RV 1 panel system

bighornram
bighornram Registered Users Posts: 8
I just completed my install of this Kyocera 135 watt / Morningstar SunSaver 10 amp controller charging 4 Interstate 6 volt golf cart batteries. I'm running an Exeltech XL1100 inverter off this system.

I ran 10 AWG wire from the controller, 30 amp fuse inline directly to the batteries. The panel is mounted with the flat mounting brackets from AZ Wind/Sun. I ran the wires from the panel along side the black tank vent pipe. I drilled through the mounting ring right next to the pipe. The wires went nicely through an interior wall into the storage space in the front of the trailer where I routed them to a mounting board by the battery storage box. The batteries fit nicely in a heavy duty storage box ($10 at Home Depot) that I am venting from the top with the original vent hose and a hole drilled in the floor.

I wired my inverter output through a 15 amp circuit breaker/box to the General Power/wall outlet line. I did this by removing the romex from the trailers circuit breaker and connected it to the inverter breaker using a heavy duty extension cord (hard wired) running in the basement of the trailer. The inverter/batteries are in the front of the trailer and the breaker/charger unit for the trailer is in the back. I can run the TV/satellite, computer, phone charger etc. from the wall outlets using the inverter.

Comments

  • bighornram
    bighornram Registered Users Posts: 8
    Re: RV 1 panel system

    Reserved for follow up after using this system boondocking.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: RV 1 panel system

    Keep in mind that the 135 watt panel, when all is said and done, on an average day, with perfect sun exposure is likely to provide only ~ 2-300 watt hours of useable power out the inverter.

    Buy the time you take into account all system loses, including PV efficiency, charge controller efficiency, basic battery charging ef, inverter ef, and wiring loses you will lose ~50%. Couple that with mostly likely less than ideal panel tilt relative to the sun (unless you are on the equator!) 4 hours of good sun might be a good average. So 135/2*4=270 watt hours.

    Enough to keep your batteries topped off while boondocking, but not enough to recharge them if you are going to draw more than ~250 wh/day.

    Also, keep in mind that your 450 ah of batteries would ideally like between 5-15% of ah capacity as a charge rate (~22-45 amps) Your 135 watt panel is likely to only put out maybe 8 amps on an ideal day, ideally sited.

    Good luck, and welcome to the forum. Let us know how this system works for you.

    Tony

    PS. I realize that wishing one good luck after a somewhat critical reply may sound a bit snarky. It is not meant to be, but rather a real expression of good luck with your system.
  • bighornram
    bighornram Registered Users Posts: 8
    Re: RV 1 panel system

    Thanks icarus for your honest input. This was my sincere hope that based on the system that I put together, based on hours of researching solar product and RV sites someone would have constructive feedback. I found some information about the internet on RV forums, systems other RV'ers have put together, their experiences etc. My inverter useage will be mainly TV and TiVo/DirecTV receiver. The receiver uses 120 watts and the TV about the same. Additionally, I will utilize the inverter for computer, cell charging etc. I got such a large inverter because I was able to get this factory rebuilt unit at a price comparable to a new unit putting out 300 watts max. I may never use that much but I am happy that it is available if I need it. That said I will still carry my Honda 1000 as a backup. I also have a 4000 watt gigantore unit I carry only if I need to power my AC unit while on the road, rest stops etc.

    Maybe this thread will help someone else attempting to put together a non full time system for their RV.
    icarus wrote: »
    Keep in mind that the 135 watt panel, when all is said and done, on an average day, with perfect sun exposure is likely to provide only ~ 2-300 watt hours of useable power out the inverter.

    Enough to keep your batteries topped off while boondocking, but not enough to recharge them if you are going to draw more than ~250 wh/day.

    Probably will meet my expectations. While we do use this trailer a lot in the summer months during off work times we don't live in it full time and it wouldn't be cost affective to try to supply more than my basic usage requirements for traveling or boondocking.
    icarus wrote: »
    Also, keep in mind that your 450 ah of batteries would ideally like between 5-15% of ah capacity as a charge rate (~22-45 amps) Your 135 watt panel is likely to only put out maybe 8 amps on an ideal day, ideally sited.

    Can you perhaps explain the relationship between charge rate ah capacity? What I hear you saying is I would require minimally 3 X 135 watt panels at ~8X3=24 amps to keep my batteries happy?
    icarus wrote: »
    Good luck, and welcome to the forum. Let us know how this system works for you.

    Tony

    PS. I realize that wishing one good luck after a somewhat critical reply may sound a bit snarky. It is not meant to be, but rather a real expression of good luck with your system.

    Thanks for the input and as I stated earlier I hope someone else will benefit from this thread. I will post my experiences with this system after my next trip out.
  • dmiller
    dmiller Solar Expert Posts: 68 ✭✭✭✭
    Re: RV 1 panel system

    The 5-15% ratio assumes that the systems is sized for solar as the primary power source. Less than 5% and there may not be enough solar for the cc to equalize the batteries, and that too much money was spent on battery storage that will go unused. More than15%ish and there likely isn't enough storage for the watts captured.

    But on an RV the system is often below 5%. First, solar is one of three or four power sources that also include gen, shore and engine alternator. You would probably want to do equalizing while plugged in anyways.

    The right size system for an RV depends on lifestyle and goals. There really isn't an economic rationalization except for full timers as the saving on gas and generator maintenance will only be a fraction of the solar cost. Especially with the nice little 1000 watt generator you have.

    Like your little generator solar works well for the absorption phase compared to a big non-inverter genset.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: RV 1 panel system
    dmiller wrote: »
    The 5-15% ratio assumes that the systems is sized for solar as the primary power source. Less than 5% and there may not be enough solar for the cc to equalize the batteries, and that too much money was spent on battery storage that will go unused. More than15%ish and there likely isn't enough storage for the watts captured.

    Er, not exactly.
    A charge rate of less than 5% of the battery bank's "20 hr" Amp/hr rating leads to sulphation, unmixed electrolyte, and resultant premature battery death. This is something you don't see until it's too late; the batteries' actual capacity diminishes over time. Whereas this is a naturally occurring process, low recharge rate will accelerate the deterioration.

    Too high a charge rate (generally more than 13%) heats up the battery too much when recharging. This causes excessive water loss, warped plates, and much faster destruction of the batteries.
    But on an RV the system is often below 5%. First, solar is one of three or four power sources that also include gen, shore and engine alternator. You would probably want to do equalizing while plugged in anyways.

    RV systems are often badly designed. You'd be amazed at the crap installed by "professional" RV shops. It doesn't matter what the end usage is; the performance characteristics of a solar electric power system are the same.
    The right size system for an RV depends on lifestyle and goals. There really isn't an economic rationalization except for full timers as the saving on gas and generator maintenance will only be a fraction of the solar cost. Especially with the nice little 1000 watt generator you have.

    Yep; your generator is your best friend. RV applications suffer greatly from lack of good insolation, unlike a "fixed" site. You really should shoot for as much panel as you can get, if you plan on being "totally solar" - which as you say is about as economically sensible as buying the Brooklyn Bridge. :p
    Like your little generator solar works well for the absorption phase compared to a big non-inverter genset.

    Curiously, solar does a better job of "finish" charging than generator charger. This is one of those odd phenomenons that defies explanation - so far. "Bulking" with the gen and finishing with the panel works well.

    I don't mean to criticize, just clarify. Hopefully I haven't obfuscated! :p
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: RV 1 panel system

    And to clarify a bit more... The 5-13% battery charging current is just a starting rule of thumb... Sometimes there are good reasons to go above/below--depends on your needs and also the type of batteries you have.

    AGM's, for example, can go well above the 13% charging rate (still may not be cost effective in terms of $$$ spent on solar panels).

    We always recommend that you read the manuals/specifications for your batteries/charge controllers/etc. to insure that your final system is withing specifications (i.e., Voc-array / Vmp-array for the solar charge controller input, etc.).

    Using generators to "bulk" charge a bank works better because you are near the maximum battery charger current (and hopefully near or above 50% generator loading)... That is the point at which the generator is most fuel efficient (below 50% loading, generator fuel flow remains pretty near 50%--and diesel gensets don't like running below 60 or 50% loading--they tend to build up carbon deposits and glaze piston walls).

    When the battery hits "absorb" voltage, the battery begins to regulate its current down from 100% maximum current to near 2% (near 100% state of charge)--which causes the genset to use a lot of fuel to provide very little electricity.

    Generally, once the battery is ~80-90% full (end around early or mid-morning) and the charging current is tapering down--Then you let the sun + solar array do the rest of the charging (and no wasted fuel).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset