Case study

Installing solar and saving energy

Terry and Chris Rigden live near Coventry and are now retired.

They’ve been living in their detached bungalow for the last 12 years. Shortly after buying it, they decided to install a four kilowatt (kW) solar panel system as an investment. Since then, they’ve added a diverter (a device that sends surplus power from their panels to their hot water tank), and a battery that can store electricity at their home.

From mid-March to mid-October each year they hardly need to buy any electricity from the grid. In the winter, they charge and use the energy from their battery and top this up with solar power. This has made them practically self-sufficient and saved them lots of money.

They’ve kindly agreed to tell us all about it.

Why did you decide to install solar panels?

“I’m very concerned about the environment, particularly for my grandkids,” Terry explained. “They’re going to have to deal with a very difficult situation in the future, and we’ve got to do something now to try to limit the impact. We can’t just leave it to them. We’ve got to take action now.”

Chris added: “In the early 2000s we started thinking ‘how can we cut down our energy use?’ because we were beginning to be concerned about climate change. And we started by simply turning off what we weren’t using. So, nothing on standby, the microwave and oven were switched off at the wall. When it came to installing the solar panels, we could afford it and we knew that it would have benefits. We just felt it was the right thing to do; saving money was a secondary added benefit.”

What was the installation process like and what were the results?

Chris and Terry fitted 16 panels on their roof. The four kWs of power they generate translates to about 3,700 kilowatt hours (kWhs) of energy annually.

When it came to getting the panels and installing them, Terry said that there were two parts to it.

“The actual installation was all done in a day with minimal disruption. Shopping for the system took a while. It’s important to find an experienced company that is MCS certified, has built up a good reputation and will get the necessary permissions.”

The MCS certification is a quality assurance scheme supported by the UK Government, which certifies products and installers. You can search for an MCS installer in your area on the MCS website.

You should try to find an installer who is also listed on the Competent Persons Register. Registered installers can self-certify that their work complies with building regulations and will give you a certificate of compliance when the work is complete so that you don’t need to submit a building notice.

Chris further explained: “Your chosen company will also consider the direction your roof is facing and whether you have any shading. South facing roofs are the best, but east or west facing roofs will work too. Our house is L-shaped and it’s southeast and southwest facing, so it works great.”

Adding a battery

In 2021, after having the solar panels for a few years, Terry decided to add a battery to the system so they could store and use more of the electricity they generated.

“I had been looking at batteries for many years, and now was the time that we felt that the technology was right as well as affordable,” he said. “I researched various brands of batteries and systems out there and decided on the one that I thought would work best.”

The battery they bought can store eight kWhs, which is roughly 20% above their average daily energy consumption.

“We wanted it to be able to store more than an average day’s supply of energy to help us through the winter days when it is cloudy. This has been working quite well,” Terry added.

Adding a battery means they can store the electricity that’s generated during the day to use in the evening, at times that suit them best.

“We’re on a tariff where we get a cheaper electricity rate at night compared to during the day, and we got this some years ago. In the winter months we charge the battery, then we run the dishwasher and heat the water tank at night when it’s cheap. The cost of energy from the grid is more expensive during the day, so we rely on the battery during this time to minimise our costs.

The electronics of the solar panels and storage battery in the garage.

“As spring comes, the amount we need to import from the grid drops gradually. We can be almost completely self-sufficient for electricity use, including hot water, during the next seven months of mid-March to mid-October.

“I think of it as a system. It’s not just one gadget: it’s the panels, the battery and the diverter that operate together.” Terry explained.

Chris said: “For me, having a battery has made a huge difference to making the most of our solar panels. Before, I was always trying to use what electricity I could while the sun was shining. Now it matters less when I do it, as long as I don’t choose a very cloudy day to use the most energy, or a day in middle of the winter when there’s snow on the panels.”

Using solar panels during the winter

We also asked Terry and Chris whether they still get use out of their panels in the winter.

Terry pointed out that during the colder months, from the end of November to February, “the panels still generate some electricity, except on rare days when there is snow on the panels. But the overall generation will be about 10% of what it is in the summer.”

As this is not enough to get through the day, they import electricity from the grid during the months when they can’t be self-sufficient.

Have you made any other changes around energy efficiency?

Other than their solar panel system, Terry and Chris explained that they’ve slowly been making changes in the way they use electric and heating for a long time, which has also helped them make the system work better.

Terry said he bought a plug-in power meter which he connected to their appliances, and it told them how many kilowatt hours they consumed. “And that’s how I learned that our microwave, which is quite old, used more power on standby than it used in the six minutes it took us to cook baked potatoes.”

They also started unplugging everything that they weren’t using, which they reckon saved them about 10% of their electricity use overall. They also added some extra insulation to their outer walls and loft space to reduce their heating costs.

Chris also explained: “When I need to cook dinner, I don’t just put everything in the oven or under the grill, because that uses a lot of power. I cook it on the hob or in the slow cooker if I possibly can, which uses a lot less. I do bake cakes in the oven, but I try to make two or three things at a time rather than intermittently. I also air dry all the washing. I was gifted a tumble dryer many years ago and only use it very sparingly on cool to give towels a final softening tumble after line drying them.”

How much did the solar panels and installation cost and have they helped you save on your energy bills?

Terry and Chris spent about £7,000 on the solar panels, £300 on the diverter and £4,500 on the battery. They both agree that the solar panels have made a huge difference.

Terry said: “When we had the solar panels installed, they predicted about a 10% reduction in our bills and a seven-year payback. But we actually did it in five and a half. Now, 10 years later, they have paid for themselves more than twice over.

“This is because from mid-March to mid-October, we hardly buy any electricity, apart from a few kilowatts here and there. For example, our bill for August was £0.79.

“To put this in annual terms, I know we consume about 2,750 kWhs a year in electricity. Solar generation gives us 1,800 kWhs a year either directly or via the battery, and we import around 950 kWhs a year, mainly during the winter and with the cheap overnight rate.”

Terry and Chris have achieved these results with an older, cheaper tariff. With the new Energy Price Guarantee*, which is much more expensive than the older tariff, the savings you could make if you choose to install solar panels and use the electricity they generate could be higher too.

Terry also said that since getting the battery they’ve taken the opportunity to swap as many appliances in their home as possible from gas to electric, and now have an electric induction hob, and a couple of electric radiators.

Chris explained, “We recently had our Energy Performance Certificate (EPC) updated and it went from D to B mainly due to the panels.”

If you’re looking to improve your EPC, installing better insulation and efficient heating systems can also help.

*After the announcement by the UK Government on 17 October 2022, the Energy Price Guarantee will only remain in place for all households until April 2023. We’re waiting on further details on what support may be available after this date and will update our website as soon as we can.

What advice would you give to other people thinking about installing solar panels?

It can be difficult to know where to start if you’re considering getting solar panels. Terry gave this advice:

“When you are shopping around, go to a local company with an established reputation and good Trustpilot score. We decided to avoid the big national companies with large advertising budgets as we felt it could have been easy to pay twice as much as you need to.”

“Also, think about what you are already doing in your house and what else you could do, and get all the systems to work together. It’s about prevention rather than the cure. This is what will save you the most money.”

Why do you use Energy Saving Trust?

Terry has used our website on multiple occasions:

“I think your website is useful. You’re not trying to supplement or sell anything, and you are impartial.”

If you’re considering installing solar panels, check out our solar panels advice page for extra recommendations on what you can do. You may also want to explore our page on the Smart Export Guarantee for information about receiving payments on any exported electricity.