Cool. So, how much power does the thing output in full fun? And kWh/day would be nice, too.

Still at $105 it's a pretty good deal...

Heck yes!!! Sign me up!

I read some stuff from Steve Harris at Knowledge Publications. He suggests contacting highway contracting companies ... they operate those solar powered highway info signs and they get hit by drunk drivers and get beat up a lot. They end up having panels lying around that insurance has paid for and they might give them away.

Also for building solar hot water heaters... if you need some good plate glass, contracting companies might have some lying around from damaged doors received in shipping. If you're buiding a box for hot water, it doesn't matter if it has scratch.

vsk

Anthony said:

"So, how much power does the thing output in full sun?"

It's in the article. 18.5 volts and 3.05 amps. That's 56.42 Watts. Multiply by about 8 (I don't know how many hours of sunshine Arizona gets in a day, so I'm certain this is an underestimate, but at the same time some of that day will result in less than optimum conditions as the sun moves across the sky) and you get 451 Wh/day, or 0.451 Kwh.

Since an observatory doesn't use a lot of power (a laptop, the telescope, and a couple of very low powered red lights, if any at all) and amateur observatories don't see a lot of use (weekends... maybe) this is probably at least several times as much power as he needs (although there's charging/discharging inefficiencies that he mentions, there's also the fact that it's weekends only). It won't, however, power your home. In fact, that won't even power my entertainment center or my desktop computer for more than a couple of hours.

I would try that with a swimming pool surround which works equally well as anything in general so if you got one of those rolls of plastic be careful using a circular saw cutting it cause they chip and pieces can fly into the face and chest or the arms and hurt as much as a weed eater slinging rocks against a leg which is exposed cause your wearing short pants.

Needs way more articles like this.

You can repair broken panels

http://www.fastonline.org/CD3WD_40/JF/JF_OTHER/SMALL/Solar%20panel%20testing%20and%20repail...By%20Donald%20Koehler.PDF

(sorry, haven't quite figured out tinyurl)

Or broken panel covers
http://www.fieldlines.com/story/2003/8/5/121012/8923

Goodle can be handy for these things

Enjoy!

A great project! I'll try to do it.

Erik -

www.instructables.com - Way more articles like this!

Come over to the Treehugger Forums and check out the Supplemental Solar thread where a few of us are doing similar projects and help others who want to do the same.

Where in the article does it say 3.05 A? I doubt that 3"x6" panel would produce that much current.. a couple of hundred miliamperes will be the most.

"Where in the article does it say 3.05 A? I doubt that 3"x6" panel would produce that much current.. a couple of hundred miliamperes will be the most."

isn't 3 amps at 18.8 volts only 56 watts? That sounds about right, no?

Does anyone have the link for the Treehugger forum mentioned in this post:

"Come over to the Treehugger Forums and check out the Supplemental Solar thread where a few of us are doing similar projects and help others who want to do the same".

When you measure solar panel output you measure *no* load voltage, then you measure *short circuit* current... the 3amp figure given is short-circuit, i.e. connect the ammeter directly to the panel (be sure you're on a range than can handle it!). It won't put out half a kilowatt, I can guarantee you that... but it *will* charge a motorcycle battery, especially if not drained for a week.

For the Treehugger link, look at the adspace to the right.

Don't charge a 12V battery at 18V. You will run it dry.

You're best to charge them at 13.6-14.4v, then have a maintenance charge around 13.6 or lower once the battery is 'topped up'. The load of the battery when empty will pull the voltage lower, as you don't have enough amps to raise it enough. You can still overcharge and damage the battery once it reaches capacity.

Yes, running 18V is a better idea if there is distance between your solar cells and your batteries, but make sure you install some sort of voltage regulator within close range of the batteries to be sure.

The guts out of a dead 'automatic' battery charger are a great idea if you're handy.

Great project, but if you can't handle it, you can find $3.00/watt solar panels here: http://www.ecobusinesslinks.com/solar_panels.htm :)

How much power would this put out if you reflected sunlight onto the panel by surrounding it with several mirrors?

This is all very well and good....BUT....I have never seen anything like 36 @ 3 amp cells for $75 on E Bay. That is a hell of a bargain, but not available as far as I can see. That would be about $1 a watt and the best I have found is about $4 a watt and I can buy NEW for that price.

Apparently yay-hoo's like us drive up the price. :)

Has anyone found a great video for this kind of DIY solar panel? Might be interesting to try, but I'd like to actually see it being made first.

Let me know if you know of some good videos.

THhanks!

Jonathan

Well, you might be OK with this design for a couple of seasons in Arizona, but using masonite and wood for a PV panel backing is asking for trouble in any climate with any significant moisture. PV panels are subject to extreme changes of temperature in their daily cycles. This type of solar cell is very brittle and delicate. The slightest warping can crack the cells, and the plexi for that matter. If one cell goes down, the whole panel goes down. Also if moisture can get inside the panel, it can short out. This may be a cheap way to go in the short term, but in the long run it's cheaper to invest more up front and build a substrate that will protect your cells and produce electricity for many many years.

http://www.goodideacreative.com/solar_panel.html

Nice to see someone take the initiative and build a solar panel on their own - it's not impossible to do.

Two issues though. 1) durability. As constructed this unit wouldn't last very long. I guess no more than a year or two. If the mosture, rain, snow - doesn't get it, then twisting in the wind will. Plus the plexiglass will cloud up.
2) You can't say this unit cost $105... you have to add in the cost of every item, even if you happen to have it sitting around. Not including the price of the plexiglass, paint, screws, etc. is the same as lying. With this logic, I could purchase ALL the parts one day and then "start" the project the following day with all the parts "on hand". Total cost = $0.00 FREE.

Add up the total cost and the lifespan of homemade vs 30+ years for manufactured and it's not a good return on your money, even with no dollar value assigned to your time/labor.

Mike also built a wind turbine from scratch. The parts are cheap and it works. Keep up the good work Mike.

great idea. just goes to show solar power doesn't have to cost a fortune

Thanks. I'll try one day.

I think I will earn some money with your article.

Ok I build two panels using this design. First off the cells themself cost 300.00 off ebay in 2008. The wood and paint cost about 60.00 the plexiglass was 100.00. So true cost for 2 panels was abit over 460.00 I have them charging 4 deep cycle batterys thru a charge controller. Running my sprinkler system. thur a 1500 watt inverter. Worked great all summer. For the winter I moved the panels inside and have not had a problem with them. They are mounted to the board with silicone so the board can flex all it wants too. I too worried about breaking the cells as they are really brittle. Had a breakage rate of about 6 per bundle I bought. Any way just wanted to let you know that it worked out ok for my test. Guess we will see if they can stand the test of time. I get about 20 volts in strong sun and I did get the 3 + amps short circuit they talked about. Guess that makes them 60 watt panels.