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Green Home SE725 - David Jones's solar panels charge his electric car and heats his water for free on sunny days in Midlothian

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David Jones lives in a detached house, built in 2013 and of cavity wall construction, in Midlothian. He has installed several energy efficiency improvements over recent years to reduce his energy use and carbon emissions.

Installing solar panels

Back in 2015, at a cost of £8,000, David installed a 4kW Panasonic solar photovoltaic (PV) array alongside a Solax inverter. This system can achieve a maximum daily generation of 25kWh.

David says he was quick to act and get the system up and running before the planned reductions of the Feed-in Tariff (FiT) at the time. There were no dramas with the installation, and it was completed in time and on budget.

David says he’s had no issues with the panels since their installation. David has a FiT contract, and the power that he exports to the grid is metered and paid for in addition to the FiT payments. During the summer of 2020, David’s panels exported between 100 to 200kWh to the grid each month, at a rate of approximately 5p per kWh.

Making the most of solar energy with an electric vehicle charge point

In 2019, David took advantage of a deal through Octopus Energy to install an electric vehicle charge point. Octopus Energy commissioned the installer EVI UK to carry out the work.

David has a Myenergi Zappi smart charger; this has enabled him to use the electricity generated by his panels to charge his car on a sunny day. The charger also gives him flexibility because he can also charge his car overnight without using the solar panels. This means he benefits from a reduced rate of 5p per kWh at night - the day rate would usually be three times that amount.

Later that year, David capitalised on the electricity generated by his solar panels to address his household’s hot water requirements. He approached a local electrician at Dalkeith Electrics to install a Myenergi Eddi diverter. This can communicate with the Zappi charger to heat the water if the amount generated falls below a threshold of 1kW. Alternatively, if the amount generated is above 1kW, it will charge his electric car. Similarly, water can still be heated overnight at the same reduced rate as charging the car.

The electrician was also on hand to replace his first charge point which had failed but was luckily still under warranty. There were no issues with its installation, and it was delivered on time and to the agreed price.

Installing an air source heat pump

In October 2020, David installed an air source heat pump. David says his main reason for doing so was to reduce the amount of energy used to heat his home. His heat pump was installed and funded in 2020 through the Electrification of Heat Demonstration project, a UK Government programme.

David’s heat pump is a Mitsubishi Ecodan 8.5kW system – this only requires approximately 3.2kW of electrical power to operate. David is also happy to have supported local suppliers as many of the heat pump’s parts are assembled in Livingston. The added benefit of using local suppliers is that it reduces the overall environmental impact from producer to consumer.

The installation took three days to complete. His installers (BRB) said this was the most complex single house project they have undertaken!

New, larger radiators were installed because of the greater water flow, albeit at a lower temperature, that would be required to meet the same thermal comfort levels. Similarly, the pipes needed swapping out for a larger bore size to accommodate the increased water flow. David is quick to highlight that this upheaval is only required if the outgoing gas heating system has small bore pipes, which isn’t always the case.

Enjoying the benefits of a heat pump

David has no complaints about his home’s cosiness. In fact, because heat pumps operate at lower power than gas heating and increase the house temperature more slowly (as opposed to allowing the house to cool during the day and then warming up for the evening), the temperature is normally kept higher. David says this means it’s ideally suited to him working at home. 

He’s also found that his household’s energy use has reduced. For example, when he compared his household’s energy consumption over winter 2020 to winter 2021, he found that his daily usage had approximately halved. Even on the coldest winter days, he still found his home’s energy use had reduced by around a third.

David is also keen to emphasise that “our heat pump kept the house warm during the prolonged cold weather in early 2021.”

David says there will also be a small reduction in energy consumption during the spring, summer and autumn when his space heating isn’t required due to the higher efficiency heating of water. He anticipates this reduction to be approximately 1.5kWh per day.

David’s change in energy requirements means he longer needs the Eddi diverter, and he’s looking to pass the diverter to a friend who can heat water using their own solar PV system.

Feeling satisfied about saving energy

Interested in reducing your carbon emissions? David says, “Get a heat pump: they are great, and will reduce your energy use. [However], be clear about the motivation for installing a heat pump. If it is to reduce energy use and CO2 emissions then go ahead, if it is to save money then check that the sums add up if changing from gas.”

He adds, “installing an integrated solar PV, electric car and water heating set-up is a thing of true beauty. It feels good to sit out on a sunny day and watch the car charge and water heat for zero cost.”

If, like David Jones, you’re thinking about installing renewable technologies, our Home Renewables Selector will help you discover your options and calculate your savings. You can also use the Renewables Installer Finder to find professionals in your area.


Updated June 2021.

Post 2003
Air source heat pump (air to water)Electric vehicleElectricity charge pointSolar PVSolar water heating
Low energy lighting systemsSmart meters

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