SOUTH PORTLAND — The city’s move toward environmental sustainability took a step forward this week when it received two competitive proposals to develop and operate solar farms on municipal properties, including the former landfill off Highland Avenue.

The city sought proposals for photovoltaic systems as part of an overall effort to reduce its municipal carbon footprint and optimize utility rates. Both proposals received by Wednesday’s deadline offered power purchase agreements that would provide electricity to the city at below-market rates.

One proposal came from Ameresco Inc. of Framingham, Massachusetts, and the other from Revision Energy of Maine and New Hampshire and Energy Systems Group of Newburgh, Indiana.

Ameresco’s proposal offers two options. The first calls for installing a 658-kilowatt array at the capped 28-acre landfill that would generate nearly 846,000 kilowatt-hours of electricity in the first year. The second option calls for four separate but interconnected 660-kilowatt arrays at the landfill to generate a total of 3.38 million kilowatt-hours of electricity in the first year.

Revision and ESG offered a two-phase proposal. The first phase calls for installing a 245- kilowatt array at the 146-acre Wainwright Field complex on Gary L. Maietta Parkway that would generate more than 321,000 kilowatt-hours of electricity in the first year. In the second phase, a 924-kilowatt array would be installed at the landfill that would generate nearly 1.2 million kilowatt-hours of electricity in the first year, with the potential to add two additional arrays. The second phase also would include sustainability projects related to wastewater treatment, wind energy and transportation.

Analysis of the two proposals, comparing the financial and sustainability benefits to the city, is expected in the coming weeks.

The proposals are being analyzed and compared by Julie Rosenbach, the city’s sustainability coordinator, and Competitive Energy Services of Portland, an independent consulting firm that helps companies and nonprofit organizations manage energy costs.

Eleven firms attended a mandatory pre-bid meeting held on Sept. 22, when any company that planned to submit a proposal was expected to tour sites that were included in the city’s request for proposals.

“I expected to receive two to four proposals,” Rosenbach said Friday.

The city sought proposals to design, install, finance, own, operate and maintain the photovoltaic systems for up to 20 years.

The city is following a 40-page Municipal Climate Action Plan that puts South Portland at the forefront of the Maine communities taking wide-ranging steps to reduce pollution and increase sustainability. Recently the city has hosted zero-waste municipal gatherings, purchased electric cars and installed public charging stations, banned plastic foam food packaging and imposed a 5-cent fee on single-use plastic and paper shopping bags.

City Planner Tex Haeuser is participating in stakeholder meetings hosted by the Maine Public Utilities Commission that aim to streamline and clarify state laws related to solar power generation and distribution.