UPS for country cabin

My friend just bought a cabin and would like to protect from power interruptions. He wants to provide 20 amp capacity for an hour +. Thanks. 
best deal is a ’on line’ ups, with extra batteries.

Xantrex makes excellent gear (inverters) but that is more purely a 120vac generator system. The kind of gear you use in conjunction with a solar set up and deep cycle batteries. Which is dirt cheap these days..

Liebert or Eaton UPS systems on eBay.

You can buy refurbed units and maybe add on you own battery packs. Depends. These are pure sine wave generators which are always on, and they switch to battery generation when the power goes out. When in normal operation, they pull from the line and make the sine wave, so you are always protected and have very clean power.

Considering the complexity and costs, A xantrex based deep battery and solar set up might be the best and most easy to install.. Solar is about $0.70 a watt, these days, so that is probably the best way to achieve it and have a permanent always working back up system.

A thousand watts in panels (less than $800 right now), a small rack of deep cycle batteries (~$2k), and a xantrex inverter ($2-3k). With the xantrex wired to interrupt and come on line if the power goes out. the panels and the batteries work together, and you get a charge controller and battery conditioning all in one setup. 

If properly handled, this set up can self maintain while one is away, for a bit of time, at the least. It has to do with the battery top up and maintenance. the other alternative is gel type batteries for low maintenance but their density is low and their cost is high.

Flow batteries for consumers are starting to happen and that’s where battery technology is going.

Much appreciated teo. I’ll pass it along and look into it for personal curiosity. Thanks :)
He is in a forested area. Can’t use solar with regular wet weather. West coast wet foggy weather. Has electricity. Just wants unit that will keep stereo going for an hour or so, modest volume jazz/classical when power cuts in rainstorms. 
Then the Eaton/Liebert 'always on' UPS with battery pack might be the way to go. He'd get clean power and the back up, all at the same time.
Second for Eaton’s on line UPS
products. They operate with the battery always in the picture, without any transition glitch when utility power fails. Look for units with pure sine wave output instead of the units that approximate a sine wave. I use Eaton’s 9130 UPSs, and wouldn’t look elsewhere. Reliable as a bag of hammers.