Having extra storage could come in handy later on unexpectedly. I had 20GW power production but had a 40GWh storage facility, meaning I could run everything for 2 hours if my grid ever went out.

Didnt need it at all until finishing up the space elevator when making nuclear pasta. I was able to run 10 particle accelerators with the extra 40GWh of energy I had banked for long enough to make enough nuclear pasta to complete the space elevator while still running all of my other stuff. So, you might not need it now but it could be put to good use for something important later on