100Ahrs a day is a reasonable figure for consumption
, but it vary enormously between boats.
Even without living on board you can measure the power consumption
of at least the major items and do a crude power budget
On the production side 300w of solar will just about produce about 100AHrs, but it will also vary enormously depending on location and time of year.
If you are keen to fit solar at this stage I would simply fit the biggest solar array that will physically fit.. No one complains they have too much solar power.
If you are consuming 100AHrs a day you will also need to think about upgrading the size of the battery
bank. Somewhere in the range of 400-600AHrs will be needed, but I would leave this until your current
house bank needs replacing and your consumption patterns are clearer.