Another daft One Two Both switch question

[onesea]

A bit or not depending on sunlight. Why don't you do as Paul has suggested and fit a VSR? They are neither expensive or difficult to install in place of a 1-2-both switch.

Why remove the 12off Both switch?
I have a VSR and 12OB switch. if engine is running and battery full any spare charge guess into domestics, the same vice versa for solar on domestic.
It makes wiring easy as you can run cables from 12OB switch.

Previous boat I just had 2 separate systems domestics and engine and a VSR my 12OB switch was some jump leads.
I never needed jump leads and the battery's where 10 years old when I sold her

Am thinking will just go with using the alternator to keep the engine start battery topped up.

That works fine on the Portuguese boat.

It worked fine 99.9% of the time for every one before solar.
There is no reason it should not now.

However at the chance of upsetting some, its a bit like having a smart phone and not having a data contract.

You really don't get all the benefits.