When using a dc to ac converter as an uninterruptible power supply there are several options. From gasoline based solutions such as a generator or dc to ac power inverters. When deciding how to convert dc to ac power you need to look at several components to make sure you setup the most cost and energy efficient solution that works best for you. If you are going to be using a solar power system or wind based charging system you will probably want to use 12 volt power supply to store your reserve power. You can acquire larger battery reserve by adding additional batteries in parrallel to meet your charging ability. You can then use a 12 volt power inverter to convert dc to ac current to power your electronics. If those electronics requires an uninterruptible power supply such as a submersible pump then a power inverter with charger and automatic transfer switch will be the best solution. There are auto transferring gasoline generators but the gasoline will require to be refilled and wont be rechargeable such as a 12 volt battery. Also if you require to power a heavy load the gasoline will have to be refilled often. Although the original cost with a generator might be lower the constant cost of gas in the long run cost much much more. When a dc conversion is required the most important thing to remember is to find a solution that fits best with your task at hand. If you are simply powering a small device off grid then there is less to consider, but if you are setting up a complete home backup then size of the converter and capabilities will be crucial. The right uninterruptible power supply from dc to ac current will make your life a lot easier. So consider all your options and consider all possible issues you might encounter before finalizing your system.