Many of the comments seem to be focusing on the initial install costs and missing a big point here. Solar can save a lot of money and even make a nontrivial amount of money for the owner.

As you would expect, there a lot of factors that go into how much an array would save/produce (generation, storage, etc.), but a regulatory factor that changes everything is rate structures. Rate structures are far from a standard thing, pretty much wherever you go, there's something different, it varies by state and even at a smaller, city level for municipally-owned utilities (about 15% of the US is served by these, including parts of Bay Area, LA area, Phoenix, Seattle, etc.).

For consuming energy, there is usually a flat-rate or a time-of-use rate (many varieties) but there are more and more capacity fees and fixed charges taking over. For producing energy, it gets much stranger. Many cities and states use versions net metering [0], some will pay you the wholesale power rate and others will pay you the retail rate (retail is ~3x wholesale), some will use a Feed-In Tariff [1], some will factor in a more time-based rate (like time-of-use above), and some others too. If you want to know more about rate structures in general, check this out [2].
[0] https://en.m.wikipedia.org/wiki/Net_metering
[1] https://en.m.wikipedia.org/wiki/Feed-in_tariff
[2] https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...

Rate structures are heavily regulated, for good reason. Their design is a very difficult task and is pretty murky. On one hand are the consumers and their desire to connect solar and other DERs [3] like storage to lower costs. On the other hand are utilities, usually not acting malevolent, wanting to maintain reliability, and, at all costs, avoiding the death spiral [4], which basically means that more people connecting solar and even leaving the grid will skyrocket costs and tank reliability. Though sometimes, the generators will desperately lobby against them. Depending on where you are, the utilities can be the generators too, another matter.
[3] http://www2.epri.com/Our-Work/Pages/Distributed-Electricity-...
[4] https://www.greentechmedia.com/articles/read/this-is-what-th...

Rate structures are arguably the largest factor in installing solar. Initial costs are important, but the rate structures will affect them over their 30+ year life. In some places, like North Carolina, it can lead to solar flourishing. In other places, hostile rate structures and other regulations can severely harm solar's adoption, like Florida which should be the best place in the US for photovoltaics.

Even more complicating is the ability of the grid to handle a lot of solar, let alone other DERs. The energy grid in the near future can be highly distributed, 100% renewable, and even more reliable than it is today, but there are some big system levels problems to solve before than (these rarely get any attention, most attention goes to node-level problems like sheer generation). I am fully engulfed in this field and am working on these things now. I thought I would present an important point and give y'all some information on this field that I find absolutely riveting. :)