Schletter Group has supplied the mounting systems for a solar project on the grounds of a retired gravel pit near Chicago.
According to the company, 7,260 solar modules generate roughly 2 MWp of solar power for Thelen Sand & Gravel. The two-support structure Schletter FS Duo was installed with extra-strong pile-driven foundations. Project development was carried out by SunPeak, based in Madison, Wis.
“The plant for Thelen Sand & Gravel was not one of these large off-the-shelf projects,” says Fabian Huber, head of technical advisory for ground-mounted systems at Schletter.
“The soil in the gravel pit is extremely compressed and stony, and at the same time, plants in this region have to withstand high snow and wind loads in winter. We had to come up with a special solution,” he adds.
Because of the difficult ground conditions, Schletter carried out a series of test pile-driving during the planning phase. In order to solve this problem and to ensure the structures were safely anchored in the ground, extra-strong pile foundations with a material thickness of 4 mm were used. They also have a special profile geometry that prevents deformation when rammed into hard ground.
Although systems with only one support are often used for ground-mounted installations in the U.S., Thelan decided in favor of the FS Duo two-support structure, as the system is capable of supporting heavy snow and wind loads.
Thelen Sand & Gravel is using all of the solar power generated by the plant, thus covering around 30% of its energy consumption. The company installed the system to save energy costs and to improve its carbon dioxide footprint.
Schletter Group has worked with SunPeak, the project developer, for several years. The two companies have collaborated on several other projects, with a total installed capacity of more than 20 MWp.
Photo: Schletter Group’s Thelen solar project
