Using Solar Panels and Battery to Fire Kilns
Having found it difficult to find anything on the internet about potters and ceramicists using solar panels and batteries to fire kilns I thought I’d document my experience. Perhaps it might help as I really didn’t have a clue to start with and I have built up a picture. I will share as many details and figures as I can.
First, beware of solar panel companies. I recommend engaging with companies with good, or at least ok reviews, as long as they’re genuine. I ended up with a good company in the end with good customer services which is essential but had put down a deposit down on another, ruthless and unreliable solar panel provider. They’ve since gone bankrupt but promptly started another solar panel business. As far as I can tell there was no expertise, just salespeople and no one to deliver. (I got the deposit back but had to go through small claims)
I have 3 single phase kilns -
10kw kiln
1230℃ firing takes 12 hours, approximately 125kWh
1080℃ firing takes 8 hours, approximately 70kWh
7kw kiln
1230℃ firing takes 10 hours, approximately 90kWh
1080℃ firing takes 7 hours, approximately 40kWh
3kw test kiln
My yearly electricity usage varies between 7000kWh - 15,000kWh a year. Typical annual usage in the UK, medium user, 2-3 bedroom house; 2 to 3 people, is 2,700kWh. (ofgem.gov.uk). The typical way to decide whether solar panels will be cost effective is how much you’ll save on your bills. The solar panel fitters will use this as a pitch and I find the estimates are quite modest. Especially as you get into the idea that the natural next steps would be heat pump and electric car which would further save you future bills and get you off gas entirely. With my electricity usage I would have no trouble making the money back in just a few years.
I opted for 10 solar panels as that’s all I could fit, and 18.8kWh batteries which is a sizeable battery.
The initial idea was to switch to Octopus Go and receive cheaper rates at night when I would fire up the kilns. I thought if I spent the night before loading up the battery at cheaper rates / or solar in the summer months, I could put the kiln on and drain the battery, use cheap night hours electricity whilst also charging up the batteries. If the kiln was still ramping up at this point, I thought that the batteries could kick in without having to pay for the peak expensive electricity that usually starts around 7am.
When geeking out with another ceramicist about this issue prior to fitting my panels, he pointed out that he saw a potter on Youtube who uses battery and kiln firing talking about the delay in batteries kicking in with the ramp (the kiln switching on and off of the kiln so that the temperature goes up at the desired rate eg. 100℃ an hour). Indeed I find there is a delay in the battery and some electricity is downloaded from the grid whilst there is plenty juice in the battery. In the same way there is a delay when you put the kettle on. I find all this goes into the calculations in my head when I’m deciding when to switch the kiln on. I fire quite fast, 350℃ an hour to 1000℃ and then 60℃to 1080℃ for bone china glaze, and for bone china bisque 350℃to 1230/1245℃ depending on my kiln. So after an hour or so, it’s not such a big issue for me. I understand the firing temperatures might be opposite for most other clays but you get the idea.
In the summer months, around 400-600kWh is generated with my panels, 6 on a flat roof, 4 East facing which isn’t the ideal direction but it still works fine. The winter months of November - February do not generate much. For me, the batteries have been the best thing to work with. I switched to Octopus Agile which follows the wholesale pricing and the prices change at half hourly intervals. As a consequence I’ve become fascinated with electricity pricing in the UK and what affects it. As it turns out, the UK is very fortunate as an island with very gusty shores: wind turbines generated 24 % of its electricity in 2020, 13% offshore and 11% onshore. Apparently, the UK has the largest offshore wind farm in the world which is located off the coast of Yorkshire (https://www.ons.gov.uk/economy/environmentalaccounts/articles/windenergyintheuk/june2021). But I’m not clear how localised electricity generation/consumption is. For example, would London be using electricity made in Yorkshire? Unlikely I think, but if anyone can point me to any information on this, please do.
The Octopus Agile Pricing looks like this:
You’ll notice that the price has two peaks - one in the morning (typically 7 - 9am) and one in the evening (often 4 - 7pm). A vague recollection of the supply and demand curve comes to mind from my A-levels, but I think anyone with life experience can see why. Kettles, ovens and other heat generating electricals are very energy consumption heavy as anyone who has switched to a smart meter will have been shocked to discover.
With the batteries, and my ability to choose when to turn the kilns on (where work permits), I make it work with the Agile tariff. At times it charges a lot more than normal so without a battery this tariff would not make sense. Large parts of the wholesale electricity pricing are still a mystery to me, (apart from the oil cartel - nothing mysterious there). When it’s very windy, offshore especially, I find electricity prices plummet, especially around 11pm - 5am. At times, the price plummets to below zero - they essentially pay you to use electricity. The wind turbines and renewables are making electricity in excess of demand and the grid, as I understand it, finds this hard to store. I will be working through the night sometimes to fill a kiln, packed as tightly as possible to get the most out of the space. My maternal family are proudly from Yorkshire after all! These days are occasional but I found quite a few days in October when the rates were very favourable at night. The image below shows this favourable tariff with the weather.
Instead of social media, I have found something else to pore over - the wind forecast. Windy app creates these beautiful wind visuals. I love to understand where the weather is coming from, because I understand where the wind is coming from. To see in real time, the way winds swirl around the globe and how they interconnect is a truth of sorts, I believe.
In conclusion, I do not regret getting the battery and solar panels in the slightest. I feel more in control of how I use energy generated through my panels and from the grid, using excess electricity where possible. I can see a future where each home has their own battery, and even if they don’t have solar, at least they would be able to control when to download electricity and help with the unpredictability of renewable energy production. In this scenario, lithium is a big issue with mining and demand, but if the UK can waste 5 million disposable vapes a month (with spare lithium capacity), I might suggest a home battery for every home might be possible. The other thing I am aware of (and I am sure there are many more, please let me know of any others) is that many solar panels are produced in forced labour camps (https://www.shu.ac.uk/helena-kennedy-centre-international-justice/research-and-projects/all-projects/over-exposed).
How can I end this on a happier note? Let’s do what we can, where we can. Good luck with your project if you are starting out on a similar journey.