I've reached one of those critical decision junctions in moving forward with a small solar PV system for a remote weekend location. Please note this is a remote shack, not an RV - there is no engine to charge from! I can see that, within a sensible budget, a couple of 12v batteries won't give a spectacular longevity to operations. The critical thing working against direct 12V DC operation is the relatively low volts presented to the rig, which expects nearer 14V than 12V. Based on this, some suggest it's better to use a DC-AC inverter, as a more stable and 'expected' supply is presented to the rig. But this chain is 12V DC to mains AC, and then a PSU back down to 13.8VDC. I guess the stability comes at a fairly considerable battery duration penalty. Once again, to save some money and make what I have go as far as possible, I'd be interested to hear from those operating (effectively!) from batteries on a regular basis.