This is a discussion on Easy Backup Power... Cheap within the Alternative Energy (Wind, Solar, Hydro etc) forums, part of the Off-Grid Lifestyle category; Solar power is great, but whole-house systems can get expensive fast. However, for about $150, you can get a decent rig that will give you ...
Solar power is great, but whole-house systems can get expensive fast. However, for about $150, you can get a decent rig that will give you enough juice to power an LED light, small radio, or recharge your portable devices. Such a system won't keep your freezer running, but it can certainly make life easier in short-term power outages. Clever squirrels can also use it as a basis for a more capable system.
The OmniVS 1500VA 940W Line-Interactive UPS would be a good start. This unit (and many others like it) plug into the wall and use household electricity to charge a battery. If the power goes out, they sense it and very quickly switch to battery backup mode. In this mode, power comes from the battery and goes through an inverter to provide 120VAC to the receptacles on the back of the unit. This particular unit also features a USB port. Handy!
It's possible to hack these units and make them more useful. One popular upgrade is to replace the stock battery with a more powerful battery bank in order to store more energy. This hack uses the UPS' built-in charger to keep the batteries topped off. If you want to go this route, however, make sure the unit you choose has a float charger and not just a trickle charger.
It's also pretty easy to wire in a 12V cigarette lighter socket directly to the battery to power CB or mobile ham radios. These typically draw far less power than a computer, so you can expect way longer run times than you would get using the UPS in its intended role.
The ultimate hack would be to have the ability to recharge the battery with solar power. This would involve adding a solar panel(s) and a new charge controller. I would preinstall the controller and provide some way to attach the panels as needed, but would just let it charge from the wall as long as the power is on. Should the grid fail, it would be easy to unplug the unit from the wall and attach the solar panels.
YouTube is full of detailed info about hacking these things. Here's a few to get yer juices flowing...
Success Is going from failure to failure without losing your enthusiasm - anonymous