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BUILDING GREEN: Sweet Arrangement
TEN MILES (16 km) inland from the Pacific Ocean shore, the city of Santa Maria, Calif., enjoys cool coastal breezes and ample sunshine. Moderate 70 F (21C) summers and mild 50 F (10 C) winters support a strawberry-growing season that lasts up to 10 months a year. The conditions also are ripe for solar power production, as Santa Maria-based Melfred Borzall Inc. can attest. Two photovoltaic roof installations on the company’s Santa Maria plant provide 90 percent of the manufacturing facility’s electrical power.
DESPITE THE FACT THAT THE ENTIRE 30,000-SQUARE FOOR (2,787-m2) METAL ROOF IS COVERED IN (PV) PANELS, ONLY ONE PENETRATION THROUGH THE METAL ROOF ON EACH SIED-FOR THE POWER CONDUITS-WAS NECESSARY.
SEED OF AN IDEA
The Melsheimer family runs Melfred Borzall, which produces drill bits and tools for underground horizontal directional drilling. In 2003, California was in the throes of rolling blackouts. Like many business owners across the state, the Melsheimers became frustrated with spiking utility rates and unpredictable power availability rates and unpredictable power availability. When they heard about the benefits of generating on-site solar power, they became intrigued.
“It was by no means a purely financial decision,” says Eric Melsheimer, vice president of engineering at Melfred Borzall. “Reducing our reliance on foreign oil was a large part of our decision. It’s not sustainable to have an operation based on imported fossil fuels.”
The company’s first photovoltaic installation was in 2004. As the company grew and its power needs increased, the Melsheimers decided in 2007 to produce a larger portion of their electricity by adding another PV array in 2007. The first installation of 648 PV panels took place in the south-facing side of the facility’s standing seam metal roof system. The second addition consisted of 347 larger solar panels on the roof’s northern slope. In both cases, the panels wee affixed to the standing metal seam with clips.
Melsheimer is extremely pleased the system didn’t require hundreds of potentially leak-causing penetrations in the metal roof. Despite the fact that the entire 30,000-square-foot (2787-m2) metal roof is covered in panels, only one penetration through the metal roof on each side-for the power conduits-was necessary. In addition, clipping the panels to the roof was quick and kept installation costs down.
BASED ON THE INITIAL RATE OF SAVINGS FROM THE SYSTEM, THE SILICON-BASED PV PANELS WILL SAVE AT LEAST $1 MILLION DURING THE WARRANTY PERIOD OF 25 YEARS.
Facing south is important for solar power production because the system can capture sunlight all day long, especially in winter when the angle of the sun is low.
The south side of the roof has a natural tilt of 4 degrees. Although a 20-degree tilt is optimal, Ryan Park, commercial sales manager of REC Solar, Inc., San Luis Obispo, Calif. said that simply raising the panels isn’t always the best solution. The difference between a 20-degree tilt and a 4-degree tilt offered a 5 percent increase in electrical output, but when panels are tilted higher, space must be provided between the rows to prevent the panels from shading one another.
“We had a choice of higher panel density or better production value,” explains Park. “We decided to forego the 5 percent increase in production. In return, we gained more panels, installation efficiency and material cost effectiveness, as fewer system components were needed without the additional tilt.”
Because a north-facing orientation is exponentially worse that a southern exposure for solar power production, the team decided to raise the panels to face the southern sky on Phase 2. First, they had to compensate for the north side of the roof’s 4-degree slope, which faced the opposite direction of the sun they wanted to capture. By tilting the panels up 8 degrees, the north panels would equal the same angle as the southern ones.
The plant’s annual electric bill dropped from $36,000 in 2003 to $3,064 in 2008. The savings are even more dramatic considering the facility increased its electrical needs by adding 150 horsepower of tool production equipment in 2006. Based on the initial rate of savings from the system, the silicon-based PV panels will save at least $1 million during the warranty period of 25 years.
Rebates and tax credits offset the company’s initial costs. The first system cost of $575,000 was reduced to a net cost of $214,500 through a combination of a 50 percent rebate from San Francisco based Pacific Gas and Electric Co., 10 percent federal tax credit and 15 percent California tax credit. The second system cost of $466,700 was reduced to a net cost of $215,480 through a combination of a 25 percent rebate from San Dimas, Calif.-based Southern Californial Gas Co., 30 percent federal tax credit and 7.5 percent California state tax credit. Accelerated depreciation provided additional benefits. The utility-sponsored rebates were funded through surcharges applied to ratepayers bills. Since the Melsheimers installed their system, tax credits and rebates, locally and nationally, have changed.
The combined system is rated to produce 136 kW of peak power. The panels produce direct-current electricity, and inverters convert it to alternating current. Through net-metering agreement with PG&E, the alternating current is fed into the local power grid. The plant draws from the grid if solar energy production does not meet demand. When the PV system generates more power that needed, it sends it into the grid, spinning Melfred Borzall’s meter backward.
The utility’s seasonal rate structure also works in Melfred Borzall’s favor. During the summer when the PV system generation is at its highest, the utility credits the power generation at its steeper seasonal rate of $0.199 per kW hour. When the company needs to supplement its energy production in winter months, the utility’s price is at a lower $0.137 per kW hour.
Last year the system produced 227,000 kW of energy, which equates to 90 percent of the facility’s total electric usage.
IMPROVEMENTS OVER TIME
In the three years between Phase I and Phase 2, Park says although the efficiency of panels increased by approximately one percent, advancements in system monitoring took a big step forward.
“Now, you can dive down into details and see what’s really happening.” Park explains. “A PV system is an energy asset, and monitoring lets you evaluate whether or not that asset is working.”
Another advantage monitoring provides is the ability to troubleshoot. If an inverter shuts down-which will happen if there’s a voltage spike in the utility grid-the monitoring system notifies REC Solar. The inverter automatically turns itself back on but without a monitoring system, it would be difficult to determine why the shutdown occurred. Melfred Borzall also provides real-time solar production information on its Web site, www.melfredborzall.com.
By sending solar power into the grid when overall electricity demand is highest, Melfred Borzall is supplying its community with clean energy. The company’s PV system will reduce CO2 emissions by 9.3 million pounds (4.2 million kg) throughout the next 25 years, which is the equivalent of the CO2 absorbed by 17,810 mature trees.
Melfred Borzall is planning an expansion and, although solar panels won’t be part of the initial construction. Melsheimer says they intend to continue their solar energy legacy. “The expansion will be structurally equipped to support solar panels and we plan to add electric vehicle charging stations to increase our independence from fossil fuels.’”
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