We have been living in a TT full time for well over a year. Now its high time we start weaning ourselves off of grid power. We will be moving our camper onto land without shore power. So we plan to get a generator. Primarily for running tools and such. But also as a crutch by plugging into the camper. But overall, we want to implement solar as much as possible. But GRADUALLY due to cost. My biggest question here is this. (And I apologize if this has been discussed before, I couldnt find it)Would it make sense to put together a smallish solar system and plug the generator and solar inverter into an auto transfer switch? Then plug that into the RV main outlet? Eliminating any modifications inside? I have a basic understanding of electricity and wiring. And realize that I would need to consider any DRAW there might be inside, sucking the life out of the batteries. The idea here is to keep the solar batteries separate from the camper converter system. At present, we have a single deep cell on the camper, like traditionally seen. And I wonder if I might have to unhook that battery to keep from charging it using the solar batteries.I hope someone can give me a good answer on this. THANKS!!PS. Another reason I am thinking about keeping my solar system separate from the camper inside wiring is because we will eventually build a cabin that I will "move" the solar system to.

Generally no, I don't see any merit to what you're doing as I read it.However....joem789 wrote:Would it make sense to put together a smallish solar system (30A inverter) and plug the generator and solar inverter into an auto transfer switch?I don't know what you mean by 30a inverter.

Sorry about that. I was looking at an inverter/charger that listed 30a on the outlet. I removed it to avoid confusion. I am thinking of starting out at around 200 watts solar. But want an inverter somewhat bigger.

An inverter that will pump out 30a @ 120v = 3600w. That takes a whopping amount of solar panels.I think you're advocating "running things" directly with solar. It doesn't work like that in an RV. Solar is for charging batteries. You hook the inverter to the batteries.

Stand-alone solar of any reasonable size is really only going to be useful for charging batteries which are in turn used to power a load as needed. Might as well set it up to charge your camper battery directly for now, then re-wire to charge whatever battery pack you put in your cabin when the time comes.Residential solar only works without batteries because it is essentially treating the electrical grid as a giant battery (sell power when you over produce, buy when you under produce). This doesn't work if you are off the grid.

I understand how the inverter hooks to the batteries. Let me rephrase things a little. Can I build a 200 watt solar system and plug it directly into the camper outlet and run it like usual. I realize that many things will have to be shut off inside the camper to avoid draining the batteries. I just want to know if it will technically WORK and if so, how is the efficiency of the solar system affected by running into the camper electrical system. Thanks.

Another SOLAR question!!! | Good Sam Community

Doug33
Explorer
Aug 12, 2015
The other factor may be location, which you do not list in your profile. This is especially true in the winter when the sun is at its lowest. The further north you are, the less sunlight you will get in the winter. So there will be significant fluctuations in availability throughout the seasons.
joem789
Explorer
Aug 12, 2015
Ok. I ended up with (2) SolarWorld panels, 250 watts each. They are 30v panels. I ended up getting the MPPT Tracer 2210RN Solar Charge Controller since it was only $100 and seems to get rave reviews. I also got some 10AWG copper wire (50') since I am putting the panels on top of the RV right above where the battery bank sets. Finding batteries in my area is limited. So I went to Sams Club and picked up (2) Duracell GC2 Golf Cart batteries.

I am amazed at how the panels will put out the 30V even in a shade. They seem very efficient. But I am no expert.

Do I need to worry about the wire that runs from the camper to the battery? Normally this camper came out with a single low hour 12v deep cycle. I am taking it off and putting the two 6 volt batteries together. If the wire is okay, then do I have to worry when I go to add two more batteries in parallel? I just didnt know if this would put a heavier load on the camper wire.
JiminDenver
Explorer II
Aug 05, 2015
You can run things off of your solar system, you just have to have a big system and small loads. With a 230w system I can turn on every light, fan and even the furnace and have the solar provide the power. That power stops as soon as a cloud goes by or the sun goes down, so having a battery is kind of important.

I would suggest getting a general feel for what you need and how you will set it up before picking out specific components. Each interacts somehow with the others and a poor choice now can be limiting as you go along.
joem789
Explorer
Aug 05, 2015
That's good to know. And thanks alot for clearing things up on the inverter. You mentioned that a PWM controller is only about $35+. Any particular one you would recommend? I had actually been looking at this Morningstar model, which apparently is overkill and expensive? http://www.amazon.com/MorningStar-ProStar-Battery-Controller-30/dp/B0070OS4JS
pianotuna
Nomad III
Aug 05, 2015
Solar charging plays well with other forms of battery replenishment.

joem789 wrote:
Thanks! That's helpful.

The other thing here is this. And I think a real important one. Having my solar system connected to the battery(or batteries) for charging. All the while they are still connected to the TT as usual. What happens if I decide to connect the camper to my generator while the solar is charging the batteries? It seems to me that the camper electrical system will try to charge the batteries at the same time as the solar? Will this be a problem? Will I need to disconnect the camper charger from the batteries at the fuse panel?
Golden_HVAC
Explorer
Aug 05, 2015
SunElec.com had a 140 watt 12 volt solar panel for $229 a few weeks ago.

I would recommend spending the money on a PWM controller, not a more expensive MPPT controller. They are only about $35 for a 20 amp controller, good for 2 of the 140 watt panels.
Your RV will consume about 35 AH daily just to run the refrigerator, CO meter and propane leak detectors. This is about what one 120 watt panel will make in one day.

I lived full time in a RV with 400 watts of solar panels, and 4 golf cart batteries. Normally I did not need to run the generator, but might if I used more than 120 amp hours overnight. I liked to watch a lot of satellite TV each night.

I would also recommend a small inverter, like 200 - 500 watt size. It can plug into cigarette lighter, and run small things like a laptop, DVD player, TV set, all at once. I would not recommend a larger inverter, as they discharge the battery to quickly, and are not nearly as energy efficient.

I have a built in 1500 watt inverter, but normally use my portable 300 W inverter instead. It will use about 2 AH less than the larger one.

Good luck,

Fred.
Muddydogs
Explorer
Aug 05, 2015
Nope doesn't matter if the solar is connected while camper is plugged in. What you need to know is the solar controller regulates the incoming solar to only charge at so much, most controllers are setable. The trailer converter if a 3 stage converter will change the voltage going to the batteries and if not a 3 stage then the converter is probably charging around 13.6 volts.

So when your trailer is plugged in and your batteries are charged your converter is only running a maintaining charge of say 13.6, well if your solar controller is set at 13.6 then the controller will basically shut off the flow from the solar panel. If your solar controller is set for 14.6 volts charging then your converter would be putting in 13.6 volts and the solar will make up the other 10 volts.

If you don't want your solar charging when plugged in then adjust your solar controller to the lowest charge setting. Most don't worry about adjusting anything when camping and leave their solar set around 14.6 and if they happen to run the generator it takes care of itself. The only time I touch my controller is when the trailer is in storage and the batteries are charged, I will then set my controller to a maintainer charge of 13.6 so I don't boil out the water with the trailer setting for a month or so.
joem789
Explorer
Aug 05, 2015
Thanks! That's helpful.

The other thing here is this. And I think a real important one. Having my solar system connected to the battery(or batteries) for charging. All the while they are still connected to the TT as usual. What happens if I decide to connect the camper to my generator while the solar is charging the batteries? It seems to me that the camper electrical system will try to charge the batteries at the same time as the solar? Will this be a problem? Will I need to disconnect the camper charger from the batteries at the fuse panel?
pianotuna
Nomad III
Aug 05, 2015
Your biggest energy draw may be the laptop--depending on how many hours it is used.

A hair drier is going to require a 1000 inverter. That will demand 100 amps from the battery bank.

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.

Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!

Solar spreadsheet by N8GS
joem789
Explorer
Aug 05, 2015
ok. thanks.

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