The Desert Research Institute, the environmental research arm of the Nevada System of Higher Education, has installed a number of solar arrays to demonstrate what can be accomplished with renewable energy.
One installation, however, proved to be particularly challenging. A facility located outside Reno, Nevada, had plenty of electric demand but limited space to build. An uneven and rocky hillside was the only viable location for its 1-MW array.
Contractor Hamilton Solar needed adjustability, strength and a fast install from its mounting. Solar mounting provider Mounting Systems was able to use a combination of its versatile Sigma II system along with earth screws to provide a product that met these expectations.
“With the rocky terrain, piles were not a feasible solution,” said Justin Upchurch, business development manager at Mounting Systems. “Earth screws are a fast and easy way to install a foundation for a ground mount system.”
Earth screws use a pull-test similar to what’s used with piles. Rocky terrain may call for pre-drilling, but ground screws are typically much faster than installing in concrete, Upchurch said.
The MSI Sigma II system includes legs that attach to concrete, piles or earth screws. Some projects call for a combination of foundation types on one table. Mounting Systems has also developed adapters that speed up the racking-to-screw attachment. When properly installed, earth screws allow for vertical adjustment, which can be helpful on uneven terrain.
One of the inherent challenges at the Desert Research Institute project was the variety of tables and the intricacies of managing different table sizes. Mounting Systems tackled the challenge through constant communication with Hamilton Solar and the adjustability offered by earth screws.
“As long as a certain percentage of the earth screw was in the ground, you could modify the height to match Sigma II legs perfectly,” Upchurch said. SPW