10 Jul 2023
Shaniyaa Holness-Mckenzie

Battery energy storage buildout report 2023: what came online in Q2?

Over 400 MW of new battery energy storage capacity became operational in Great Britain between April and June (Q2) 2023. This brought the total grid-scale battery capacity in Great Britain to 2.9 GW.

Shaniyaa explains where Q2’s new battery energy storage capacity came from.

This is the second-largest increase in a calendar quarter ever. So, what got built in Q2?

11 new sites - including one 100 MW battery - came online in Q2

11 new battery energy storage sites (>7 MW), with a total capacity of 413 MW, came online in Q2 of 2023.

This means that the average size of new batteries was 38 MW - but the median was just 24 MW. Essentially, one particularly large site skewed this average:

  • Dollymans - a 100 MW site, owned by Statera - was the biggest new asset to come online in Q2.
  • Statkraft operates the site - and it’s the first 100 MW battery to operate under a single Balancing Mechanism Unit (BMU) ID.
  • In its first week in the Balancing Mechanism, it repeatedly received the largest ever dispatches (up to 99 MW) for a battery in the BM.

Overall, total battery energy storage capacity in Great Britain now up to 2.9 GW.

New battery energy storage owners entered the market - and another re-entered for the first time since 2021

Seven organizations or partnerships own these new assets.

  • Pulse Clean Energy activated four batteries - its first in the UK - with a combined capacity of 83 MW / 100 MWh. The assets, which are part of Pulse’s diesel-to-battery conversion program, are all optimized by Habitat Energy.
  • Nippon Koei and RNA Energy have both made their first foray into the British battery market - with their jointly-owned Tollgate site (49.5 MW / 99 MWh). It is optimized by Yuso - which is itself owned by Nippon Koei.
  • West Gourdie (optimized by Flexitricity) is Foresight Group’s first new battery in Great Britain since 2021 - when its previous portfolio was sold to Gresham House.

New one-hour battery energy storage systems dominate in Q2

Four new sites, totaling 130 MW, have a duration of two hours.

Broadditch, Farnham (both Harmony Energy Income Trust), Chapel Farm (Harmony Energy/Tag Energy), and Tollgate (Nippon Koei/RNA Energy) are all operating with a two-hour duration. The remaining sites have durations of 1 - 1.55 hours.

Therefore, the average duration of the grid-scale batteries in Great Britain has risen to 1.2 hours.

Some owners/optimizers are choosing not to register assets in the Balancing Mechanism

All of the new Pulse Clean Energy batteries from Q2 are not Balancing Mechanism-registered.

In recent months, the total capacity of non-BM-registered assets has increased.

Head here to find out why owners are choosing not to register their assets.

New batteries came online all across Great Britain

These new batteries are spread across England, Scotland, and Wales.

  • Scotland gained 100 MW of new capacity, from two new assets: Dunsinane, and West Gourdie.
  • South Wales gained 45 MW of new capacity, from two new assets: Briton Ferry, and Tir John.
  • And England gained 268 MW of new capacity, from the remaining seven new sites.

This brings the total battery energy storage capacity in Scotland to 295 MW; in Wales to 71 MW (Wales more than doubled its battery capacity in Q2); and in England to around 2.5 GW.

New battery energy storage capacity in Q2 2023 was much lower than ‘expected’

In our annual buildout report - published following the release of the Capacity Market results for T-1 2023 and T-4 2026 - we assigned an expected new capacity number for each quarter, based on a range of sources.

We assigned a total of 1.4 GW of new capacity - from 33 sites - to Q2 2023. As you can see, the vast majority of this didn’t materialize.

  • 125 MW of our expected Q2 capacity actually came online at the end of Q1, following the publication of our report.
  • In the interests of transparency, we haven’t included these assets in this Q2 update.
  • 163 MW of the capacity we expected to come online in Q2 actually did so.
  • The other 250 MW that came online in Q2 were from sites that did so earlier than expected.

However, this still leaves us around 1.1 GW short of expectations. So, why were we so far out?

Many projects are still ongoing (and going and going...)

When we tallied expected new capacity by quarter, we used the most up-to-date commission dates available.

However, this didn’t take into account the fact that some dates had been carried over from previous quarters - i.e. the commission dates of sites were already delayed (and, in some cases, massively).

In fact, over 660 MW of the capacity we said was due online in Q2 that never materialized came from sites whose dates were carried over from previous quarters.

Big sites can have a big impact

Also, we are yet to see some large sites that were previously due online in Q2. For example, Clay Tye, Richborough Energy Park, and Melksham will each have a capacity of around 100 MW.

These three sites alone make up over a quarter of the ‘missing’ capacity.

Still, 1.1 GW didn’t come online - what happens now?

  • 290 MW of this capacity comes from assets whose owners or developers have since updated the commissioning date. So, in our new buildout estimates, these new dates will be used.
  • The remaining 850 MW of batteries have no newly declared commissioning dates - for the time being, we will average out that capacity across the next four quarters.
  • We will continually assess sites with repeated delays - to decide whether or not we think they are still going ahead.

Please feel free to contact us if youre working on a project that you believe should be included in our buildout report - or to give us any other updates.

So, what does the buildout look like now?

Total battery energy storage capacity to reach 4 GW by the end of 2023 🔮

The past three quarters have seen battery energy storage buildout really start to ramp up.

  • An average 407 MW of new capacity has come online per quarter (Q4 2022 - Q2 2023).
  • In the three quarters prior (Q1-3 2022), the average new capacity was just 106 MW.

Because of the reasons stated above, our updated buildout estimate is more conservative - but we still think that overall battery energy storage capacity in Great Britain should hit 4 GW by the end of 2023.

You may notice we have added storage set to be co-located with CfD-backed renewables to this buildout chart. Head here for more details.

Q3 is set to be the biggest quarter for battery energy storage buildout yet

On average, since 2020, total battery energy storage capacity has increased by 10% each quarter. However, in the last three quarters, the average quarter-on-quarter increase has been 18%.

Based on this recent upward trend, the total capacity of new assets to come online in Q3 2023 should be around 500 MW.

However, it could be more than this:

  • If we take the latest published commissioning dates of planned assets (including some that were initially due in Q2, like the aforementioned 100 MW, Gresham House-owned Melksham battery), around 470 MW of capacity is due online in the next three months.
  • This includes some of the expected capacity from batteries with Capacity Market contracts that are due to start in October. A large number of these sites should come online in time for their contracts to start.
  • In addition, we have estimated that around 215 MW of carryover capacity from previous quarters will also come online. (That’s the 850 MW of capacity with no newly declared commission dates that didn’t come online in Q2, spread over four quarters.)

This would be the biggest jump in capacity of any quarter ever. And it would lead to the total fleet capacity in Great Britain exceeding 3.5 GW by October 2023.

Download the data

If you have a Modo Plus or Enterprise subscription, you can download the data behind our revised buildout report.

Just drop an email to - and we’ll send you a link to download the spreadsheet!

(Note: this article was updated on 11th July to include Tollgate.)