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Old 10-14-2015, 09:25 PM   #1
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Help with solar set up.

I have tried searching the web and this site for the answer. If someone has a link that will answer this I would be more then happy to follow it.

I just purchased a new 36' gooseneck "toy hauler" and am trying to move my solar/inverter charger/battery system from my old unit to this one.

My current set up is 2-128 watt and 2-136 watt flexible panels, Tristar 45amp MPPT, Xantrex HF 1000 inverter charger with 30 amp pass though, and 4-Trojan 105 RE batteries. This system has been used as a stand alone set up mostly to keep the batteries charged and running 12v equipment and small AC items like laptop. When I would plug into shoreline at home I would simply use the circuit breaker to shut off the solar charger.

My issue comes when trying to install it in the new trailer since I have a built in generator and this one is also uses the vehicle alternator to charge the batteries.

I plan on using the generator as little as possible most of the time. It is currently wired for 30amp service, but think it is capable of more, 5500 watt Onan. All of my lighting is 12v direct off the battery right now, so that is easy. Right now the panel has 6 circuits; Outlets (I want to run off inverter), rear flood lights, side flood lights, microwave, fridge, front AC. I plan on running a 30 amp sub panel for the inverter. This will have 2-15 amp breakers to power the outlets and 1-20 amp outlet for the rear air conditioner. I know the inverter will not run the AC, but often I just want to run a fan. The AC unit can run just fan at 3 amps, and there is only one roof opening in the area so adding a Fantastic vent is not an option.

So my basic question has to deal with battery charging and not "back feeding" anything. Here are my basic operating conditions I will see;

Op1, solar will feed batteries, batteries will run inverter and 12v operations. Everything works like before.
Op2, I need to start the generator. The generator charges the battery (5a I thing), now power is going into pass through on inverter and is now a charger (20a), and solar charging (~20a).
Op3, I shoreline. The inverter is now charging, and the solar is still charing also.
Op4, Solar is charging and I am driving so the alternator is also charging.

My question is for Op2, Op3 and Op4, do I need to isolate or worry about having more then one charging system working at a time? Can I have all of these charging systems on a single positive 12v buss bar?

Hope I got all the info in there.
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Old 10-14-2015, 11:06 PM   #2
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I think you are asking if you can have multiple battery charging devices connected simultaneously and they will interoperate without having to isolate them from one another. If so, the answer is yes.
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Old 10-15-2015, 08:20 AM   #3
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That is basically I am asking. The second half was if I need to isolate each source from each other? Can I use a common buss bar that ties all 4 charging sources and the batteries together?
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Old 10-15-2015, 11:02 AM   #4
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I always attempt to tread lightly in these types of discussions as I do not consider myself an expert. That said...

Assuming we are talking about reasonably "typical" equipment (your's is) - yes, a common buss bar will work. Some equipment (solar charge controllers) sense battery voltage via a "sense line" - this should be wired directly to the battery bank.
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Old 10-15-2015, 11:14 AM   #5
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I used a common buss bar before, but only had 2 charging choices and I did isolate them.

I do have the MPPT controller set up with separate sensing line and temperature line.

I just wanted to make sure if both the inverter and MPPT were "charging" at the same time, and hooked directly to the same buss bar, that they would not damage each other.
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Old 10-15-2015, 05:19 PM   #6
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They will not damage each other. No reason to turn off the solar when you are running the gen or plugged in.
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Old 10-15-2015, 05:58 PM   #7
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Originally Posted by Nwcid View Post
... Can I use a common buss bar that ties all 4 charging sources and the batteries together?
Sure. All sources can be charging simultaneously connected to one buss bar. Once the constant voltage set-point is reached for any source, the device with the highest voltage will take over all charging. For example, lets say your alternator is set for 14.2 volts, inverter/charger for 14.3V, PV solar is 14.4V. When you are below 14.2 volts, all sources contribute some power. When you reach 14.2V and above, the alternator stops contributing. Same for your charger when you hit 14.3V.

I have a vast knowledge about PV solar, batteries and inverters. I'll try to provide the best answer if I know it and hopefully correct some "Campfire" talk. Full-time 1999-2004. Part time now. '92 Hawkins, 360AH Lithium Battery, 1480 Watts PV solar.
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Old 10-15-2015, 10:13 PM   #8
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Awesome information. Thank you very much.

I got the batteries installed today and my ground and positive buss bars in today. I got my inverter/charger mounted and the will be getting it wired in tomorrow. I have the charge controller mounted, but still need to do all of the wiring for it.

Next will be the fun of removing the self sticking flexible solar panels from the old roof and mounted on the new roof.
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