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Anyone running an electric kiln off solar battery storage (tesla powerwalls)?


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I don't have a meter on my kiln, but seems like they would just draw too much power for a normal cone 04 or 6 firing as I'm guessing it's in the 40-60 kW range (Is that right? More? Anyone have data from the kiln meter to share?).

Since a single powerwall can only store 13 kW, you'd need FIVE powerwalls to fire your kiln. Would be cool to be off grid, but since powerwalls are ~10 grand a pop, that's too rich for my blood. 

Would love to hear if anyone is doing this successfully, or if my assumptions about power draw is just way off.

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If local power company does "net metering" - where your meter runs backward when solar is producing more than is being used - you can easily "bank" your kiln runs.

We're still on 100% "net," however, many power companies are not doing straight deals. Eighty percent - get back 80 kwh for 100kwh - is common.

Another issue, sizing, it's not always possible to get a big enough array to cover periodic events - like firing - without having the billing history. Our array, for example, is sufficient for running the house and charging the car, but not enough to cover periodic kiln runs.

My take on battery storage, makes good sense at least two ways, i) where there are significant power outages, the storage can get you through; just use less than your solar array generates (minus loss) each day, and ii) where the power company doesn't do straight metering, the storage and loss costs can eventually be recovered. I'm saying at least two ways, for there are several other arguments for battery storage.

There's an energy hit in stuffing into, then pulling out of the battery (loss), so there's that to consider as well. Net metering is more cost effective, and no additional outlay.

As for calc, looks like I'd need five Powerwall 2 units to run my kiln, but it wouldn't run the kiln long enough for a glaze fire, let alone a bisque! 

 

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My skutt kiln is a 48 amp draw. I have run 4 bisque fires which are about 8 hours long.The kiln ramps from 2- 3 hours to be full on so lets say an average of 5-6 houirs at 48 amps.

Now most solar systems on homes are 12 panels-My system has 24 -400 watt panels = 9.6oo watts =9.6k

Most  solar inverters are fixed  in size but they make them that are more flexiable like a sol-ark

I have a Sol-Ark 1200K which can handle up to 12k so you can add  more up to 12k later-its a top of the line inverter with lots of flexibility

This inverter will handle any battery now produced or new ones in the future as its connected to internet and is programable when needed.

Now in reguards to powerwalls any big time brand name like Tesla will cost more

I have 15 kw  in storage which is two of these units  below-toptal cost for the batteries was about 10K

I avoid Tesla or Generac power walls-as you pay for the hype

KiloVault® HAB™ Series
7.5kWh LiFePO4 Battery Storage System

sold by Alt -E -https://www.altestore.com/store/deep-cycle-batteries/lithium-batteries/kilovault-hab-75kwh-150ah-48v-lithium-battery-p41596/#KLVHAB7_5V3

If you buy them on sale they cost just under 5K each 

These carry us every night off on there own.

We are not off grid but use very little grid power as the batterties carry us thru the night with plenty left over

We pump our own water(220v 30 amp well pump) 

I SHOULD ADD A FEW DETAILS

We have extra power with these setup which is used to heat a 80 gallon solar water tank  with a 3500 watt element when extra power is available which is also heated from two 4x8 roof  water panels since 1983 (thanks to Jimmy Carter and his solar incentives)This tank feeds our natural gas fired water heater. 

I built  and wired these systems myself as I have worked as a sparky before in life.Our panels are ground mounted as well so easy to keep clean.

So to answer your question our system which is hooked up to a 50 amp breaker (most home solar systems are either 30 to 50 amps in total output) will fire the electric kiln on a sunny day about 2/3 or a bit more along with the hosue power needs. I only fire it during daylight hours so not to use battery power but we have enough to add that to it. I start it by 8 am and its off in 8 hours and I have not yet done this in winter (lesser daylight) Our system is less than a year old and our kiln fire does show on bill bits it a small amount . We live in a very high electric rate area as well. 

 Some more info=Kilns suck watts and solar does not like the on and off cycling that controllers do-say 48 watts on and off like my fire right does so I tend to turn off the solar/kiln connection for a few hours until the kiln is on full as then its constant load which solar is great at (the inverter in the main isssue of on and off not the panels)

So yes I'm doing it but I also invested 25K into this system so I have prepaid for our electricity so of speak.

I have yet to know  what our payback time will be until this years taxes are done as I bought another battery this year as well as a few odds and ends so the tax credit needs to be included into that calc. Then added to last years tax credits. It was a great thing to knock 7 k off my tax bill last yaer and rool some over to this year as well. 

Using just batteries makes no sense but a larger panel system does make some sense and I got a great deal on the 24 -400 watt panles at $195 each so the panels where the cheapest part of the system. I love mechanical ssytems and this job was a great fun but lots of work.

We are not on a net metering contract with utility -just using very little from them . 10 years ago I put in a 12kw natural gas generator fro backup power which was for outages (we average 5-7 a year). This system is also still hooked up and is auto on when the grid goes down. Our power system is very complex.

Hope this answers some of your question

 

 

Edited by Mark C.
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There’s a potter in my area with a large homestead property and a 100ft solar panel array. She says in most months, she generates more power than she needs. I wouldn’t run kilns on solar unless you have the space to get an oversized system. 

20 years ago I bought a rechargeable battery lawnmower (back when that idea was new and the technology wasn’t very good). It really sucks when you run out of juice before you finish the lawn. The battery should have been enough for my little yard, but lots of unforeseen factors would come up (wet lawn), which can happen in a kiln too (aging elements). I would imagine if this happened with a glaze firing it would be incredibly frustrating. If this is a business it could be ruinous. 

Whatever you choose, make sure you never start a firing thinking I HOPE there is enough juice. 

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I agree with @GEP . Unless you have a huge solar array, the best way to combine solar and kilns is to remain on the grid and produce enough to offset the cost.

11 hours ago, Mark C. said:

Some more info=Kilns suck watts and solar does not like the on and off cycling that controllers do-say 48 watts on and off like my fire right does so I tend to turn off the solar/kiln connection for a few hours until the kiln is on full as then its constant load which solar is great at (the inverter in the main isssue of on and off not the panels)

I wonder if the the fast (1/2 second) cycling of SSR relays would be better or worse?

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15 minutes ago, neilestrick said:

I agree with @GEP . Unless you have a huge solar array, the best way to combine solar and kilns is to remain on the grid and produce enough to offset the cost.

I wonder if the the fast (1/2 second) cycling of SSR relays would be better or worse?

I think better as the shorter surge would be best. Either way large surges are not great for any inverter. They work best on constant loads

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Not worth it IMO.  As Mark C. noted above a little 48amp kiln in 8 hours would use 92,160 watts  (92kw) if it was on continuously.  Same reason solar/electric heat isn't used on swimming pools.  Maybe someday, as we get more efficient in both kilns and solar arrays.

 

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With respect, Mark_H, I disagree. Swimming pools require constant, else near constant circulation and (seasonally) heat.

With net metering, one may easily "bank" your 92 kwh within a reasonable time, e.g., our son's system is generating ~35kwh/day this time of year, of which they are using about half of that*.

Worth it, that's key. We figure that we'd recover the outlay for our (small) system within eight years, however, as we run an electric car, more like 4.5 years, however II, as electric rates have gone up considerably, just over four years flat - a year ago.

*Granted, they go through most of their "banked" power during the short days, which are quite short, as they are well North and in a canyon - "just sayin'"...

Edited by Hulk
out o' th' red over a year now
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I think sellling back to utility as Hulk says is a very reasonable way to fire a kiln and use solar . You bank the hours for a year  with your utility (everry one has different rules and some this will not work with) and settle up once a year so doing so will pay easliy for kiln firings . The amount of fires will matter but a dozen is not out of the question .

I am a solar Pirate  sort of speak for other reasons not kiln firing.

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https://batterytestcentre.com.au/wp-content/uploads/BatteryTestingReportMarch2021.pdf

A nice report to browse through. Interesting that Tesla does it’s own test according to the protocol.. Also interesting is you might find less popular producers actually appear to produce the best battery arrays / systems.

Based on energy density, cycles, charge / discharge, deep discharge, etc…. using the grid as your personal battery storage has many benefits if you can get it at a decent rate.

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Banking excess would mean the system is way oversized for the kiln, after all your household use.  Unless you're firing the kiln at a frequency you have time to 'bank'.  It could offset it, but at the time I ran the numbers it wasn't feasible for that large of a system.  I'd be interested in the frequency of kiln firing to get away with a substantially lower cost.

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On 7/7/2021 at 9:21 AM, Mark_H said:

Not worth it IMO.  As Mark C. noted above a little 48amp kiln in 8 hours would use 92,160 watts  (92kw) if it was on continuously.  Same reason solar/electric heat isn't used on swimming pools.  Maybe someday, as we get more efficient in both kilns and solar arrays.

 

So my system is 96kw which  is in optimum conditions can do a fire-the most output I have seen is 8,600.  If I was to use the utility as a bank its easliy done. Just spend 25k and firing is near free

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