# Low End Solar Set-Up



## Rick (May 10, 2002)

Greetings

We have 3, 30 year old, 15 Watt solar panels. They were putting "something" out when I checked them a year ago- I dont remember what though.

Does anyone have a suggestion for how to check them with my multi-tester, and what values are needed to make it worth trying to use them? They are hooked up in series.

I would like to invest a minimum to get them working for me. I want to use an old deep cycle battery that is "trash" (charges up to 12 volts using a 110v charger- but drops to 7 volts after 2 weeks of no use) to draw the power, and then run a 12 volt fan or light, or even invert 200 watts with my inverter.
The battey does run a 12 volt fan!


My other questions are: do I need a charge controller for an old battery like that? I can keep the battery unhooked whrn not in use. 

Where can I get a one-way diode to protect the panels?

What type of wire should I run here, and is solid core, 1 aught wire what I should use? The distance is roughly 120 feet.

Any help will be appreciated. I may not be back on-line for a few days.

Rick


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## Tango (Aug 19, 2002)

I wil leave the other questions to someonemore qualified but can answer the wire size. 1/0 wire will take 4 amps up to 725 feet. Your panels probably are less than 3 amps so a 6 gauge wire is sufficient for 120 feet. You should take the money you would have spent on the 1/0 wire and invest in a new battery.


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## wy_white_wolf (Oct 14, 2004)

Rick said:


> Greetings
> 
> We have 3, 30 year old, 15 Watt solar panels. They were putting "something" out when I checked them a year ago- I dont remember what though.
> 
> Does anyone have a suggestion for how to check them with my multi-tester, and what values are needed to make it worth trying to use them? They are hooked up in series.


For a 12volt system you would need min. of 5volts from each panel when wired in series or 15 volts from each panel when wired parallel. Unwire the panels and set the multimeter to check volts and touch the leads to the panel connections when it is in direct sunlight. If no reading reverse the leads and try again.



> I would like to invest a minimum to get them working for me. I want to use an old deep cycle battery that is "trash" (charges up to 12 volts using a 110v charger- but drops to 7 volts after 2 weeks of no use) to draw the power, and then run a 12 volt fan or light, or even invert 200 watts with my inverter.
> The battey does run a 12 volt fan!


I wouldn't bother with it. Get a new one. A fully charge lead acid battery should read 13.6 to 13.8 volts when fully charged.



> My other questions are: do I need a charge controller for an old battery like that? I can keep the battery unhooked whrn not in use.


I have been told a charge controller is not neccessary if your panel/array wattage is less than 1/20th of the amphour rating of the battery. By that, 15 watts for each panel would be 45 watts total so the could be used on a 135 ah battery without one. I've never ran a system without one though.



> Where can I get a one-way diode to protect the panels?


Radio shack or any other hobby/electronics store. 



> What type of wire should I run here, and is solid core, 1 aught wire what I should use? The distance is roughly 120 feet.


As per tango 6 gauge would work fine. Standed or solid core really makes no difference



> Any help will be appreciated. I may not be back on-line for a few days.
> 
> Rick


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## Rick (May 10, 2002)

Thanks for the thoughts.

I will eventually buy a charge controller, and many batteries- and more panels.

I will indeed buy some 6 guage wire, knowing I will need thicker wire once I begin to produce more current down the road. We have a radio shack within 10 miles where I can pick up the one-way diode!

This poor old battery ran a little 12 volt fan for several hours on stored voltage- that is all I want right now. 

What would be the worst thing that coukd happen if I use it to run a fan with no charge controller. 

Could the battery burn up/ explode?

Many thanks,

Rick


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## wy_white_wolf (Oct 14, 2004)

Rick said:


> What would be the worst thing that coukd happen if I use it to run a fan with no charge controller.
> 
> Could the battery burn up/ explode?


We would need to know the voltage output of the panels to answer this one.


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## mightybooboo (Feb 10, 2004)

My non expert opinion is no controller you would be boiling the battery if it overcharged,meaning keep the water level upthere.Other than that,thats all Ive read on the subject.

There are dirt cheap controllers out there,let me find you a link.

OK,they say it IS an explosion hazard
www.homepower.com/files/hp72-68.pdf?search=charge controller

Here is a nice controller with a couple 12 volt compact flourescent bulbs,60 bucks to your door.Put in charge controller in ebay search,they have even cheaper ones.

http://cgi.ebay.com/CHARGE-CONTROLL...6QQihZ010QQcategoryZ41980QQrdZ1QQcmdZViewItem

Anothr low cost controller,26 bucks!
http://www.affordable-solar.com/morningstar.sunguard.4.12volt.charge.controller.htm
http://www.affordable-solar.com/charge.controller.htm
BooBoo


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## Rick (May 10, 2002)

Thanks for the links, BooBoo!

Wolf-

I haven't had a chance to take the panels apart- it's gonna take a lot of ww40 and elbow grease.

Rick


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