Many of the delays affecting renewable energy connections in the UK are not being caused by planning or construction, but by Grid Code compliance issues that are identified too late in the project lifecycle, according to a leading expert.
Enspec Power, a specialist power quality and grid compliance engineering firm based in St Helens, Merseyside, says harmonic compliance is by far the most common issue it encounters, with delays relating to reactive power compliance also a recurring theme across its portfolio of utility scale renewable energy and battery storage projects.
Tim Rastall, Chief Technical Officer at Enspec Power, said one utility scale battery energy storage project experienced significant harmonic issues following commissioning, resulting in export being heavily curtailed for around eight months. A delay that resulted in millions of pounds of lost revenue.
In a separate case, harmonic non compliance on a large utility scale solar project was only confirmed shortly before energisation. The required harmonic filter has only recently entered the design phase, with a manufacturing lead time of approximately fourteen weeks, creating a significant risk of delayed energisation.
In another case, Enspec supported a transmission connected battery energy storage project where the requirement for a 400kV harmonic filter was only confirmed late in the programme, introducing around £2.5 million of unplanned capital expenditure and requiring an accelerated delivery programme to protect the connection date.
Rastall said delays of three to four months caused by late Grid Code compliance issues are becoming increasingly common, with the commercial impact extending beyond engineering costs to include lost generation revenue, liquidated damages, increased financing costs and, in some cases, the risk of missing important connection milestones.
“In our experience, the underlying issue is not simply network capacity but the timing of technical studies,” he said. “Grid compliance is often underestimated outside specialist engineering organisations and studies are frequently completed too late to effectively manage project risk.”
Mr Rastall said the highest risk studies, particularly harmonic assessments, voltage fluctuation studies and reactive power compliance, should be completed as soon as the outline design is known, once the proposed generation capacity, technology, connection point and approximate cable lengths are established.
He added that harmonic filters typically represent less than one percent of total project value, meaning the issue is rarely the cost of the solution itself, but the late identification of the requirement, leaving insufficient time for design, manufacture and installation.
On the wider pace of UK infrastructure development, Rastall said the country is making good progress in expanding its electricity network, but achieving Net Zero will require both continued investment and improvements in the way projects are technically prepared for connection. He pointed to a shortage of specialist Grid Code expertise as one of the biggest gaps facing the industry, alongside inconsistent interpretation and application of technical standards across developers, network operators and engineering consultants.
Enspec is calling for a more consistent industry approach to when the highest risk Grid Code studies are undertaken. In its experience, completing these studies at a consistent early stage in the project lifecycle gives developers the opportunity to identify and address technical risks before they begin to affect programme, cost and connection dates, alongside a more consistent approach to modelling requirements and acceptance criteria. The company also believes improved inverter harmonic models, combined with better quality background harmonic data and network impedance information, would significantly improve the accuracy of early stage studies.
“Manufacturing is often viewed as a constraint, but in our experience, it is not the root cause,” Rastall said. “Specialist equipment can generally be delivered within project timescales provided the requirement is identified early enough.”
Rastall said greater collaboration between equipment manufacturers, developers, consultants and network operators would improve both the quality of studies and confidence in their conclusions, adding that Grid Code compliance should ultimately become a formal project risk assessed during feasibility and concept design, rather than an engineering exercise undertaken shortly before energisation.
