Solar panels added to a grid is not plug and play.

When you're connecting solar to a municipal grid (which is what most homes are connected to), it could theoretically be taxed or even subjected to a tariff. The "added" power (often excess) is monitored for billing credits/payout/other, among other reasons like grid integrity.

Plenty of grids have different sorts of net metering ratios, grid maintenance fees, etc. But it's nothing compared to what you'd be paying taking power off of the grid, and there is a break-even period often measured in single-digit years. I still do not understand the point of what the GP was trying to make w.r.t. "taxes".