Putting a 20 year old System to use

[SolarCeramics]

Hello all - I'm looking to upgrade my 20-year-old 2.5kw (now about 1.5kw) system. It looks like I'm going with an entire replacement with a battery back-up. However, this new system will be taking up very little roof space - enough that I could keep my old panels up on the roof.

I'm interested in getting an inverter/charger and battery storage system to have a separate off-grid ceramics studio. I have some homework to do to figure out how much electricity my electric kiln needs for a Cone 6 firing (I know it's a single-phase 220v kiln) to know if a battery storage system could be big enough for me to fire it up maybe twice a month.

Any ideas what inverter/charger I might need to look at? My old panels are Kyocera 110W 24v panels in series (24 of 'em). And ideas for a battery storage system? A Cone 6 firing (if it's a fast firing) takes about 8-10 hours, heating up to about 2200F. After that it cools down slowly over another 10-12 hours. It's that 8-10 hours of electricity usage that I wonder what size of battery storage (or what numbers I need to calculate that) I'd need.

Thanks so much for the help!

 

[400bird]

You first need to define loads. The kiln sounds like the largest, any others? What is the amperage the kiln draws when running? Does the cool down run the heaters at all, or does the temp just coast down naturally?

 

[cdherman]

I *think* when you start pricing a battery bank capable of firing that kiln, you will decide against it. Would make a lot more sense to use the grid and time your use of electricity to get better rates.

Agree with 400 that until you know what that kiln draws, you cannot begin this process.

 

[SolarCeramics]

Looking at the paperwork, it looks like it draws 30A - 7.26kw over 240V. But I haven't run a meter on it while it's running.
No other loads, I'm dreaming up a backyard covered kiln area for better venting, and not heating up the house so much in the summer time when I'm firing much more frequently. It's a natural cool down, unless I need to cool it down much more slowly, but it's so insulated that it takes hours and hours for it to cool naturally.

 

[400bird]

For easy math, that's (7.26kW x 10 hours) 72.6 kWh.
That's lots of battery storage needed to run the kiln. Plus, you don't want to use 100% of the battery capacity. I'd be happier with some cushion on the storage capacity. Call it 85-90kWh

So, 18 of these, as an example would be 90kWh

SOK SK48V100-NCBT - 48V 100Ah Base User Serviceable Rack Battery | Current Connected

The SOK SK48V100-NCBT: 4000+ cycle life, Replaceable BMS & Cells. Overcharging, discharging, and short circuit protection. 7-year warranty & support!

www.currentconnected.com

So, $24,000 in just battery. Then you need an inverter and solar.
It's doable, but not cheap.

 

[rhino]

For easy math, that's (7.26kW x 10 hours) 72.6 kWh.

It isn't running continuously for 10 hours so this wouldn't be correct. It just needs to maintain a temp so it will be turning on/off over that timespan. You'd need to be able to measure how much energy it actually uses over 10 hours.
nvm, that one does take that long

 

[DougfromdaUP]

The amount of storage depends on the solar input, too, which 400 ignored. My 10 kW of PV panels would come close to running it on June 21 without storage, but may not make that much energy in two weeks during November.

 

[Quattrohead]

I would remove the old panels and put all new ones up.
Battery does not have to be sized to run the kiln, just fire on sunny days and the resistive load will not mind if the sun is popping in and out behind the clouds.
But depending on your climate area, your highest daily load is going to be AC or heating, you would be better off covering those daily loads.

 

[SolarCeramics]

It isn't running continuously for 10 hours so this wouldn't be correct. It just needs to maintain a temp so it will be turning on/off over that timespan. You'd need to be able to measure how much energy it actually uses over 10 hours.
nvm, that one does take that long

I think you're actually correct, in your first point. When it's firing, it activates the coils (imagine the innards of an old electric oven or electric dryer) in bursts, so it's not a full 10 hours of the coils being on at full. I do need to run a firing and measure how much energy it takes. Is there an easy way to monitor a load - is there something I can tag onto the breaker that the kiln's on and clock the kWs? Looking it up now on Amazon.

It's a 10-50p plug and receptacle - I don't see a kill a watt device that can plug into those. But I do have a clamp ammeter, contactless, that I can monitor the amperage from the circuit breaker and roughly work out how many amps over how much time.

And - I just signed up to put in a whole new solar package with battery backup for the house. I'm just hoping to put my old panels to use - whether to help my neighbors in a wide-scale emergency, or maybe run my kiln in the back yard studio.

 

[efficientPV]

I use a $10 AC power meter with a current sense coil. Just remove one wire and put it thru the sense donut. The AC voltage sense and power to the meter is connected to a 120V AC plug. This makes it very convenient to just plug into any AC outlet and only have to remove one wore for the current sense. I used this to monitor my heat pump which is 240V. I just double the reading of what it is seeing at 120V.

What you want is a blended system with a battery. I have a washing machine that runs off of PV array voltage. For three years I had no problem running it purely from panels. This year I had to supplement it with a battery due to this horrible weather this summer. In good sunlight it consumes no battery power. If a little cloud passes, the battery will supply 150W of the 450W the machine needs in a spin cycle. Anything I do is way too complicated.