Two issues I see missing from NREL's analysis: land use and distribution.
I don't see a cost attributed to land in there. It's free for residential because it's already put to use, but not so for utility-scale and probably hard to estimate broadly. Environmental impacts of that land use should also be accounted for in addition to direct land acquisition cost and/or leasing. Solar generation does not have land impacts when placed on a roof. That land is already "disrupted" and therefore allocated for human use.
Either way, labor is now the dominant piece of the cost for residential, and it's obvious that one-off small jobs in high-price metros are more expensive than a crew operating in rural areas. An accounting looking strictly and materials + labor is going to heavily favor utilities, but it doesn't capture the full picture.