it seemed too much money and effort even though it would be interesting.

backstay

To get the rating, the panel must produce at a sustained level at the 25C temp. A panel will not reach 25C if the air temp is below 40F in full sun(that's a guess on my part, someday I will do some temp checks at different temps.

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When "deleted" called the Seals, they killed Bin Laden. When the Seals called "deleted", he denied them.

Electric_Light

What about much above 25C?

As you know, in full sun, it will get too hot to touch even if the ambient is quite low.

BBQ

Here is a random cut sheet for a PV mod. It provides what you need to calculate output at the temp of your choice. 25C is just the STC temp for comparison.

http://us.sunpowercorp.com/cs/BlobSe...ble=MungoBlobs


As far as the high temps dropping the output that is well known, that is why good design takes that into consideration. For example when the array will be flat on a roof good design will raise it up on standoffs and / or leave gaps between the panels for airflow.

We have done a ton of solar in New England and we are sure to keep doing it.

That said if there were no incentives for it there would be no reason for anyone to want to do so. Still way too much money compared to cheap grid power.

wildleg

BBQ - have you done any houses, or was that all commercial ? If you have done houses, what was the largest size pv install you did for a house ?

__________________
As President Roosevelt said: "We have nothing to fear but fear itself. And Chuck Norris. And 滿口胡言. And Grabthar's hammer. And Gort. and 江南 Style. and rotting in the street and Zombies . . . and Wayne Griffen "

BBQ

I don't think we have done a home.

We have done systems from about 15 to 550 KW.


I was one of the first guys in the company to be doing it, it was cool at first but quickly became a bore. Worse than doing a hundred of the same fixtures because now you have to do it on a roof.


Truth be told, it made me nervous to be in charge of guys on a roof 8 hours a day for many days. It just seemed the likelihood of an accident was just a matter of time.

Electric_Light

So, derate 0.38% per K temp at cell above above 25C and assume 1,000W/m^3

Well, keeping 25c at the cell when ambient is likely easily above 25c and high radiant energy is not realistic without chilled water cooling.

Cars get pretty hot in the sun as you know, so I think 55C at the panel is a reasonable temperature to use.. so derate to 89% of rated output at 1,000W/m^3 of solar irradiance.

BBQ

No one has said 25 is realistic operating temp in all areas. It is certainly a realistic operating temp in some areas.

It is simply a temperature to compare modules, that is all it is. Like Government fuel economy ratings.

Yes, and no one is hiding that fact. It is well covered in any PV training. OTOH on a cold winter day we can be well below 25C and well above 1,000W/m^3 irradiance.

We have not even touched on inverter losses yet ..........