I was also contemplating windshield wiper motor and solar panel. My tests showed I needed at least 30 watt panel, which was too cumbersome in a kayak. So my col

I was also contemplating windshield wiper motor and solar panel. My tests showed I needed at least 30 watt panel, which was too cumbersome in a kayak. So my collapsible windmill equals 24*30 = 720 Watt hours of solar energy. I had 10 liter can and I needed 3 liters/day, so I started the windmill only twice per week.