I've been part of numerous automotive/diy/fabrication communities the last 20 years, and a few times a year someone makes a statement like you did about not "UL Listed" or not installed by a "certified professional" or "not up to current code" and the scare of insurance not accepting a claim due to these reasons... and in those years not 1 person has ever been able to find a case that has shown that to be true.
Do you have any proof of insurance denying claims because of something wasn't UL listed, wasn't installed by a certified installer, or wasn't installed up to code? And those were reasons given to deny insurance... I'd still like to get an answer on this.
Where I live people are
stupid (said with kindest tone) and often cut down trees themselves very close to home/property to save the 300-500$ a licensed/bonded/arborist would charge, and as you guessed it often lands on the house. I haven't heard of insurance denying these people either. Or the people who leave their pipes open to prevent freezing, forget, then turn the water back on 100% and flood their house.
Not to get too far off topic, but I'm really curious if you've seen any actual claims denied due to any of these reasons, or any other negligence caused by the homeowner, which, IMHO seem to be the
most insurance cases there are aside from natural disasters, which of course carry their own additional add-ons/plans/limitations/etc...
Now, regarding insane amount of batteries... DIY with that capacity is scary as heck and I'm with you, I'd def. want to use a proven, reliable management/regulation system. Ideally a redundant system because I've heard about 10k$+ Lithium packs becoming useless because of the charge method got stuck, or they went to trickle instead of 100% off, etc... IMHO, lithium has a year or two more to go so installers/professionals can understand them more outside of their Automotive and high-end/niche home/boat installs. Right now that info is valuable (read: $$). Not saying it's not out there but it's very hard to compare equipment, setups, etc, when there's very few people dealing with 500AH+ capacity at 12-48v.
I think it would be cool if people had LINKS/URLS to DIY Lithium Packs for home backup, etc...
Def. an area I plan to work with in the next 24 months.