Historic Vermont Barn Gains 18kW Solar Array with Secure Power Supply

When BuildingGreen Inc. founder Alex Wilson started to re-build his home and barn in West Dummerston, Vt., he knew that he wanted it to be “net-zero.” Net-zero means the property will produce 100 percent of the energy needed to run the house and barn. To make this happen, Wilson needed a solar-electric, or photovoltaic (PV), system that could generate as much energy as was consumed. 

A reinforced roof supports 72 PV modules for the 18 kW PV system. Photo Credit: GreenBuildingAdvisor.com

Wilson also knew that he wanted to protect the nature and beauty of his 10-acre property; to him, this meant a ground-mounted PV array was not an option. “Wherever land can be used for farming — now or in the future — I prefer to install PV arrays on buildings, keeping the land open for agricultural uses,” said Wilson in his recent article published on www.GreenBuildingAdvisor.com.

Building a Solar Barn

SMA inverters mounted inside a barn, the Sunny Boy TL-US is third from the right. Photo Credit: GreenBuildingAdvisor.com

Fortunately for Wilson, his 19^th-century barn, with its long roof facing almost due south, was the perfect location for a PV system. After repairs and reinforcement of the roof, with the help of Wilson’s builder, Eli Gould, the barn’s standing seam metal roof could support the PV system’s 72 REC modules. One SMA Sunny Boy 5000 TL-US inverter was installed by Integrated Solar Applications, alongside two Sunny Boy 6000-US inverters. Wilson originally wanted a full battery back-up PV system, but budget would not allow for the $8,000 – $16,000 in additional costs. The Sunny Boy TL-US multimode inverter, which recently was selected as a 2014 Top-10 Green Building Product by BuildingGreen, was the perfect solution with its revolutionary Secure Power Supply feature. “The cost of the battery system and other components was just too much for a budget that has been stretched pretty thin with our complex building project — which is finally nearing completion. What we did do, however, was install a brand-new inverter from SMA that has an outlet that can continue delivering some electricity when the sun is shining during a power outage,” said Wilson.

Secure Power Supply

A dedicated outlet is mounted below the inverter, providing up to 1,500 watts of power when the grid is down. Photo Credit: GreenBuildingAdvisor.com

Secure Power Supply (SPS) is an SMA exclusive feature that supplies 1,500 watts of daytime power to a dedicated outlet in the event of a grid outage. While the SPS doesn’t supply enough electricity to power an entire house, it does offer a cost-effective alternative to purchasing expensive batteries. “Unlike other islanding systems, there is no requirement for battery storage with this option. This isn’t enough power to operate all the loads in our house that I’d like to power during a power outage, but it’s far better than nothing,” said Wilson. Read the full article by Alex Wilson, on GreenBuildingAdvisor.com.