Need help in Wisconsin...

KAIFSKAIFS Registered Users Posts: 3

Greetings all.  Below is what 'I am working with' - its already purchased/delivered and that is what 'client'  (in-laws want to use).

first off - this is an off grid, no utilities or running water property.  Property has a small shack (mouse paradise right now) aka 'Staging Point'. Property has a pond and a garden. Property now has a Big Arse camper with a mini split and 30A ShorePower plug to power it.

System is 12VDC.  There is a 825Ahr battery bank (comprised of 15 12V 55Ahr each Marine Batteries). 

So current supplies I am need to tie in:

6 - 160W 12V mono crystalline solar panels.

connected to a buss bar.

traveling on 1/0 for 36ft.

(there are number of shut off, I am not going to mention them all).

Outback FlexMax FM80 MPPT

Into a battery bank (825Ahr)

From battery bank, on 1/0 into a 350A DC fuse and into:


40A AC Service box (two space: one is 30A single pole, another 20A single pole).

30AAC runs for 148ft on 6/2 UF-B cable to a post with a ShorePower receptical mounted on it - for the BigArseCamper.

20AAC is for two double AC outlets (12/2 Romax) one outside of the shack /another inside.

there is also a power buss bar (12VDC) that connects from the battery bank to the outside of the Shack for: Water Pump (to water garden/washdown), Aerator pump (to prevent pond from freezing (winter primarily), Some minimal draw 12VDC LED sights (inside and outside the Shack), Regular cig lighter plugs for misc electronics charging on the fly...

Single ground (via two 24" spaced ground rods).

We are in NE Wisconsin, thus 'realistic light' is about 3.5hrs.  So question is:

AIMS PICOGLF40W12V120V 4000 WATT 12V PURE SINE INVERTER CHARGER:  has a 2-wire Generator wire and 120VDC input terminals.  I am thinking on using some of that 6/2 solid copper AC cable leftovers to mount a plug on the outside of the Shack for an auto start GASOLINE generator to recharge a battery bank if/as needed???

So, What type of a Generator I will need and is there something with a 2-wire auto start/shut off that is not a million dollars (basically an automatic transfer switch) to kick in for battery recharging via AIMS unit?

Supplement question:  I am NOT an electrical engineer by trade :), does all of above line up sounds solid?

Noone will be using camper full time, however, there might be periods of 2-4 days every other week or so when either AC or Heat from that Split system will be used to occupy it. 

12VDC aerator pump is connected both on a timer (kicks in during the non-light periods via a timer) and a diversion load during sunlight times.

12VDC 5.5gpm 60psi pump operates 2hrs daily during May-October as a means to push water into a 4-outlet timed valve for 225ft (pump in the middle of this run) to water the large straw bale garden.  Garden is surrounded by the 2-row electric fencing, however, it was more feasible just to connect it to a single deep cycle battery and run a 25W chappo solar mainanier panel right into it (without charge controller) to detract wildlife from feasting on the veggies.

Thank you in advance for any and all input.


  • littleharbor2littleharbor2 Solar Expert Posts: 1,569 ✭✭✭✭
    I'm sure you will get more detailed info here but Here's two points; Fro a 12 volt bank of batteries your panels should be configured into 2s x 3p into a fused combiner before sending to your charge controller. Second and really important. 15, 12 volt 55 ah batteries in parallel are going to nose dive into a pile of scrap lead in no time at all. There is no way to get that many batteries in a parallel configuration to charge evenly. if you actually need that much storage capacity you need to think about larger 6 volt batteries. Better yet, seriously consider going 24 or 48 volt.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • KAIFSKAIFS Registered Users Posts: 3
    I am picking up the pieces of what is already ordered/on hand - I would have went with a 48vdc if it was my 'project'.  I am just trying to put everything together that is already piled up in there...
  • BB.BB. Super Moderators, Administrators Posts: 31,157 admin
    Do you have an estimate of your daily loads (summer/winter)?

    Would you be willing to run the AC/Heating/Larger Living space loads from a genset?

    And as you can see from here (you can find a closer city?), not a lot of sun during the winter:

    Green Bay
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 46° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    Jul Aug Sep Oct Nov Dec
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,091 ✭✭✭✭✭
    15 paralleled batteries is unworkable and a hazard.   I would walk away and say it's too dangerous to mess with, till it's corrected,
    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

    gen: ,

  • KAIFSKAIFS Registered Users Posts: 3
    Green bay is about 50miles North of where the property is.  When inlaws first got a camper, ShorePower was connected to some kind of splitter/adaptor and went into the garage via an extension cord and everything, apparently, ran fine off a 20A Commercial AC outlet.  Again, this is not my camper/property/supplies.  They want to limit 'noise pollution' thus the solar.  I contemplated installing a supplement 600W wind generator - apparently these are 'horrible for the birds and environment'. 
    I have no idea how much it will be used - likely very minimal, they have a nice house 3miles away.  My guess will be 2-3hours tops during peak summer temps for AC, but who knows.  I know I am hoping to use it :) in November-December for a few 2-3days during the deer season, if they  let me utilize their 'baby'.   these are sealed lead acid group 31 batteries.   I frequently visit a remote cabin of a friend who has a hybrid system set up and has been using 8 battery bank of Optima D31M (I believe those are sealed lead acid as well, however 75Ah vs inlaws 55Ah per cell) without any issues and in a 12VDC configuration for over 3 years now.  They 'walked' into a deal on a pair of 2000W (4000W peak) pure sine wave inverters and just run extension cords from those to AC needing gear (granted, fridge and stove are propane tanks) but it runs a vacuum cleaner, some small tools and LCD Tv just fine, besides few other AC items (including a ceiling fan).

    mike95490, Can you please elaborate on the hazards of connecting identical batteries (15) to a single parallel bank? Please and thank you.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    KAIFS said:
    Can you please elaborate on the hazards of connecting identical batteries (15) to a single parallel bank? Please and thank you.
    Mostly, the reasons to avoid parallel banks is that they are not cost effective... they will have a shorter life and they cost a lot more to properly connect and fuse.  But you asked about hazards. 

    The hazard is thermal runaway.  A battery can catch fire or explode.  When you charge parallel batteries, the current does not divide equally among the parallel paths.  If one cell in one string develops a short, the entire string will receive way too much current... you need a fuse on each string for safety.

    Full featured chargers and controllers have a battery temperature sensor.  As the battery warms up the charger reduces its voltage to compensate.  When you have multiple strings of batteries, where will you put the sensor?  One string of batteries can be approaching thermal runaway, but the sensor doesn't see that if it's not on the faulty string.

    Here's a short discussion of parallel batteries:

    and here are some other discussions on the topic:

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.BB. Super Moderators, Administrators Posts: 31,157 admin
    Just to give you an idea of what winter power will look like... Take 3 hours of sun:
    • 600 Watts * 0.52 off grid AC system eff * 3.0 hours of sun = 936 Watt*Hours of AC power "on average" per day
    A 1,000 Watt*Hours is enough for most people to run LED lights, charge a small laptop computer, cell phones, run an LED TV, run a 12 volt RV type water pump, etc.

    However--As soon as you talk about a Fridge/freezer/heat pump system/etc... That is (usually) well out of the league of a 600 Watt array system. Just adding a full size energy star rated refrigerator would bump you up to ~3,300 Watt*Hours per day. Perhaps in Summer you could run a fridge or a chest freezer to refrigerator conversion--But still not really any A/C system.

    A heat pump type mini-split system may use 300 Watts on low... That is 3 hours per day during winter (and no power for anything else). And perhaps closer to 5 hours per day in summer (enough?).

    Sizing the loads then helps you size the battery bank... And then you can size the solar array. But solar is neither cheap or "easy"--You need to understand your loads/power needs--Then design a system to support those needs.

    In general, conserve as much energy as you can first... For seasonal/weekend use, larger power loads are (generally) going to be better served with a Honda eu2000i or eu3000i (or similar) genset vs building a "larger" solar power system that is only used on summer weekends and a couple weeks during winter (let alone the issues of theft in remote locations--Not really good too leave $10,000's unattended).

    So, sizing you system to 1,000 WH per day (based on 600 Watt array during winter):
    • 600 Watt array * 0.77 panel+controller deratings * 1/14.5 volts charging * 1/0.05 rate of charge = 637 AH @ 12 volt battery bank maximum
    • 600 Watt array * 0.77 panel+controller deratings * 1/14.5 volts charging * 1/0.10 rate of charge = 319 AH @ 12 volt nominal
    • 600 Watt array * 0.77 panel+controller deratings * 1/14.5 volts charging * 1/0.13 rate of charge = 245 AH @ 12 volt minimum
    If you  use a 319 AH @ 12 volt battery bank (nominal recommendation), assume 2 days of storage and 50% maximum discharge, your "bad weather" (and/or over night) supported 120 VAC loads would be:
    • 319 AH * 12 volts * 0.85 AC inverter eff * 1/2 days storage * 0.50 maximum discharge = 651 Watt*Hours
    If you assume you use mostly at night (5 hours per night):
    • 651 Watt*hours * 1/5 hours of usage = 130 Watt average AC load
    So--Instead of using a large AC inverter--A much smaller 300 Watt 12 volt TSW inverter would probably be a better match for the "600 Watt Array system".

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