The Section 48 commercial credit can be applied to both customer-sited commercial solar systems and large-scale utility solar farms. The rate is effectively at 30% until Treasury issues guidance on new wage and apprenticeship standards. Two months later, the rate will be at 6%, with an additional 24% (for a total of 30%) available for meeting these new labor standards.
So utility-scale solar farms can get the same 30% credit as rooftop solar. They're both tax-advantaged compared to (e.g.) building a new gas plant, but the rooftop credit isn't any higher, at least not on the federal level. Self-consumption from rooftop solar may avoid other taxes, like sales tax, but in many states there is no sales tax on residential electricity to begin with.
It's part of the "Inflation Reduction Act of 2022" (and at a higher rate than before): https://www.solar.com/learn/inflation-reduction-act/
https://www.seia.org/initiatives/solar-investment-tax-credit...
> The solar Investment Tax Credit (ITC) is one of the most important federal policy mechanisms to support the growth of solar energy in the United States. Since the ITC was enacted in 2006, the U.S. solar industry has grown by more than 200x - creating hundreds of thousands of jobs and investing billions of dollars in the U.S. economy in the process.