Need help with my fathers golf cart setup

johannsjohanns Registered Users Posts: 2
edited March 11 in Solar Beginners Corner #1
First off I know very little about solar panels so please bear with me as I try to help my father with his golf car configuration.
He has a single Solar Frontier SF170-S panel that is attached to the roof.
Maximum power 170 W
Module efficiency 13.80%
Open circuit voltage 112.0 V
Short circuit current 2.20 A
Voltage at maximum power 87.5 V
Current at maximum power 1.95 A

He also has a 36V battery bank  (6x6V)

We are trying to figure out what solar controller is needed for the panel to charge the batteries?
I am not even sure if his solar panel is correct, so any input anyone can provide will be much appreciated.

Thank you!


  • littleharbor2littleharbor2 Solar Expert Posts: 1,112 ✭✭✭✭
    You need to find an MPPT charge controller that will charge a 36 volt battery bank.

     This panel outputs less than 2 amps at 87.5 volts this should translate to a tad over 3 amps into the 36 volt battery. Bear in mind the solar panel alone will only supplement regular charging. By itself you wouldn't have enough amperage to properly charge the battery, which would result in the batteries getting prematurely sulphated and basically ruined.

     The higher end MPPT charge controllers do 36 volts. Most of the cheaper ones only do 12/24 volts The forum's host, Northern Arizona Have a great selection of charge controllers which will do the job.

    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.

  • mike95490mike95490 Solar Expert Posts: 8,030 ✭✭✭✭
    Sadly, you are going to have to spend a lot of money on a high end charge controller, to provide a tiny bit of charge, 

    In the daytime, you might get an additional 50 or 60 feet of range on the cart, that's how little the solar will contribute.
    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: ,

  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    here is a link on a solar powered Golf cart, headaches and all but successful in the end.
    and this one  about using a MidNite  solar KID CC on 36 volt batteries.

    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • johannsjohanns Registered Users Posts: 2
    thank you, for your responses back.
    So if I were to purchase a 36V charge controller, what should be the AMP on the MPPT Solar Charge controller?

    What would be the ideal amperage and voltage needed into the 36V battery bank to make it charge properly?
  • EstragonEstragon Registered Users Posts: 3,043 ✭✭✭✭✭
    The charge regime should be done as per battery maker spec. For typical flooded lead acid golf cart type, absorb voltage (set in the charge controller, and temperature compensated) might be around 44v. A 170w panel will likely put out more like 100-120w in real life (suboptimal angle, etc), so the controller might put out something like [email protected]

    Note that the panel appears to be high voltage - low current, with Voc over the limit for some lower end mppt controllers.

    At a 2.5a rate of charge, a 50% discharged 225ah bank would take something like 50 hrs (10 days at 5hrs full sun equivalent per day). Realistically, 2.5a is enough to float a full bank, but not to charge a depleted one. To charge properly, you would want 10x or more (25a) rate of charge.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • littleharbor2littleharbor2 Solar Expert Posts: 1,112 ✭✭✭✭
    Your choices are quite limited for a MPPT controller that has a high Voc. limit and does 36 volts. I just looked on the NAWS site here and you will need a 30 amp minimum controller. The Midnite kid is under $300.00 the rest are costlier. I thought the Morningstar 15 amp MPPT controller would work for you but the Max Voc. is too low for your panel. You might think of getting a different panel with lower voltage so you can save money on the charge controller.

    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.

  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    For your 36 volt battery and if you use a PWM controller (I believe some of the MorningStar PWM controllers can be programmed to 36 volt charging with a PC and comm interface--not free). The Vmp-array would need to be ~52.5 to 60 volts. That could be 3x ~130 watt @ ~18 volt Vmp panels in series, or 2x ~200+ watt panels in series (Vmp~30 volts). Picking your "optimum" configuration will require you to paper design several options and see what works out best.

    atts Module Single Module Price Single Module Pallet Prices
    130 Solartech SPM130P-S-N 12V $273.00 $2.10  $1.995
    130 Solartech SPM130P-WP 24V $286.00 $2.20  $2.09
    140 Solartech SPM140P-S-N 12V $200.20 $1.43  
    190 Solarland SLP190S-24 $224.00 $1.179  
    290 AXITEC 290W all black $217.50 $0.75  
    295 AXITEC 295W mono $191.75 $0.65  
    295 Hanwha Black Q.Peak 295W $215.35 $0.73  
    300 Hanwha Q.Peak 300W $228.00 $0.76  
    305 Canadian Solar 305W $222.65 $0.73  
    310 Silfab Solar 310 Watt $272.80 $0.88  
    325 Panasonic HIT 325 Watt $310.00 $0.954  
    330 AXITEC 330W poly $222.75 $0.675  
    350 Silfab Solar 350 Watt $269.50 $0.77  
    Other solar panels may be available - this is what we normally stock in depth

    For MPPT controllers--It is usually better to run higher voltage Vmp arrays--Call it ~70-100 Volts Vmp-array for a typical higher end MPPT charge controller with ~140-150 VDC maximum panel (cold winters/warm summers)--If you have a narrower temperature range (tropical island).

    There are many different Wattage and Vmp configurations for panels... The above are pretty common. The ~140 panels tend to be more expensive ($$$/Watt) vs the >200 Watt panels. You have to decide on the price and charging current you would like... ~5% is Fine for weekend/sunny season use. >10% rate of charge is better for daily usage.

    You also need to figure out how much energy the golf cart uses per day (Watt*Hours or Amp*Hours @ 36 volts). And the size of the batteries (i.e, 6x 6 volt @ 200 AH golf cart batteries?).

    We need to know both the AH of the battery bank (and if flooded cell, AGM, etc.) and energy use per day + the rough location (nearest major city--Hours of sun)--They are two different calculations that both need to be satisfied.

    Also, is this intended to be the only charging power (i.e., charge during the day, and drive after charged or charge day 1 and charge on day 2, etc.) or if it is intended to "float the battery bank" during storage/off season (typically 1-2% rate of charge).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 4,769 ✭✭✭✭
    edited March 12 #9
    I don't know where you are located, I, personally, would bail on using that panel. It has high VMP, but will be difficult to match with a charge controller. It's possible in many places to find, if you hunt a bit, 60 cell panels for less than $1 a watt. 60 cell panels will normally have a VMP of 27-30 volts I'd find 2 - 60 cell panels and run them in series and use an inexpensive PWM charge controller. 

    That will handle 36 volts. I helped find this with no idea of it's quality for a fellow on Facebook group, he's using it and it appears to be functioning very well with his 48 volt system.

    It's easy to find inexpensive panels around 60 cents a watt, but shipping get's ugly! Look locally on craigslist and through facebook market place, letgo phone app. If you give your general location. I'd be glad to hunt a bit for you.

    Here is an example, near to me but still 110 miles away. a couple of these at $120 for 235 watts each would cost $240 plus the controller for $50 and for about the price of a Midnite Kid charge controller + gas, you could have a realistic 6 amp charging 36 volts in full sun.

    Trina 235 watt
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • mryimmersmryimmers Solar Expert Posts: 112 ✭✭✭
    Get him a proper battery charger and be done with it, haha!!
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
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