# Solar power question



## gal5 (Jan 5, 2015)

I purchased a 100w solar panel that came with 30a charge controller. I bought a deep cycle 12v battery and hooked everything together and all works great. I'm just starting solar. I want to add a couple of lights in my small barn which have goats stalls. I'm stuck now, I don't know how to add more batteries or what lights to use. Can someone please help me an point me in the right direction??? Thank you so much &#128515;


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## Mattie420 (Apr 2, 2013)

I would like to do that exact thing in my barn because its over 100 years old and has no electricity running to it but because of the goats and the soon to be chickens I want a little lighting in there without running wires out to it. Interested to see the answers


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## MichaelK! (Oct 22, 2010)

Your 100W panels could produce a maximum of 8.3 amps at 12volts, so you could add two more panels to your controller and stay below it's 30 amp limit.
8.3X3=24.9 amps. If you added three more it would be 8.3X4=33.3 amps. In the real world your panels might not ever produce that much, but that's the math.

You can add both additional panels, and additional batteries to your system if they are all wired in parallel. What that means is that all the PLUS (red) wires from the three panels are coiled together and wrapped around the PLUS (red) terminal of the charge controller that is marked "IMPUT" or "Panel". Use heavy 8 gauge wire for all the connections.

Then, all the NEGATIVE (black) wires from the three panels are coiled together and wrapped around the NEGATIVE (black) terminal of the charge controller that is marked "IMPUT" or "Panel".

So, all the amps produced by all the panels will be going into the charge controller at 12 volts.

You can then add more batteries to your system. Buy the same brand/size of battery. The sooner you do this the better because it's not so good to mix new batteries with old ones.

Lets say you have three batteries that you want to wire in parallel. You take a heavy gauge wire and connect the negative terminal (black) of battery #1 to the negative terminal of battery #2, then another wire going from the negative terminal of battery #2 to the negative terminal of battery #3. You do the same thing to the positive terminals on the other side. A wire will go from +1 to +2, and then from +2 to +3.

The very last thing you will do is wire the batteries to the charge controller. There will be two terminals marked "battery" and either +(red),-(black). The plus terminal could be connected to the plus terminal of battery #1. The minus terminal would then be connected to the minus terminal of battery #3. 

Alternatively if more convenient, connect the controller minus to battery #1 minus and the controller plus to the plus terminal of battery #3.

This will wire the whole system for 12 volts in parallel.

Getting back to the capacity issue. Your general rule of thumb is to not deplete your batteries more than 10-20% of their total capacity before recharging them. You can, but it shortens battery life. The battery life at 10% depletion is measured in years. The battery life at 90% depletion is measured in weeks. It's good that you are thinking about upgrading your system now. 

Let's say the battery you've chosen is a Trojian T105 with a battery capacity of 200 amp hours. Ten percent of 200 is 20. If you have three of them, your daily limit would be 60 amp hours. Say you have six compact flouresents that consume 1 amp per hour. All six would consume 6 amp hours in one hour. Keep those lights on for 5 hours per day and you'd consume about 1/2 of your total capacity (at 10% depletion) or 30 amp hours.

One more little detail. When wiring in parallel, the voltage stays the same but the amperage adds up. When wiring in series, the volts add up while the amperage stays the same. If you had wired your both your panels, and your batteries +,-,+,-,+,- instead of +++,--- you'd get 8.3 amps at 36 volts instead of 24.9 amps at 12 volts.

Good luck!


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## TnAndy (Sep 15, 2005)

gal5 said:


> I'm stuck now, I don't know how to add more batteries or what lights to use.


Michael covered batteries pretty well.

As for lights, use 12v LED type lights. Most energy stingy lighting out there.

There are loads of automotive type out there, you can also find them with "Edison" bases ( the regular screw type light bulb you are familiar with for standard 120v bulbs)

Here, for example: http://www.ledlight.com/12-volt-led-lightbulbs.aspx

That means you can use fairly standard wiring, switches, and bulb holders, while getting ultra low electrical use bulbs (LEDs).


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## Gary in ohio (May 11, 2002)

The problem is we dont have enough info. need more info on the panels..
Depending on your panel You might not be able to get the full 100 watts of power your panel can produce due to the PWM charge controller you most likely using. MichaelK calculations are correct if the panels put out 12v but more than likely they put out more. Most of the recent panels put out close to 20v at 5amps, but because the pwm controllers drag the batter down to 12v you get slightly over 1/2 the power out of the panel.
20v*5 amps is 100 watts. 12v * 5 amps 60 watts. 

Adding batteries is just putting them in paralle, positive to positive and negative to negative. Think of them as just a bigger battery.


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## gal5 (Jan 5, 2015)

I'm going to be buying more batteries next week and buying the LED lights. Thank you do much for your quick responses. I'm going to start a new post on the website I went to that explains the whole solar thing but is a bit overwhelming to me at least.


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## Gray Wolf (Jan 25, 2013)

You might think about adding an inverter to your system so you can use standard 120 volt AC wiring, switches and bulbs.

I think you'll find that the proper DC light switches, outlets, wire sizes, fixtures, and 12 volt bulbs will be more costly than you think... especially if you have long wire runs. 

Having a 120 volt AC outlet or two will also let you plug in a radio, drill or extension cord if you want. Your battery bank and a small inverter won't run heavy power tools, and won't run little ones very long, but it sure is handy when you just need to drill a few holes or____.

Solar is intimidating but once you get past that inital deluge of information, somebody else has already done what what you want and lots of vendors are selling just the parts you need.

Enjoy!


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## idahodave (Jan 20, 2005)

Lowe's sell a LED work light that works from either 12vdc or 120vac. It's in the lighting department. Look close there's two sizes and only the smaller has a DC input. Look for the box with a picture of a cigarette lighter plug cord. I've a couple of them and they put out a lot of light for 0.8Amp dc input.


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## gal5 (Jan 5, 2015)

Thank you so much !!!!!!!


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## 12vman (Feb 17, 2004)

If you're crafty and don't mind building light fixtures, these things work wonderful. These are the major lighting units that I use in my house..

http://www.xoxide.com/dual-white-cold-cathode-kit.html

Just keep the water away from them and they'll work for years. I have an outdoor yard light that I built several years ago that's weatherproof and it works every time. Never had to touch it since I installed it. It's mounted ~12' off he ground on a pole so it sees all of the elements. Work fine, Last long time! 

One set will light up a nice area if you spread the bulbs out as far as possible with the supplied wiring. They draw ~1/2 amp @ 12 volts D.C. for the 2 bulb set. More bang per watt for area lighting than most all LED fixtures, IMO..


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## Ky-Jeeper (Sep 5, 2010)

[ame]https://www.youtube.com/watch?v=xELqluPUsuQ[/ame]


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## Ozarka (Apr 15, 2007)

Another good source of equipment and info is OYNOT Solar.


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