Yes it is if you read the article, that's exactly how he had it set up, and then you just have to manually move the battery where power is needed. You just can't use your wall outlets when there's an outage.

48v 100ah battery with Bluetooth BMS built in is around 700$ on ali express... Slightly more direct from Amazon in the USA if you want it fast. Will store close to 5kwh which I guarantee you beats out this solution. Of course you'd still need to buy the grid sync inverter (available in many places) as well as a solar mppt charger and solar cells. Still will come below this cost - or you'll simply blow by the capacity of what you would have paid for this solution. But gotta have the old noggin on straight to do it yourself.