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SimonB's avatar
SimonB
Explorer
Aug 07, 2020

Solar research

I want to add a solar system to my camp and was looking for some information. I am still in the process of doing my research but I am stuck on a few items that I cant seem to find any information.

I plan on having all my setup (inverter/charger, mppt, batteries, etc.) in our small shed close to the camp and the solar panels mounted on a stand on our lot. Currently we have two power sources. 12v battery that is charged with a all in on small solar panel and we connect a generator to our shore line from the RV. Of course the small all in one solar panel and 12v would be removed.

First question, i would like to have the solar setup and generator on a automatic transfer switch. I would like to install my transfer switch with the entire setup in the shed and be able to connect my shore line to a plug on the transfer switch. Is this something that can be done? I see allot of people cut their wires and modify the RV breaker panel but I would like to not touch anything on the RV and just use the existing shore line plug.

Second, most inverters/chargers I've looked at have standard plugs (2 to 4) as their outputs. How would I connect this type to the transfer switch to get the full amperage or is this possible. My knowledge is that plugs are either 15a standard plugs or 20a (plug with one prong sideways) so getting the full inverter amperage is not possible unless it has output connections for wire. Is this correct?
  • Answering both questions...I suggest you Find a knowledgeable solar company to design your system for you. That's the easiest and will save you many hours of Internet time and quite a few mistakes. Also read more about Packaging and Transport Business Consulting Articles. Nevertheless…You will need an inverter that can do three phase. That's really the only difference between a single phase and a three phase system. That said, your options go down and prices go up for three phase since it's less common. You will need to do a lot of homework before you power the system up, because you're playing with some expensive equipment that may not play nice together. Good luck!
  • There are different flavors of solar... if you're like us, you can do well for under $1000 and have a setup that simply recharges the batteries you already have. We don't currently use an inverter right now, and only need about 100-300W of panel power to top off our dual deep cycle batteries from running the 12V side of the house.
  • Your question seems better answered by an off-grid solar interest group, since you seem to be creating a power generation station out of your shed. Not sure what your full requirements are, but I will try to answer from what I know.

    From your question, it seems that you are only interested in accessing 120VAC household current from the shed. Then, yes, you will need to connect to the shed's transfer switch with a full 20A cord, or whatever is the maximum to get full power safely to the trailer. All internal shed wiring on the AC side needs to match amperes needed. Automatic switching would be done on the 120VAC lines, just like the units used for houses which switch between emergency outdoor generators and the utility provider. They are not cheap. In your case, the utility provider is the solar system and its inverter. I imagine that the shed's generator is expected to kick in once the solar powered batteries have expired. However, the rub is that you want to keep 12V lead acid batteries preferably at no less than 70% charge. Repeatedly going to anything less than 50% charge and your batteries will soon die. Therefore the transfer switch has to be smart enough to hand over the power to the generator at the appropriate voltage.

    However, like others have mentioned, you need to plan you power needs before expanding your solar system. For example a 1000W, 12V appliance requires 83 Amps to run (1000/12). A 12V battery rated at 120Ah will run your appliance for 86 minutes at best. But, then, don't run your batteries to less than 50% meaning you get 43 minutes of run time.

    My experience is that solar is a convenience, a talking point, for dry campers and that a generator is a must for glamping or CPAP.

    If it were me, for solar assist, I would go for a couple sets of portable 12V solar panels and a couple of extra batteries for the trailer. I could stick the panels in the shed when I'm done. A remote start for that generator in the shed would be nice. If the generator is a Honda EU2000is or EU3000is, convert it to dual fuel propane and get a big propane tank for it. My 2 cents (1.28 US).
  • I have a similar set-up for my cabin. I have 4 GC-2's, 6 solar panels, a 400 watt 12 volt wind charger, a 3500 watt generator and a 1500 watt invertor
    In the cabin I have a mix of 12 volt (lights, RV furnace, water pump) and 120 volt ( TV , coffee maker, fan, etc).
    The solar panels are run to a 100 amp controller, wind charger has a built in regulator. I have a 4 stage, 80 amp RV charger that I ran a single cord outside that I can plug into the generator. If there has been no sun or wind for 3-4 days I run the generator for about 4-5 hours to charge the battery's.
    Do not need a transfer switch I can take 5 minutes to start the generator and plug in the cord for the charger.
    As far as having 3 different charges coming to the battery's it does not matter. The battery's will accept the highest voltage coming in. I do have the solar controller adjusted(14.2v) close to the wind charger (14.1v).
    It has been working REALLY well for going on 6 years.
    All told I have about 2100 hundred invested. Power company wanted 6700.00 to run power to me plus the cost of whatever I use.
    I once figured it out over a 20 year time frame, with replacing battery's every 6 years, generator once. It cost me around 20 dollars a month. Compared to a minimum of 65 per month from the power company.
  • Start with your average daily power use...times 1.5 or 2. What is it?
  • If you plan to put all of your solar gear, plus the generator and inverter charger in the shed, you will need batteries in the shed and a converter and battery in the RV (which you likely already have).

    Samlex makes an inverter/charger/automatic transfer switch that has "hard wire" outputs. Their 1200W unit has one input,



    while their >2000W units have two inputs, line and generator.



    The two input version can start the generator if there is no line voltage and the batteries are low.
  • Higher power inverters have hard-wire lugs. Post should be in Tech.
  • First Question - yes, you can have the output from the transfer switch be a RV plug.

    Second question - Your output from the inverter can be hard wired into the transfer switch. No plug needed.

    You really know what you are getting into with an automatic transfer swich? Once you start figuring out everything you need for an automatic transfer switch and the money it will cost - not to mention the cost of the solar - you could buy a generator and a lifetime supply of gasoline three times over.

    A manual transfer switch would cut the cost in half±.