May 17, 2013

Puyallup longhouse uses solar to go net zero

Photo courtesy of Puyallup Nation Housing Authority [enlarge]

Northwest Wind & Solar installed a 26-kilowatt photovoltaic solar system for phase two of the Puyallup Nation Housing Authority Longhouse, which provides 10 units of low-income housing on the tribe's northeast Tacoma campus.

The PV array was designed to “net zero” the electrical loads annually.

“This is the second phase of a two-part project,” said Annette Bryan, executive director of the housing authority, in a release.

"On the first phase we chose to go with geothermal, which resulted in reduced energy bills," she said. "For phase two we chose solar and received technical assistance grants to monitor both phases side-by-side and share the results with other tribes around the nation.”

The housing authority originally planned a 10-kilowatt system, but chose the larger system to reach the net zero threshold.

Shawn Oram, mechanical engineer and energy consultant with EcoTope, said the project likely has the lowest energy use index of any housing in the state.

The system uses SolarWorld SW 250 Mono panels with SMA transformerless string inverters that have a 98.7 percent maximum efficiency. The array was installed over two sections of a standing-seam metal roof.

David Boots, the owner's construction superintendant, said, “Currently we are heating the building 24/7. Power bills are coming back zero and we are banking credits for our energy production.

“An additional benefit of the project was that NW Wind & Solar hired TERO workers (tribal members) to help with installation of the panels, giving the workers experience that they can take into other jobs,” he said.

The longhouse was completed in April. It was designed by Environment Works. The contractor wasn't disclosed.