You are very observant @oldtimer !!!!
I have a solar powered home, and if you look behind the wood stove you will see a black vent grate. I circulate cooler bedroom air with a powered fan and it blows over the wood stove. On the dark December nights solar power is at a premium, and you could say I have a hybrid home. I can run 100% solar, but there are times I can switch to grid power......I have both. I have one duplex outlet on the grid circuit, and next to it a duplex outlet on my solar inverter circuit. The power is at the duplex's so I can choose what I need just by unplugging and replugging into the needed outlet. The line then runs to a wall switch where I can turn the fan on or off !!!!
I didn't think anyone would notice that !!! :)