The UPS approach is novel, and intriguing.
When I think about what is inside a UPS, I realize that the net effect is that there will
still be an inverter (built into the UPS) and there will be two
batteries - one dedicated to 12VDC use, and one to feed the inverter for 120VAC stuff. The result is that while off of shore power, either one of the two batteries could run low, leading to the frustration of having juice... but just in the wrong box.
If you add a solar panel
, which battery
would it charge?
The advantages of the UPS
are that recharging (of one
battery...) is automatic and switchover between shore power and battery/inverter mode is seamless
, while to do this with a separate inverter and common battery
means an autotransfer switch, some wiring, and some form of automatic charger setup.