Hold a bunch of special rocks close together. They get hot and make water hot. And turns into hot, wet air, which turns a big fan. Hook a magnet to that fan, and spin it in some hoops and you get electricity. Oh, and always, always, always keep the rocks from getting too hot.
Compare that to solar cells, which are semiconductors doped with cleverly designed impurities, and layered to exploit quantum effects to deliver electrical power simply by pointing it at the sun. You can make it more useful by hooking it to a rechargeable battery, which also exploits clever quantum chemical effects to store that electricity. And the combo of these two wonderful quantum-technological devices is cheaper than the reactor.
Both technologies require understanding of modern physics, but it's pretty telling that you can do enough math to make a fission reactor with a hand calculator, and not a high-powered computer.