Golf cart solar charging station.

Welcome to the forum Bobo,

I will do a "generic" back of the envelope design first... There will be issues (like 36 VDC is not popular for AC inverter input voltage these days--12/24/48 are standard lower voltage inputs). And some other issues such as flooded cell lead acid batteries are not really able to recharge from 50-100% state of charge in one day usually--They need something like 8-10+ hours to go through bulk/absorb states--And the sun, especially in winter, is just not in the sky that many hours per day (for many places).

But to start... First, guessing that you have 6x 6 volt @ 200 AH flooded cell batteries in series for 36 volts (many solar charge controllers can be programmed to charge a 36 volt bank):

• 6 batteries * 6 volts * 200 AH * 0.50 (half discharged) = 3,600 Watt*hours of storage/one day to recharge

Next, there are two calculations that we make for the size the solar array. One is based on the size of the battery bank and rate of charge. The other is based on loads per day and hours of sun per day.

First, charging based on rate of charge... 5% can be OK for weekend/summer usage, 10-13% rate of charge is better for full time off grid usage. And 20% or so max rate of charge. 10% or greater is typically mfg suggested rate of charge:

• 200 AH * 43.5 volts charging (aka 36 volt bank) * 1/0.77 panel+charge controller deratings * 0.05 rate of charge = 565 Watt array minimum
• 200 AH * 43.5 volts charging (aka 36 volt bank) * 1/0.77 panel+charge controller deratings * 0.10 rate of charge = 1,130 Watt array nominal
• 200 AH * 43.5 volts charging (aka 36 volt bank) * 1/0.77 panel+charge controller deratings * 0.13 rate of charge = 1,469 Watt array typical cost effective maximum

And then there is sizing the array for amount of energy per day, and where the system will be installed (and seasonal variations). For an example, a fixed, tilted array, around Orlando Florida:
http://www.solarelectricityhandbook.com/solar-irradiance.html

Orlando
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 62° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
4.29	4.76	5.36	5.79	5.75	4.99
Jul	Aug	Sep	Oct	Nov	Dec
4.96	4.87	4.74	4.89	4.55	4.16

Lets say you want to use 50% of battery energy every day (usually suggest 25% of an FLA battery bank per day that is charged from solar), and use 4 hours per day sun (Florida has pretty good sun in winter, perhaps not as much during summer due to afternoon thunderstorms, etc.):

• 3,600 Watt*Hours per day * 1/0.61 of grid DC solar system eff * 1/4.0 hours of sun per day (thru December) = 1,475 Watt array "break even" on 4 hours per day of sun

Say you pick a 1,475 Watt array--An MPPT type charge controller, the rated amperage of the controller should be:

• 1,475 Watt array * 0.77 panel+controller derating * 1/43.5 volts charging = 44 Amp minimum rated MPPT controller

https://www.solar-electric.com/victron-energy-smartsolar-mppt-150-45-tr-charge-controller.html

So, you would need to find a 45 Amp (minimum) MPPT solar charge controller that can be programmed to charge a 36 volt battery bank. Should be easy to find a higher end MPPT controller that can do that (lots of options too, Internet server, most of remote battery temperature sensor, etc.).

The bigger issue is finding a 36 VDC input AC inverter (suggest around 1,000 Watts or so maximum AC inverter rating for your 200 AH @ 36 volt bank).

https://www.amazon.com/s?k=36+vdc+ac+inverter (a fair number of choices here--Don't know anything about them or the sellers)

And you need a ~1,475 Watt array (your choice to size/configuration/etc.). Larger solar panels cost around $0.50 to $1.00 per Watt depending on brand/quality/source... Note that shipping & insurance can be a huge cost adder...

Another issue is how to connect your golf cart to the charge controller/AC inverter/etc. Will the hardware be installed in the cart or at the "charging station" (reconnecting the 36 volts to the charge controller can be an issue if not done correctly. AC inverters can take some pretty heavy current--You need to have relatively heavy/short copper cables and power connector to support these loads).

When you talk about a charging station... Do you want to charge the cart at night and drive during the day? If yes, then the "charging station" would use its own battery bank to charge from the sun during the day, and discharge into the Golf Cart at night.

I will stop here. Questions/corrections/etc.?

-Bill