How much solar do I need to run a watermaker?
Somewhere between 92 W and 493 W of panel to make 100 litres a day — a spread of more than 5× that comes down to which system you buy, not how much sun you get.
That is array dedicated to the watermaker, on top of whatever the fridge, the autopilot and the electronics already take — so the upper end of that range means well over a panel of genuinely spare generation, not a panel you already have. It is also a clear-day figure: a week of overcast is the case that actually sizes a cruising system, which is why tank capacity is the cheap buffer.
The honest version of this question is not "how much solar" but "how much spare solar" — and the answer is on your own boat, not in a table. The calculator asks for your surplus rather than your array.
Where this is worked through
Other quick answers
Where these numbers come from. Every figure on this page is computed at build time from the comparison table — rated output and rated draw as the manufacturer publishes them, with watt-hours per litre derived as one divided by the other. Nothing is typed in by hand, so nothing here can drift from the table. Where a figure is an assumption rather than a specification it is labelled as one. Methodology · the table.