Home batteries are a terrible idea. As a municipality -- or a neighbour -- you don't want 30 houses with 35 different batteries, installed by some nephew who's handy with DIY-stuff.
To just timeshift from daylight to evening/night/morning, you'd need batteries in the 25-35kWh range, 40-50kWh if airco on in the night, another 80kWh if you're driving electric and typically away from home during the day, charge at night. That is a lot of energy to pack, even at the low end. Imagine if everyone finds the cheapest set on AliExpress and DIYs it themselves, and then looks for a new model once current installation no longer matches their needs (capacity loss or use increase)... this must be a fire brigade worst nightmare.
Due to generation being more localised, we also need some form of much more local redistribution and/or storage. But not the nightmare that is one or more poorly installed and poorly maintained batteries of dubious origin per house.
There are a couple points to consider and a couple that refute some of your concerns.
First, you don’t need a full off grid battery setup to benefit. With time of use rates a battery that covers peak usage and even recharges under low time of use rates is a big benefit over its lifetime.
On safety, to sell back to the grid you need an interconnect agreement and inspection of your system. California utilities can install meters that can apparently detect secondary sources of back feeding the grid. Lastly if you try to DIY a correct setup you’ll have to buy UL1741 spec equipment for managing back feeding and equipment with other safety standards relevant to your use. Often this is not a code requirement but in the interconnect agreement and utilities have enforcement powers.
For off grid solar it’s a different story but the NEC always applies. If someone wants to do a comically bad job at their electric work they’re probably going to burn down their house anyway.
In my current home I’ve recently finished removing and replacing all the electric work accomplished by a previous owner’s “contractors.” Nothing like having electrical work run through low voltage grade audio visual wall plates and connectors for zero fire protection IN AN AIR PLENUM THAT GOES FROM MY BASEMENT TO MY SECOND FLOOR. That way if something does catch on fire it didn’t have all those pesky layers of protection between the floors of the house. Literally $30 in parts later and shorting wires get two hours to melt and trip a breaker.
The energy flowing through the batteries is the same despite the different battery brands and inverters. There's now APIs like Enode and others that have open standards for connecting dozens of EVs, batteries, HVAC equipment to react to grid events. Hopefully not too many DIYers out there but we're starting to see new models emerge where aggregators like Tesla, Sunrun, Currents, etc. (still needing PTO) can join the grid thanks to the APIs
Beyond fire risks or whatever, I actually don't see a problem with different battery models etc. The interface to the grid isnt exactly complicated, and decentralised storage seems like it would actually be quite robust and useful.
In a legal sense, most jurisdictions require some form of certification for such systems anyway, and the true diy versions are never going to be very common regardless.
To just timeshift from daylight to evening/night/morning, you'd need batteries in the 25-35kWh range, 40-50kWh if airco on in the night, another 80kWh if you're driving electric and typically away from home during the day, charge at night. That is a lot of energy to pack, even at the low end. Imagine if everyone finds the cheapest set on AliExpress and DIYs it themselves, and then looks for a new model once current installation no longer matches their needs (capacity loss or use increase)... this must be a fire brigade worst nightmare.
Due to generation being more localised, we also need some form of much more local redistribution and/or storage. But not the nightmare that is one or more poorly installed and poorly maintained batteries of dubious origin per house.