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Damariscotta Hardware is a family owned and operated hardware store located in the mid-coast Maine town of Damariscotta. The business was started in 1955 by Bob Gardiner, the father of the current owners. The store is located on US Business RT 1 just north of the downtown shopping district. The business is currently housed in its third location, a 24,000 sq ft. structure built in 2003.
Maine Energy Performance Solutions (MEPS) approached Rob Gardiner, current President of Damariscotta Hardware, about the potential of installing a Photovoltaic (PV) system on the store. Mr. Gardiner has made great efforts to make his store more energy independent. Last year, he installed a wood gasification boiler that was reducing his heating oil consumption by 90%. He had also replaced high-wattage lighting with more efficient fixtures. Mr. Gardiner therefore thought a solar installation would be another substantial step toward achieving his long term goals. “We recognized a few years back that controlling energy costs was going to be instrumental for the long term viability of our company,” he said. “This project will help ensure that we will be around for another 50 years.”
MEPS recommended that Mr. Gardiner begin with an audit to inventory the store’s baseline energy usage and identify what other steps might be taken to make the facility more efficient. Since the store’s oil consumption had been reduced by the new wood boiler, the audit revealed that the biggest energy cost was now electricity. In 2008 electric use was 129,605 kW; at $.11 per kW, the electricity bill came to $13,633. This represented 61% of the store’s total energy expenditures. A PV installation was the logical next step to further reduce these costs.
As MEPS began designing the system, it became evident that challenging factors would be the rooftop space and the project costs.
MEPS teamed up with local boat builders, Lyman Morse, to develop a custom racking system that allowed us to optimize the south-facing roof.
We addressed project expenditures by designing a 69.2 kW system with an average annual output of 87,771 kW, to provide 68% of the store’s electricity needs. The initial system costs were estimated at $347,300. A USDA REAP grant was also applied for; if approved, it will reduce costs by 25%. When this grant is added to tax credits, depreciation, and a state rebate, the cost of the system is reduced to $76,742.50. A photovoltaic system pays for itself through the cost-savings of the electricity it generates and the Damariscotta Hardware system could potentially be paid back in 7-8 years. After that, any power it produces will be free. At current prices, the system would make close to $10,000 worth of electricity per year. Of course if electric rates increase the PV system saves even more money.
The site location was nearly ideal with a south facing roof having no obstructions. It was preferred to make no penetrations into the standing seam metal roof so the custom designed racking system was attached using S-5 metal roof attachment clamps. The racking system holds 301 BP solar panels rated at 230 watts each. Design considerations, including limited space for mounting DC inverters and the desire for advanced internet monitoring, led MEPS to choose micro inverters for this project. These inverters manufactured by Enphase Energy convert the generated electricity from DC to AC on the roof. The AC current from the inverters feeds directly into the existing main disconnect box where grid power enters the building. The Micro inverters also provide sophisticated web based monitoring that tracks the production and history of each solar panel. A large viewing monitor will be displayed in the stores public area for customers of the store showing the systems output.
Today’s renewable energy systems can provide decades of power. The BP PV modules used on the Damariscotta Hardware are guaranteed to provide no less than 80% of their rated power for 25 years. Micro inverters have a 15 year warranty but with solid state technology they have a projected lifespan of over 30 years. MEPS expects the system at Damariscotta Hardware to produce power for thirty to forty years. The system is rated at 69kW and will produce about 235kW per day on average. This is over 2 Giga watts (2 Billion Watts) of power over 25 years.