Here's a redneck way to build something like that: 1) Get a beefy inverter and a beefy battery - the inverter should be rated at 150% of your load, and the bat

Here's a redneck way to build something like that: 1) Get a beefy inverter and a beefy battery - the inverter should be rated at 150% of your load, and the battery should be whatever car battery happens to be on sale. 2) Get a beefy car battery charger. It has to be able to handle 150% of your load as well. 3) You now have a UPS that doesn't discriminate where its power comes from. 4) Get some beefy diodes, as beefy as possible. You'll need quite a few, so buy a 25-pack on digikey. 5) Hook up your solar panels so that they give you 12 volts nominal. Then, use 21 of the diodes to create a shunt that triggers at 14.7 volts (just connect them in series). That is your overcharge protection. 6) Use four more of the diodes to connect the battery charger and solar panel to the battery, in such a way that each power source does not "see" the other (common ground, two diodes in parallel from panel+ to battery+, two diodes in parallel from charger+ to battery+) 7) For the love of God, ground this thing (battery-, charger- and panels- to a metal pipe or a ground connector in a socket). You now have a complete, if small, setup for only calling upon the power grid when your solar panels aren't cutting it. This system can be dismantled into its components quickly, which is nice if you need to charge a battery or need an inverter.