The Westbrook Planning Board on Tuesday approved an expansion to the Vertical Harvest project and reviewed plans for two solar arrays to provide municipal power.

Vertical Harvest, a parking garage, farm and housing hybrid project planned at Mechanic and Main streets downtown, got the OK to add 7,000 square feet of retail space on the ground floor, along with 10 more apartments above.

Developers said they hope the retail space would be rented to a specialty grocery store that would also offer take-out and on-site dining.

Representative Mark Burns with Harriman Associates, representing the $60 million, 300,000-square-foot Vertical Harvest project, said the market could be a “seller or reseller of the Vertical Harvest products.”

“We think that is one of the greatest needs in the area, there is no walkable grocer,” Burns said.

The expansion actually reduces the building’s footprint and allows for a second sidewalk. Parking spaces in the garage would be reduced from 430 to 370. Parking at the downtown site lot now has just over 100 spaces.

“It’s a great idea adding the retail and the sidewalk is a big plus,” Ward 2 Planning Board member Jason Frazier said.

The city will pay $15 million for the parking garage through an agreement using tax revenue from the project, City Economic Development Director Dan Stevenson said, meaning there will be no direct impact on taxpayers. Developers will take on $40 million of the cost and pay for maintenance of the garage, which will continue to be a municipal lot.

Burns said they hope to begin work in August.

The solar arrays, planned for the former Rocky Hill and Sandy Hill landfills, would offset municipal and school electricity and provide some savings, Sustainability Coordinator Lynn Leavitt said at the meeting.

The Sandy Hill project would be 15 acres and produce 4 megawatts of electricity, while Rocky Hill, at just under 6 acres, would produce 1.24 megawatts.

C2 Energy would build the arrays to specifically offset both municipal and school power use, presenting sustainable energy and “some savings,” Leavitt said.

On average, the city and schools use about 7,600 megawatts per year, and the company would be contractually obligated to provide at least 5,000 megawatts per year, although it is too early to tell how much they will actually produce over that, City Planner Jennie Franceschi said, but it would likely offset nearly all power used.

“We always see the dichotomy that good for the environment is bad for business, but not always and this is an example of that,” Leavitt said.

Project engineer Chris Byers with Boyle Associates said there will be no upkeep costs to the city. The projects will look like the ReVision Energy solar array off Westbrook Street in South Portland.

“The structure and concept is nearly identical,” Byers said.

The city is still working on contracts that would determine exact savings before the City Council gives final approval for the solar arrays, but Leavitt said the small savings will “grow in time.”

In a previous interview, City Engineer Eric Dudley said the “agreement locks in an electricity rate at just below what we have been paying.”

Leavitt said C2 is already working with the schools on curriculum and tours on solar energy.

“Hats off, this is a great conception,” Planning Board alternate member Larry McWilliams said.

The solar array final application is set for May, in time for the June Planning Board meeting.