Mast Energy Developments PLC

(Incorporated in England and Wales)

(Registration Number: 12886458)

LEI :213800HFVHGJ9YGO9F71

Share code on the LSE: MAST

ISIN: GB00BNG90H86

('MED' or 'the Company')

Dated: 14 October 2025

MAST Energy Developments PLC

("MAST" or "MED" or the "Company")

MAST's 100% Owned Pyebridge 8.1 MW FlexGen Power Asset Revenues Surge

And Produces Record High Monthly Electricity Generation During September 2025

London, UK - Mast Energy Developments PLC (LSE: MAST) is pleased to announce, further to its RNS announcement dated 31 July 2025, an update on its 100% owned Pyebridge 8.1 MW flexible generation power asset that is in commercial production, including details of revenues generated during the third quarter of 2025 and year to date. Key highlights are outlined below.

Key Highlights:

·     Pyebridge generated and sold c. 2.5 Gigawatt/hours ('GWh') of electricity during Q3 2025, representing a c. 24% increase compared with Q2 2025 and a c. 44% increase compared Q3 2024;

·     Notably, in September 2025, Pyebridge achieved a record monthly electricity generation output of c. 1 GWh;

·     Increase in production due to successful completion of refurbishment programme at Pyebridge as previously announced, and increase in flexible generation power demand due to intermittent renewables;

·     Total revenues generated for the first 9-months of 2025 came to c. £1.1 million, representing Pyebridge's highest income generated over the first 9 months of any year, and a c. 300% increase compared to the same period in the prior year;

·     Total revenues based on an average of c. 5.4 MW in production over the period, representing c. £276,000 per MW per annum;

·     During the first 9-months of 2025 Pyebridge achieved an average electricity sales price of c. £143/MWh representing a c. 72% outperformance compared to the average wholesale market electricity price over the same period; and

·     During the first 9-months of 2025 Pyebridge generated and sold electricity for an average of 10 hours per day, which is clear evidence of the critical need for flexible power generation and validates MAST's business model.

What this means for MAST:

·    Validates business case: The strong results at Pyebridge are clear evidence and align with MAST's projections of rapidly increasing demand for flexible generation power, driven by intermittent renewables and the rapid increase in AI datacentres; and

·    Investor confidence: The strong results at Pyebridge has established a solid foundation and provides clear sight of what investors can expect from every Megawatt that MAST adds to its portfolio as it continues to build toward its 1 GW vision.

Tanya Zwemstra, Head of Finance at MAST Energy, said: "We are delighted to report the increasingly positive trading results of Pyebridge, the Company's 100% owned flagship producing flexible generation power asset. The time and capital investment into the refurbishment program are clearly yielding results, with both operational and financial performance showing strong momentum."

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About MAST Energy Developments PLC:

MAST Energy Developments PLC (LSE: MAST) is a UK-based developer, operator and owner of flexible generation power assets. The Company has deep expertise in infrastructure planning, grid access, gas access, and efficient power supply. Its new AI power supply strategy is intended to position MAST as a leading AI infrastructure platform on the London Stock Exchange (read more here).

ENDS

This announcement contains inside information for the purposes of the UK version of the Market Abuse Regulation (EU No. 596/2014) as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018 ('UK MAR'). Upon the publication of this announcement, this inside information is now considered to be in the public domain.