The Future is Bright for Solar Energy on Capped Landfills

Solar energy production has taken off in Minnesota over the past few years, and especially in the last handful of months. In 2017, according to the Minnesota Department of Commerce, the solar energy capacity has tripled in the state during the first quarter of the year. Currently, the energy capacity for solar in Minnesota is twelve times what it was in 2015. Community solar projects have been the main catalyst for Minnesota’s solar surge. The practice where multiple parties buy into an energy supply is attractive to many because it is a more manageable method of obtaining solar energy.

Landfills just may be another piece to the puzzle that helps Minnesota further increase solar energy production. Within the past year, landfills in Lake Elmo and St. Michael installed solar panels to assist in powering equipment that prevents the pollution of toxic gasses from the landfills. This is a practice used on capped landfills and the excess energy produced is then converted to the grid. In 2015, the city of Hutchinson unveiled the largest landfill solar project in Minnesota when 400 kw of ballasted racking mounted solar photovoltaic panels (PV) were installed on a capped landfill.

What solar energy projects need is suitable land that provides quality solar exposure. Capped landfills have the capability to provide land serviceable for (PV). A covered landfill is often not viable for commercial or industrial construction, but renewable energy is a useful alternative. Given that capped landfills tend to be flat and are mostly unhindered by surrounding trees or buildings, they provide optimal solar exposure. More often than not, landfills are located in areas with easy access for utilities and construction crews. Around the country, municipalities, utilities, and landfill owners have found that solar can be the ideal fit for capped landfills. The limited uses in repurposing can provide new economic generation for the site.

There are certain characteristics that need to be in place for a closed landfill to be suitable for a solar energy system to be installed. A south facing landfill is the optimal direction in order to obtain the most solar throughout the course of the year, and having the landfill be tilted at the corresponding latitude. Also, the waste that is underneath the landfill cap will decompose and shift over time, which alters the landfill cap. Ballasted racking systems are the traditional solar installation needed for capped landfills so that the cap is not penetrated. Concrete blocks are positioned on the ground to allow for a structure to be built that holds the solar panels while not having to install anything below the surface of the ground.

Some new technologies are emerging that negate the use of ballasted racking systems for capped landfills. Hickory Ridge Landfill in Conley, GA is on the leading edge of landfill geomembrane solar cap technology. The landfill’s 45 acre geomembrane cap is covered with 7,000 PV rolls that covers 10 acres of the landfill cap. Overall this landfill produces 1 MW of energy that is sold back to a local utility. The benefits of the solar geomembrane cap are that the panels lie flat on the surface and it allows for shifts in the land composition below the cap itself. In addition, installation is easier than a ballasted racking system. Check out a video of the science behind the Hickory Ridge Landfill.

With there being limited options available for repurposing an old landfill, solar energy has emerged as an attractive option. Solar PV installation offers a new economic incentive and with developing solar technologies, such as the PV rolls used at the Hickory Ridge Landfill, landfill solar energy can become a feasible alternative for capped landfills in Minnesota and across the country.

Visit the Minnesota Pollution Control Agency’s Closed Landfill Program for information on alternatives for closed landfills in Minnesota.


– EPA Best Practices for Sitting Solar Photovoltaics on Municipal Solid Waste Landfills