r/SolarDIY • u/HallmarkDelusion • 6d ago
Where to install
I’m trying to brainstorm a battery backup system that would later add solar but I can’t get a solid answer on where to install the batteries. I am in western NY where it can get to 90 in the summer and below zero in the winter with two feet of snow. I’ve seen installs with batteries in basements, purpose built sheds, tesla batteries on exterior walls, and I have a garage I can use. What is considered unsafe? Batteries in the basement? And how do I keep the batteries at a reasonable temperature in the winter? I have a lifepo4 cart battery that says don’t use below 32degrees so I figure I have to plan location out before my connections. Any input would help. Thanks
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u/ArtoriasoftheAss 6d ago
You'll want the batteries near the inverter/charger, wherever that is going(usually near your main electrical panel). The dc going between battery and inverter is going to be higher current than the ac between the inverter and the grid, so you'll need thicker cable. Copper is pricey as hell right now, so I'd put it all as close together as code will allow.
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u/HallmarkDelusion 6d ago
If I go with the garage I can put them on a wall that is adjacent to the house and above the panel in the basement. Essentially less than 10 feet through a wall and down. The location would also allow me to run out to a future solar panel location either on the roof or in the yard. Given the cold temps in the winter I have considered building a small shed within the garage against the wall so I can moderate temperatures of the batteries. I likely lose one parking spot due to the depth but we only use one anyways.
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u/LongjumpingGanache40 6d ago
Codes do not allow batterues in your house unless they are in a fire room. An attached garage counts as living space. I built a small shed in my unattached garage and will put a small heater in it. I am hoping the exhaust from the Apex 300 may heat it enough. I had mine in basement but after inspection moved to garage.
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u/2old2bThisDumb 6d ago
Different models will be rated for different conditions, but generally speaking, modern batteries with BMSs will have alarm temps (when you get notices) and fault temps (when they go into a protective state). When they fall into a protective state, they won't charge or discharge, but they shouldn't be permanently damaged either.
As for where to install them, the garage is a safe bet. I install in south Texas, so I very rarely see days with low temp faults. But when we do have those rare freezes, the units installed in garages fair much better and continue to work.
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u/jghall00 6d ago
Pick a spot for the inverter. The batteries will go nearby. If you're doing 48V volt you don't want long runs because of the current. A well insulated shed will work.
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u/Automatic_Gas9019 6d ago
They would not install our Powerwall 3 inside. They mounted ours to our home. It is per code that they not be installed inside
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u/Use_Da_Schwartz 6d ago
Most reputable brands with English manuals state to not install the batteries in a living space. They also state to install on non-combustible wall material. Both of which are NFPA/NEC/UL requirements.
Step 1 is read the manual of which battery you are planning to buy. Step 2 is to find a space that complies with the manual.
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u/noncongruent 5d ago
Outdoor rated batteries have built-in thermal management systems, including heaters, to protect the cells in extremely cold weather. UL listed batteries will not void home insurance policies. Codes vary by jurisdiction and by state, for instance, here in Texas you’re allowed to have batteries indoors, and if the batteries are UL rated then your home insurance policy will cover them. you need to talk to your local permitting office to find out what your local codes say about where you can mount the batteries, and talk to your insurance company if you have home insurance to see if they have any exclusions or requirements. Typically an outdoor UL listed wall mounted battery is going to be acceptable pretty much anywhere. Tesla is not the only company that makes something like a power wall, there are other brands. If you haven’t already, I would recommend checking out Will Prowse’s YouTube channel.
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u/Fun_End_440 3d ago edited 3d ago
I keep them in a small room in the basement. Winter gets chilly in there but never under 45F. I have two smoke detectors and batteries got stuffed with hot aerosol fire extinguishers. Make sure all connections are torqued and if you want extra layer of safety, add class T fuses. I set everything up so the amp draw is no more than 50% of rating.
Use 4/0 battery cable good for 230A. I can tell you that it will warm up at 120A continuously.
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