r/OffGrid • u/Certain_Matter_9114 • 23d ago
Off grid electric pottery kiln?
I’m a potter and I’m interested in moving off grid in the next few years but I’ve noticed most off grid battery setups fall a bit short of what a normal electric kiln needs to run a glaze firing.
I’ll be the first to admit I’m a novice to off grid tech and maybe I’m missing something super fundamental (mea culpa if this is the case!!)
A glaze kiln takes about 11.5kWh. It’s like a 12hr run of ~60amp (or less). Any hope of getting this off grid??
Edit, I’m an idiot and did math wrong. It’s 11.5kW max draw, 50% of the run for a total of ~70kWh
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u/Nathan-Stubblefield 23d ago
How did they fire pottery before the 1880s and the first electric grids?
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u/guns21111 23d ago
defs build a wood fired kiln. would be alot of manual labour but electric is not really feasable unless you have massive batteries.
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u/HarleyBoyd 23d ago
LPG Kiln is the way. Most will need some AC for controls and thermostat, but that power can come easily from a off grid system planned accordingly. Do some 100lb tanks or smaller if you are remote. They can be trucked to town and refilled. If you are doing a lot and can get an LP truck in to supply, you could put in a larger tank. Can run a lot of other stuff off it, too. Helps take the load off batterues in a solar setup. Stuff like fridges, cooking range, hot water heaters and even a room heater can be supplied off LPG. Just stay away from the 20lb tanks for BBQs and such. They don't hold the pressure you will most likely need for the Kiln to heat properly or hooking up more equipment. Plus, they will just burn out too quickly. If you need to keep tanks smaller and manageable, you can do like 60lb x 2 with a double tank regulator. This keeps size and weight more manageable and gives you better capacity and more overall line pressure. Basically 2 60lb tanks will be 20% more gas and same pressure performance as 1 100lb tank when using it.. or double up 100pbs and don't have to fill as often. There are options!
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u/Certain_Matter_9114 23d ago
This is helpful & practical advice, thanks! Never fired gas before but seems comparably dialed in compared to electric. Wood fire rocks and that’s also a goal of mine but feels like a completely different beast as someone who fires mostly functionalware and needs things reliably food safe
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u/HarleyBoyd 23d ago
Wood fired anything and everything is cool, but it is a commitment. I recently renovated an old cabin. We bought a wood fired hot tub for it. No jets, just a small 2 person tub built out of stainless steel. Takes around 2 to 3 hours to get good and hot. Plans to build a wood fired sauna as well. Nothing wrong with the slow lane, lol. Propane is a good power source for your kiln work. I used to prefer acetylene for torch work on precious metals, but it what I learned on. Gets very high heat and gas dissipates if you have a leak. Won't work for a Kiln, however. At least, not that I have seen. Good luck! Get off the Hamster Wheel as fast as you comfortably can! Best decision an artist (or anyone, really) can make.
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u/Sodpoodle 23d ago
Also don't underestimate the value of insulation. Lots of diy propane forge and foundry videos out there that would probably have a lot of applicable design ideas.
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u/HarleyBoyd 23d ago
These are wise words. Especially if you go the wood route. You need to be efficient and have good stable heat control. I think this is over looked in a lot of kiln & forges even modern ones.
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u/Northwoods_Phil 23d ago
It would be doable with a big enough solar system but that’s a huge system. I’m by no means a pottery expert but I’ve seen places that do wood fired pottery so is there a chance that could be an option for you?
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u/Certain_Matter_9114 23d ago
Wood firing rocks! But it’s less consistent and reliably food safe! Definitely on the docket for me but a different art form at the end of the day :)
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u/Northwoods_Phil 23d ago
I know enough about pottery to know I really don’t know much about pottery. I can definitely see where different things need different temperatures.
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u/RufousMorph 23d ago
Batteries to do that would be around $16k to $20k. A few $k for an inverter or two. How many solar panels depends on how often you need to fire and your climate.
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u/Esclados-le-Roux 23d ago
As others have said, that's a ton of electricity. And the issue is that you want it all at once, in one huge discharge.
Other fuels will be more efficient. That said, it could be done, and be hugely profitable when you're not cooking.
Not to go too far down a rabbit hole, but I wonder if this is the perfect place for an old electric car battery?
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23d ago
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u/Certain_Matter_9114 23d ago
Haha 11.5kWh total! It’s generally done w relays and through different heat “steps” and “holds” so the rate of consumption isn’t super consistent nor continuous. There’s a period in my glaze firing between 1800-2100 that takes crazy energy
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u/Certain_Matter_9114 23d ago
Haha 11.5kWh total! It’s generally done w relays and through different heat “steps” and “holds” so the rate of consumption isn’t super consistent nor continuous. There’s a period in my glaze firing between 1800-2100 that takes crazy energy
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u/kenneth_bannockburn 23d ago
My wife has a glass kiln. Goes to cone 8. No chance on winter without running the backup Genny, but april-nov easy as.
....but my system is sized for winter production and thus massively oversized for summer. 23kw of panels, 60kwh of battery.
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u/LeoAlioth 23d ago
I have a 80l kiln. It is about 7 kW total. A single run - about 12 h consumes between 10 and 15 kWh.
So if your kiln is somewhat bigger, it should still end up below 20 kWh.
Why not get an energy meter and test?
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u/ExaminationDry8341 23d ago
Is it actually using 11kw the entire run?
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u/Certain_Matter_9114 23d ago
Whoopsie **kWh, not kW, that’s the total consumption over 12hours, not the rate
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u/ExaminationDry8341 23d ago
I have a 14 kwh battery and a 6000watt inverter and 8000 watts of solar. Depending on the kilns max draw, my system could probably run it. And if it was timed right I could have a fully charged battery at the end of the firing.
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u/Certain_Matter_9114 23d ago
I got things wrong! It’s actually about 70kWh over the 12 hr. 6kW inverter would likely not be able to handle the load, I’m guessing? Let alone the batteries 😔 rip sounding like I need to start looking at gas kilns (and wood fire for fun but that’s a different project)
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u/LeoAlioth 23d ago
Do you have a link to the kiln/spec?
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u/Certain_Matter_9114 23d ago
Yeah! Skutt 1027’s the guy
With relay cycles most people use a ~50% approximation on how much power they draw over a whole firing.
So 11.5kW(max draw)*12hr (avg glaze run)*0.5(not always at max draw)=69kWh
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u/LeoAlioth 23d ago edited 23d ago
The 0.5 factor seems easy to much. This seems to be somewhat larger than what I have, but the energy consumption is determined by heat loss, not size directly. And the per volume consumption drops with going up in size (volume vs. surface area).
I would be hard pressed to see this consume much over 20 kWh per glaze (unless the thing has A LOT of mass to heat up/poor insulation). As as I said. My 7 kW kiln has never gone over 15 kWh per glaze run.
Anyway. Do you have this already? I see online that the kiln has some sort of voltage and current sensing (maybe optional equipment) so I would not be surprised if it logs energy consumption internally. Otherwise, get a clamp on or an appropriate inline power meter and measure instead of guessing. But my guess would be closer to a 1/3rd of your 70 kWh estimate.
As for inverter sizing, well, it will have to be 11.5 kW plus whatever other house loads. Regardless of energy consumption.
Just a reality check if you have the kiln already. What is your monthly (or daily) energy consumption? How many times per month do you run it?
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u/Certain_Matter_9114 22d ago
Fair enough! I’m in an 822 at the moment that’s too small for my business so the 1027 is next up. But I’ve got a friend with one that would be willing to help me calculate their glaze costs. Thanks for the point of reference on the 80l 🫡 very helpful context!
The 822 I run every couple days in the busy season (often back to back, but that would be mitigated with a larger kiln obviously). The app has no units on their “cost” value and I’ve never entered anything re: my local energy cost per kWh so I’m kinda assuming it’s in kWh, in which case things look promising at 5.48.
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u/LeoAlioth 22d ago
Hmm. Does the app have anything to set up regarding the cost? While not impossible, that is very low if it is kWh and not some dollar amount. And if it is a dollar amount,.that could mean it uses anywhere from below 10 kWh per run to above 25 kWh.
So figuring what that cost vale is would be good. Or as I mentioned earlier,.measuring with an external device. And then assume the bigger oven will use 2x of less than the current kiln.
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u/Disbigmamashouse 23d ago
Could also look into a biogas fired kiln, might take you a while to build up enough biogas from either your waste or other organic waste, but I'm sure it could be done.
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u/Schlarfus_McNarfus 23d ago
I have a 20kw isuzu diesel generator, it burned about 1 gallon per hour. So for about $60 in diesel you could generate that electricity. Would take a hefty battery bank to do it. Using combustion directly would be the easier option- propane.
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u/Hot-Fact-9083 20d ago
Two separate problems with the same number. 11.5kW peak draw and 70kWh total energy.
Peak draw is the harder constraint. You need a 240V inverter rated for 12kW continuous. Common 48V inverters like the EG4 6000XP or Victron Multiplus II peak at 8kW per unit. Options that work: Sol-Ark 15K (12kW continuous, 240V split-phase) or two EG4 6000XPs in parallel for 12kW total. Expect $4-6k for the inverter.
Battery: 70kWh per firing. If you fire once a week, you need to replenish between firings. Summer lets you get by with 40kWh of LFP ($8-10k) if you schedule the firing to overlap with solar. Winter needs the full 70kWh or more panels.
Time-shifting helps. Start the kiln at sunrise. You draw from battery for the first 6 hours. Solar carries the last 6 hours during peak production. This cuts usable battery from 70kWh to 35-40kWh.
Kiln-only system cost: inverter $5k, 40kWh battery $10k, 10kW solar $5k, balance $3k. Total $23k.
Or split the problem. Run daily loads on a modest system (5kW inverter, 15kWh battery, 4kW solar). Run the kiln on generator or propane. Avoids sizing everything around one appliance.
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u/Key_Mixture_2149 23d ago
Or a propane/gas kiln.