I have a 400w system on my boat. 4x100w Monocrystaline panels and a 30 amp MPPT. 8x100ah batteries
Even on a modest cloudy day, I can run the inverter, fridge, laptop all day without the State of Charge falling below 100%
On a day like today (28 degrees full blue summer sky) I can run the washing machine or the dish washer on economy washes, again without the SOC dropping below 100% The washing machine and dishwasher are both hot fill, so you have to have hot water in the tank, obviously.
All I am saying is that you will be suprised what you can get away with even on a 12v system.
I fitted a system on a freinds boat last month with a Tracer 30a MPPT with remote panel (deffo needed) and it hasnt skipped a beat.