So before I buy anything, I wanted to know how much I can do with just two 100W solar panels I had lying about and a ~300Wh battery I built myself from lithium cells. Well, turns out, quite a bit!
Not only did the solar panels kept my home networking (internet modem, wifi access points, router, switches, about 20W power draw) running all day — it charged the battery full and it lasted until the morning, zero grid power used — half a kilowatt saved.