rv solar set up suggestions batteries, controllers, and inverters?????

I am buying an rv soon and studying Solar energy I was considering an 800 watt solar array, connected to 4 110 amp 12 volt batteries.  Should I run them in series or both parallel and series for higher voltage would that be 24 volts at 220 amps and amps or run them 4 for the 440 amps, if I run the 24 volts do I need a diferent inverter, and suggestions on solar controllers, what I would use it for would be tv, computer, lights, short microwave, video games.  a dyson fan-heater there low amp and seem to work good, coffee pot.  some one informed me that I shouldn't drain my batteries daily lower then 20% to 30%  for long term use.  Suggestions on inverters sine vs other,how many watt inverter should I get?  should I get a mttp controller.  when you run a battery bank do they connect directly to the rv power source like the rvs plugs like an 30 amp outside connection to the fuse box, or do you run battery bank separate and use the plugs in the inverter.  some people use 6 volt batteries with higher amps how do they perform cost effective.  Is there anything else I need to know?  Thank You

RV and Solar Newbie

Comments

  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Welcome to the forum,
    The first step in designing a system is to know the purpose of the system.  The purpose of the system is to power your loads.  So, what are your loads?  You need to know the peak load (watts) and the daily energy usage (kilowatthours). 

    We have all sorts of formulas to calculate battery size, size of array, etc... but these formulas use numbers.  In order to help you, we need to know your energy usage numbers.   Similarly, if you asked us what pickup truck to buy for your trailer, we couldn't answer without knowing the weight of the trailer. 

    Some of your loads may be problematic if you only have 800 watts of array... electric heater, coffee pot, microwave.  What about refrigeration?  Air conditioning? water pumping?   Do you have a generator?  Do you have the capacity to carry a thousand pounds of battery?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • mike95490mike95490 Solar Expert Posts: 7,309 ✭✭✭✭
    use propane for the coffee, that is a huge electric drain.  A microwave for 30 seconds is a manageable load.  Heating functions that can convert to propane, have to be done before thinking of solar.   An electric room heater is completely out.
    There are several solar design stickies of how to calculate your loads, how to size the batteries for them, and finally calculating the size of the PV array to recharge.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Marc KurthMarc Kurth Solar Expert Posts: 411 ✭✭✭✭
    Danny, you can waste a whole lot of precious time/energy/money by not following vtmaps simple, but dead accurate first paragraph.

    Get a handle on your loads. Figure out what you will run, what the power draw is and how long each one needs to run. Until you do that, you are sort of just peeing into the wind :)

    Once you have a list of your "wants" you can get GREAT input from the experienced folks here, on how to balance what you want and what fits your budget - whatever it is.

    Investing the time at this phase is a critical step to success!

    Marc

    I always have more questions than answers. That's the nature of life.
  • scrubjaysnestscrubjaysnest Solar Expert Posts: 165 ✭✭✭
    All the above are good points; one not mentioned is how often do you dry camp? a couple of times a year for a week at a time and solar won't pay for itself.

  • softdownsoftdown Solar Expert Posts: 1,563 ✭✭✭✭
    Unless you have a huge solar array, it is almost always a bad idea to heat water/cook or rooms with solar.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 150 watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • Iceni JohnIceni John Solar Expert Posts: 99 ✭✭
    edited November 2016 #7

    Vtmaps' and others' suggestions are correct  -  know your loads.   However, 800W of panels on an RV roof probably won't generate as much power overall as the same amount of panels on a house roof, because RVs often are not oriented ideally to the sun or are partially shaded.   For this reason alone, I suggest carpeting your roof with as many panels as will fit!   PV is still cheap, so a few more panels aren't much more in the context of what the RV will cost you anyway.   Just don't put panels next to roof-mounted A/Cs or stink pipes or fridge vents or whatever sticks up above the roof  -  even the slightest partial shading such as from RV roof impedimenta will drastically reduce their output.   If you can mount your panels on tiltable mounts they will produce slightly more power in the summer but probably appreciably more power in the winter when the sun is lower.   1000W of panels is about the most that a charge controller can handle for a 12V system (which your RV is).   If you can charge your batteries at a 10 to 13% charge rate they will charge quickly, maybe allowing you to also power opportunity loads in the afternoon after they're fully charged, such as power tools or a washing machine or other non-time-sensitive but power-hungry loads.

    Have fun!

    John 

    40' Crown bus with 2kW of panels on the roof:

    Eight tiltable Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries eventually, and maybe a smaller inverter for the fridger.

    Southern California

  • softdownsoftdown Solar Expert Posts: 1,563 ✭✭✭✭
    I believe that poly panels perform better when partial shade is an issue.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 150 watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators Posts: 26,876 admin
    No--I do not believe there is any advantage of mono or poly crystalline panels when there is shading. They both operate with pretty much the same physics (I could be wrong--But I do not see any reason for a "difference" during partial shading).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 1,563 ✭✭✭✭
    You are probably right about that. When I was comparing the two technologies, one web site made that claim. Not "scientific proof" by any means. Though "scientific proof" is getting "more affordable" every year. A jab at the current crop of "scientists".
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 150 watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators Posts: 26,876 admin
    Some have claimed that Mono panels do better in overcast skies vs poly crystalline--I have no opinion on that (other than it probably does not make enough difference to spend more on Mono panels because of this).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • toppinishtoppinish Registered Users Posts: 6 ✭✭
    edited July 5 #12
    4 x 110 amp batteries with 800 watt panels seems like a ratio to use if your in sunlight most of the time.

    I live up in the Northwest and that panel wattage to batteries amps wouldn't work out very well as often you can go days without sunlight, possibly a week to a couple of weeks, then  several days with sunlight. Depends on you location and altitude, weather in the mountains is usually not the same as weather along to coast, low lying areas,  etc. There are areas that average over 150 inches of annual precipitation, 20 miles or so away only around 20 inches of annual precipitation.

    For up here in the Northwest I would want more battery storage as I never know how much sunlight will be available.

    However the previous comments are correct. You also need to figure the demand or common daily loads. Do you require AC, TV, Computer, Microwave, etc.?

    When off-grid a stock RV won't operate without a certain amount of 12 volts power to run a Fan for RV furnace (which often are 7+ amps, check the amp rating of your RV furnace) and 12 volts to run the RV gas absorption refrigerator. (12 volts is normally required for a RV gas frig to operate) Plus a few other items such as the  water pump,  bathroom and stove fan.

    What I did with my RV was to install an additional Catalytic Heater in the RV that requires no elect. to operate. It's best to get a catalytic heater built for an RV such as Olympian or a heater that designed for a permanent installation. One that puts out a constant heat where the btu ratings may not be as high as portable camping heater, etc. These are much more reliable and maintain room temperatures throughout the day and evening.

    When the batteries become drained it often requires from a half to a full day to recharge (sometimes a bit longer, depending on the size of your battery bank). If no sun a geny is usually relied upon. Also it's not a good idea to run batteries below 50 percent then recharge again, potentially shortens the life of the batteries.  As a general rule you want to try to keep the batteries maintained and charged somewhere above 50 percent of their capacity. At least this is what I have read about charging battery banks, perhaps others have other ideas about keeping batteries charged.





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