Ally

Could be the battery, go get a free battery health check or buy a tester. Could also be bulbs, loose wiring or the ballast as mentioned above.

Hi John, Have you tried bumble campers in Peterborough, they convert Alphards and Vellfires and pretty much anything else, to what you desire, so no doubt they may assist: https://www.bumblecampers.com/ I have recently purchased a 2014 Vellfire and that has an inverter beneath the front centre console that runs off the battery, but it has a Japanese mains plug at 100w. From what I have read, some have removed the invertor and made it into a 12v or USB, a 230w UK mains invertor could be placed there also, but it would be a drain on the battery but if the engine was running while you boil a kettle in 2 minutes I doubt it would matter. I don't see why you couldn't run an invertor off your solar / EHU, and maybe an auto electrician could assist. The cheapest solution if you just want to boil your kettle or run a fridge, or TV is a portable power station from Jackery or Bluetti, just google them, type in 'Portable Power Station' or go on to Amazon. They can be hooked up to solar panels or charged before you leave (or wherever) and last for a few hours to several days depending on your use. They usually start from £200 but go up to £2,000+ if you want to power a house As always the best time to but is Amazon prime day, Black Friday or sales periods. Lastly, 'Go outdoors' et al sell £15 gas hobs and you can buy a pack of 4 gas cartridges for £8. Hope that helps, Al