Much to Gail's consternation this 'off grid' is pretty new to us and we (Brian) keeps learning things.
On the way to Karijini we learned that the Projecta a) wasn't working properly on solar and b) didn't charge from the car if it could see any solar input (by design). So to address this Brian used a Victron 75(V)|10(A) charger he had installed for the little panel, but it was clearly limiting charging to 10A (by design). So in Perth a 100 (V) | 30 (A) controller was installed and purchased and a serial cable manufactured so the 2 solar panels would pick up the early morning sunshine (by giving 30V, rather than 15) and get going. This worked brilliantly, however on day 2 at Cape Le Grand it stopped about 9:30am. Whoa, no more power in an off grid site. This was going to get sticky even cutting the stay there short. The Victon showed plenty of voltage from the panels, but no current, plenty of voltage on the battery terminals (& then the correct voltage for the battery after a while) and no current. Like all things: in hindsight it is obvious. The fuse had blown, the Victron was showing the voltage it would like to send to the battery and the battery voltage picked up by Bluetooth from the shunt on the battery, but no power was flowing. Brian had uprated the cable, but not the fuse and been totally confused about lots of voltage and no current. A new fuse and it all cam to life.
Hopefully we are just about at the end of learning about how this all works! Also waiting to review the whole setup with Adrian when we get home.
Just to complicate things it looks like the Projecta only charges the battery at limited (but sufficient if you do a full day's drive) current. So far that hasn't caused grief, but needs watching!