No, I am sure those business entities did the calcs. But read the advertising literature by solar installers which typically says something like "for $10,000 you will save $1,000 on your bills each year, so you get your money back in only 10 years." They conveniently neglect to mention that $1 in the future is worth a lot less than that $1 today because of inflation and lost opportunity costs. So the payback is really a lot longer than10 years and in some cases, is never paid back when correctly calculated.
I think we may be saying the same thing differently. Yes, the entity that is subsidized does OK, but basically as a public policy, it shifts the costs of renewable sources to others. So millions of ratepayers and taxpayers have larger bills so a few thousand of their peers who sign up for solar get lower bills. Fundamentally unfair. If these renewable sources of electric power were truly economic, there would be no need for a subsidy. One of the major costs is the need for backup generation to cover times when renewable sources are not available, not full sun, not enough (or too much) wind, etc. That very substantial cost is a significant part of the subsidy structure.
For the described Princeton operation, the system would need such a backup source which is costly unless it can shift the cost to others by qualifying for a subsidy program. Note also that unlike the business organizations, there is no tax benefit to tax exempt entities so the payback is longer.