I found this linked through a thread over at ecomodder.com -
linky,
linky. It's an uninteruptible solar power supply that switches to mains power when solar is insufficient. Calling it a solar UPS is a bit of misdirection though, it's really an offline UPS where primary power is provided by a solar array and backup power is provided by the grid. Depending on the size of your array and batteries, it should be ok for a small electrical load.