AC Unison with Integrated Microinverter Changes Installer’s Home Too

Overview
Project: Wilmers Home
Location: Scandia, MN
Date Commissioned: November 2011
System Size: 60 modules
Module Manufacturer: BenQ Solar

Array Capacity: 15.07kW

When Rebecca Lundberg, co-owner of Minnesota-based solar installer Powerfully Green, first met her customer Bob Wilmers, she had no idea that the PV system she would install for his home would eventually change her own home too.

Inspired by an educational workshop given by Lundberg at his church, Wilmers decided to have solar modules installed on the garage and back roof of his residence in Scandia, Minn., located on the historic St. Croix River near St. Paul. Inspecting the site, Lundberg realized that there would be two challenges: Most of Wilmers’ roof faced east instead of south, and nearby trees would reduce light even further.

Preferring to offer her customers more than one option, Lundberg first considered the use of 250W DC solar panels with 215W AC detached microinverters or with two separate string inverters. But the pairing of the microinverters with the modules would have created the potential for significant power loss, and the string inverters would have shading issues.

After conducting further research, Lundberg discovered a solution which also interested Wilmers: BenQ Solar AC modules with integrated SolarBridge Pantheon microinverters. The modules would provide a better energy harvest, and the black cells paired with the black frame were aesthetically pleasing. It would be Lundberg’s first-ever AC module system.

In November 2011, Lundberg installed 46 250W modules on the south-facing garage and back (east-facing) roof of Wilmers’ house, for a total capacity of 11.5kW. During the installation, Lundberg became increasingly appreciative of the integrated product, as it precluded the need for the additional installation required by detached microinverters.

Initially, Wilmers didn’t want to place solar on the front (west-facing) roof of his home. Before a year had passed, however, he became so impressed with the modules’ performance and black-on-black aesthetic appeal that he asked Lundberg to install 14 more 255W modules on his front roof, for an additional generating capacity of 3.57kW. “That’s the kind of callback I like to have,” said Lundberg.

Like Wilmers, Lundberg has been impressed with the power-generating capacity of the modules. The pairing of BenQ’s 255W module with SolarBridge’s 225W microinverter means that less power is left “on the roof.”

“This puts SolarBridge above their competitors,” said Lundberg. Wilmers has been delighted “under the roof,” too, since his 60 modules now address 100% of his home’s electrical needs.

Wilmers’ system is interconnected with East Central Energy, a small utility whose lean paperwork system is highly appreciated by local solar installers. One day after completing the initial application for the utility, Lundberg received approval to proceed with the project.

This story has an unusual ending, in that the customer’s system has inspired its installer, Lundberg, to add to the “showcase of solar technologies” on her own home.

“We’ve decided to add eight modules with integrated SolarBridge AC microinverters to the east-facing roof on our house because of their performance on Bob Wilmers’ residence. The black-on-black modules will look really nice too. In fact, the city of Champlin is so excited about our house that they’re considering a solar installation on city buildings!”