Atlantic Power Corporation — Proxy Solicitation & Information Statement 2021

Feb 8, 2021

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Date: February 8 2021

100 University Avenue, 8th floor Toronto ON, M5J 2Y1 www.computershare.com

To: All Canadian Securities Regulatory Authorities

Subject: ATLANTIC POWER CORPORATION

Dear Sir/Madam:

We advise of the following with respect to the upcoming Meeting of Security Holders for the subject Issuer:

Meeting Type : Special Meeting Record Date for Notice of Meeting : January 20, 2021 Record Date for Voting (if applicable) : January 20, 2021 Beneficial Ownership Determination Date : January 20, 2021 Meeting Date : March 18, 2021 Meeting Location (if available) : Virtual Meeting Issuer sending proxy related materials directly to NOBO: No Issuer paying for delivery to OBO: Yes

Notice and Access (NAA) Requirements:

NAA for Beneficial Holders No NAA for Registered Holders No

Voting Security Details:

Description CUSIP Number ISIN 6% SER E CONV DEB DUE 31/01/25 04878QAT0 CA04878QAT00

Sincerely,

Computershare

Agent for ATLANTIC POWER CORPORATION