The rapid growth of solar farms, battery energy storage systems (BESS) and onshore wind in the UK is creating substantial and growing demand for specialist HV cable jointing and fault finding services. Every solar farm, every BESS installation and every onshore wind project that connects to the distribution or transmission network requires HV cable jointing — at 11kV for distribution-connected projects and increasingly at 33kV for larger schemes. R&D Cable Jointing provides 11kV and 33kV cable jointing, substation installation and HV fault finding for renewable energy infrastructure across the UK.
Why Renewable Energy Projects Need Specialist HV Jointing
Renewable energy projects are not simply a new version of a commercial development HV connection. They have characteristics that make specialist jointing experience particularly important:
- Long cable routes — solar farm inter-array cables and grid connection cables can run for hundreds of metres or several kilometres. Long cable routes mean more joints, and more joints means more opportunity for installation quality to vary. Every joint on a long rural cable run needs to be right first time — return visits to re-do joints in remote field locations are expensive and disruptive.
- 33kV connections — larger projects increasingly connect at 33kV, where the tolerance for error in termination and jointing is lower and the programme consequence of a rework is greater.
- Remote and challenging environments — solar farms, BESS sites and wind installations are typically on greenfield sites with variable ground conditions, limited access and weather exposure during installation. Work needs to be completed efficiently within programme windows.
- Critical energisation dates — renewable energy projects have financial and contractual drivers tied to the energisation date. Delays to jointing or testing that push back the connection date have real commercial consequences.
- Post-commissioning fault response — once operational, renewable energy sites need rapid HV fault response if a cable or joint fails. A solar farm that cannot export is losing revenue every hour it is offline.
Solar Farm Cable Jointing
A solar farm's electrical infrastructure has two main HV cable scopes: the inter-array cables that connect the inverters and transformer units within the site, and the grid connection cable that runs from the site substation to the point of connection on the distribution or transmission network.
Inter-Array Cable Jointing
Inter-array cables on solar farms are typically 11kV XLPE cables — single-core or three-core depending on the design — running between string inverters, central inverters, combiner boxes and transformer units. The inter-array cabling is usually installed and jointed during the civil and electrical installation phase of the project, working alongside other trades on an active construction site.
We provide 11kV inter-array cable jointing for solar farms, working to the project's electrical design, the ICP's connection specification and the principal contractor's construction programme. Clean workmanship, adherence to manufacturer joint procedures and clear documentation are the foundations of our solar farm jointing work.
Grid Connection Cable Jointing
The grid connection cable — running from the solar farm's point of connection on the DNO or IDNO network to the site substation — is often the most technically demanding jointing scope on a solar project. Grid connection cables may be 11kV or 33kV depending on the project scale, and the route may traverse significant distances of agricultural land, road crossings and environmentally sensitive areas.
We provide 11kV and 33kV grid connection cable jointing for solar farm projects, including any intermediate straight joints along the cable route, the terminations into the site substation and the terminations at the point of connection on the DNO network.
BESS Cable Jointing
Battery Energy Storage Systems are being deployed at an accelerating pace — standalone BESS, co-located BESS alongside solar or wind, and grid-scale BESS on dedicated sites. Every BESS installation has HV cable infrastructure connecting the battery containers to the site substation and from the substation to the grid connection point.
BESS Site HV Infrastructure
A typical BESS site has multiple battery containers, each connected via LV or medium-voltage cabling to a central substation. The substation connects to the grid at 11kV or 33kV via an HV cable that is jointed at the substation end, at any intermediate joint positions along the route and at the grid connection point.
We provide HV jointing for BESS site infrastructure — within-site inter-connection cables, substation terminations and grid connection cable jointing. We also provide the substation installation scope — earthing, protection panels, LV STC panels, CT wiring and commissioning support — and SAP attendance for connection day.
BESS Fault Response
BESS sites are typically unmanned or remotely monitored, which means a cable or joint fault may not be identified immediately. When a fault is confirmed, rapid response is important — a BESS site offline cannot charge or dispatch, losing both trading revenue and grid service income. Our fault response service at CableFaultLocation.co.uk provides specialist HV fault finding for BESS and renewable energy sites, with R&D Cable Jointing available for the repair on the same mobilisation where possible.
Wind Farm Cable Jointing
Onshore wind installations typically connect to the distribution network at 11kV or 33kV, with inter-turbine cables linking the wind turbines to the site substation. Cable jointing for wind farm infrastructure follows similar principles to solar farm jointing — long cable routes, multiple joints, remote environments and energisation date sensitivity — but with the additional complication that inter-turbine cables are often buried in difficult terrain on hillside or moorland sites.
We provide 11kV and 33kV cable jointing for onshore wind installations, including inter-turbine cable jointing, substation terminations and grid connection cable works.
HV Fault Finding on Renewable Energy Sites
Once a renewable energy site is operational, cable faults can occur — from third-party damage during maintenance works, from joint deterioration, from sheath damage by agricultural activity on the site or from manufacturing defects that appear under in-service conditions. Fault finding on a solar farm or BESS site follows the same technical principles as fault finding on any HV cable network, but the remote location and the scale of the cable infrastructure can make it more challenging.
Our specialist fault location service at CableFaultLocation.co.uk provides TDR pre-location, decay method and acoustic pinpointing for HV cable faults on renewable energy sites — locating the fault precisely to allow targeted excavation and repair. R&D Cable Jointing then provides the jointing repair once the fault position is confirmed.
33kV for Larger Renewable Projects
As individual renewable energy projects grow in scale — solar farms above 5MW, BESS installations above 50MWh, multi-turbine wind sites — the grid connection increasingly moves from 11kV to 33kV. 33kV jointing requires tighter controls, higher consequence management and careful attention to termination procedure. See our 33kV Cable Jointing and 33kV Termination Procedure pages for more detail on what good looks like at this voltage.
Working With Renewable Energy Contractors
We work with the principal contractors, electrical contractors, ICPs and developers delivering renewable energy projects across the UK. If you have a solar, BESS or wind project with HV jointing or fault finding requirements, contact us with the project details — voltage, cable type, number of joints, location and programme — and we will confirm what we can deliver and on what timescale.
Need HV fault finding on a renewable energy site? CableFaultLocation.co.uk provides specialist HV fault location for solar, BESS and wind sites — TDR, surge pre-location and acoustic pinpointing, with R&D Cable Jointing available for the repair.