Powering RV, Inverter or DC?

bmetbmet Solar Expert Posts: 630 ✭✭
I'm replacing an RV on the ranch, going to be a 'guest house' for family needs. I don't yet know my loads. It'll have shore power available, but I'd like to add the option of using the 1800W of Evergreen panels I purchased. There is plenty of space for an array next to the RV without obstructions.

I am trying to compare a typical off-grid plan, vs. putting everything at the array and running inverted AC the distance to the RV. We've had just enough wet weather to delay putting it in, so at this point nothing has been committed.

I can think of a couple of reasons to go either way, but I'd appreciate any thoughts you folks have on a preference. Thank you.


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Powering RV, Inverter or DC?

    Without knowing the actual loads it is difficult to determine if 12 VDC will be practical. Whereas many RV's run this way, sometimes you want that 120 VAC for certain things.

    And yes distance makes a big difference; 12 Volts suffers from V-drop quite quickly, requiring fairly hefty wires for even the most modest loads.

    Sorry it's not much of an answer, but as is always the case with an off-grid system the expected loads are the basis for the rest of the design. If all you need are a few lights and such, eliminating the expense of an inverter is certainly worth considering. But on the other hand the Morningstar 300 Watt is such a nice little unit, not too expensive, and capable of running most everything you might plug in save a refrigerator or washing machine or such like.
  • solar_davesolar_dave Solar Expert Posts: 2,382 ✭✭✭✭
    Re: Powering RV, Inverter or DC?

    If you have grid power, shore power, that is reliable, fairly close, consider doing that, you will not incur battery costs and get full usage elf all of your solar power. Grid tie is much more bang for the buck. The loses via battery charging can be a substainal portion of your solar production. Being a guest house it may not be occupied some times and then you will get nothing from the solar, but if grid tied you can help defer the main house as well. Check with your utility as well, they may have some guidance or financial considerations as well.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Powering RV, Inverter or DC?

    what voltage you are going to output from those PVs (series)
    how far it is from PV to battery bank to RV
    how far to potable water
    how far to septic
    how close you want the guests
    how long you want them to stay

    Maybe you could build a solar shed and park the RV under it on a back corner of the ranch?

    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Powering RV, Inverter or DC?

    Thanks for your responses. These are all great questions with few answers at this point.

    I got 1800 W of 24V panels.

    Imp 7.65A
    Vmp 29.5V
    Isc 8.33A
    Voc 36.1V

    The RV is a 31 Foot 5th wheel, with 30A AC connection. It was retrofitted for an additional 20A option in case the 30 wasn't enough. It has 60 Gallons capacity for Propane, and one house battery which I haven't been able to access yet.

    The stove's top-burner are gas, the oven is electric. The fridge can be either LP or electric. The water heater is electric. Air Conditioning is electric. The lights are all 12V automotive type, and will be replaced with LED.

    I am still figuring out the division between AC and DC. There is a 'power convertor', with breaker panel for AC. There is also a distro-block for DC, with automotive type blade fuses. Some items are either AC or DC, so I would have to supply AC and let the power convertor do it's thing. Seems wasteful.

    The typical RV connections are all there; AC, septic, potable water, and a meter(so I can distinguish ranch usage from 'non-ag'. It was the original location for the previous RV when our house was being built some 15 years ago. I figure it's easier to get the RV off-grid than our house, so this is where I've decided to start. The RV location is also much closer to our well, so having the array here would put it within workable distance if solar conversion becomes necessary.

    Still waiting for data on the loads, the ground is finally drying up here to allow setting RV in place, probably by 2nd week of Jan., will get some numbers.

    Edit: RV has been on a meter now for two weeks, and so far is showing about 1 KW per day with no one living in it (Fridge and Water heater on). I've got a relative visiting in a couple of days, so this should help get real world data.

    Thanks for all your input.
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