What is average length of outage? If it is a few hours then the battery seems like a good idea. If it is days then the battery will probably run out.
> around 50% of the houses in its programme with home batteries also have solar panels
I'm assuming most of these outages are from snow storms. Do these people have to go up on the roof and clear the solar panels?
In New England for decades and power outages >12 hours were very rare for me and I don’t recall any >24 hours. Multiple states and downtown/rural.
If you're in a power outage with solar and a battery you are so much better off than without that.
Most are hours but there are enough that are a day or more that it is a valid consideration. As to when, honestly I think there are more not snow related. Long stretches of wet (or floods) and high winds not a good mix.
In my experience as a VT homeowner we have relatively frequent short outages. It's pretty rural and the weather is brutal. I think the grid doesn't have as much redundancy as denser areas. We had one 3 day outage 2 years ago in the middle of winter which got quite dangerous, but otherwise I haven't had anything more than a few hours.
Also we have propane heat - but I need electricity for the blower and control board. So the electric consumption is pretty minimal, but it is critical.