You are asking whether the cost to upgrade the entire home electric service is includable as part of the cost for installing an EV charging point. That's a problem because the law (26USC §30C) refers to section 179 for the definition of qualifying property, and section 179 was repealed for other reasons, making it hard to look up the actual definition of qualifying property. In other situations, sometimes only the installation cost of the qualifying item counts, and sometimes, you can include the cost of other upgrades needed to install the qualifying item, so there is no "usual rule" to fall back on, and the instructions for form 8911 don't provide an explanation for line 1 (the allowable cost).
Therefore, I can't find an authoritative answer as to whether the cost of upgrading the entire home's amperage can be included in the installation cost of the charge point for purposes of the tax credit.
