Koichiro Otaki started taking aerial pictures of photovoltaic power stations in April 2015. At first, it was an innocent desire to capture their sheer scale and aesthetic value that motivated him, he says.

Solar parks, mostly in rural, desolate areas, were also among the few places where he could practice flying a drone without having to worry about hitting people or tall structures, he says.

Weather permitting, the 38-year-old freelance photographer would toss a compact drone into his backpack and venture out to the suburbs of Tokyo or up north to the Tohoku region by motorcycle, snapping away at solar panels neatly lined up along river banks, mountain slopes and even abandoned golf courses.