I don't know anything about the particular brand, but when I was in college and taking an Energy-Efficient Design class, as a way to illustrate solar heat gain the prof had us make solar ovens. You'd be surprised how much you can cook on a sunny day with just a basic box oven and a black cast-iron pot! Then again, this was in southeast Texas, where it often felt like you could steam veggies just by leaving them out on the porch.
It's an efficient and effective cooking method, but it requires planning and sunlight. On a hot day I daresay it would be a better way to bake or roast than using the oven inside a trailer already struggling against the heat!