New here and need saome good advice for off-grid

Hello,
Please if u can help to find a best way to conect following eq.
3 solar panels 200w
40A Mppt charge controler
4 x 180 Ah VRLa Agm deep cycle batteries ( i wil accept also 2 240. Ah if i must)
150 vdc 3000w inverter 12/24/48v


Basicly i was thinking to put modules in series ,
Bateryes 2x180 seris then paralel thos to banks to get 24 v system

Any help is wellcome.
Thanks.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New here and need saome good advice for off-grid

    Welcome to the forum.

    Some of those specifications seem a bit off. For instance "150 vdc 3000 w inverter 12/24/48". An inverter will have a fixed system Voltage of 12, 24, or 48 Volts DC. Its output will be 120 Volts AC or 240 Volts AC or 230 Volts AC for most applications outside North America.

    4 x 180 Amp hour VRLA/AGM batteries of what Voltage? Again this comes back to what the actual system Voltage will be and how that relates to putting multiple batteries together.

    I have never seen a 40 Amp MPPT charge controller and would be suspicious of one if I did. There are many "no name" controllers out there that claim to be MPPT but aren't really.

    3 solar panels of 200 Watts is another matter. They could be "12 Volt" panels or "GT" panels. Here you need to get the numbers for Vmp, Voc, Imp, and Isc not just the wattage.

    Maybe we're going at this the wrong way: could you tell us what you're trying to achieve and where?
  • ukukaukuka Registered Users Posts: 3
    Re: New here and need saome good advice for off-grid

    Thanks for your reply , also you are wright on all accounts.

    the system i am building is in Croatia, but i find this forum has lots to offer...

    i will try to be more specific.

    on account of inverter it will be operating on 24v conected battery (4x180 AH 12v or 2x 300AH 12V baterys),
    output is 230 Volts AC

    Battery is 12V as u can read from above it will be 4x180AH or 2x300AH 12 V battery

    MPPT charger is probablly no name so if i can find a diferent one on our market, i will try.... but not to expensive.

    Solar panels of 200-240w will be nominal voltage of 24V and i dont have other inf since i havent bought them yet.

    and finaly i am trying to get more-less stable off-grid system that can handel 2,5 kw.

    it will have 4 bulbs of LED sort so 2w a bulb,
    1 refrigarator cca 100W draw
    CRT tv - dont know how many power it draws
    and cant test it becouse there is no power on spot, iti is a winter cabin but would be from now on non -stop resident for 2 peaople.
    tv will be on maybe 4 h a day,
    refrigarator is non-stop. light is lik 6-8 hours.

    thanks for your patience , and understanding of my bad spelling :).

    best regards.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New here and need saome good advice for off-grid

    Okay, an off-grid system is based on the batteries so let's look at the two choices proffered:

    Four 180 Amp hour 12 Volt batteries configured for 360 Amp hours @ 24 Volts. This is two parallel strings of two in series. Using 25% depth of discharge you'd have about 2kW hours of power from these. You will probably find that to be on the low side for supplying your needs.

    Two 300 Amp hour 12 Volt batteries in series would be 300 Amp hours @ 24 Volts. This will be even less power available; about 1.8kW hours.

    For what it's worth, I have a 24 Volt system powering my off-grid cabin, including standard refrigerator, water pump, satellite Internet access, and lighting. It has 232 Amp hours of battery and 700 Watts of panel. It works fine in the Summer when there is lots of sun available. It would be impossible in Winter when our daylight hours shrink to 6. If I were to add more load I'd either have to run the generator more or increase the batteries and panels.

    If you could push your battery bank size up to around 400 Amp hours you would be able to meet your 2.5kW hour goal (which is realistic). It is best not to do this with multiple parallel batteries if at all possible, as they can have problems keeping the current even between batteries during discharging and charging.

    As for recharging them, you should try to size the array based on at least 10% peak charging current:
    10% of 400 Amp hours = 40 Amps (@ 24 Volts). Factor in the average production derating of the panels (77% typically) and you'd have an array of (40*24/0.77) 1246 Watts. If using the 250 Watt panels that would be five, a number that's 'awkward' to work with for an array. If at all possible go up to six: three parallel strings of two in series. You will likely need two in series as panels of this size tend to have a Vmp around 30 which is too low for properly charging a 24 Volt system.

    You should also be looking at a generator to supply power and charging when the sun doesn't shine enough. It always pays to have a back-up source.
  • mike95490mike95490 Solar Expert Posts: 8,757 ✭✭✭✭✭
    Re: New here and need saome good advice for off-grid

    If you have not purchased the inverter yet, consider a 48V system. It lets you use smaller wire, and has less losses, and less issues when loading the inverter heavily. system would be same wattage, just a different voltage.
    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 ,

  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: New here and need saome good advice for off-grid

    Agree with others for your expected loads your pv is too small. You have too choices, use enough pv to get you by or rely on a generator to fill the gaps. Cheap generators are not always nice, and a decent generator can set you back enough to buy 2kW of PV.

    Your third choice, and often the best choice is to reorganise your loads. The CRT would be a good place to start.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • ukukaukuka Registered Users Posts: 3
    Re: New here and need saome good advice for off-grid

    Thanks for your reply,

    Since i am limited cost wise, i am planing to go with the following

    3 modules 240w 24V in series
    Gel tech or agm deep cycle 300 ah 12 v x 2 in parallel for 300 ah storage
    Will use 40 Amp Mppt charge controler is that enough?

    I will also mention we have cca 8-9 hours dayligt on winter of wich direct sun will be minimum 6 hours on panells

    What size inverer would u recomend for the above system?

    Thanks for your patience
  • mike95490mike95490 Solar Expert Posts: 8,757 ✭✭✭✭✭
    Re: New here and need saome good advice for off-grid

    limited funding, I would use a pair of conventional 12V deep cycle boating battery. It's pretty common for a
    new user to forget something, and destroy their battery(s) so the first one should be a cheap one.

    Inverter size, should match it's peak surge capacity to your loads peak surges. You need to define your
    loads first, otherwise you end up adding more water. add more concrete, add more water, add more concrete....

    Panels - 3 in series will give you an open circuit voltage of nearly 100Vdc. Be very sure your charge controller will
    survive that high of voltage. I'd say, get 4 panels, just 2 in series, and then parallel the 2 series strings. Open
    circuit voltage will be closer to 65V, more controller choices. And 2 strings in parallel don't need fuses, 3 in parallel will
    need fuses.

    Inverter, if you have not bought it, consider putting batteries in series, and building a 24V system. No parallel battery issues,
    more efficient (less ohmic losses) better surge capacity. And your charge controller can now handle twice the array wattage
    it did at 12V. [40a @ 12V = 560w PV limit, @24V +1,000 watts]
    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 ,

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