We'll see. But I have an outbuilding with a large two plane roof and the south facing plane has no penetrations and is pretty much unshaded. Our utility rates have pretty much doubled over the last three years, and there's another ~30% increase scheduled over the next three years. Said roof is coming up on the end of its expected life, so it may be a good time to put on a new roof and put on solar at the same time.
Could someone get better ROI doing a larger solar project somewhere else? Probably. But if it maths for me, I'm going to do the project on my roof, because I don't have anywhere else to do it (well I could do a ground install, but I'd lose aesthetically)
If it maths with that, great. If not, but it's close, we'll look again when we need to do the roof. Utility prices are rising, panel prices are dropping, it'll probably make sense eventually... Installer costs are going up too though.
I have a system this size and it's fairly rare for me to make less over the day than I use (we have pretty sunny winters where I live and at -27 degrees latitude am not super far from the equator). In summer I tend to produce at least twice as much energy than the house draws.
The economics have skewed a bit as export tariffs have dropped (due to there being so much solar) but batteries have become so cheap and are now subsidised quite a bit too that most people aren't getting just solar systems anymore but now are doing solar+battery.
It would probably technically be a bit more efficient to do larger neighbourhood arrays and batteries, but if they're cheap enough it works fine to do individual homes.
The electricy is consumed in the houses and not on the empty land.
Parking lots become a win-win with electric cars. They also keep the cars cleen and sun protected.
Plus, most solar installs are grid connected so a significant portion of the electricity tends not to be consumed where it is produced. It’s not as if installing solar is an alternative to grid connections for most practical reasons.
E.g. Disconnecting your energy supplier or a power outage will still result in no power usage, despite solar panels generating power.
More expensive inverters and battery systems allow this, although this is far from the norm.
I'm aware of the arguments about how it can be that much cheaper when deployed at mass centralized scale rather than decentralized across a bunch of rooftops, however the way the electric markets are prices is based primarily on the cost to produce the marginal supply, which is usually gas.
So while the power company might flood a bunch of solar panels trying to capture the profit between cost to generate solar vs. cost to generate using gas, those profits haven't been lowering electric costs at residential rates. If anything those costs are still climbing.
It's actually not hard to get rooftop solar to pencil out in that situation, especially if you assume even moderate growth in future electricity rates or inflation. In my own tracker it would even be superior to paying down additional principle on my home mortgage!
Admittedly it would be less of a slam dunk if the net metering was less generous around here as you'd basically be required to add battery to the mix if you weren't already. But even that just prolongs the time to payoff, it still ends up having good ROI economically speaking.
Electricity generation in the event of a power outage was another consideration for me.
But yeah as a techy I also just enjoy having them.
You can't just blindly say "PVs save you money". It matters very much how much sunlight you get, the orientation of your roof, how much electricity costs, how much labor and installation costs, etc.
My location is far from ideal for solar. But with incentives - which are funded in my country via a per-kWh surcharge on everyone's electricity bills - it just barely makes financial sense to have solar panels on my roof.
It is really condescending to dismiss their choice as motivated by vanity rather than assuming that other people might have done their homework and made a rational decision. It might very well be that you have done your own homework and it doesn't make sense for your situation, but other people face different tradeoffs which make it worthwhile.
Off the top of my head the only thing that's really doable without replacing a depreciating asset are certain kinds of insulation upgrades. (And I guess potentially ceiling fan installs.)
On the other hand it can make sense based on arbitrage. In a lot of markets the cost of the system is unfairly subsidized. People on the losing side of that can lower their costs with roof top solar.