Just about right,it works like this,batterys will discharge to 60% so 40% down though this is not so good,so if you double from one 100ah to 200ah ie two batterys then you will only cycle down 20% which will give a longer life,again at least 200w of solar to keep up,but do remember about six mths of the year they may well if lucky only give about 1/4 of there output.Think of it like this - more solar power means you collect more sunlight. More batteries means you can store more of it. If you have too few batteries you can't store all you collect. Too few solar panels and you can't fill the batteries up.
Work out how many mAh you would normally use based on the power and hours of each device.
Yep double up to harvest solar and you also will not cycle down the battery bank as much making them last longer with reserve power on tap,good luck.Thanks everyone...
So, given my 200w of solar panels I need two 100ah batteries or bigger? Or have I missed the point. Yes, the solar is going on because I have the Highlands on my doorstep and wild camping is legal here! I suspect for most of our trips the panels are overkill, but don't want to be let down once we hit the continent on longer trips.