One of my favorite ovens is the Nesco Solar Cooker, which I built was from an old 1940's Nesco electric roaster I watched my mom bake turkeys in while I was growing up. Once it stopped working, she threw it out to be taken away to the dump, and I retrieved it, hoping to fix it. Well, after having it for over 25 years, I realized it could work again, but this time, in the sun. So, I converted it into a solar oven, and it reaches well over 225°F, many times, 300°F on a really clear day. Here are some videos of it: The curved reflector was a pleasant surprise in how strongly it heats the oven.