Ground Source Heat Pump and Solar PV Project in Somerset

Example of ground source heat pump

The Project

Earlier this year we were contacted by a client who wanted to cut the running costs of his family home, and reduce their carbon footprint by eliminating their reliance on heating oil. Paul made a site visit to discuss their options, and it soon became clear that this would be an interesting and unusual project.

After more discussions, help and advice from Kensa Heat Pumps, and some excellent suggestions from the homeowner, Evergreen was able to come up with a suitable system design.

The Solution

There are two dwellings on the same site. This opened up the possibility of two Ground Source Heat Pumps being installed, both connected to a Shared Ground Loop Array, (SGLA). This arrangement allows the owner to apply for 20 years of Non-Domestic RHI payments from Ofgem.

The incoming electricity supply was upgraded from a single phase to a three-phase supply by Western Power Distribution.

The two dwellings were each provided with a Kensa 15kW Evo three-phase Ground Source Heat Pump, a 250-litre unvented hot water cylinder and 150-litre buffer vessel. Evergreen also carried out the necessary alterations and additions to the existing space heating systems and the upgrade of the electrical system.

Fortunately, this site had plenty of room for the required slinky trenches. The trenches were dug and the slinkies and header pipework installed. Sand was used to protect the slinkies and the trenches then backfilled (as seen in the images below).

Illustration of how ground source heat pumps work
Trenches dug ready for the slinkies for a ground source heat pump install
The ground after refilling for a Ground Source Heat Pump

Evergreen also designed and installed an 11.7kW ground-mounted solar PV system. This system consists of 36 all black monocrystalline modules, mounted on a ground mounting frame supplied and expertly installed by Chris Searle of Solar Frames South West, (inventor of the ‘Cornish Rocker’ mounting system). A three-phase SolarEdge inverter was then installed in the plant room.

SolarEdge inverter installed in the plant room in a ground source heat pump install

We also installed two SolarEdge immersion controllers to further reduce running costs. These devices send spare generated power from the solar PV system directly to the immersion heaters, meaning more self-generated power is used and less gets lost to the grid. These can be controlled via the online monitoring App. 

The monitoring has proved to be a really useful feature. It shows how much power is being generated by the solar PV system, how much is being self-consumed, how much is being exported and how much is being imported from the grid. Crucially, it shows when this is happening. This allows the home owner to change behavior and change settings on current using devices to utilise as much of the free self-generated power as possible.

An air-source heat pump was installed (by others), to heat the new swimming pool. The solar PV system will greatly reduce the running costs of this, particularly during the summer months.

With a team of expert plumbing and heating engineers and qualified and experienced electricians, Evergreen was able to carry out all the associated plumbing and electrical work. Then properly commission the systems, notify building control, and then carry out DNO notifications for the heat pump and solar PV installations. Most of this was done ‘in house’. The only subcontractors used were Chris Searle installing the ‘Cornish Rocker’, and a groundworker who excavated and back filled the slinky trenches.


"We used Evergreen for our renewables project. At the time, we were new to renewables technology, and our project was quite complex and it was a significant investment for us. Evergreen impressed me from the outset, with their knowledge of the renewable technology options available, their guidance on the different government incentive schemes and the approach they took to helping us determine a solution design. 

They particularly impressed with their full in-house capability to carry out the whole project. This meant that they could install our renewable solution without needing to bring in additional subcontractors, reducing the complexity for me to manage and reducing the disruption to us during installation. 

They helped us a lot at the design phase - and were very patient as our requirements changed! During the project scoping and the installation phase, the team on-site was always very professional and personable. Since the project has been completed, the after-care has been great. I'm a happy customer and pleased to recommend Evergreen!"

Another satisfied customer!

Posted on November 23rd 2020

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