Have CC, inverter and batteries - having trouble selecting panels

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Dan_
Dan_ Solar Expert Posts: 61 ✭✭✭✭
in Solar Beginners Corner #1
Hi all, I have 8 GC2 FLA 6v 208Ah batteries at 48v and an Outback FX3048. Have been running it since September charging via generator but have an Outback FM60 ready to be installed once I have panels

I'm not sure what the right panels for me are and what criteria I should be selecting. Clearly price is the easiest criteria to shop with and so far I've seen panels 78c per W at sunelec and 68c per W at solarblvd. (Sunelec does have Trina thin film for 34c per w also).
What else should I be looking at?
Thoughts on how much panel to get?
Have about 5.4hr peak sunlight according to online calculator

TIA
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #2
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    After you decide how much panel you need, you should enter the panel data in one of the string caculators for your charge controller. Outback
    http://www.outbackpower.com/outback-support/string-sizing-tool

    If you can't get this one to work midnite has one for their classic controller that will work for your fm60 if you keep track of the amp imput.

    Panels have different voltages and you need ones that you can get your voltages above your highest battery setting but not so high that in cold wheather it will go over 150 volts.
    gww
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #3
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    Re: Have CC, inverter and batteries - having trouble selecting panels
    Dan_ wrote: »
    Thoughts on how much panel to get?

    Generally, a 10% charge rate (based on battery ah) is a good starting point for design purposes. That would mean that you want your charge controller to be able to put out 20.8 amps. I will assume your charging voltage is 59 volts.

    20.8 amps at 59 volts = 1227 watts into the battery.

    Now, to get 1227 watts into your battery you must consider that there will be some losses in the wiring and the controller, and that the panels (when hot) do not produce their rated output. Figure about 75% of the panel's rating will get through to the batteries, so:

    1227 watts ÷ 0.75 = 1636 watts

    Now that is just a starting point, there are many factors that go into deciding how much you really need... you might do just fine with as little as 900 watts, or you might be better off with over 2000 watts. Tell us more about the system, climate and loads.

    Once you decide on a panel, tell us the specs and the distance from the controller, and we can then advise you on the series/parallel configuration of the panels, the combiner, circuit breakers, and cable.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #4
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    Do you know what loads you have and what you want your system to do, or is this just a bit of charging to minimize the amount of time you'll need to run the generator?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    #5
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    Really helpful replies thank you very much
    Hopefullu can use solar primarily and generator only with significant loads or foul weather. Power is for our small family home. We're frugal users. Small Well pump and chest fridge are the main consumers but power tools ocassionally also. We are right now using only 500Whr per day but would use more if we had it.

    This panel any good? http://www.solarblvd.com/Solar-Panels-&-Systems-Individual-Solar-Panels-175-Watt-+-(11)/c1_25_203/p2955/Hanwha-SolarOne-(Solarfun-235--JLS)-235-Watt-24-Volt-Solar-Panel/product_info.html
    String of 4 seems to be pushing the limit so maybe 3 strings of 3 for approx 2kW

    Plan is to keep the panels close to controller. Likely will be roof mount on shop and then equipment inside
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #6
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    Make sure you include shipping/handling/insurance to your door step... Shipping small qualities of large solar panels can be expensive.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #7
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    Re: Have CC, inverter and batteries - having trouble selecting panels
    Dan_ wrote: »
    This panel any good?

    String of 4 seems to be pushing the limit so maybe 3 strings of 3 for approx 2kW

    Plan is to keep the panels close to controller. Likely will be roof mount on shop and then equipment inside

    Mounting on a roof? Try to find UL listed panels.

    If your panels are close to the controller, there is no good reason to have a string length any longer than the minimum to charge your batteries.

    Three of those panels in series is better than four, and this is NOT just because you might exceed the controller Vmax in cold weather... the controller will actually work more efficiently with a lower input voltage.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #8
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    Re: Have CC, inverter and batteries - having trouble selecting panels
    Dan_ wrote: »
    This panel any good? http://www.solarblvd.com/Solar-Panels-&-Systems-Individual-Solar-Panels-175-Watt-+-(11)/c1_25_203/p2955/Hanwha-SolarOne-(Solarfun-235--JLS)-235-Watt-24-Volt-Solar-Panel/product_info.html

    I haven't heard of them, but that isn't saying much. Hanwha has apparently been around since 2004, so at least they're not fly by night.

    The page you linked advertises it as a 24V panel, which it isn't. That would give me pause. Vmp seems oddly low to me, seems like it'd be hard to find matching panels if you wanted to expand down the road.

    Price is right, though, one panel shipped to my zip code is $1.02 per Watt, which is crazy cheap.

    I used some off-brand 12V Chinese panels in my system, they work fine. But options in the 12V market are limited. If I were to buy "grid-tied" type panels, I'd personally try to buy a known quantity. Sharp, SolarWorld, Kyocera, etc. Assuming I could afford it.
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  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    #9
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    Good point on UL

    Interesting about efficiency. This why I queried on the matter since I'm unclear. So for an mppt controller you want to keep the input voltage above but close to charge voltage? How much loss are we talking given the option between 3 or 4 in series? I was under the impression that mppt was not so picky about voltage and you just had to keep it under the controller maximum (150v for fm60)
    vtmaps wrote: »
    Mounting on a roof? Try to find UL listed panels.

    If your panels are close to the controller, there is no good reason to have a string length any longer than the minimum to charge your batteries.

    Three of those panels in series is better than four, and this is NOT just because you might exceed the controller Vmax in cold weather... the controller will actually work more efficiently with a lower input voltage.

    --vtMaps
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #10
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    Re: Have CC, inverter and batteries - having trouble selecting panels
    Dan_ wrote: »
    Interesting about efficiency. This why I queried on the matter since I'm unclear. So for an mppt controller you want to keep the input voltage above but close to charge voltage?

    They work most efficient at about 2x the battery voltage.

    I think I looked up these panels for someone else here and the model appears to have passed UL (or ETL) but it might be from before they passed or not marked for other reasons. Also the panels appears to have a standard warranty 5, 10, 25yr warranty. I would check to be sure they aren't blemished panels or discounted for other reasons, perhaps out of spec higher wattage panels relabeled.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #11
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    Re: Have CC, inverter and batteries - having trouble selecting panels

    Hi Dan,

    One more thing about the PV module that you linked -- it appears to be a 54-cell module. These are very uncommon. Kyocera appears to intermittently also make their 215 W 54-cell PV, but, if you choose these PVs, and you wish to add more later, it might be a bit difficult to find more that are compatible.

    Suppose, that if you ran these PVs in strings of four, you could later use strings of three 36 Vmp PVs and be fairly compatible with your FM CC.

    The largest production of PVs presently appears to be 60-cell modules. It appears that 60 cell PVs will be made for quite some time, although 72-cell PVs are coming back into production.

    All FWIW, Have Fun designing the rest of your system. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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