There’s a lot of focus these days on solar energy, on harnessing the light from our nearest star to fuel our daily activities. Plants, of course, have been doing just that for millions of years.

Tom Laidlaw wastes no time when there’s a new skill to learn. The 80-year-old retired electrician has always been a “do-it-yourself kind of guy,” he said. For a while, it was skateboards he fancied, ...