Storage needs to move beyond the megawatt headline

The UK has a power problem. That’s a fact pretty much everyone seems to agree on. It’s one of the reasons so many seem opposed to the expansion of data centres, and yet one of the solutions staring us right in the face seems to have been caught in the crosshairs.

Last month, a parliamentary petition called for a moratorium on battery energy storage systems outside designated AI Growth Zones. It was launched by a Liberal Democrat councillor from Devon, but has since received 15,000 signatures and will now get a response from the UK Government.

While it’s unlikely to go anywhere, it does signal a problem facing the sector – and it’s one of messaging.

Of course the UK shouldn’t be limiting BESS construction to AI Growth Zones. Britain needs more storage – a lot more storage. The Government has set an ambition for 23 GW to 27 GW of grid-scale battery capacity by 2030, while the latest monitoring table in its Clean Flexibility Roadmap records 7.3 GW in June 2026.

The problem is that the average person reading those headlines doesn’t really know what any of it means. Those figures tell us how much more storage needs to be built, but much less about whether we are building the storage the system actually needs.

A 100 MW battery capable of discharging at full output for one hour and one capable of doing so for four hours can carry the same 100 MW power rating, but their contribution to the system is obviously very different. That number also tells us nothing about whether an asset is built where its flexibility is most valuable or whether the system can actually make effective use of it.

That matters when combating the idea that BESS should be restricted to AI Growth Zones. These are areas selected in part because they can support large new power users, so restricting storage to them raises an obvious question: why should that determine where batteries are most useful to the wider electricity system?

Thankfully, Government policy is beginning to recognise the distinction. The latest Clean Flexibility Roadmap says storage’s contribution is not simply determined by how much is deployed, but by how well it is used. Its monitoring framework now looks at capacity in both GW and GWh, long-duration storage and battery skip rates rather than installed power alone.

That skip rate stood at 35% in May. It doesn’t mean more than a third of battery capacity was simply sitting idle, but it does show that having storage available and making the best use of it are not the same thing.

Then there’s duration.

Ofgem’s current proposals for the first Long Duration Electricity Storage cap-and-floor window cover 16 projects totalling 7.6 GW and 137 GWh across several technologies.

That mix matters. We’re increasingly using the word ‘storage’ to describe assets capable of doing very different jobs over very different periods of time. Simply adding them together and celebrating another few gigawatts doesn’t tell us whether we have the right mix.

And that brings us back to the petition.

AI Growth Zones were never intended to dictate where grid-scale storage should be built. Storage needs to be located where it can provide value to the electricity system, whether that means making better use of renewable generation, relieving constraints or helping balance supply and demand.

But simply telling communities that another 200 MW battery is good for the grid probably isn’t going to win many people over either.

That’s where the storage sector has some work to do.

Developers will continue to announce projects in megawatts, and there is nothing inherently wrong with that. It’s an easy way of communicating scale and an important measure of what a battery can deliver at any one moment.

But we need to get better at explaining what sits behind that number.

How long can the battery provide that output? Why does it need to be built there? Is it helping make better use of renewable generation that might otherwise be constrained? What does it allow the grid to do that it couldn’t do without it?

Those answers matter far more to the average person than whether Britain has installed another gigawatt of battery capacity. They should matter to the industry too.

Reaching 23 GW or 27 GW by 2030 would undoubtedly be an achievement, but it shouldn’t become the only measure of success. We could hit the headline figure and still end up with storage in the wrong places, providing the wrong duration or simply not being used as effectively as it could be.

The UK doesn’t just need more batteries. It needs the right storage, in the right places, doing the jobs the electricity system actually needs.

And if the sector wants communities to understand why those projects are being built in the first place, it needs to get much better at explaining that too.