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Black River Produce is looking Greener …Big Time!

By Katherine Leversee

Mark Curran and Steve Birge, co-owners and founders of Black River Produce, a fresh food distributor serving Vermont, New Hampshire, western Massachusetts and New York, have always been committed to organic, sustainable agriculture. But now Black River is making a major move toward renewable energy.

“We’ve always been focused on the sustainable. We source our produce from local farms when available, we’ve installed high-performance lighting in our facility, our delivery trucks run on bio-diesel from White Mountain Biodiesel in Haverhill, NH”, says Curran. He adds that sustainability has always been one of Black River’s values, and now that net metering, tax incentives and the ever-dropping price of renewable energy hardware and installation have made using solar power an economically viable option, Black River is jumping in with both feet.

“Unfortunately, we require a lot of electricity” he says, referring to the 40,000 sq. ft. of refrigerated space used to transfer their produce.

Curran and Birge have hired Prudent Living, an upper-valley company in Windsor, VT specializing in energy-efficient architectural design, green strategies for homebuilding and renovation and renewable alternatives like solar, wind and geothermal, to install just under 1,600 “fixed” or static solar panels on the roof of the main building and the roof of the garage. Tim Biebel, Vice President of Prudent Living, has been working with Curran and Birge, and hopes to begin construction on the project this summer. Each panel will be mounted on the roof, facing south, at a 15º tilt to capture the maximum amount of sunlight. The bulk of the electricity will be generated in the summer months when the sun energy is most direct on the panels.

“We have a great location for solar”, Curran says, “with lots of clear southern exposure”.

240 watt solar panels will be installed, and when multiplied by the number of panels installed, the whole installation is rated at over 382 kilowatts. This system will offset almost 50% of the Black River plant’s total energy use. This means that Black River will only have to purchase half as much electricity from their traditional power supplier as they did before. The rest of it they will generate themselves.

What is unique about Black River’s installation is a “micro-inverter” system, where each panel installed has its own inverter. The inverter is a piece of equipment which converts the sun’s energy, collected by the photovoltaic cells on the panel, into alternating current electricity which can be used to power the lights, refrigeration units, etc. inside the plant. Many solar installations will have one inverter for a row or group of linked panels. When this is the case, if some of the panels in that row or group are compromised (covered in snow, shaded, etc.) the whole group is compromised, significantly lowering the output of the system.

“Since there are many vent pipes and different roof elevations on the plant it made sense to use micro inverters to maximize the available roof space and not have to worry about little shading problems that might otherwise limit the production of the entire PV system if a typical string inverter had been used”, says Biebel.

Installing solar power isn’t the only project Black River has going. Recently, the company purchased the old Ben & Jerry’s plant in Springfield, VT in order to expand their refrigeration capacity to match the growing demand for locally raised and processed meat. The expansion is expected to double their power usage.

This will be the second retrofit project Black River has undertaken. In 2005, the company elected to convert the old Idlenot Dairy Plant into their present headquarters, and now they’ve decided to go the re-use route again. “The greenest building is a building that already exists” says Curran.      For now, only the current Black River facility will be outfitted with solar panels, but Curran aims to do the same with the new building once the roofs have been replaced.

According to Biebel, the second system will be somewhere between 150 kW to 210 kW in size, depending on available roof space when the remodeling is complete, and will use racking methods and micro-inverters similar to the first project.

“We’re already beginning to map it out”, says Curran. “It’s the logical next step in becoming an ‘even’ greener business”.

2 comments to Black River Produce is looking Greener …Big Time!

  • Griffin

    Great article, and good for Black River Produce for using their roof space to offset electricity consumption!

    I do have a few questions about the PV array:

    The micro-inverters sound like they improve efficiency of the array during partially shaded conditions, but what is their effect on efficiency (compared to string inverters), in unshaded conditions?

    Is the array expected to produce about half of the building’s electricity on an annual basis or only some months? Is it possible the system could ever deliver excess electricity to the grid?

    How was the panel tilt of fifteen degrees chosen to maximize production

  • Griffin,
    the micro-inverters will increase the efficiency of the array during unshaded conditions as well. Solar modules are rated at a certain power (240 watts in this case) but that rating is within a tolerance of -0W to +5W which means that even though some panels are rated at 240 watts, they could actually be closer to 245 watts. By using micro inverters we can maximize the production of each panel that is on the + side of the power rating. This is not possible with a string inverter.

    The array is expected to produce approximately 50% of the energy usage on an annual basis. It is unlikely that the array will produce enough excess electricity to deliver excess to the grid because it will likely be consumed by the facility before it has a chance to make it to the grid.

    The 15 degree tilt was chosen because it minimized the amount of ballast required to keep the system on the roof should there ever be a 90 mph wind. If the panels had been tilted to a higher degree the array would have required much more ballast in order to withstand such a strong wind. There are always trade offs when designing a system to fit a specific site. This was one that had to be made in order to not overload the roof with too much weight. As a result the system will produce much more electricity in the summer than the winter.

    I hope these responses are helpful to you.

    -Tim Biebel, Vice President, Prudent Living

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