For future reference. Anytime people are talking about “their tax bracket” in a progressive tax system, they are talking about the top level bracket.
It’s typically redundant to, mid conversation, list all the tax brackets that exist under the one you’re talking about.
What part wasn’t worth it? You said it’s not worth it, then made it sound worth it.
The ROI is 10-25 years based on the electricity prices you locked in at the start.
With regular inflation, and general increases in the electricity rates, over the long run you’re going to save money. The return might not be investment market level returns, but if you can justify the up front costs it’s unlikely to not come out ahead.