From “Green" MWh to “Green, Shaped and Firm”

For years, corporate PPAs in the UK have been built around volume. That logic is breaking down. 

In a system where renewables now generate more than half of UK electricity and negative prices occur regularly due to oversupply, the real question is no longer how much green power you buy. It is when and how that power is delivered. This is the shift from “green MWh” to “green, shaped and firm”, and it’s driving the rise of hybrid PPAs. 

Value is moving from volume to timing 

As intermittency increases, so does the gap between production and value. Wind alone now accounts for around 30% of UK generation annually, with periods where it dominates the system. At the same time, negative price events have expanded from a marginal phenomenon to a structural feature of the market, with 176 hours of negative prices recorded in 2023.  

For corporate buyers, this fundamentally changes the risk profile of a PPA. 

A traditional pay-as-produced structure passes through capture price risk, profile mismatch, and increasing exposure to imbalance. That is no longer neutral. It is an active position on volatility. 

The market response is increasingly clear. Buyers are shifting focus from provenance to performance, asking how closely supply can match demand and how risk is allocated. 

Hybrid PPAs as the contract response 

Hybrid PPAs are emerging to solve precisely this problem. By combining renewable generation with flexibility, most commonly battery storage, they introduce a layer of controllability into an otherwise intermittent product. 

In practical terms, this allows output to be shaped in line with demand, rather than simply delivered as generated. It also enables active optimisation across intraday, balancing, and ancillary markets. 

A simple example illustrates the shift. A wind PPA can be paired with a co-located or portfolio battery, where excess generation during low-price periods is stored and dispatched into evening peaks. The result is a supply profile that is materially closer to baseload, with reduced exposure to negative pricing and lower capture price erosion. 

This is not just a technical enhancement. It changes the commercial proposition. The contract moves from volume delivery to profile delivery. 

Batteries move into the contract core 

This evolution is underpinned by the rapid scaling of battery storage in the UK. System scenarios point to around 20–30 GW of storage capacity by 2030, reflecting how central flexibility has become to system stability.  

Batteries are no longer a standalone optimisation play. They are increasingly embedded in how PPAs are structured. 

Their role is twofold. First, they enable profile shaping by shifting energy across time. Second, they unlock stacked value by participating in multiple markets simultaneously. 

At Centrica Energy, this is not a separate layer. It is integrated into how we structure and optimise portfolios. The combination of renewable sourcing, trading capability, and BESS allows us to deliver power with a higher degree of control and granularity. That is increasingly critical for large-load customers where consumption is continuous, but renewable generation is not. 

A UK market defined by demand and volatility 

The UK is at the forefront of this shift because both demand and volatility are moving in the same direction. 

On the demand side, data centres and digital infrastructure are driving structural load growth, with a requirement for high reliability and round-the-clock supply. At the same time, corporates face increasing pressure to demonstrate credible progress towards net zero. 

On the supply side, the system is becoming more complex. Renewables dominate generation at times, constraints are more visible, and price formation is less stable than in previous cycles. 

In that environment, hybrid PPAs offer a way to align decarbonisation with operational and financial certainty. The value is not just in securing green power, but in securing how it behaves within a volatile system. 

Shaping, firmness, and explicit risk allocation are becoming central to procurement decisions. This is most visible in data-intensive sectors, but the same dynamics are now extending across broader corporate demand. 

There are still barriers. Structures are more complex, and internal capability requirements are higher. But the direction is clear. The cost of unmanaged exposure to volatility is increasing, and the tools to address it are maturing quickly. 

From our perspective, this is a structural shift. As renewables scale, value will continue to migrate towards flexibility and control. Hybrid PPAs are simply the first manifestation of that change in contract form.