Wow - lots of great replies guys - thanks for those.
What power source do I use? My primary source is Will Power.
I have a petrol generator, but I rarely use it. The vehicle alternator keeps mobile phones and power banks charged. As mentioned, I also use the electricity provided for customers in various restaurants and cafes.
We English are quite hardy individuals, and that is why we bred so many of the world's greatest explorers. I've never really felt the cold, and as a kid I used to roll naked in the snow I believe, I've probably build a healthy supply of brown adipose tissue, so as long as I keep eating the correct food, I'll probably maintain that. Heat is more over a problem. The van has a plastic roof, and it can become very uncomfortable on a hot summer day. I've recently bought a Fiamma roof ventilator, so I hope to rectify that soon. Damp from condensation is another problem, and I'm about to install a Chinese diesel heater to overcome this.
A couple of clarifications. I'm not mining Bitcoin at the moment, but I would like to if I can work out a way to secure solar panels on a van with a plastic roof. I refer to the van as a conversion, but this is a fairly optimistic reference. It is what is commonly called a "no build conversion". This means you get hold of a few bits of furniture, throw them into the van, and then move in. I've been experimenting with various options for a few years, and now I am prepared to customise the van to suit my anticipated needs.
I have a Volvo 740 saloon car which I use as a daily driver, so the van is really becoming a moveable house. I also have a high spec Volvo 740 estate, and I plan to use that as a show vehicle at various classic car meetings.
A lot od English words seem to have changed their meanings recently, and I think "offgrid" is one of them. Other example are "burglary", originally it meant housebraking during the hours of darkness, but now it seems to mean any form of housebreaking. "Gay" is another useful word that we have lost from the general vocabulary. The Americans seem intent on removing "ensure" from general usage, and replacing it with the financial word "insure". Buying a remote hill farm in Wales used to be an example of offgrid living, but now it seems to refer to any lifestyle that doesn't have a dedicated connection to the utilities. It is this expanded definition that I use, mainly because I hope to pick up some extra revenue from a Youtube side hustle.
@Mindrust You electricity situation sounds pretty bad, and I hope we will never come to that. It's difficult to understand how it could be applied to van dwellers though. Maybe they will try to force us to use environmentally damaging electric vehicles, and force us to charge them with the electricity they generate by burning fossil fuels and ancient forests.