RedHood -32°C and overcast here currently. I would be dead.
SteamPoweredKleenex Yeah, but this is supposed to be a DYI supplement to your existing system, not a replacement. It kind of reminds me of the solar water heaters being made in Africa with black plastic bags.
It's also something that doesn't appear to have an "off" function, apart from maybe plugging the holes. Even Oregon has to have some hot days once in a while.
Nikon The nice thing about this design is it's not permanently hooked up to the house (he rents). He can disconnect the tubing connected to it when it's warmer.