Per KM driven. Your EV vendor will gladly use the telemetry to report that to government

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.

Voters vote for Republicans that drive up TCO for EVs, like higher annual registration fees.