2500 Watt Sump Pump Backup Battery System, Automatic Switching to Battery Inverter Power, Professional Backup System in Case of Power Failure, Pure Sine Wave Output Remote Controller with LCD Screen

My brain also went to a UPS, except I was thinking more eliminate the problem. That and a battery would protect OP overnight and they'd have plenty of time to get the generator running before the battery runs out. I'm not knowledgeable enough to explain how but I know you can use the usb port to facilitate a setup that alerts you when the inverter starts providing power. There are also smart ones that have that functionality built in, I believe, but I'm sure those are pricier. And in the future OP could invest in more batteries and chain them in parallel so power outages could be totally hands-off.