I am looking to mount my solar panels on an uninsulated pole barn about 30m from my house.
Does it make more sense to route my 48V dc lines to my climate controlled house or should I build a climate controlled space for just my solar inverter/batteries in my barn?
Are there any off the shelf containers for battery storage? Like a chest freezer designed to keep the interior at 15c?
The system will be hybrid grid tied with about 7kwH of battery capacity. My house is very shaded, but the pole barn is not. That is why mounting panels on the house is not an option.
Are there any off the shelf containers for battery storage? Like a chest freezer designed to keep the interior at 15c?
A modified chest freezer might actually work extremely well for a DIY solution.
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Already extremely well insulated.
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Keeping a small space like that conditioned to the right temperature will use much less energy than trying to condition an entire (and likely poorly insulated) shed.
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Already has a built-in cooling circuit for when/if the batteries need cooling. You just need to modify or replace the thermostat so you can set it to the temperature range you want. Then you just run the freezer’s compressor whenever the batteries are too hot.
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Just need to add in some resistive heating coils somewhere inside the freezer space (maybe a small space heater), with their own thermostat, giving you the ability to heat the space. (Maybe the defrosting circuit of the freezer can be used for this. Something to look into.) (If you wanted to be really efficient, maybe you could look into adding a reversing valve to the freezer’s refrigeration circuit, allowing it to operate as a heat pump for more efficient heating … but that’s starting to be a really involved modification.)
But … yeah. A chest freezer with some relatively minor modifications could actually be an ideal temperature-controlled battery box!
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Lithium based batteries will perform poorly if they get too cold. How badly depends on the speceific chemistry but all will take a hit.
Depending on how DIY you’re going, you may want to look into Sodium Ion batteries. They are much much more tolerant to cold and still have full performance down to -40 degrees C.
There are exhaust fans with temperature control, that plus some insulation could be a mild diy option.
You definitely want the batteries in a conditioned space. You didn’t say what type of batteries, but I’m assuming LiFePO4. You can store them at a fairly wide range (my hybrid battery does fine all winter parked outside) but charging/discharging them has much more restrictions if you want your batteries to remain healthy and happy.
- Discharging Range: Typically from -20°C to 60°C (-4°F to 140°F). This is the widest and most permissive operational range.
- Charging Range: A much stricter range, typically from 0°C to 45°C (32°F to 113°F). Respecting this range is critical for battery health.
- Storage Range: The ideal range for long-term health is between 10°C and 35°C (50°F to 95°F).
– https://www.anernstore.com/blogs/anern-solar-insights/lifepo4-battery-temperature-range-guide
Those are “absolute” limits but there’s a table on the linked page with the recommended temperature limits and they’re quite a bit more narrow.
Whether it makes more sense to condition the shed or run your PV output 30 meters from the shed depends on the amperage and voltage from the PV. The higher the voltage, the less amperage and thus smaller conductors can be used and less loss along the way. Not sure what your charge controller accepts, so you’ll have to check.
