C&I Battery Storage: The value shift explored by Maria Flowers

The tipping point for commercial battery storage in Europe

Over the past two years the commercial and industrial (C&I) battery storage market in Great Britain and across Europe has undergone a fundamental shift. What was once an add-on to solar projects is now becoming a core driver of value.

When I joined Joulen to expand our presence into GB, the contrast between residential and C&I solar-plus-storage was stark. While homeowners were rapidly adopting batteries, installers in the commercial space were far more hesitant. The reason was simple: economics.

At the time, adding battery energy storage systems (BESS) to a commercial solar project often pushed payback periods from around five years to seven or eight. Even where end customers understood the long-term value, this created friction in the sales process. Businesses wanted storage but not at the cost of slower returns.

The real step change has come through optimisation. By combining tariff optimisation, weather-driven dispatch and access to wholesale and capacity markets, batteries have evolved from a passive add-on into an actively managed, revenue-generating asset.

Today, the equation has changed completely.

Battery costs have fallen dramatically, by roughly 90% over the past decade, and continue to decline. At the same time, optimisation and market participation have become more sophisticated and accessible. The result is that we are now regularly seeing commercial projects achieve payback periods well below five years, and in some cases, less than two.

This is not theoretical. In one recent manufacturing project, a 700 kWp solar installation paired with a 1.5 MWh battery delivered annual benefits of approximately £400,000 on a £500,000 capex. The result: a payback period of just over one year and a ten-year net benefit exceeding £3.5 million. Crucially, the battery also provided backup power, avoiding costly downtime that could otherwise last several days.

At the same time, external pressures from geopolitical instability to energy market volatility are reinforcing the need for energy independence. Businesses are no longer just optimising costs; they are actively managing risk.

This combination of falling costs, improved optimisation, and market access is also unlocking entirely new commercial models. We are seeing growing interest in funded solutions energy-as-a-service or battery-as-a-service where installers or developers finance the asset, pass on savings to the customer, and monetise flexibility in energy markets.

For installers and developers, this represents a significant opportunity. Battery attachment is no longer a barrier to closing deals it is increasingly the reason deals get done.

At Joulen, we work with partners to maximise the value of every installed asset through intelligent optimisation and market participation, helping turn storage from a cost into a revenue-generating asset.

If you’re looking to increase attachment rates, improve project economics, and unlock new revenue streams for your commercial clients, we’d love to talk.