Why Big Solar Batteries Don’t Belong Inside Your House

Added: 2026-05-10

[00:00:01]I want to take a minute and talk about battery safety again.

[00:00:04]Like a lot of you, I've got batteries everywhere. Lead acid, LFP, EV batteries, bunch of different high voltage solar batteries.

[00:00:14]So, I'm not saying this is somebody who's scared of batteries.

[00:00:17]I'm saying it as somebody who uses them every day. Large battery banks shouldn't be treated like harmless boxes, especially when they're installed inside a house.

[00:00:27]Before I get too far into this, I want to give a credit to Stash Dee Training.

[00:00:32]He did a really good breakdown of an LFP battery incident that happened in California. I'm not going to replay his video here. You should go watch it. I'll put a link in the description. But, the part that got my attention was this wasn't some half-assed install. It wasn't a pile of random batteries wired up in a corner. This was a dedicated battery building.

[00:00:52]It was insulated, sealed, and climate controlled. From the outside looking in, it looked like somebody really tried to do it right.

[00:01:01]According to the video, the system had six Discover AES LFP batteries with roughly 44 kWh of stored energy.

[00:01:10]This incident wasn't just about fire.

[00:01:13]There was gas, also.

[00:01:15]The battery failed, vented flammable gas, and because the room was sealed tight, that gas had nowhere to go, ignited, and blew up the whole building.

[00:01:25]That's the part I think more of us need to think about. LFP has a good reputation. It's generally a safer chemistry than a lot of other lithium batteries. It's what I'd rather see in most home solar systems. But, safer doesn't mean impossible to fail.

[00:01:41]A battery management system can help a lot. They can protect against overcharge, overdischarge, too much current, and temperature problems. That's all good, but if a cell has internal defects, or something fails inside the battery, the BMS might disconnect the battery, it might shut things down electrically, but once a cell is failing internally, there's only so much the electronics can do.

[00:02:06]At that point, you're dealing with chemistry.

[00:02:09]And when lithium batteries fail, they can vent gases you don't want trapped indoors. Hydrogen, carbon monoxide, hydrocarbons, and other things you really don't want to breathe. So, location matters here.

[00:02:21]If a battery vents outside or in a separate outbuilding, that's still a serious problem, but it's a very different problem than having those gases build up inside your house. That's why I always recommend large battery systems go outside or in a separate structure away from the house.

[00:02:39]Not because every battery is sitting there wanting to explode. That's not what I'm saying.

[00:02:44]I'm saying once you start storing 10, 20, 40 kWh or more of energy, you need to think about where the failure goes. Where does the smoke go?

[00:02:54]Where does the gas go? Can it spread to the house?

[00:02:58]Can it block an exit? Is it near a bedroom?

[00:03:01]Is it under the same roof where your family sleeps?

[00:03:05]That's what I'm thinking about before I ever bolt batteries to a wall.

[00:03:10]And this is why I'm not a big fan of battery closets inside living spaces. I understand why people do it. They want a clean install. They want temperature control. They want the batteries protected from heat, cold, dust, and moisture.

[00:03:24]That all makes sense.

[00:03:26]But if that room's sealed tight and a battery vents gas into it, the same room that protects the battery can also trap the failure.

[00:03:35]That's the problem. So, my rule's pretty simple. Small batteries, use common sense. Big batteries, use separation.

[00:03:43]Put them outside if you can. Use an outdoor-rated cabinet if you can.

[00:03:48]Use a dedicated shed if you can.

[00:03:51]Don't put a large battery bank right next to bedrooms. Don't put it where it can block your way out of the house if you've got a better option.

[00:03:59]If it goes bad, I want it going bad away from the house. That's why my bigger battery systems aren't inside my house.

[00:04:06]I've got batteries in the shed.

[00:04:09]I've got batteries in the barn and in the shop.

[00:04:12]Now, I'm not showing you this as some perfect design because it's not.

[00:04:17]I'm not telling you to copy it. I'm showing how I've chosen to stack the odds. These battery areas are separated from the house and they're not built like a sealed battery closet. You can see the open rafters here.

[00:04:30]That's not an accident.

[00:04:32]If a battery ever vents, I don't want that gas trapped in a tight little room.

[00:04:36]I want it to have somewhere to go. This stuff can hurt you, so install it like it can hurt you. There's a big difference between a battery problem in a separated ventilated outbuilding and a battery problem inside the house where your family sleeps. That's my whole point. I like LFP. I use LFP. I recommend LFP for solar storage all the time.

[00:04:59]But, I don't treat a large battery bank like it's just a harmless box with a Bluetooth app.

[00:05:05]It's stored energy and once you start stacking up real capacity, you need to stop thinking about it like a gadget. This is real equipment.

[00:05:14]And real equipment needs a safe place to fail.

[00:05:18]If you're doing DIY work, you've got to be honest about the risk.

[00:05:23]I'm not saying don't build.

[00:05:25]I'm saying build it like it can fail someday because everything can. You don't design around everything going right forever. You design around what happens if something goes wrong. I can't make a battery failure impossible, but I can try to make sure a bad day stays a bad day and doesn't turn into losing the house. So, for large battery banks, my preference is simple. Shed, barn, shop, outdoor cabinet.

[00:05:51]Something separate from the living space. LFP is a good battery chemistry, but it's still a battery.

[00:05:58]Still stores a lot of energy. So, give it space, give it ventilation, give it proper protection.

[00:06:05]And whenever possible, keep it out of the house.

[00:06:08]Worst case, I'd rather lose a battery shed than my home.

[00:06:13]Or worse.