I made my decision based on the price and availability of inverters.
If you are not going for grid connect or full home system then, like me, you'll probably be looking at a modified-sine inverter (they are WAY cheaper). The number of batteries determines your total system power storage independently of the system voltage but the higher the voltage, the less losses you'll get from cables and connectors. Go to too high a voltage and the inverter price starts going up!!
I traded these off and went for 24volts - trucks use 24 volt systems so are common and a 3kw Chinese inverter can be had for $500. I'm using T105 style deep cycle batteries, 3 strings of 4 eventually, that will give me a total storage capacity of 16kwh but since I'll only use the top 30% of that then I'll be able to run a 1kw load for the best part of 5 hours.
Robin - Down Under (or are you Up Over)
