Assuming that the capital cost of the photovoltaic unit and the even larger cost of the storage system is of no consequence to you, UPS systems come in all sizes, up to those large enough to power a small city (e.g.: Fairbanks, AK) for as long as it takes to start up standby generators powered by diesel, propane or natural gas. If your energy needs are small, you could survive. I am certain that you and society would be better off to purchase your electricity from the commercial power grid and encourage greater efficiency at the commercial/industrial level. A large unit powering a whole neighborhood is more efficient than lots of tiny units. An even larger unit powering a small town is even more efficient... and so on.
If the total cost of solar were actually lower than coal, why would the Chinese be burning billions of tons of the stuff each year? Do they hate blue skies that much?
When the solar panel from the grid has the same efficiency as the solar panel on the roof of a house, it's less efficient to use electricity from the grid due to loss from transmission. It could be cheaper to build due to utilities getting better deals on large orders but from an overall system perspective, it's more wasteful. The cost won't be that different, it will be of no importance for those living in cities though, as they can't exactly generate enough energy for a multi level building with the area on top of it. I'm not talking about an apartment I intend to take off the grid, but a house.
As for China, it has already started to shut down coal plants and invest hundreds of billions in solar with ambitious targets for the future. It can't happen over night (pun unintended) because it takes time to ramp up production and build the farms and more importantly, it's a slave to energy storage and the cost of said technology which is lagging a couple of years behind in terms of where it has to be to work well with solar, but it's getting there. That's why they haven't switched yet completely, but it's in progress.
Speaking of blue skies, the Chinese billionaire behind NIO has this to say "Blue sky coming".https://youtu.be/c7RBK-xSAS0
If you're not familiar with the brand, it's a new-ish company that built the million dollar electric supercar called NIO EP9 which set an EV record at the Ring in Germany late last year of 7 minutes and 5 seconds and an autonomous record at COTA recently. It also unveiled plans for a concept called EVE, a 2020 project for a level 4 autonomous car but it should be known as a participant in FormulaE under the NextEV brand name.
The lap record short cliphttps://www.youtube.com/watch?v=fcJd8wD9qeI
On board videohttps://www.youtube.com/watch?v=nuwKu5fc-U8
I'm just saying, anecdotally Chinese people seem to yearn for a blue sky and their actions in the last couple of years reflect that desire. I mean, where exactly in the U.S. or Europe can you find this?https://www.youtube.com/watch?v=sLo3Pn4KC3w