I am seeing it as a potential race condition. It would appear the EG4 14.3kWh indoor battery is designed with high quality safety features. Even has built in fire suppression. While it looks like it was built for compliance, I admittedly have no idea if it will be. If it doesn't, I can repurpose it for use by my business.
Not sure what kind of race condition you're thinking of (and I think about race conditions multiple times per week for work so I'm pretty creative about it).
So if you forgo inspection (which 6000XP won't pass in California unless you get a DC ESS -- check out this
thread for the limited user experience with it on this forum), please look at R328 and enforce it on yourself. It includes limits on battery stack size and prohibits a lot of installation locations in a residence. It also prescribes vehicle impact protection.
There are summary PDFs provided by AHJ
The fire suppression is pretty common among 9540 compliant batteries. That indoor wall battery is 9540 listed with the 18kpv inverter So even though a battery might not be 9540 listed (*) to work with all inverters, it would still be held to a high safety standard.
IMO installing outside is better b/c you definitely have a robust fire barrier in the form of the house siding. In my case, I don't want batteries indoors anywhere. My garage is old enough to have bare studs and exposed rafters, so it would have to all be covered by drywall (not sure if it needs to be Type X) before I can install batteries.
Looking at the Discovery ESS, that is $1950 per 5kWh rack mount. Then $2000 for an enclosure that holds 6 batteries (fortunately this makes it weatherproof). VS $3500 for a 14kWh EG4 outdoor wall mount that can only be used with the 18kpv.
So let's look at this
thread for 1741 certified inverters, running on 48V. These are all hybrids, I believe CEC listed and approved for all POCOs in California. SPH10000TL is the most compelling price point. $6500 gets you a hybrid with 5kWh outdoor battery that you can connect to the grid. VS $8500 for 18kpv with 14kWh outdoor battery. And the 18kpv can be configured with a 5kWh indoor battery, with 9540 certification, for $6500.
(*) which is what DC ESS means/helps with -- cross inverter compatible battery. Non DC ESS 9540, IE 9540 without clarifications/qualifications, is always approved with a combination of inverters and batteries. So if you look at the EG4 9540 listings for the 18kpv, you will see a list of like 20 different batteries and battery combinations that it is listed with. It's not really scalable since they have to test & list the full cross product. Well, the testing might not need to be destructive for all combinations, it might be extrapolated after destructively testing one combination. if they actually tested all 10 combinations listed on that certificate, that would be pretty expensive and polluting.