I am guessing all 6 - 6 volt batteries are wired in series for 36 volts nominal and that they are of the 220 amp hour (@ 20 hour rate) range like the Trojan T-105's?
It would be simpler if they made these golf carts so that the battery bank could be easily removed (like some forklifts) so that, while one bank is being charged by photovoltaics during the day the other can be in use during the day, but thats nether here nor there, so...
If your interested in re-charging directly from a PV array it will ether take a very large array with surplus electricity before and after the re-charge or the golf cart can only be used at night because it will have to charge during the entire day.
A start would be to know how many amphours are removed from the battery bank during a typical days usage.
If I took a guess and said 100 amp hours then -
36 x 100 = 3600 watt hours
that 3600 watt hours would then have to be divided by the number of hours of equivalent full rated charge available per day in your region.
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/ If I guessed and said 4 hours per day averaged out over a year then -
3600 / 4 = 900 watt PV array at 36 volts nominal, but, this is bare minimum and it would take all day to re-charge the golf cart on the best days. So you can see why a very large PV array might be needed in order to re-charge the golf cart in a shorter period of time which would then result in a surplus of electricity before and after the re-charge. A second or third golf cart might be an option. One in use while the other(s) re-charge.
It makes a grid intertied PV system to offset the usage of coal fired power plant electricity look more inviting. Just keep in mind that this would involve; permits, contractors, and inspections but there maybe a benefit of tax incentives to offset the cost of them.
http://www.dsireusa.org/library/includes/map2.cfm?CurrentPageID=1&State=NC&RE=1&EE=0I geuss its true what they say, "theres no such things as a free lunch."
http://www.motherearthnews.com/Nature-Community/1982-09-01/Take-an-Eco-Village-Vacation.aspx
