Domestic Case Study with Solar PV Installed

“I was happy with the installation as I know it became very challenging and time-consuming due to the nature of my existing installation. I appreciate the effort that was put in to make sure the new consumer unit matched the existing one and the installation was as neat as possible.”
Chris, Yeovil, June 2017

Case Facts

• Domestic installation
• 3-bedroom end-of-terrace property
• Existing solar PV installation
• Existing solar PV water-heating switch fitted
• Hot tub in the garden
• Annual electric bill c. £1,000 to £1,200
• Savings per annum projected to be c. £120
• Carbon saving c. 13.1 tons over 20 years
• Installation time 5-6 hours

The Customer

Chris and his family have already demonstrated how energy-conscious they are. Faced with rising energy costs, they have fitted solar PV to generate enough electricity to meet some of their needs. They also installed a solar PV/immersion switch that takes any unused electricity from their solar panels and stores it as hot water for later use – a neat way of getting the best out of their own generation and keeping the hot tub warm and ready to use.

The Problem

Although Chris has already lowered his electricity bills through the installation of solar PV and the immersion switch, he was keen to see further reductions in his bill. Chris and his family are acutely aware of rising electricity prices(*).The pumps and heating elements in hot tubs consume a significant amount of electricity and for Chris, this means his household electricity consumption is around twice the national average at c.8,400kWh per annum. The solar PV will help offset some of this – Chris’s system generated 3,450kWh in the last year and the immersion switch will ensure that all the generated power is used in the house without needing to export back to the grid.

(*)Electricity prices have increased by 19% in the last 5 years and 62% in the last decade. (Source: Domestic energy price indices, Department of Business, Energy & Industrial Strategy, 24 Nov 2016.)

The Solution

The key to delivering even lower electricity bills was to manage the voltage in the property to a lower level. Supply voltage measurements were within specification but at the upper end of the permitted range, varying between 237 volts and 251 volts with an average of 246 volts. By keeping the voltage at a steady 220 volts, many of Chris’s appliances – particularly the pump for the hot tub and his fridges and freezers – would consume less electricity, delivering lower bills. In addition, the life of his appliances would be extended as a result of stable voltage and less heat wastage; the lower consumption would enable the immersion switch to deliver more electricity to heating the water; and finally, the BlueGreen app would provide good visibility of what power was being used in the home and what savings were being delivered.

The Results

With BlueGreen remote monitoring, it can be seen that Chris’s BlueGreen Power Saver is reducing his home’s power consumption by 11.6% and delivering savings of £120 to £150 per annum – a great return on an investment of £550– and Chris’s BlueGreen will deliver savings for the next 20 years.