Hard to say without more information from you because I would like you to consider having a system that will use solar and never have to do anything special when grid power fails. Your computer will not even know the grid failed you. No tending an emergency device.
I've long pondered two projects of this flavour:
- Install an offgrid setup in my shed: solar panels, battery, batter charger, inverter
- Implement an automatic integrated UPS for critical 120V circuits in my house
(1) Would be an interesting project that avoids permitting headaches and would provide some degree of utility - I could use the shed as a home office/mancave, just maintain some semblance of climate control, or gamble that the regulations on renting out ADUs loosen up and further upgrade it with plumbing and rent it out to someone adventurous enough to live in a net ~100ft² structure.
The fundamental problem with (1) is that of location. Winter sun is iffy due to the neighbor's house to the south. Summer sun is iffy in the afternoon due to trees to the west. I doubt I can overprovision enough panels to run even a very small window unit. If I ever want to make the structure habitable I'll just run electrical to the house's main panel somehow.
(2) Has utility similar to the OP's request, albeit without solar integration. The finances however would be questionable - power outages are uncommon and since I live in a standalone detached house a generator works well for emergency power and can run all day on a small amount of fuel for considerably less CAPEX than a few hours of battery power.
More info was asked for , but that is about it. I'm actually inquiring for my son-in-law. They live in an apartment in town. He works from home on the computer/Internet. A few times a year, for whatever reason, they get an outage. It can be anything from a few minutes to a few hours. I thought there would be some simple power source device that he could get and plug his computer into it and be back in business in a few minutes. I've seen these gizmos that folks charge their cell phones with and figured there may be something like that only bigger. Heck, laptops can run on batteries, why not desktops?
An
enterprise UPS is probably what you want. The benefit of a UPS is that you don't have to stop working to futz with reconnecting and repowering your equipment.
One of the many incarnations of the
APC 1500 should provide 30+ minutes of runtime for a high-power setup with its nominal 2x 17Ah/12V batteries - considerably longer for a lighter load such as a laptop, router, phone charger. There's a 3000 variant that looks to double the battery capacity, however it looks to be more than twice as much. These can be found used all the time, however you should plan on replacing the battery promptly in said units.
Do note that the lead-acid batteries in UPSs are effectively wear items that need replacement on a 12-24 month timespan. APC Cyberpower et al are fond of selling "cartridges" at significant markup, however they all use standard SLAs which can be sourced independently for markedly less (use quality batteries for this, natch) so long as one recovers the connectors from the old "cartridge" then reassembles them with new batteries.
The UPS market is ... slowly ... embracing alternative chemistries such as LFP which offer longer lifespans and better density than lead-acid. They're a tad bit pricey and selection is limited.
This, and several spare batteries. Total cost < $500. Milwaukee also makes a similar item.
I've used this very setup before. It's not unreasonable for a short outage where an absolute minimal power demand is needed - i.e. laptop + tethered phone. I determined that two 4Ah batteries would last almost an entire workday.
But it was also disruptive - had to undock the laptop, fire up the hotspot, and reconnect to everything.
