14 Mar 2024
Shaniyaa Holness-Mckenzie

How are individual batteries performing in the Open Balancing Platform?

ESO relaunched bulk dispatch for battery energy storage units in the Balancing Mechanism on 8th January 2024. In the eight weeks since, there has been a 47% increase in weekly dispatched volume compared to eight weeks before.

  • The increase comes from both system-flagged and energy actions and was mostly led by an increase in offer volume, which rose by 54%.
  • Around 50% of battery unit dispatch volume is being instructed through the Open Balancing Platform (OBP), based on ESO data.

But what does this look like on an individual, battery-by-battery basis?

Shaniyaa talks through the impact of bulk dispatch in the Balancing Mechanism on a unit level.
  • 86% of individual battery units have experienced an increase in dispatch volume. The remaining 14% has seen a reduction since the relaunch of bulk dispatch.
  • Dispatch rates are now more influenced by price and less so by unit size. More competitively priced assets are seeing higher dispatch rates.
  • Units in Scotland are also seeing higher levels of system-flagged actions as part of ESO’s overall strategy to enhance the utilization of storage units in the Balancing Mechanism.

86% of units saw an increase in dispatch volume following the relaunch of bulk dispatch

There was an increase in the amount of volume almost all units were dispatched for each week. On average, before bulk dispatch batteries were dispatched at 2.2 MWh/MW of the unit’s rated power. Following bulk dispatch, batteries are dispatched at 3.6 MWh/MW.

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This is an average increase of 1.4 MWh/MW for each unit. Of these, Hill Farm has seen the biggest increase at 8.4 MWh/MW, leading to weekly dispatched volume three times what it was before. Creyke Beck has seen the biggest decrease of the remaining registered units, at 2.7 MWh/MW.

Batteries in Scotland see an uplift in system-flagged dispatch volume

While most of the increase has come from Offers for energy actions, some units have seen an increase in system-flagged Bid dispatches.

Units in Scotland, and the Red Scar battery based in the North West of England, are the only battery units typically receiving system-flagged actions. This is because units in Scotland are based in a supply-constrained region. These units have seen a 3% increase in dispatch volume for Bids.

System-flagged actions are not dispatched via the Open Balancing Platform. However ESO is working to enhance the utilization of storage units in the Balancing Mechanism overall.

So what is leading to the increase in dispatch volumes overall?

All units have seen an increase in the number of instructions received each week

On average units are receiving five times as many individual instructions since the relaunch of bulk dispatch than before.

  • Enderby has seen the greatest increase in average weekly dispatches at 198 additional dispatches a week
  • Despite receiving 1.7 MWh/MW less in dispatch volume per week, Dollymans is receiving 99 more instructions a week.

While all batteries are receiving more dispatches, these dispatches have reduced in size.

All units have seen a reduction in the size of their Bid/Offer Acceptances (BOAs) since bulk dispatch

Following bulk dispatch all units have seen a reduced average volume required per instruction. However, this means that batteries are being dispatched more uniformly when taken in proportion to the unit size.

This means that, in general, units that were seeing smaller volumes per instruction have had the smallest decrease in instruction size. While units that were receiving the largest instructions have seen the biggest reductions.

In the eight weeks before the relaunch the difference between the smallest and largest instructions on average was 0.4 MWh/MW, whereas it is now 0.1 MWh/MW.

Dollymans saw the biggest reduction in terms of total energy at 14 MWh less per instruction but per MW of capacity, there are several units that have had greater reductions.

Jamesfield Farm 1 which began operations in December 2023, has seen the biggest reduction in instruction size per MW at 0.3 MWh/MW.

Bulk dispatch has made it easier for smaller units to be dispatched.

Dispatch rate has increased for smaller units

Previously, units with a higher rated power had a higher dispatch rate. This is because, before the bulk dispatch function, these units were easier for the control room to dispatch within the timeframes required.

However, since the relaunch of bulk dispatch for batteries, there is no correlation between unit size and dispatch rate.

  • Batteries under 50 MW saw over twice the in-merit dispatch rate from the eight weeks prior to bulk dispatch relaunch.
  • The 100 MW Dollymans is the only BMU with over 50 MW of capacity and it has seen a 17% reduction in in-merit dispatch rate.

Now that the size of a unit does not determine how easy it is to dispatch, price has a greater impact on dispatch rates.

Batteries priced more competitively are getting higher dispatch rates with bulk dispatch

Due to limitations in the control room prior to bulk dispatch, there was less correlation between batteries that were priced more competitively and dispatch rates. Here, dispatch rate is the ratio of actioned volume to all available volume, whether it was ‘in-merit’ or not. However, since the relaunch of bulk dispatch, dispatch rates are highly correlated to price.