Most of standard solar panel installations in homes and buildings don't actually provide decentralization, as they tend to be linked to the grid in a way that they will not provide power at all if the grid is down.
Enabling decentralization requires extra hardware and installation costs, so it's usually not done. Essentially you need a solution to disconnect all your house from the grid in that case for safety reasons - so that your panels/batteries don't send voltage back to the grid potentially killing the repairmen fixing the broken lines, and when the grid does come up, re-linking to its frequency safely is a bit tricky, etc. It's not very hard, but it does require some extra stuff and thus expenses.
There’s absolutely an extra switch that needs to be installed, but I think it’s not so much the transfer switch requirement but two main things; 1) the battery cost, and 2) net metering.
Grid tie solar with net metering gives you all the benefits of a battery (except blackout coverage) with none of the cost. In other words, you get full retail value for 100% of your solar generation no matter when it comes or how much power you happen to be using at the time (because the meter runs backward, the grid acts like an infinite perfect battery)
Net metering is a nice solar subsidy while batteries where extremely expensive, but as battery costs plummet I assume net metering will also disappear. It’s not really fair for the utility after all to be paying solar customers retail rates for their generation.
Without net metering you will only get paid for solar power that you happen to use while it’s being generated, or that you can store for yourself to use later.
Finally, I’m not 100% sure but I would imagine a solar system with a transfer switch and no battery will just immediately overload or brownout if the grid is not there to keep the voltage steady. I would assume you need a battery to be able to serve any variance in your demand (e.g. a compressor turning on) even if your 1 minute average demand is actually running below your generation capacity.
TLDR: Batteries need to be cheap and net metering needs to die before you see most solar deployments that can run off grid.
The good news — if batteries are durable then a battery backed grid tied system can actually pay for the batteries and then some, if you can arbitrage the demand pricing curve. This is a win-win for everyone (including utilities) and IMO absolutely the future we’re heading towards.
Makes sense then,provided each building is self sufficient with it's own batteries to account for low sun exposure (few days of rain with <8hrs daylight)
Unfortunately, they will all be controlled by a smartphone app with its backend somewhere central... That’s just how it always seems to play out these days.
They still will likely connect to the internet in some form, and sets will have the same attack vulnerabilities that can have passive bot-nets that turn on when needed.
