The project in Caterham, Surrey will generate 12MW and has a 2025 connection date to the grid

We’re excited to announce that we have received planning permission for a new battery energy storage site in Caterham, Surrey.

The site, adjacent to Caterham Bypass, will add a further 12MW to Root-Power’s growing portfolio when it goes live in 2025, and has been designed with a 4-hour storage duration, enough to power around 24,000 homes which is equivalent to the entire population of Caterham.

The news comes following an exhaustive development process resulting from the project’s sensitive location within both the Greenbelt and the Surrey Hills Area of Outstanding Natural Beauty (AONB).

Our team consulted extensively with the AONB officers and local wildlife groups ahead of submitting the planning application in late 2023 and then supplemented the planning application with a comprehensive Alternative Site Assessment (ASA) and Greenbelt Justification Report.

Development factors such as proximity to the Point of Connection (POC), distance from residential properties, size and location of potential alternative sites within the area, were all considered to rule out alternative locations. The report concluded there were no other suitable locations for development which fell outside of the AONB or green belt, a conclusion which was supported by the ANOB officer.

The development site is also designated as one of the UK’s 56 ‘Habitats of Principle Importance’ (HPI) and it was required to demonstrate that the existing habitat was possible to replace before planning the development could progress. We achieved this through a combination of on-site biodiversity initiatives and through an agreement to secure off-site biodiversity units via a habitat bank making the project one of the first in the country to be consented conditioned on securing off-site biodiversity units and the first for Tandridge Council.

Neil Brooks, Managing Director at Root-Power said: “We’re thrilled to have received the planning consent for our new site in Caterham, Surrey. Because of the project’s unique combination of planning constraints it has been a challenging project to secure planning consent for and we are pleased we’ve been able to secure this consent via delegated decision, without the need for appeal.

I’m delighted with the outcome and impressed with the team’s efforts over the last few months. This project is further evidence of Root-Power’s ability to secure planning permission for renewables projects in the most challenging of environments.

“I would also like to thank the people and organisations we worked with along the way, including Tandridge Council and the Surrey Wildlife Trust. Their expertise and advice were second to none, and we’re glad we could work together to establish the best possible conditions for the site.”

We are looking forward to the Tillingdown Farm site joining our portfolio of battery energy storage projects when it goes live in 2025.”

In July, the National Grid Electricity System Operator (ESO) proposed changes to the Capacity Market (CM) de-rating factors methodology to a ‘Scaled Equivalent Firm Capacity’ (EFC) approach. The first time they will be in use will be for the T-1 and T-4 CM delivery years.

The EFC approach is a method used to determine the reliable capacity contribution of a variable renewable energy source – such as wind or solar – by calculating the amount of firm, conventional generation it can replace while maintaining the same level of system reliability. This approach quantifies the contribution of renewables in terms of the equivalent amount of reliable, dispatchable power they provide to the grid.

A de-rating factor is a reduction applied to the nominal capacity of electrical equipment or power systems, such as those managed by the National Grid, to ensure reliable performance under varying operational and environmental conditions. It assumes that nameplate capacity may not be available when its needed – for example, for solar, this could mean the system producing significantly less power due to reduced sunlight on a cloudy day.

Making the market more competitive

Years had passed with the de-factoring calculating methodologies largely being unchanged – however, at the time of their inception in 2017, the UK Battery Storage Database report from 2017 shows installations for large-scale battery storage only reached 100MW of capacity across the UK. As the Battery Energy Storage Systems (BESS) sector was still in its infancy compared to today, the ESO de-rating factors assessment mostly focused on pumped hydro.

Under the old methodology, the ESO published its de-rating factors assessment for duration limited storages. Those with a smaller energy duration were penalised more than those with a larger energy duration. This allowed asset owners to get creative by entering their batteries at a higher duration than the nameplate. They could enter a battery at 1MW for nine hours rather than 9MW for one hour. The energy received by the grid is the same in both examples, but the higher duration was penalised less under the previous system.

The proposed changes to the EFC approach are good news for battery storage in the CM auctions. This is because the proportion of the asset’s capacity that is paid under a CM contract will increase due to changes in the de-rating factors. This will tip the scales in time as more assets will count towards ESO’s overall procurement volume, therefore marking the market a more competitive space.

Extended Performance Testing

Extended performance testing (EPT) is a demonstration of the asset’s capability to deliver its CM obligations (power and duration) if it secures a CM contract.  The threshold for passing this test is >= 95% of the full nameplate capacity, not its de-rated one – which is typically much lower.  So, a 50MW/100MWh BESS needs to demonstrate a minimum of 47.5MWs (95% of nameplate) over a two-hour period. If it’s secured a two-hour CM contract, then this test is repeated every three years – usually in the winter months.

For a reasonably new asset, EPT is not a problem as it is able to deliver this comfortably. For an older asset, this becomes more difficult.

Batteries degrade over their useful life, which creates a problem for asset owners. A battery may be considered ‘end of life’ when it’s somewhere between 60-65% of its beginning of life capacity.

At this point, a 100MWh battery is now somewhere between 60-65MWh, and it can no longer meet the CM obligations of 50MW for two hours. If an asset has a 15-year CM contract, and degradation hasn’t been factored, there is a risk of defaulting, and the contract would be terminated.

An asset owner could consider bidding their asset on the degradation towards the end of the capacity warranty. However, this approach is counterintuitive for asset owners, as it leaves potential additional capacity on the table that ultimately cannot be optimised in this way.

Another option is to turn to the secondary market to ‘trade’ the capacity shortfall to a different Capacity Market Unit (CMU). Under the previous system, it could lead to unnecessary termination of CM contracts, or a reduction in volume so the EPT could still be passed.

The purpose of the CM is to strengthen the UK’s energy resilience. So, if the additional volume is being left outside of a contract, it will not help to strengthen energy resilience in the UK.

Removing uncertainty for BESS asset owners

This year, the UK Government outlined changes to the Capacity Market Rules. Previously, Capacity Market rules were understood to outline that, once a generating unit had prequalified for the CM, no changes could be made to that Capacity Market Unit (CMU). Although, it was later clarified that a battery could be augmented.

In the CM rule updates in July 2024, there is now updated guidance around the original rule that removes any ambiguity. Rule 4.4.4 now includes wording specifically for batteries. The new rule definition allows for augmenting and repowering of the Battery Energy Storage System (BESS).  This is welcome news for BESS asset owners because it removes all uncertainties that existed before.

Most conscientious asset owners will be thinking of the ‘end of life’ from the beginning of life, such as when to consider replacing the batteries, or augmenting them. However, it’s not that straightforward, and considerations need to be made from the start of the project in the planning and procurement stages.

The recent changes to the UK Capacity Market, including the introduction of the EFC approach, and changes to EPT testing, present a promising opportunity for BESS asset owners. The changes offer enhanced revenue potential and a more stable investment environment as energy storage becomes increasingly critical in the UK’s energy transition.

Root-Power is pleased to share that we have partnered with e-STORAGE, which is part of the Company’s majority-owned subsidiary Canadian Solar Inc.

We have awarded Canadian Solar Inc a contract of 11 MW AC / 22 MWh AC energy storage solutions The energy storage solutions will be used for Root-Power’s Coryton Energy Park project, in Corringham, Essex, England. The project is slated for completion in the first quarter of 2025.

e-STORAGE and Root-Power have entered into an Energy Storage Supply Agreement and Long-Term Service Agreement. This is the first of many projects with plans to build over 1 GW energy storage systems in the UK, over the next three to four years.

The Coryton project will employ Canadian Solar’s SolBank 3.0, the Company’s latest proprietary energy storage solution. SolBank 3.0 achieves over 5 MWh nominal capacity within a 20-ft container, marking a 45% increase in product-level capacity compared to the previous iteration. Certified under UL standards for safety and performance, SolBank 3.0 features high-density lithium-iron-phosphate (LFP) cells, an active balancing Battery Management System (BMS), and an innovative liquid cooling Thermal Management System (TMS).

With its superior energy density and compact design, SolBank 3.0 offers significant land cost savings, making it an economical choice for large-scale projects adapted to UK project requirements. The battery’s intelligent control system and plug-and-play setup also streamline commissioning, ensuring projects are completed on time.

Neil Brooks, Managing Director of Root-Power, said: “We look forward to working with e-STORAGE to enhance the UK’s grid at Coryton Energy Park, and we plan to add 150 MWh of storage capacity to our portfolio in 2024 and 2025. We selected the e-STORAGE product based on Canadian Solar’s proven track record in the delivery of these systems and the Company’s strong performance in ESG and supply chain management.

As the UK continues to decarbonize, energy storage will be crucial for storing renewable energy on days when it may not be as windy or sunny to meet our energy needs. We are committed to contributing to a greener, more sustainable future and growing the UK’s renewable energy landscape.”

Colin Parkin, President of e-STORAGE, added, “We are excited to announce another project in the UK, delivering the new SolBank 3.0 to Coryton for our partners at Root-Power. At e-STORAGE, are proud to be a trusted partner in the country’s transition to green energy.”

The projects will bring Root-Power’s total number of submitted applications to 1GW

In August our in-house team submitted planning applications for a further 210MW of battery energy storage projects, enough to power over 380,000 homes. The five projects will be located in Reading, Manchester, Lancashire, Rotherham & Rochdale.

These planning applications help us in our mission to establish ourselves as one of the largest owner-operators of energy storage systems in the UK with capabilities to design, build and operate these assets in-house. Its portfolio now exceeds 2GW, with projects ranging from 10MW to 100MW.

Planning applications for the five proposed projects were submitted last month. The largest of the submitted proposals, in Lancashire, will be capable of exporting 60MW for a period of 2 hours once operational. The sites in Reading and Rochdale have an export capacity of 50MW and 30MW respectively, and the sites in Manchester and Rotherham can export 30MW and 40MW respectively. Root-Power’s approach focuses on strategic site finding, securing locations near to a point of connection on the grid network while also avoiding sites with high planning risk.

The Reading site in particular is placed extremely close to the point of connection and has been designed to align with the agricultural character of the surrounding landscape. The Rotherham site has been strategically positioned on a dormant strip of land between a major motorway and a B-class road, the placement of this site therefore mitigating planning risks such as landscape and noise issues.

Together these sites would see around 60% of biodiversity net gain produced, primarily on-site, with the site at Rotherham generating 40% Biodiversity Net Gain alone. In total, these projects will see over £1 million of economic investment into each of their respective Council areas.

Neil Brooks, Managing Director at Root-Power said: “We’re incredibly excited to have submitted five further planning applications over the past month, which will see Root-Power go from strength to strength as we look to grow our portfolio of owned and operated battery energy storage projects across the UK.

“This latest announcement reflects our unwavering commitment to innovation and growth. As we continue to expand, we will be able to drive meaningful change toward a more sustainable future. Our market-leading team of industry experts are looking forward to developing and growing our portfolio throughout the rest of 2024 and into 2025.”

In July 2024 we also appointed five different planning consultancies to process 40 BESS applications, with applications due to be submitted throughout the remainder of 2024.