Harmony Energy Income (HEIT ) has defied widespread grid connection problems and announced the energisation of two batteries on schedule, which should more than double its operational capacity to capture higher revenues during winter.

In a stock exchange announcement, the youngest of the three battery funds said its newly operational Buckinghamshire-based Bumpers, a 99-megawatt asset, was the largest in Europe, taking the mantle from its first operational project, Hull-based Pillswood, which is 2MW smaller.

The other asset to go online is Fife-based Little Raith, which has a capacity of 49.5MW. The trust’s last seed asset, the 35MW Rusholme, based in North Yorkshire, will be energised in the first quarter of next year.

Construction was managed by Tesla and the assets will be operated through Autobidder, Tesla’s algorithmic trading platform, which is already in use at the Pillswood, Broadditch and Farnham projects.

The Wormald Green and Hawthorn Pit projects, which HEIT bought last December, are under construction and progressing on schedule.

Chair Norman Crighton pointed out the strength of Harmony’s delivery team and its relationships with suppliers and district network operators to get assets online ahead of schedule, despite grid connection delays.

‘To have delivered 277.5MW through construction to operational by the second anniversary of the company’s initial public offer is a significant achievement,’ Crighton said.

The 10.3%-yielding portfolio of UK assets now benefits from capacity market payments as Pillswood, Broadditch and Farnham begin delivery of their respective T-1 contracts, which the government uses to top up energy supply for one year.

The early energisations of Bumpers and Little Raith have allowed Harmony to procure an additional £403,000 of revenue by acquiring additional T-1 contract capacity. HEIT expects to procure further contracts in the coming weeks.

On top of that, added capacity means the £176m trust can capture more winter revenues, which are significantly higher as demand drives up prices. Portfolio revenues rose in September, driven by a 25% increase in day-ahead wholesale market price spreads, or the difference in price between buying energy and selling it, compared to August.

While the UK’s mainstream ancillary services market has become saturated, the market for Harmony’s two-hour-duration batteries has been positive as they can sell more energy at a higher price than a one-hour battery in the wholesale market.

High wind generation last month also caused cases of negative wholesale pricing, providing an opportunity for batteries to be paid to charge, increasing demand on the network.

Peel Hunt analyst Markuz Jaffe said the news was an important development given the challenging market backdrop, with commentary around improving revenues, particularly for longer-duration batteries, pointing towards the seasonality of certain revenue opportunities.

He noted that there is plenty of scope for a rerating across the battery sector, with Harmony currently on a 33% discount to net asset value, while Gresham House Energy Storage (GRID ) and Gore Street Energy Storage (GSF ) trade 43% and 40% below par respectively. Investors have been rattled by recent warnings of a decline in short-term revenues as a result of grid connection problems, causing Gore Street to complain last week that the market was ‘wrong’ to price its shares so lowly.

HEIT shares eased 0.5% to 76.5p. They launched at 100p in November 2021 and peaked at 125p last December.