Item 1. Security and Issue
This Amendment No. 13 (this Amendment No. 13) to the Schedule 13D initially filed on March 9,
2018 (the Original Schedule 13D), as amended by Amendment No. 1 filed on April 27, 2018, as amended by Amendment No. 2 filed on November 21, 2018, as amended by Amendment No. 3 filed on November 27,
2018, as amended by Amendment No. 4 filed on February 15, 2019, as amended by Amendment No. 5 filed on May 13, 2019 (Amendment No. 5), as amended by Amendment No. 6 filed on May 24,
2019, as amended by Amendment No. 7 filed on June 3, 2019, as amended by Amendment No. 8 filed on April 6, 2020, as amended by Amendment No. 9 filed on December 10, 2020, as amended by Amendment No. 10 filed on
January 7, 2021, as amended by Amendment No. 11 filed on August 4, 2021, as amended by Amendment No. 12 filed on May 10, 2022 with the Securities and Exchange Commission on behalf of Algonquin Power & Utilities,
Corp. (Algonquin), Algonquin (AY Holdco) B.V. (AY Holdco), and Liberty (AY Holdings) B.V. (AY Holdings) (collectively, the Reporting Persons), relates to the ordinary
shares, nominal value of $0.10 per share (Ordinary Shares), of Atlantica Sustainable Infrastructure plc (the Issuer), a public limited company incorporated under the laws of England and Wales, as described
herein in more detail. The Issuers principal executive offices are located at Great West House, GW1, 17th Floor, Great West Road, Brentford, United Kingdom TW8 9DF. Unless otherwise indicated, each capitalized term used but not otherwise
defined herein shall have the meaning ascribed to such term in the Original Schedule 13D.
Item 2. Identity and Background
Item 2 is hereby amended as follows:
Schedule A
to the Original Schedule 13D is hereby amended and restated as set forth on Schedule A to this Amendment No. 13 and incorporated by reference herein are the names, business addresses, present principal occupations or employments, and
citizenship of each director and executive officer of the Reporting Persons.
(d), (e) During the last five years, none of the Reporting
Persons and none of the persons set forth on Schedule A (i) has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) was a party to a civil proceeding of a judicial or administrative body
of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any
violations with respect to such laws.
Item 4. Identity and Background
Item 4 is hereby amended as follows:
The information set forth
in amended Item 6 below is incorporated by reference herein.
Item 6. Contracts, Arrangements, Understandings or Relationships
with Respect to the Securities of the Issuer.
Item 6 is hereby amended as follows:
On May 27, 2024, the Issuer and California Buyer Limited, a private limited company incorporated in England and Wales
(Bidco), a vehicle controlled by funds managed or advised by Energy Capital Partners (ECP) and which includes a large group of institutional co-investors, entered into a Transaction Agreement (the
Transaction Agreement), which provides, among other things, that subject to the satisfaction or waiver of the conditions set forth therein, Bidco, will acquire the entire issued and to be issued share capital of the Issuer
pursuant to a scheme of arrangement under Part 26 of the U.K. Companies Act 2006 (the Scheme and such acquisition, the Transaction).