Energy consultant Modo Energy has released data confirming a 47% increase in weekly battery storage dispatched volume compared to eight weeks prior.
In January 2024, National Grid ESO (ESO) relaunched bulk dispatch for battery energy storage units in the Balancing Mechanism (BM) following its closure in December 2023 due to technical issues.
The bulk dispatch functionality allows for more battery instructions to be issued simultaneously.
According to ESO data, approximately half of the battery unit dispatch volume is now being instructed through the Open Balancing Platform (OBP).
The impact of this re-introduction was felt across the battery storage marketplace, both in the increase of weekly dispatches and a newfound lack of correlation between unit size and dispatch rate.
Modo noted that the increase from both system-flagged and energy actions and was led mainly by an increase in offer volume, which rose by 54%. In addition, 86% of individual battery units have experienced rises in dispatch volume, whilst the remaining 14% has decreased since the relaunch of bulk dispatch.
On average, batteries were dispatched at 2.2MWh/MW of the unit’s rated power before bulk dispatch. Following bulk dispatch, batteries are dispatched at 3.6MWh/MW.
Regional differences
Units in Scotland are also seeing higher levels of system-flagged actions as part of ESO’s overall strategy to enhance the utilisation of storage units in the BM. In fact, across Scotland and the Red Scar battery based in the North West of England battery units typically only receive system-flagged actions.
Modo suggested that this is because units in Scotland are based in a supply-constrained region, so these units have seen a 3% increase in dispatch volume for bids.
The ESO’s approach in all this has been to expand its BM’s capabilities, as is evident from the operator’s recent addition of 300MW of flexible assets to the mechanism.
The firm aims to create greater consumer participation in flexibility, meaning the capacity from small-scale assets like electric vehicle (EV) chargers and electric heating systems to balance the electricity system’s demand.
Following instructions
Once bulk dispatch had been reintroduced, Modo reported that all units saw 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.
Units that were seeing smaller volumes per instruction have had the smallest decrease in instruction size. Meanwhile, units that received the largest number of instructions saw the biggest reductions.
During the eight weeks before the relaunch, the difference between the smallest and largest instructions on average was 0.4MWh/MW, whereas it is now 0.1MWh/MW.
For example, Jamesfield Farm 1, which began operations in December 2023, has seen the biggest reduction in instruction size per MW at 0.3MWh/MW. Therefore, according to Modo’s analysis, bulk dispatch has made it easier for smaller units to be dispatched.
Missing correlation
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, there has been no correlation between unit size and dispatch since the relaunch of bulk dispatch for batteries. As a result, batteries under 50MW saw over twice the in-merit dispatch rate from the eight weeks before the bulk dispatch relaunch.
Now that unit size does not determine how easy it is to dispatch, price has a greater impact on dispatch rates.