A lot of problems I see here. First of all, "those who can afford 3-5KW systems" are not going to generate revenue. Average home use is reported to be just shy of 900 KW-Hr per month. That's 30 per day, meaning a 5KW system will require 6 hours of sunlight 12 months out of the year. That may happen in some parts of the country, but not too many. Folks "who can afford" a solar system are going to live in larger homes, which means more energy consumed. They likely will have more electric than the average home. I'll use myself as an example, I average 2245KW-hr per month, and 77 therms of natural gas.......which has heat energy equivalent to 2247KW-hr. I can afford a 3-5KW system (and will be doing notably larger in my upcoming build), but I use a LOT more than that can provide.
The financial stress on the grid. Um....the big reason for-profit utility companies are incentivizing solar is not because they are trying to attract the investment of tree hugging Millenials. It is because the grid, and the ability to produce power, are to a point where powerplants are going to need to be built. Nuclear being one of the big ones (that frankly I think should be pushed pretty hard, but that's another discussion). There is not a single one of these utilities that want to make an investment in a powerplant that will take decades to pay for itself. Anecdote, when I was an engineer at Ford, our cost savings ideas had a target of a 30% TARR (Time Adjusted Rate of Return)........that equated to somewhere in the neighborhood of 18 months. Now, powerplants (again, especially nuclear) have HUGE upfront costs, often take YEARS to come online, and don't pay for themselves that quickly. If you give a utility company a way to either delay or eliminate the need to build a big powerplant, they are going to jump at it. So all these micro powerplants (i.e. home solar) are going to be much less costly than building a new big one. Furthermore, for net metering, they are often able to sell the power a home solar system produces at a premium, while providing power back to the home when rates are lower. So they can still make money.
As for how it affects the poor. And for the premise that regulation usually hurts the poor. That's a whole Pandora's box to open up. But the problem is less about it affecting the poor, and more about the lack of information which would allow the free market to handle this. I'm not trying to get political, I'm just presenting the other side of the coin. Low income housing is often poorly built, poorly insulated, and/or very old. Low income housing, in short, is HORRIBLY inefficient. Energy hogs. The energy usage of these places is never part of the discussion, it is just the monthly rent (or mortgage). Some places in the country have started requiring energy usage information to be provided, much like our cars have to have fuel economy information on the labels. Now, if someone is looking at either spending $700 a month in rent and comparing it to $900 per month, they may be looking at $700 rent plus $400 in utilities, compared to $900 plus $150 in utilities. That information will help the market start more properly valuing energy efficiency. But as it is around here, when looking at HVAC and other systems, the energy efficiency improvement has to be measured in terms of a few years (average homeowner lives in a home about 7 years off of memory, and for most homeowners, it is likely lower, as folks move much more frequently in their younger years, as older folks tend to settle in a house for decades). A "better" way would be to just strictly look at NPV. Is it positive over the life of the unit, rather than a few years, then buy it. That gives one a different answer.
I'd contend that the same practice would extrapolate to solar. At least where I live, solar doesn't seem to offer any sort of premium. One of my neighbors just listed his house. Same size house, and it is listed for $13/SF less than mine is valued, AND his home has a nice pool, whereas mine does not. His system would offset about $160/month in utility costs, which would be about $25K on a 30 year mortgage. But again, his listing price does not reflect any added value from his system.
So, yeah, in my mind, one of the keys to solar would be to have the energy costs of an entire house reported, which would then make it a factor in the markets where it is now considered to be financially out of reach. Not that I really want regulation, but if regulation can help make the free market operate a bit more efficiently, I think it can be a good thing (and frankly, I'd expect that kind of regulation to appeal to the normally anti-regulation crowd).
And again, I'm not trying to argue the politics of any of this, just stating factors that are not always considered.
