how old are the golf cart batts? if around 1 year old, i'd add to them with identical batts. if over 2 years old, i'd start a new bank.
$/Ah l-16's aren't as good of a buy i've found. not to say that they aren't more robust ect.
i run eight trojan t-125's (24v) with ~600w of solar, and an 8.5' wind turbine feeding them. i only need more power on those gloomy days with no wind.
sixteen of a similar battery would give you quite a bit at 24v. maybe 6Kwh usable??? without damaging the bank.
adam