Ok, so at it's most basic level, off-grid power requires the following things - a solar cell (nearly said solar sail there - not so practical) - with MC4 connectors - they are standard solar connectors that allow you to easily retrofit extra panels in serial if required and are fully waterproof - it's exactly the same system as they wire into your loft. My particular solar panel is rated to 100 watts and 12 volts and is designed to be waterproof and flexible (for mounting anywhere, even in inclement conditions)...
You might find you need an MC4 extension cable depending on how far apart you are putting your solar panel and your battery, ideally it must be in direct sunlight for the maximum amount of available daylight and the battery should be somewhere cool and dry.
At this point the simplest and cheapest thing to do is buy something like this -
- it's got a small battery pack built in (26,400mAh), plus an inverter to use DC via a standard Type G British 3 pin plug and also has an adaptor for 9v cigarette lighter and a number of variously rated USB ports. Now I stressed entry level here - I tested this power pack vs the High Gear 28L cool box - it lasted almost exactly one hour before the battery was flat. So I'm not expecting any miracles here - equipped as I am - Infinite power to charge telephones and laptops is priority 1 - we will see how far that can be extended as we move forwards - if we can even hit objective 1 on this next camp then I am very happy.
Down the line some small changes I need to make to the setup are immediately obvious - I'm thinking a waterproof box with a 100Ah deep cycle LiFePO4 battery (basically a caravan leisure battery) and a proper inverter/solar manager (that shows charge speed etc.) rather than this jack-of-all-trades charger that I know can't really cope with 230-240v for very long - the fridge probably isn't going to be a thing off grid - but the rice cooker and a nice fan are both possibilities - the minimum viable product at this point is simply to be able to keep my telephone and laptops charged with no mains power - let's not try and walk before we can run.
Edit - Camping off-grid with the 'fridge might be possible after all - if my calculations are correct - even without solar top up I should get 24 hours of refrigeration from a single, fully charged 12v 100Ah battery.
