Page 29 - North American Clean Energy May June 2018 Issue

Where freezing is seasonal, it is necessary to accommodate movement
of the ground during freeze/thaw cycles. Ground begins freezing at the surface;
the resulting expansion or heaving has the e ect of applying additional upward force on the foundation. Specialized compression springs in the anchor system allow the foundation to rise slightly as
the ground freezes, and settle as it thaws, all while maintaining adequate tension
in the anchor’s cable or rod. Engineering analysis can determine the optimal tension of the spring, and depth of the anchor. Both variables depend on the soil properties, speci ed depth of the frost line, and other environmental factors.
Earth anchor foundation systems o er important advantages over traditional ground mount solar foundations. During installation, there is no need
for an excavator, pile driver, auger, or other heavy equipment, or for any costly admixtures for pouring concrete in freezing conditions. Earth anchors readily overcome the resistance to penetration caused by hard, frozen soil.
Heaving ground also applies uplift forces to vertical surfaces. In order to prevent freezing soils from adhering
to the metal or concrete of traditional foundations, it helps to replace the surrounding native soils with gravel, or install a PVC collar down to the frost line. is also prevents so-called frost-jacking, where the pile or pier rises during freeze cycles, but fails to settle when the ground thaws. e opposite problem occurs during warmer months in permafrost, where the high thermal mass of steel piles or screws, or concrete piers, can cause the surrounding ground to melt, resulting in the array sinking or settling, likely in an uneven and permanent manner.
e narrow pro le, low surface area, and virtually negligible thermal mass
Jono Stevens is the co-founder and Executive Vice President of Products at Nuance Energy Group, Inc. He is a solar industry veteran with more than 20 years of experience in photovoltaic energy and construction management, where he has helped develop over 50 MW of solar capacity across more than 1000 systems in residential, commercial and utility-scale projects. Prior to co-founding Nuance Energy, Jono held senior leadership positions at SunWize Technologies, GreenVolts and Cobalt Power Systems.
Nuance Energy | www.nuanceenergy.com
of the earth anchor, and its cable or rod, overcome all of the problems that plague traditional foundations. Fewer problems means lower costs. e earth anchor foundation system is opening new markets and creating new opportunities, by making ground mount solar viable wherever and whenever the ground freezes.
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