As much as we love the idea of "net metering" -- being able to supply power back to the grid with home renewable generation, and get credit for it -- the technology has one big drawback: if the power grid goes down in your area, you can't draw power from your home system, even if the afternoon sun is making your solar shingles output power like crazy. There are good technical reasons for this, but it's still pretty annoying. Fortunately, Treehugger points us to a company called Gridpoint, which makes a device that serves as a combined "inverter" (for connecting your direct current solar pv to the alternating current grid) and battery backup. The system draws enough power from your solar panels to keep the batteries topped up, and when the grid goes down, you can still run your home.

It may seem like a prosaic thing -- a battery back-up for the house -- but it's exactly the kind of technology that can make home renewable power that much more attractive to potential users.