kudos to the guy. Solar water heating in rural areas will reduce the amount of fuel used in cooking. According to various studies, most women in rural areas use firewood for cooking, which the WHO stated some years ago that fumes from it kill 93,000 Nigerian women annually. This solar water heater should reduce that number.

But truth be told, this is not a new invention. It's a very common undergraduate Mechanical Engineering final year project. As common as water. With hundreds of different designs produced in many countries.
Some years ago while I was still in school, a friend of mine designed and produced one for his final year project. He tried to market it but I don't know how far he has gone with it. Engineering students in Nigeria develop a lot of new machines every year as final year projects, but as soon as they graduate that's it, it gets poorly stored somewhere around the faculty into oblivion. I believe universities should further develop such projects, it could be taken over other students or the same student after graduation. Then test run it somewhere, improved upon again, patent it and one day improve lives. Universities in Nigeria should be ranked according to community impact. Let's solve our own problems.