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Reducing Our Carbon Footprint & Saving Money with Solar Panels and Wall Battery

I wasn't always green natured but in recent years have become a convert, and now take keen interest Renewable Energy development in the UK.

5 x 380w solar panels on our east facing roof

5 x 380w solar panels on our east facing roof

Our New Renewable Energy System

The System we had installed to reduce our carbon footprint, and save money on our utility bill, was:-

  • 10 x 380w solar panels: 5 panels on the east facing roof, and 5 panels on the west facing roof – Total 3.8kw.
  • 5.2kw wall battery: That works with both the solar panels and the National Grid.

Key to getting the best from the system is to have a ‘Smart Meter’ and to switch suppliers to a Utility Company who offers good tariffs tailored for people with electric cars, wall batteries and solar panels.

Our First Steps to Going Green

I did basic research a couple of years previous to help me make an informed decision. It was then that I decided I wouldn’t just get solar panels, but would also get a wall battery; which added to the costs, so it was a case of waiting a couple of years to raise the money. Then, once I had the money to pay for the installation, the next step was to start looking for quotes.

Getting Three Free Quotes

I initially visited my local government website (Bristol City Council) for information and advice, and on their website (which was very informative) they stressed:-

  • That you should get three free quotes, and
  • The Companies who does the installation should be MCS certified.

The local government website also provided a web link to a complete list of MCS certified Companies. In using the link and filter, there were ten MCS certified Companies in Bristol. I specifically wanted to get quotes from a local Company, not only to make it easier during installation, but also to make it more convenient for any after sales service in the years to come.

I studied the websites of the ten Bristol MCS certified Companies, and researched independent reviews on each company. Through a process of elimination my wife and I quickly whittled it down to three potential Companies.

We then contact each Company for a quote, but only one came back with a quote that met our requirements and budget; so it was an easy choice as to who we would give our business to.

What is MCS Certification?

MCS is the Microgeneration Certification Scheme in the UK, which quality assures and provides consumer protection for microgeneration installations and installers. In the UK, without the MCS certificate you wouldn’t be able to get paid for any surplus electricity you generate and export to the National Grid.

Installation Work

If all goes well the solar panels and battery installation could be completed and commissioned within weeks of you paying a deposit to confirm your acceptance of the quote; the actually work itself just taking a day or two.

However, for us, it wasn’t that easy or quick, the whole process dragged on for four long months; but not the fault of the Installation Company, who were very good through the whole process and always responded to my emails within hours, even on a Sunday!

The delays was circumstances; firstly a three month delay because of the chronic worldwide supply chain issues in the aftermath of the pandemic, and further exasperated by local labour shortages due to Brexit. Our solar panels and battery were stuck in China for months waiting to get loaded on a container ship bound for Britain, although our battery is made by a British manufacturer (GivEnergy), they actually manufacture it in China. Just as the UK is a world leader in off-shore wind turbines, so China is a world leader in solar panels.

The final major delay was when it transpired that our earthing (grounding) wasn’t adequate for the solar panels e.g. it kept tripping the fuse. The consumer units (fuses) were earthed to the copper pipes of our central heating system, which is normally considered adequate; but to further improve the earthing, so as to work with the solar panels, the electricity board made a visit to add an earthing block to the earthing of the mains power into house. Once they’d done that the electricians then returned to earth the consumer units to the new earthing block, so that they could complete the installation and commission the system.


Once the whole system was up and running, it needed to be commissioned, part of which is registering it via the web so that it’s integrated into the National Grid, allowing:-

  1. Any surplus energy generated by the solar panels, not needed to recharge the wall battery, can be exported to the National Grid, and
  2. The battery to be recharged from the National Grid at night (when electricity is cheap) as well as from the solar panels during the day when surplus energy is generated.
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Commissioning needs to be done during office hours so that the electricians can make a few phone calls to register the system on the web; and during daylight hours, as the solar panels can’t be seen on the web for registering if they are not generating electricity.

This caused a further few days delay, as although the electricians arrived 8am Friday morning, they didn’t finally get the battery wired up and tested until 5pm in the evening, by which time it was dark. So they had to come back first thing Monday morning to complete the commissioning.

Once commissioned the electrician then helped us to set up access to our system on the web and showed us how to use it.

Our New System Operational

Solar Panels

At the time of installation it’s mid-winter, the sun is low in the sky, days only being 8 hours of daylight, and often it’s cloudy or overcast, so we don’t see a great deal of sunlight this time of year. Nevertheless the solar panels still produce electricity throughout the day, at times enough to power the house for a while, and occasionally even enough to start recharging the wall battery.

Wall Battery

During the winter months the biggest asset is the wall battery that, although we don’t get enough sunlight to significantly recharge the battery during the day, we can recharge it cheaply from the National Grid in the early hours of the morning when electricity is cheap; just 5p ($0.07) per kWh. Once fully charged, even without any sun the energy in the battery is enough to meet all our power needs until around 1pm.

Obviously during the summer, when we have 18 hours of daylight a day, with the sun high in the sky, then not only should we be able to recharge the battery from the sun, but also we should have potentially lots of surplus electricity generated by the solar panels to sell to our Utility Company via the National Grid for on average between 10p & 15p ($0.14 & $0.20) per kWh.

5.2kw wall battery, and other electrics, fitted under our living room window

5.2kw wall battery, and other electrics, fitted under our living room window

Installing Solar Panels & Battery, and Switching to Octopus Energy to Save Money on Our Electricity

Smart Meters

The whole system of integrating the solar panels and wall battery into the National Grid, to enable import and export of electricity at market prices is only possible because we now have a smart grid in the UK; made possible with the rollout of smart meters over the last few years.

Our home smart meter monitor

Our home smart meter monitor

The image above shows our energy usage part way through the month after we've had the solar panels and battery fitted. Two thirds into the month, and showing a significant reduction on what we were previous paying for electricity.

Smart In-home Display (SMETS2): A Quick Guide

Switching Utility Company

To gain full benefits of our new system we had to switch our utility company to one that:-

• Sells electricity to the consumer at the cheap rate overnight, when it’s cheaper because of lower demand, and

• Buys surplus solar energy from domestic users at a reasonable rate.

In the UK at the moment the Obvious choice is Octopus Energy, who not only sells cheap electricity between 12:30am & 4:30am for just 5p ($0.07) per kWh, but will buy any surplus solar energy we produce for typically between 10p & 15p ($0.14 & $0.20) per kWh – dependent on market forces.

Benefits of Cheap Electricity Overnight

The benefits of cheap electricity between 12:30am & 4:30am are that:-

  • Recharging your electric car battery at a cheap rate.
  • Recharging your wall battery at a cheap rate.
  • Putting your dishwasher & washing machine/dryer (devices that uses a lot of electricity) on timer to come on during the cheap period.

We don’t have an electric car yet, but recharging our wall battery during the cheap night-time rate, which (even without the solar panels) then supplies all our electricity usage until 1pm cuts our electricity bill quite noticeably, as does using the dishwasher and washing machine on time so that they come on at the cheap rate.

Introducing Octopus Energy

Octopus Energy

Savings on Our Utility Bill

During the first week of operation; although it’s been overcast and grey skies all week, and therefore not a great deal of electricity generated from the solar panels; we have nevertheless made great savings by recharging our wall battery from the National Grid between the hours of 12:30am & 4:30am (when electricity is cheap) for just 5p ($0.07) per kWh, So even with hardly any sun the wall battery has met all our electrical usage until around 1pm.

Further savings are made by putting our dishwasher and washing machine on timer to come on at the cheap rate time.

So currently the system has cut our electricity bill by about 50%; and of course, during the summer months, when we get 18 hours of daylight instead of just 8 hours during the day, we should not only be almost self-sufficient in electricity but should also be able to export a fair amount to the National Grid, and get paid between 10p & 15p ($0.14 & $0.20) per kWh that we export.

Therefore, over a 12 month period our new solar panels and battery system should cut our electricity bill by at least 75% to 80%, and pay for itself within less than 10 years.

The first two chart shows our battery being recharged from the National Grid (2nd image zoomed in), and the washing machine and dishwasher in use, between 12:30am and 4:30 am; when electricity is just 5p per kWh ($0.07).

  • The red below the ‘0’ line is power being used from the National Grid (the brown being the battery recharging); and
  • The green above the ‘0’ line is our electricity usage; which from 4:30 until around 1pm is predominately from the battery.

The next two charts above shows a brief moment on a cloudy wintery day when the solar panels generate not just enough electricity to power our house, but also surplus to start researching the wall battery (the latter image zoomed in).

On this particular occasion, although it was quite cloudy, the solar panels were producing 1236w, of which 763w was used to meet current usage, and 470w sent to help top up the battery.

Going Green & Reducing Your Carbon Footprint

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2021 Arthur Russ

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