MGE ENERGY INC

UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of theSecurities Exchange Act of 1934

Filed by registrant: ☒ Filed by a Party other than the Registrant: ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ Definitive Proxy Statement ☐ Definitive Additional Materials ☐ Soliciting Material under §240.14a-12 MGE Energy, Inc.(Name of Registrant as Specified In Its Charter) (Name of Person(s) Filing Proxy Statement, if other than the Registrant) Check the appropriate box: ☒ No Fee Required ☐ Fee paid previously with preliminary materials ☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a6(i)(1) and 0-11

About MGE EnergyMGE Energy is the parent company of Madison Gas and Electric (MGE), your community energy company. With roots in the community dating back more than 150 years, the utility provides affordable natural gas and electric service in south-central and western Wisconsin.

From Our Chairman, President and CEO

Dear Fellow Shareholders: You are invited to attend MGE Energy's 2024 Annual Meeting of Shareholders online at 11:00 a.m., Central Time, on Tuesday, May 21, 2024. I look forward to sharing with you MGE Energy's performance and our plans for the future. Your Company continues to deliver for those we serve. In 2023, MGE Energy reported strong earnings and increased the dividend for our 48th consecutive year. We also continue to deliver top-ranked electric reliability. Madison Gas and Electric (MGE) has ranked in the top three utilities in the country for the fewest number of outages per customer for more than 15 years, according to an annual industry survey of investor-owned electric utilities nationwide. Excelling at Fundamentals, Realizing Our Vision for the FutureMGE is excelling at our fundamental obligation of safe, reliable energy while growing our investment in cost-effective clean energy to achieve our sustainability goals, maintain safety and reliability and provide continued value and affordability to those we serve. In the past year, MGE:

Jeff Keebler

Chairman, President and CEO

•

Obtained regulatory approval to purchase a 10% share of the 300-megawatt (MW) Koshkonong Solar Energy Center currently under construction.

•

Purchased a 10% share of the 92-MW Red Barn Wind Farm, which began serving the grid with carbon-free energy in spring 2023.

•

Partnered with other investor-owned utilities to move forward a proposal for an innovative long-duration energy storage system at the site of the Columbia Energy Center.

•

Grew our use of solar with the second 150-MW phase of the Badger Hollow Solar Farm and the 6-MW Tyto Solar project both coming online. The Badger Hollow Solar Farm is Wisconsin's largest solar project.

•

Obtained preliminary regulatory approval to purchase another 25-MW share of the existing West Riverside Energy Center and filed to purchase a 10% share of the 300-MW High Noon Solar Energy Center to be constructed.

With our ongoing investment in cleaner energy, the planned retirement of the coal-fired Columbia Energy Center and the planned transition of the Elm Road Generating Station from coal to natural gas, MGE is positioned to achieve our goals while maintaining energy affordability. Under our 2030 commitment, every MGE electric customer will have 80% fewer carbon emissions (from 2005 baseline) simply by being an MGE customer. Ensuring the energy that powers our communities remains affordable throughout this transition is a top priority.

MGE also is introducing a flexible option for our natural gas customers who are interested in reducing their environmental footprint through renewable natural gas. We look forward to continued engagement and innovation in partnership with our customers, stakeholders and shareholders as we work toward a cleaner, smarter energy future.

Vote Your Shares

Thank you for your continued confidence and investment in MGE Energy. Your vote is important. Please vote your proxy promptly and join us for our Annual Meeting.

Sincerely,

Jeff M. Keebler

Chairman, President and CEO

From Our Lead Independent Director

Dear Fellow Shareholders: Your board's top priority is providing effective and sound corporate governance and oversight of risk management, business strategy and operations. As the Lead Independent Director, I thank you for the trust you place in us and look forward to your participation in our Annual Meeting on May 21, 2024. Oversight of StrategyWith hundreds of millions of dollars of clean energy investment planned in the next several years, your board is actively engaged in oversight of MGE's generation planning and capital investment to implement the Company's vision. Board members regularly hear from and engage with management as part of the Company's comprehensive approach to enterprise planning and risk assessment.

Mark Bugher

Lead Independent Director

The energy industry continues to transform as new technologies emerge and develop, offering new opportunities to provide

long-term value and to enable meaningful growth. From the Company's leadership in electric vehicle charging to its innovative partnerships, such as the Columbia Energy Storage Project, your board understands the importance of consistent and strong financial and environmental performance, continued operational excellence and customer satisfaction and value.

Board Refreshment and Succession Planning

It has been a privilege to serve on the board and, in recent years, to serve as Lead Director. I, along with Director Tom Stolper, will be retiring at this year's Annual Meeting. I am pleased to share that Director James Possin will be the board's Lead Director effective at the conclusion of this year's meeting.

Your board takes a deliberate and thoughtful approach to board refreshment and succession planning with regular self-assessments. On behalf of the board, I am proud to introduce three new independent directors who joined the board this year.

As a former officer at A.O. Smith with oversight of investor relations, corporate responsibility and sustainability, Director Patricia Ackerman brings considerable experience and expertise in sustainability-related matters to our board. Director Daniel Kelly, prior to his retirement last year, served in many roles at American Family Insurance, most recently as Chief Underwriting Officer. A certified public accountant and former Chief Financial Officer, Mr. Kelly brings skills in financial analysis and strong oversight in risk management. Director Angela Rieger currently serves as Executive Vice President, Chief Transformation Officer at Lands' End, where she is responsible for merchandising and product life cycle. Ms. Rieger brings a strong customer and operations focus to our board, among other skills.

In keeping with our commitment to community involvement as well as to a broad range of perspectives, each new member brings diverse experience, leadership and background to the board. Your board is well-equipped to address and to oversee this transformational period in our industry and in your Company.

Thank you for your investment and for the opportunity to represent your interests in this capacity. This Proxy Statement details our practices and commitment to transparency and accountability. Please review it, vote your shares and participate in our Annual Meeting on May 21, 2024.

Sincerely,

Mark Bugher

Lead Independent Director

Notice of Annual Meeting of Shareholders

Regardless of whether you plan to attend the meeting, please take a moment to vote your proxy.

MGE Energy is holding its Annual Meeting virtually, using the same format as last year's meeting. As always, we encourage you to vote your shares prior to the meeting date.

Meeting Information The meeting will be held as follows: Date: Tuesday, May 21, 2024 Time: 11:00 a.m., Central TimePlace: Virtual meeting at www.virtualshareholdermeeting.com/MGEE2024

Instructions on attending the virtual shareholder meeting are provided in the Questions and Answers under the "Proxy Summary" section of this Proxy Statement. To participate, you will need the 16-digit control number included on your proxy card. A recorded version of the Annual Meeting will be available online afterward.

By Order of the Board of Directors,

Cari Anne Renlund

Vice President General Counsel and Secretary

This notice of Annual Meeting, Proxy Statement and accompanying proxy card are first being mailed on or about April 5, 2024, to shareholders of record at the close of business on March 22, 2024.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting to be Held on May 21, 2024:

This Proxy Statement and our 2023 Annual Report to Shareholders are available atwww.mgeenergy.com/proxy.

Table of Contents