This interesting case study is written for us by Mark Harris of Melksham. It demonstrates how a large domestic solar installation can take you off grid for much of the year. Mark’s installation didn’t come through the Zero Chippenham Community solar scheme, but we do cover the Melksham area. Mark tells us his experience…

Background

I’m Mark Harris and I first got interested in solar when I came across the Government’s Green Home scheme in 2021. I filled in the forms and made my application. A very nice lady came out and spent four hours surveying my home, at the end of which I was told I’m eligible for additional loft insulation (which I declined as I didn’t feel like moving 40-years’ worth of my life) and a small solar system.

The first Solar Installation

In December of 2021 I had 6 x 405W panels and a 2.5kW string inverter installed. A year later I was so impressed with the performance of this system I wanted more.
In the Spring of 2023, I started contacting companies to come and give me a quote for an upgrade to my system. I very rapidly learned that very few companies would do that, including the company that had installed my original system. At the same time, I started watching videos on YouTube produced by people much further along the solar journey than I was. I very quickly learned that you don’t necessarily need a South-facing roof to reap the benefits of solar energy. There was one guy with an
East-West setup and another with a North-South setup so I thought “I can do both”.
However, most of the “professional” solar companies were not keen on the East-West scenario and refused point-blank to put any panels on the North elevation. By this time, I knew exactly what I wanted but trying to persuade the “professionals” was proving difficult if not impossible. They would happily sell me one of their “packages” but when I told them what I wanted to do they were less than enthusiastic.

Finding the right installer…

Eventually I found a local electrical contractor who also did solar and who would do what I wanted. They came and replaced my plastic consumer unit with two metal ones, one for normal (on-grid) operation and one for off-grid operation during power-cuts. They also upgraded my earthing arrangements as they were not up to current spec either, but when it came to buying the hardware things became difficult.
They wanted most of the money up-front (not a problem, but I did have some qualms about doing that), and they wouldn’t use the retailers I had found selling the products at the best prices. Also, they seemed to have a problem with the DNO application (applied twice, rejected twice). They eventually stopped responding to my phone calls and emails and I never heard from them again.
So, back to the drawing board. While I was going back over all the quotes I’d received and the information I had amassed through my lengthy and diligent research one of the companies who had provided a quote previously contacted me to enquire how I was getting on. When I explained the situation, he immediately offered to get his colleague to come and see if they could help. As I hadn’t warmed to this person the first-time round, I wasn’t too enthusiastic but thought ‘what have I got to lose?’.

This turned out to be one of the best decisions I’ve ever made. Danny from TPH is an engineer, not a salesman, and when I explained to him what I was trying to do (now being armed with much more information than on his previous visit) he eventually came up with a plan which worked for me as well as his company. He was also the only person who agreed to set the system up for whole-house backup, something everyone else said they either wouldn’t or couldn’t do, but I knew it could be done from the videos I’d seen on YouTube. Moral – if you’re sure of your facts, stand your ground!
BTW, there are lots of useful videos on YouTube – I can give you a list of channels to look for.

Cost, Return On Investment (ROI) & Installer Selection

My total cost is in the region of £26k, but I have gone totally overboard with everything. Based on 9 full months data (January to September) it will take about 12 years to pay the investment back, but I was more interested in being as self-sufficient as possible and having something in reserve for when the power goes off, as it surely will in the months / years to come.

Power generation improved during the summer as the sun got higher and the days were longer. I’m generating more power than I use and getting paid for the surplus I export to the grid. I have built up a healthy credit in my energy account and hope that this will go some way towards paying my winter fuel bill. Others are doing that already – you just have to choose the right tariffs to make the most of your solar generation and storage. Octopus Energy have many ‘smart’ tariffs, including several for solar / battery and EV owners.
I can also recommend my installer *TPH Solar Ltd (www.tphinfo.co.uk) who have done several installations in the Melksham area. The installer came and surveyed the house and talked everything through with me. My installer is an engineer, not a salesman, so I didn’t get a hard sell on something I didn’t want or need. I knew what I was looking for, so the installer did his best to accommodate me.
I also had to upgrade my earthing arrangements as mine weren’t up to current regulations, plus an external earth rod was necessary for off-grid operation because during a power-cut normal earthing arrangements don’t work. This can lead to a risk of electrocution, which is never a good thing!

*Please note this is Mark’s personal recommendation. Zero Chippenham have our own vetted installer partners.

Performance, Monitoring and Measuring

MyEnergi Eddi diverts solar power to the immersion heater when the batteries are full and the house load is being met. I also have two distribution boards:- one is used for on-grid or normal operation and the other for off-grid operation (during a power-cut).
When the sun shines my system powers the house, keeps the batteries topped up to 100% (for use from sunset to sunrise) and heats the water. During the winter months I exported enough energy to pay for what I buy overnight at cheap rate to charge the batteries. During the summer I didn’t need to do this.

Tariffs & Bills

I was already on Octopus Energy’s Standard Variable Tariff when the system went ‘live’ on 5 of January 2024 and then went onto Octopus Flux on the 1 March. Being an existing Octopus customer with an established export tariff the changeover was immediate and hassle-free.
As I monitor my energy consumption and export daily I noticed an immediate reduction in costs and a slight increase in earnings. This has continued to be the case despite changes to the energy price cap.

Challenges Faced & Lessons Learnt

The main challenge was finding an installer who would do what I wanted. Once I’d achieved that it was plain sailing.
In terms of lessons learned keep an eye on the installer and make sure they do everything ‘by the book’.

Would you do anything differently if you were doing it now?

I would keep the original system and just add a second system with panels on the East and West- facing elevations then maybe replace the panels on the South-facing elevation and add panels to the North-facing elevation later. Also, I would buy only two or three batteries to begin with and add more with the additional panels.

Updates as at 2 October 2024

I’ve had issues with some of the Tigo optimisers going offline (twice). The first time I lost data from the North-facing panels for 11 days. Neither Tigo nor Sunsynk had an answer to that. The installer sent his electrician to check everything through, but he couldn’t find anything wrong. In the end he just rebooted the CCA and that cured it. I didn’t get the missing data back though.
On the second occasion one string dropped out for several hours but came back onstream of their own accord. Again, neither Tigo nor Sunsynk had an answer to that, and I didn’t get the missing data back for that either.
There are two significant issues that I’ve had to deal with and I am continuing to try and resolve. The first is that the roofers didn’t map the optimisers properly, so I don’t know exactly where each panel is on the roof. I’ve managed to narrow down the North and South-facing ones, but the East and West-facing ones are trickier. Also, that should have been done as an integral part of the installation and it wasn’t. The installer has said he will come back and do it but is proving elusive.

The second issue concerns the immersion heater. The Eddi worked well for a few months but then gave up the ghost, or so I thought. The ‘electrician’ came back and discovered the wires were burnt out where the cable from the fused outlet in the airing cupboard connected to the immersion heater element and thermostat. He returned to ‘rectify’ that (with a higher-grade cable), but only connected the heater element, not the thermostat. When I informed him of his error, he came back and
connected the thermostat, but not the heater element. He now refuses to have anything to do with it so the installer has said he will come and put things right. Over a month later I’m still waiting.

Finally, a quick word about support from the manufacturers. I had excellent pre-sales support from Fogstar and Sunsynk (nothing was too much trouble) and first-class post-installation technical support from Fogstar, Sunsynk and Tigo. MyEnergi (who supplied the Eddi) will only talk directly to installers and trying to get an answer out of them by email (as the end-user) takes forever. The product is excellent though.

Zero Chippenham Footnote

Thank you to Mark for providing such a comprehensive case study. As Mark has shown, finding an installer can be stressful, particularly if you want to install a more complex system.

If you are based in Chippenham or surrounding areas including Melksham; Zero Chippenham’s Community solar scheme has pre-vetted installers, who we believe offer a trusted, local service, at competitive pricing. If you would like a no obligation quote for solar, batteries, or solar diverters, or free informal advice on solar, please visit our Zero Chippenham Community Solar Scheme page.