After stripping the stone wall of its cement coating to let it dry, the time had come to work out what to put back in its place. I considered insulated plasterboard and timber frame with breathable insulation, but in the end decided to give a lightweight insulated lime plaster a go.
As the description suggests, it is indeed very light and goes by the trade name of Cornerstone Insulated Render. I bought a single bag just to try it out, mixing it was pretty easy and then applied it by hand to wall. We were quite happy to have a traditional knobbly look to the outer wall in the spare bedroom. It took several days to dry fully but the result looked pretty good, additional layers could be applied to increase the thermal insulation value of the wall, while at the same time allowing moisture to escape unlike the cement render. At least, that is the story, time will tell how effective it is.
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While the good weather was here, I finally got around to increasing the insulation above my flat roof in the kitchen. As mentioned previously the installed PIR insulation had been cut through to allow the spotlights to be fitted, so I layed some firm mineral wool over the top. Hopefully this will make a difference come winter.
Already having an account with Octopus, (I managed to get a good fixed rate before the energy crisis for two years) I contacted them regarding removing my gas meter. Octopus dont charge for this service at the moment and I booked the first available appointment. After that no more gas standing charge :-) Having had my Mixergy cylinder fitted for a couple of weeks now, it seemed like a good time to see how it had altered my consumption. The changeover point was very obvious in my gas usage, and pleasingly the highest electricity usage since then was under 2 kWh a day. It appeared that during Spring to Autumn we would be essentially bill free.
I also contacted Octopus about changing my deemed export FIT payments so that I could get an export meter fitted. they advised me to switch my FIT payments to them, which I did by completing a form online. How long the process would take remains to be seen. After months of communications with SSE, then OVO and latterly the Ombudsman, I finally recieved cast iron confirmation that the existing 2.66 kVp solar panel FIT payments had been transferred into my name and that I would receive the FIT payments associated with them. The panels were installed in 2012 and qualified for the highest level of FIT payment, which after the last year of rampant inflation now stands at 60.23 pence per kWh for generation. What was less impressive was the rate for deemed export which is estimated to be 50% of the total generation. That was a paltry 2.1 pence per kWh. Because of this low export payment rate and the fact that I had now had an additional 4.62 kVp solar PV array installed, I thought that it would probably be in my financial interest to investigate whether it would be better to come off the FIT deemed export and instead get an export meter fitted. This would mean that instead of getting a payment for an estimated 50% of the production on my 2.66 kVp PV array, I could get a better payment rate on the actual export of my total 7.28 kVp arrays.
The market leader in these sorts of tariffs is Octopus Energy, and although my FIT provider was still OVO Energy, that should'nt be a barrier to getting the ball rolling. Even after installing my immersion powered hot water cylinder, my daily export in kWh was looking decidedly healthy, averaging at about 10-15 kWh per day over the last month. The Mixergy cylinder was performing well, getting topped up excess solar power from the Eddi which was receiving it from the Huawei solar panels. The only problem was that each of these systems had its own separate app/web software. In addition I was also using OpenEnergyMonitor for the rest of my home monitoring. What was needed was something where I could bring all these sources of information together into one place to give an overview of what was happening. After a bit of research I settled on some open source software called Home Assistant.
The software is very flexibile and already had interfaces for Mixergy, Eddi and OpenEnergyMonitor. I had also found some information on how it might be connected to my Huawei solar system too, but that looked more difficult and would be a task for another day. After a bit of time and effort, I managed to start to get together a dashboard showing some of the most important pieces of data. This could be added to and adjusted as time went on. So with the heat pump now working well it was time to get the Mixergy cylinder installed in the same small cupboard. Since it had been sitting around since last year for various reasons, I was keen to finally get it in and working. Since there were no official Mixergy installers in my area, I convinced a local plumber to have a go under the proviso that I would do all the electrical and internet connection work. Everything went smoothly and by the afternoon of the second day, the combi boiler had gone, gas was capped off and the cylinder was in and charging from the Myenergi Eddi PV Diverter for free. As it was a sunny afternoon, we had two welcome showers and a full tank of hot water from the electricity I would have previously exported.
Initially I had decided to just heat the cylinder via an immersion heater, while this is nowhere near as efficient as using the heat pump, I estimated that I only needed about 3 kWh of hot water each day and this could be supplied from my excess PV, certainly for most of the year. I was going to monitor this and if it occured that I was having to import a lot to do this, then I would reassess buying the heat exchanger needed to hook up the heat pump for domestic hot water heating. |
AuthorEx Radiographer, Information Analyst, Teacher and Self-builder. Now retired Archives
December 2023
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