The Pacific Cooperative system comprises 144, Sharp 175-watt photovoltaic modules that create a 200-foot-long array. The modules are organized into 12 strings, each connected to a 1800-watt Sunny Boy inverter. The modules are barely visible from the ground.

To understand something radically new, sometimes you just have to try it.

That’s the idea behind a recent pilot project called “PV Eugene” that installed solar electric (photovoltaic or “PV”) systems on three Eugene businesses. One of the more educational—and high profile—projects is located at the Pacific Cooperative Building, better known as the Farmer’s Union Marketplace in downtown Eugene.

The Pacific Cooperative installation included in the pilot project was intended to help EWEB staff gain experience with a new and potentially significant way to produce power using a natural, renewable and environmentally-friendly resource—the sun.

“We believe it’s important to encourage our customers to invest in this type of renewable energy technology, which enables them to generate power to be included in EWEB’s mix of power resources,” says Ken Beeson, EWEB Energy Resource Project Manager.

Anyone with enough rooftop and good solar access can install photovoltaic panels and generate their own power. In some cases, a facility or residence can generate more electricity than they actually use. In these cases, the utility meter could spin backwards and everyone would be happy.

Sounds great. But putting the idea into practice gets a bit more complicated. The experience with the Pacific Cooperative project illustrates exactly why pilot projects are useful.

Historic Compatibility
The Pacific Cooperative Building is registered as an historic building at the federal, state and city levels. What happens when you attach a 21st century power source to an early 20th century building?

That was the first question to confront building owner, Tom Bowerman. He showed historic building officials plans and set up sample modules on the roof. After some discussion, city officials agreed to allow two, 200-foot-long arrays to sit on two levels of the roof covering virtually its entire south-facing surface.

The ideal position for photovoltaic (PV) modules would be facing directly south in a spot without shade at any time of year. The modules would be tilted 30 to 35 degrees from horizontal to catch the most direct sunlight with plenty of space for cooling air to flow behind them. In many cases, the roofs of large commercial buildings offer these ideal circumstances.

The Pacific Cooperative has a large south-facing roof slope, but the angle is only 20 degrees from horizontal. To maintain the historic roof lines, a compromise was made in the tilt angle. The modules were mounted parallel to the roof, with only one-and-a-half inches of air space allowed between them and the corrugated metal roofing. While the low slope and limited ventilation space keep the collectors almost hidden against the historic roofline, this approach typically leads to a higher operating temperature and slightly reduced electricity production.

PV Pilot
Solar electric generation is just one of many small-scale renewable energy resources, such as wind, bio-gas and fuel cells. But these technologies raise a host of issues for utility engineers who place paramount importance on reliability and safety of the electric distribution system. To better understand these issues, EWEB needed hands-on experience. PV Eugene was designed to provide the utility with this necessary experience and discover any technical issues.

One goal was to test the willingness of entrepreneurial customers to privately invest in PV generation systems that would plug into EWEB’s electric distribution power grid.

The building owner purchases, installs and maintains the system, and reaps whatever state or federal tax credits that might apply. Instead of upfront financing, EWEB agrees to buy all power produced at a set price for the first 10 years of the project’s life. After this period, the system should have many years of useful life remaining and a new contract can be negotiated.

Lessons Learned
This experience shows that it is possible to mount a large solar electric system on an historic building without jeopardizing its historic registration. In this case, the historic values were preserved with a minor sacrifice in energy and economic performance.

On the technical side, the need to carefully review the interaction between inverters and utility transformers became clear. EWEB has incorporated this process into connection procedures for future distributed generation projects.

Would you like energy information with that? Building owner, Tom Bowerman installed a display in the coffee shop that shows system performance. So, you can sip latte and watch the dials move.

“In order to pursue this kind of project, you really have to be a true believer,” says Tom Bowerman, owner/manager of the Farmer’s Union Marketplace. “Fortunately, EWEB was a positive partner and very helpful in helping develop this renewable resource project.”

But cutting edge energy production technology is not for everyone, muses Bowerman. “Investment in good old-fashioned energy conservation practices will very likely pay bigger dividends.”

For more information on the technical issues and solutions related to this PV pilot project, phone Don Spiek or Alan Fraser at 484–1125.