Us Solar Fund Regulatory News (USF)

16 June 2026

US Solar Fund PLC

("USF", or the "Company")

FIRST QUARTER UPDATE

US Solar Fund plc (LON:USF (USD)/USFP (GBP)), the renewable energy fund investing in utility-scale solar power plants across North America, is pleased to release its first quarter update for the period 31 March 2026.

Highlights for the quarter to 31 March 2026:

NAV update:

· USF's NAV for the period remained stable with an unaudited NAV as of 31 March 2026 of $190.0 million ($0.62 per share). This represents an increase of approximately 2.0% from the audited NAV as of 31 December 2025

Portfolio performance:

· Generation by the Company's portfolio during the three-month period to 31 March 2026 was;

o  8.8% below forecast when compared against the long-term forecasts used in prior years and

o  0.9% underperformance compared to the revised forecasts for 2026 made at the time of the 2025 Annual Report.

· Compared to the long-term forecasts, underperformance came from technical (non-weather) factors (-9.3%) partly offset (+0.5%) by outperformance attributable to favourable weather conditions during the period

· The work being undertaken on the Chiloquin asset and other remediation work related to issues that arose in 2025 were projected to impact performance in 2025 and had been included in the revised forecasts for 2026. Lower performance in H1 is expected to be offset by higher performance in H2 once (for example) work on Chiloquin is completed. As such performance when compared to the revised forecasts for 2026 has largely been in line with expectations despite the 0.9% underperformance compared to the average for the full year 2026

· The Company's two Californian assets, which underwent significant capital works in 2025, demonstrated improved performance during the period

· As anticipated, overall performance continued to be impacted by lead time on parts and technical support as well as utility grid outages although to a lesser extent than the prior 12-month period

Additional disclosures:

· Additional disclosures relating to (i) portfolio performance during the first quarter of 2026 and (ii) interest payable on senior debt facilities, will shortly be posted to the Company's website within the Key Documents section

Potential portfolio sale:

· As noted in the RNS dated 18 May 2026, USF announced that it had granted a prospective buyer a 90-day exclusivity period following the receipt of a revised non-binding letter of intent in respect of the proposed acquisition of USF's entire portfolio of solar generation assets

· This potential transaction remains subject to due diligence and the negotiation of definitive legal documentation. Further updates will be provided in due course

Gill Nott - Chair of USF said "It is encouraging to see both improved performance and demonstrable interest in these assets following a challenging 2025 for the US Solar sector and for USF. We look forward to continuing to monitor the performance of the portfolio and the impact that sustained improved performance would have on our ability to restart the dividend".

About US Solar Fund plc

US Solar Fund plc, established in 2019, listed on the premium segment of the London Stock Exchange in April 2019.

The solar power assets that the Company acquires or constructs are expected to have an asset life of at least 30 years and generate stable and uncorrelated cashflows by selling electricity to creditworthy offtakers under long-term power purchase agreements (or PPAs). The Company's portfolio currently consists of 41 operational solar projects with a total capacity of 443MWDC and a weighted average of 9.9 years PPA term remaining as at 31 December 2025, all located in the United States.

Further information on the Company can be found on its website: http://www.ussolarfund.co.uk.

About Amber Infrastructure Group

Amber Infrastructure Investment Advisor LLC, a member of the Amber Infrastructure Group, was appointed as the Company's Investment Manager on 1 December 2023.

Amber Infrastructure is an international infrastructure specialist, focused on investment origination, development, asset management and in Europe, fund management. Amber's core business focuses on infrastructure assets across the public, transport, energy, digital and demographic infrastructure sectors that support the lives of people, homes and businesses internationally.

Among other funds, Amber Infrastructure advises International Public Partnerships, a FTSE 250-listed Company with a market cap of approximately £2.2 billion and 15-year track record of long-term investment in infrastructure assets globally. Amber is headquartered in London with offices in Europe, North America and Australia and employs c.180 infrastructure professionals.

Amber has had a strategic partnership with the Hunt Group of Companies in the US since 2015 and completed their previously announced strategic transaction with Boyd Watterson in August 2024. Amber is part of Boyd Watterson Global Asset Management Group LLC, a global diversified infrastructure, real estate and fixed income business with over $39 billion in assets under management and over 300 employees with offices in eight US cities and presence in eleven countries.

Further information on Amber can be found on its website: http://www.amberinfrastructure.com.