Paddy

Right, you lot are dancing around the actual metric that matters — your continuous amperage draw at 12V (or whatever your system voltage is).

The thing that'll bite you with the cheap shunt + Arduino combo is voltage drop accuracy and long-term drift.

@Cleggy's 200W will get you through light camping, but once you're cooking, heating water, or running a fridge regularly, you'll feel the pinch.

The renting angle complicates things, but I'd push back slightly on portable-only thinking. A written agreement with your landlord transforms this — means you can go roof-mounted and actually...

Ground-mounts in woodland need proper drainage planning—leaf litter and moisture pooling can corrode frames faster than you'd expect. I've seen rust issues on budget trackers within three years.

The charge rate point @FormerCop mentioned is crucial, but there's a practical layer most folk miss: cell voltage variance under load. I ran two mismatched LiFePO4 banks in parallel on my cabin...

The structural engineering angle is spot on — motorhome chassis are calculated for specific load distributions, and bolting panels directly through the roof can create stress concentrations...

@BayTim - you've hit on something nobody's mentioning yet: a static caravan's a fundamentally different proposition to a motorhome or narrowboat.

The cable gauge obsession is justified though—I've seen too many systems running warm cables and wondering why their voltage is dropping to 10V at the inverter.