Off grid house - back up options

My son lives in a remote house in Devon which is completely off grid. He has a 32 panel solar array, 16Kw batteries and a back up generator. Today the inevitable happened and the generator failed to start. With a multiple day wait for an engineer they are completely powerless. Fortunately he has a neighbour who is supplying water (my son relies on a bore hole and pumping station) and even power from the grid via a long extension lead (they had a supply laid years ago and to connect my son to the grid was going to cost £23,000). I'm wondering if he could use the grid power to charge his batteries somehow? He currently has no grid connection at all, so no exporting of the surplus. If he can schedule a battery charge on his invertor is there someway to connect the invertor to the temporary power supply from the neighbour?

I know a young couple who this time last year were quoted £44,000 to have their remote house connected to the grid. For a lot less money they got 30+ kWp of panels and 44 kWh of battery, victron inverter + mppt, cerbo gx and a load of other bits plus a small Genny as backup. I know the generator was the most difficult bit to get set-up and they've only needed it twice for a few hours to top up the battery just before Christmas when we had six consecutive very dull days.

It seemed a shame last summer when they had the potential to export so much power to the grid but like your son they can't. It's also odd looking at thier monthly generation graph which shows less generation in the summer than the winter.

Have they got gas.
How about micro CHP unit. Burning the gas for heating and hot water also generates electricity and vice versa. Very efficient

Buy a cheap 2-3kW suitcase genny (inverter rectified one though) and use that to keep the power on to essential.

Is the big generator petrol or diesel and do you know the symptoms? Eg is it engine or generator side that’s the issue?

You might be able to charge the battery via the generator interlock if you have a suitable 13A to commando lead. I’d check with a sparky first though.