My (tracking) back-up system was made for a unique 2-part event.
1. Heavy rain has caused ground water to rise, which will lead to basement flooding.
2. The grid fails and I need a few hours of AC power to keep my pumps working.
(I've only seen this unique event happen a few times in the last 30 years,
but we just replaced the basement flooring, from the last flood).
I also own a 5KW gas generator, which I can use in the case of an extended grid outage.
It's not something that I would want to use during an ongoing storm.
Because of the way life seems to play tricks on me, I'm pretty sure that
my back-up system will never be needed during it's life-time. (or mine).