[desman]

I've been thinking about similar setups with lots of batteries as I have excess energy I can generate during the day and a lot of otherwise barely usable space in my attic. Fire hazard is my major concern. How do you make sure old (or even new) batteries don't do their usual thing, especially if they are in an environment with unstable temperatures and scarce monitoring?

[hengheng]

Old laptop cells are going to need a lot more babysitting than a new LiFePO4 rackmount battery. Those generally do pretty well with the internal monitoring that they bring. Semiconductor fuse as overcurrent protection, passive balancing and monitoring of individual cell voltages seems to get you pretty far. Get your 48V or 51.2V battery in 5 kWh, 10 kWh or 15 kWh cell size from one of the Chinese outlets in dubious quality, or from real brand names like Pylontech. RS485 is usually present and there are kludgy home-assistant gateways, but they're not required for safety.

External monitoring is made by Victron, who initially did electrical solutions for boats. Their inverters are also very popular and pretty great.

Also, brick walls are kinda nice I have to admit, along with an exhaust for any fumes.

[desman]

yep, I have brick walls downstairs where space is more scarce, the attic has lots of space but also lots of wood lying around.

I guess another possibility is to have the battery pack outside, attached to the brick wall, and ideally away of direct sunlight... but then no wooden roofs. It looks like no DYI is really feasible except maybe a concrete bunker as others have suggested. And even then it's probably uninsurable which is considered a no-no where I live.

[txdv]

Major selling point for official solutions by companies.

Their solutions need to comply to safety standards.

[christkv]

This is my main problem with having a battery in the house. Once sodium based batteries and compatible inverters get on the market I might switch them out to lower the risk of catastrophic failure and losing the whole house.

[IAmBroom]

> unstable temperatures and scarce monitoring

You've described the worst possible place to locate them.

[newsclues]

Build a shed, or a bunker!