Stafford / Davis Residence, Port Townsend, WA

May 2004

As an architect and long-time green building proponent, Chris Stafford was able to implement and integrate many environmentally-sustainable building aspects. This home has numerous green attributes, including a rain water catchment system, solar water heating, and green building materials throughout, in addition to this 2.2 KW PV array, that is grid-tied and has a back-up battery bank.

This site is adjacent to Port Townsend's treasured 9-hole municipal golf course, and has an unimpeded solar exposure, in addition to views of the fairways and pond. The building in the photo is the studio shared by Chris and his wife for work and art projects; the house is the building to the left in the photo above. The power center and battery bank are in the area beneath the studio.

This system will produce about 3200 kwh per year. The batteries are kept floated at full voltage, and can provide power for the home's critical loads for about two days in the event of a prolonged power outage assuming there is no sun to recharge the batteries, or longer if there is sun during the outage. When the PV array is producing more power than required to run the home's loads, the excess power is fed back out onto the grid. Through PSE's Net-Metering program, this generates credits which are used when the PV array is not producing power.

• 2.2 KW of Sharp Mono-Crystalline Solar Panels
• WattSun Dual Azimuth Tracking Array system
• Xantrex SW 4024 Inverter and GTI (Grid-tie Interface)
• Trace C-40 Charge Controllers
• Outback PSPV Combiner
• AGM Batteries
• Xantrex SWCA communications adapter and Trace Tools software to allow data monitoring from a PC

• Net-Metering Agreement with Puget Sound Energy
• $1200 Rebate ($600 per KW) from Puget Sound Energy
• NW Solar Coop Membership
• Equipment Purchased as part of SYMB Special
• Sales Tax Exempt in Washington State