I'm not trying to say these guys are the definite answer, but you might get some ideas from this -
LINK
I have bought some batteries from them for my observatory on the Darling Downs.
Just to give you an idea of power consumption, I can consume 50-75amp/hrs per night running a 2 x 12V PCs, mount, cooled CCD camera and other accessories each night.
I top up my batteries during the day with a 25amp charger powered by a generator. In between visits, there is a small solar panel for trickle charging.
DT