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This carport at a city building in Montgomery County, Md., was built by RBI Solar.
Solar carports, or canopies, are becoming a dual-purpose component of more microgrids that protect critical services locations from grid shortcomings. While both carports and microgrids individually have long been gaining ground among adopters, the combination of the two enables more site-constrained critical facilities to add solar reliability to microgrids, especially where little open ground exists for standard ground-mounted solar solutions.
The basic purpose of a microgrid is to island the user facility — be it a hospital or fire station — from the utility grid when brown-outs or black-outs are at play (which are becoming more common). While the regulated utilities claim a need for state approval for billions of dollars worth of grid improvements to avoid these outages — both planned and unplanned — such improvements, if approved, are not likely to be evenly distributed.
Utility grid “investments are unlikely to be made in areas with low population density but that are likely high risk for outages. This type of situation could be aptly addressed by DER (distributed energy resources), within microgrids or as standalone resources,” observes a February 2021 report from the California Energy Commission on DER planning.
The paired solar carport + microgrid solution is finally coming of age. “We now have some decent traction with solar carports and microgrids for critical services, including hospitals, fire stations and water plants,” says Raphael Declercq, executive VP of distributed solutions at EDF Renewables. “We also see the potential for the use of EVs for vehicle-to-building solutions. In a few years, there will be some bi-directional charging with EVs that can smooth the load at home, or in a building, as a resource on top of a backup stationary battery.”
EDF defines microgrids as “innovative systems that integrate batteries, renewable generators, load control and traditional onsite generators with intelligent componentry to create a system that ensures continuity of operation during power outages.”
The integration of EVs to solar carport microgrids may come to be the tail wagging the dog. “Solar carports are now part of the integrated solution for greenhouse gas reduction,” Declercq says. “Carports and microgrids hit the bull’s eye for resiliency even before popular talk emerged about the goal of reducing climate change.”
State mandates for microgrids have helped blaze the trail for solar carport installations being added to the mix. Over the past few years, microgrids have gained traction among utilities, commercial customers and local governments, according to a September 2020 report from Guidehouse Insights, by Jared Leader, the manager of industry strategy at Smart Electric Power Alliance (SEPA), and Peter Asmus, research director at Guidehouse Insights.
The authors identified 1,639 microgrids in the United States, representing 11,496 MW of total capacity. “Given the anticipated increased frequency of natural disasters due to climate change, the value of microgrids as a resilience solution is growing,” the authors opine. “Over the past few years, policy makers in the U.S. — especially on the West Coast, Hawaii and Northeast — have proposed (and often enacted) legislation promoting microgrids. All told, lawmakers in 18 different states have proposed or enacted 112 bills over the past 5 years.”
For example, in 2018, the California Energy Commission approved $72 million for microgrids including systems for state military bases, ports, Native American tribes, and disadvantaged communities, among other locations. Funding for the grants come from the Electric Program Investment Charge (EPIC), which taps customer charges levied by the state’s three investor-owned utilities, Pacific Gas & Electric, San Diego Gas & Electric and Southern California Edison.
Medical facilities
Hospitals and other medical facilities are a primary target for solar carports + microgrids. One medical facility to recently adopt solar carports is the Department of Veterans Affairs at the Biloxi VA Medical Center in Biloxi, Miss. The system includes a 550-kW solar PV parking canopy, and a separate PV parking canopy for electric service vehicles, developed by Hannah Solar Government Services.
Similarly, M Bar C Construction recently installed a 412-kW solar carport at Vista Community Clinic, north of San Diego. The system consists of five solar carports installed throughout ground-level parking, as well as a full-cantilevered solar carport installed atop an existing parking garage.
Larger solar carports also are becoming more mainstream. For example, KDC Solar recently turned on a massive 1.6-MW solar carport at CentraState Medical in Freehold, N.J. The new system will generate approximately 2.1 million kWh of solar electricity per year, which covers 70 percent of the campus, the highest percentage of solar electricity of any hospital in New Jersey.
Fire and police stations
Fire stations typically have little extra ground space for fixed-tilt or single-axis solar, but they do have limited parking space ripe for solar carports.
Mass.-based Cape & Vineyard Electric Coop is planning microgrids for four fire stations, including some solar carports, within its jurisdiction covering 20 towns in state. The plans for the district include integrated EV charging, and solar carports may be extended to a water treatment plant and to golf courses.
In the same way, the city of Portland last year voted to adopt a fire station microgrid with financial support from Portland General Electric (PGE). The system consists of a 30-kW solar array, a 30-kW/60-kWh battery bank, and a 125-kW diesel generator, with a microgrid controller designed by Ageto.
The City of Woodland, Calif., adopted a solar carport for the city police headquarters, developed by PCI Solar, that is expected to generate approximately 636,012 kWh per year.
Maritime projects
Maritime ports, too, are a type of critical service infrastructure where solar microgrids are being adopted that have ample open parking lots. The Port of Long Beach is adopting a $7.2 million microgrid project including a solar carport, energy storage systems and advanced system management controls at the port’s security headquarters. The solution may spread to other state ports through the cooperation of students at the University of California at Irvine’s Advanced Power and Energy Program, which will analyze a year’s worth of data from the project.
Charles W. Thurston is a contributor for Solar Builder.
Credit: Brad Kreps / The Nature Conservancy / Courtesy
Via Energy News Network: When Danny Van Clief chose a career in solar energy, he wasn’t seeking a turbulence-free glide path. Instead, the CEO of Sun Tribe Development wanted the freedom to jump with both feet into formidable challenges — ones that might spook other developers.
That pluck has landed his Charlottesville company the opportunity to be the first to generate large-scale renewable power on the coalfields of Central Appalachia. If the bold venture announced this week comes to fruition, roughly 550 acres of deforested minelands sprinkled across an expansive Nature Conservancy preserve will generate up to 75 megawatts of solar energy within two to three years.
“If it were easy, everybody would be doing it,” Van Clief said about plunging into untested territory. “I’m thrilled … to play a small part in the energy transition in Southwest Virginia. This is a breakout moment for the region. There’s been a lot of talk about this but not as much action.”
Innovators within the conservancy have been itching to walk that talk since 2019 when the nonprofit acquired the diverse 253,000-acre Cumberland Forest property in Southwest Virginia, Eastern Kentucky and Eastern Tennessee. An estimated 13,000 acres of former surface mines scar the property.
But an organization whose wheelhouse is protecting land, waterways and wildlife needed guidance and hands-on partners to advance that nontraditional thinking.
All along, the conservancy had targeted Cumberland Forest as a potential showcase to prove that investments in nature could yield financial returns and critical conservation results while returning value to local communities. In early 2020, the conservancy collaborated with the Department of Mines, Minerals and Energy to map out acreage on the property accessible to utility lines and other necessary infrastructure. A few months later, the nonprofit began seeking proposals from private solar developers.
“We can do things that are good for nature and people,” said Brad Kreps, director of the conservancy’s Clinch Valley Program in Abingdon, Virginia. “A mission of conservation and economic recovery can be compatible. These two things don’t have to be mutually exclusive.”
After a nine-month review of 15 applicants, Sun Tribe was chosen as the developer. In tandem, Washington, D.C.-based Sol Systems will finance, own and operate the solar systems once they are built.
Van Clief, a solar executive for 15 years, joined Sun Tribe in 2019 to head up its large-scale solar business. In the last year, it has completed 100 MW of utility-scale projects, usually defined as 5 MW or more. Overall, the 5-year-old company has a workforce close to 80.
Yes, the conservancy wanted developers with strong track records, but a history of environmental stewardship and a commitment to renewing and diversifying the regional economy mattered just as much.
“We’re super excited,” said Kreps, who has forged local relationships during two decades with the Virginia chapter of the conservancy. “This is kind of the next big milestone. We’re trying to show how an area that has historically played a role in supplying energy can build on its past and create a diversified economy that still has an energy component.”
‘Patience and a lot of listening’
The half dozen parcels selected for solar range in size from 70 to 125 acres. Five are in Virginia and one is in Tennessee. Four of the Virginia sites are in Wise County and one in Dickenson County.
Sun Tribe is now tasked with the nitty-gritty of working with county and state agencies to secure the proper paperwork and permits. Another hurdle is connecting with PJM, the independent regional transmission organization that manages the grid in Virginia and 12 other states.
A majority of the sites are in Appalachian Power territory, but Lexington-based Kentucky Utilities also serves a slice of the region under the name Old Dominion Power.
Separately, through the end of March, Appalachian Power was accepting proposals for 300 MW of renewable generation. It was the first of several expected bids to put the subsidiary of the giant American Electric Power in compliance with the Virginia Clean Economy Act. That 2020 law requires the utility to provide a carbon-free grid in its service territory by 2050.
Appalachian Power commended the conservancy for enabling regional renewable energy.
“This represents another avenue for [us] to explore as we work toward meeting the requirements set forth in the Virginia Clean Economy Act,” said spokesperson Teresa Hamilton Hall.
Managing array construction and interconnection, however, could prove to be vastly simpler than proving to local communities that the flow of green electrons translates to jobs and growth.
“We are really seeking permission to become a neighbor,” said Van Clief, a University of Virginia graduate in his mid-40s. “First and foremost, we’re Virginians working in Virginia.”
The partners are in the midst of fleshing out an affiliated community benefits plan that focuses on economic development, bolstering a local workforce and environmental resiliency.
“That means patience and a lot of listening,” Van Clief said about engaging with communities.
Kreps and the conservancy have always maintained that success in maximizing the bounty of such a mammoth landscape hinges on achieving three ambitious and interwoven goals.
Conservation with the crushing threat of climate change is the first and overarching one. The second is yielding a positive financial return to show partners that investments in nature such as leasing land for solar projects, practicing sustainable forestry and sequestering carbon in intact trees are smart business decisions.
And third, but no less in value, is returning value to local communities with a boost in jobs, training opportunities, tourism and outdoor recreation.
“It’s a matter of figuring out optimal use and what we can do where,” Kreps said. “This requires a mix of approaches.”
Adam Wells, who spearheaded the formation of the Solar Workgroup of Southwest Virginia in 2016, is ecstatic that the conservancy is pursuing a second life for land too often cast aside as unusable.
“It’s huge. Hats off and bravo to everyone involved,” said Wells, a Wise County native and regional director of community and economic development for Appalachian Voices. “If they can do it and make it work, that is the ultimate achievement.”
He’s all too familiar with hurdles because his coalition of nonprofits, community action agencies, colleges, state agencies and planning district commissions continues to navigate a maze of obstacles that have prevented the state’s seven coalfield counties from incorporating renewable energy into a widespread economic transition.
In his view, the conservancy and its partners have two tough tests ahead. Building economically viable solar projects in remote locales is difficult enough, never mind inventing and tweaking a community benefits package.
“All of the players are sincere,” he said, “but there has to be follow-through. That’s the real trailblazing.”
That translates to measurable impacts on local quality of life, increasing tax revenue and providing long-lasting jobs that pay enough.
“I’m optimistic. I have to be,” Wells said. “That’s what gets me up and going.”
Wells and his coalition will offer support. In the meantime, he has his hands full with a related effort to guide four manufacturers in Tazewell and Buchanan counties in moving beyond their coal-centric beginnings into renewable technology.
In mid-March, The Virginia Growth and Opportunity (GO) Board green-lighted close to $500,000 in state matching grants sought by Wells and Vivek Shinde Patil, another go-getter at the nonprofit Ascent Virginia.
The venture they call the Energy Storage and Electrification Manufacturing Jobs Project could generate as many as 206 direct jobs and millions in investments. The grants are designed to help local companies pivot to exporting advanced batteries and other components that fuel cars in Asia, light homes in California or store energy generated by wind farms in Europe.
Stepping stone to a broader outcome
For several years, Wells and Sun Tribe have been shepherding a separate and smaller solar project that still has the potential to be the first one to be deployed on an old coalfield in Virginia.
Construction on the 3.5-MW array for the Mineral Gap Data Centers is now slated to begin at the end of this year and be completed in mid-2022, Van Clief said.
Wells and his solar workgroup team pioneered a novel funding method by writing a grant to tap into federal money for redeveloping old mine sites. Appalachian states began receiving federal money from what’s known as the Abandoned Mine Land Pilot Program in 2016. It’s funded through the U.S. Treasury.
Approval led to the state Department of Mines, Minerals and Energy awarding $500,000 in 2019 to the Wise County project designed to partially power on-site data centers with a new solar array. It was designed to decrease the centers’ operating budget as well as peak-load demands on the local distribution grid.
As of now, the conservancy arrays will be funded with private dollars. Van Clief said it was premature to reveal a price tag for the undertaking.
The signature biological richness of the Cumberland Forest prompted the conservancy to invest in one of the most mammoth projects ever pursued by the nonprofit during its seven decades of existence.
If the conservancy can be successful stewards of nature in Central Appalachia while also mining the sun and renewing and diversifying the economy, Kreps is assured it could be a model in Virginia and beyond.
More than 100,000 acres have been affected by coal mining in Virginia, according to figures from the state agency soon to shorten its name to the Department of Energy. That number doesn’t include other brownfields. Mineral mining (non-coal) has impacted another 40,000 acres.
“If we can demonstrate solar on unforested lands in the Cumberland Forest, it’s a stepping stone to a bigger and broader outcome,” Kreps said. “Virginia is setting strong policy. We hope that shapes policy in neighboring states and can be connected to federal policy.
“It’s very positive for climate change and the environment.”
“The Virginia Clean Economy Act let the world know that Virginia is open for solar business,” Van Clief said. “And this portfolio says Southwest Virginia is open for business.”
Now, it’s time to dig in and prove the concept.
“This is a defining moment for our business and for our industry. We couldn’t have scripted better news than this announcement as we’re coming out of a pandemic.”
Elizabeth McGowan is a longtime energy and environment reporter who has worked for InsideClimate News, Energy Intelligence and Crain Communications. Her groundbreaking dispatches for InsideClimate News from Kalamazoo, Michigan, “The Dilbit Disaster: Inside the Biggest Oil Spill You Never Heard Of” won a Pulitzer Prize for National Reporting in 2013. Elizabeth covers the state of Virginia. Her book, "Outpedaling 'The Big C': My Healing Cycle Across America" will be published by Bancroft Press in September 2020.
Fraunhofer ISE research projects like this show how dual-use PV offers protection against hail, frost and drought damage.
Boston-based BlueWave Solar has always aimed higher. The certified B Corp. (a business designation that sets higher standards for balancing profit with purpose) started out in 2010 with a focus on community solar and has since become a big proponent of agrivoltaics or “dual-use” solar. It has a few dual-use designs in the pipeline right now, one of which, the Rockport project in Rockport, Maine, was just sold to Navisun. It is a 4.2-MW, 10-acre project installed above an active blueberry farm.
“I view this as the extension of doing solar development well — if you’re in the business of optimizing projects already, which I assume everyone is, and not just stuffing a bunch of panels on the property and leaving,” says Chad Nichols, BlueWave’s managing director for the Northeast.
BlueWave Solar is just one of a handful of developers seeking to grow this nascent solar segment that will set the standard for the future of ground-mount solar. What’s different about this ag-focused, dual-use solar design, exactly? It starts by asking: “How do we preserve that farmland and put a solar array over it?” and answering with basic solar developer problem-solving. Intensively research the best use of the land, consider the racking system itself, how it impacts the earth below it and optimize spacing and tilt angle accordingly. During construction at Rockport, the team used special plywood and low density equipment to avoid disturbing the land. The fencing around the array has larger spaces for smaller animals to come and go.
These simple, thoughtful decisions get you 50 to 75 percent of the way, Nichols says.
“Next, we figure out what it takes to keep the soil underneath the array active and productive,” he says. “We’re talking row spacing in relation to the species of plants or crops that we want to survive. Do they need additional sunlight? The array would traditionally block that, so maybe we leave out every other panel. That’s an extreme example, but it’s not a huge lift to at least raise the array up a few feet.”
New research taking root
Certain sustainable greenfield solar development techniques should be common sense best practices by now: sprinkling pollinator-friendly seed mix, adding sheep to graze on the land. The agrivoltaics movement goes further, planting that solar array along with and above a crop. The research is ongoing, but there’s already a lot of evidence showing the PV as a value-add (hence the dual-use).
Future home of BlueWave's Rockport project.
Enel Green Power partnered with the National Renewable Energy Laboratory (NREL) on the InSPIRE project, including a multi-year study of quantitative impacts from native vegetation and pollinator habitats at the Aurora solar farm in Minnesota. Early results point to substantial improvements in vegetation growth and pollinator presence.
“These practices have demonstrated environmental benefits by enhancing soil properties for stormwater retention and water quality, increasing food production for pollinator-dependent crops and creating new industries for local agricultural services, such as native seed and livestock grazing,” says Peter Perrault, senior manager of circular economy and sustainable solutions for Enel North America. “There are also some food and vegetable crops that have been shown to produce higher yields when grown under the shade of PV panels.”
Studies by German research organization Fraunhofer ISE show dual-use PV design offers protection against hail, frost and drought damage, eliminating the need for protective foils and other materials. A reduction in wind load and solar radiation underneath the PV modules can help to decrease water consumption. For some crop types, the elevated PV mounting structure can lead to an increase in yield. In 2018, the yields from three of the four crops grown (winter wheat, potatoes, clover and celery) at one family farm under study produced a greater yield under PV panels. The crop yields for celery profited the most with a gain of 12 percent compared to the reference. For potatoes, the land use efficiency rose to 186 percent per hectare with the agrivoltaic system. Another pilot project installed in 2016 with 720 bifacial PV panels showed an increase in land use efficiency between 60 and 84 percent two years later, as well as improved adaptability during dry periods.
Dual-use synergy
Reducing the need for irrigation by up to 20 percent
Possibilities of rainwater collection for irrigation purposes
Reduction in wind erosion
Use of the PV mounting structure for protective nets or foils
Optimizing light availability for arable crops, e.g. PV tracking systems
Higher module efficiency through better convective cooling
Higher efficiency of bifacial modules due to larger distances to the ground and adjacent module rows
Back in Rockport, an array positioned 4 to 5 ft above the blueberries helps control temperatures, preserve water and, hopefully, boost the farm’s blueberry production. The project is being developed as part of BlueWave’s ongoing focus on dual-use development, as the company was also recently selected for a three-year, $1.8 million grant from the Department of Energy in partnership with the Clean Energy Extension at the University of Massachusetts at Amherst and other project partners to further study the applicability of dual-use. The research can be split into two broad categories.
1) Proof of concept for the health and viability of various agricultural activities (e.g. holistic grazing, ground crops, etc.) under an operational solar array. This category covers farm productivity metrics like pre and post agricultural yields and per acre production costs, as well as solar design approaches that consider farm infrastructure, farm equipment logistics, shade/sunlight percentages, stormwater management and/or bifacial impacts to the crops below the arrays.
2) Best practices for solar project construction and soil management that ensure the project is as supportive of the site's agricultural goals as possible (within and around the array).
“Our expected outcome is that not only can we still support active agriculture but, in some cases, help to diversify farm production and improve farm viability,” Nichols says. “Having credible agricultural partners at the table who can lend a data-driven, and in some cases experience-driven view will be critical for measuring our performance and for gauging potential improvements over time.”
The analogy of solar-plant-as-a-crop is made even more real as farmers and developers identify new farming equipment and strategies for taking care of this farm of the future.
“We’ve had conversations with farming equipment manufacturers to figure out if we want to farm this land between these rows. Can you do it with traditional equipment or does the project require custom equipment?” Nichols explains. “You pair those considerations with the means and methods of protecting certain things during construction, which puts you in the mindset of everyone involved.”
Enel is working with Arup to implement new tools to evaluate all of the options for dual-use opportunities in its future project development as well. The Dual Use Opportunities (DUO) Tool, for example, is being used to evaluate multivariate project parameters to inform decision making in the earliest stages of development.
“The DUO Tool was the result of a broader effort to increase the circularity of our plants and development processes, as well as programmatically implement changes throughout the life cycle of our assets,” Perrault says.
In the coming years, this process will involve solar design adaptations to facilitate robotics and farming machinery access to the land under and around panels to support large-scale maintenance and commercial farming alongside utility-scale solar applications.
Going agro on voltaics
Not everyone sees solar panels on a farm as community progress. Some rural communities are fearful solar developers are no different than any other developer, swooping into town to turn family farms into corporate profits. Representatives in Kentucky even introduced a bill to ban large-scale solar projects on farmland that could be “a detriment to the preservation of productive farmland.”
“What was once an income-producing property for the people of that county, is now possibly, you could say maybe an eyesore to the neighbor,” Republican State Sen. Steve West stated when trumpeting his bill. “Our farmland is one of our greatest resources, and so in effect if you allow these solar panels to go into an area, cover land, after their lifespan of 20-25 years, they’re filled with hazardous chemicals. It’s gonna be pretty tough from a monetary standpoint to redevelop that land into anything else but a solar installation.”
Sheesh. While that bill and that Senator may be misguided and ill-informed, the bill does reflect a genuine public fear. It’s a reminder that the success of agrivoltaics in the U.S. will require more than installation innovations and academic studies from Germany. The next step is broader community outreach and partnership — an acknowledgement that a community and its land are connected.
Minneapolis-based Blue Horizon Energy has gone as far as becoming part of a smaller community, opening an office in Marcus, Iowa.
“Placing an array on that land is what we consider a minimal impact. We’re not putting in foundations, we’re not putting in homes and we’re not building Wal-Marts,” Nichols says. “When it is community solar, you quickly have eyes opened when you say the power stays local or the utility is using it to lower their rate. But let’s go a step further to take that land and put it back to being productive acreage for the world. Look at this project with the sheep on it. We design it to stay with the project for the life of it. As more of these go in the ground, the more examples we’ll have.” Key for the community (and landowners) to understand is dual-use solar development removes the either/or proposition struggling farmers are in — they can add a generating asset and become the long-term owner while also staying a viable farm.
“Our team is very intentional when working in these communities to build a local on-the-ground presence and proactively engage with the citizens who will be living alongside these projects for decades,” says Griffin Dooling, CEO at Blue Horizon Energy. “Agriculture is always advancing as an industry, and these communities are often passionate about adopting new, more efficient technologies to improve their profitability once they understand them. Solar is a prime example of that advancement and as a new technology, the public education around these projects is one of the most important pieces to ensure that the benefits of solar deployment are understood and well-supported in the community.”
Maximum harvest
September 25, 2020 - Byron Kominek, owner of Jack’s Solar Garden in Longmont, Colo., drives a tractor away following a kickoff event for the farm. Jack’s is one of 30 agrivoltaics research sites being studied by the Joint Institute for Strategic Energy Analysis (JISEA) research partners at NREL and Colorado State University as part of the Innovative Site Preparation and Impact Reductions on the Environment (InSPIRE) project. (Photo by Werner Slocum / NREL)
Jack’s Solar Garden is a 1.2-MW community solar farm that’s the largest agrivoltaic research project in the U.S., located in Boulder County, Colo. In partnership with NREL, Colorado State University and the University of Arizona, Jack’s Solar Garden will study how best to grow wildflowers, pasture and prairie grasses, pollinator habitats, as well as crops, such as carrots, onions, tomatoes and squash that will all be planted underneath and around the solar array.
But there is so much more to it. Built by Namasté Solar, a certified B Corp., with help from solar tracker company Solar FlexRack, the Jack’s project emphasizes the value of community while also cultivating the next generation of agrivoltaic farmers. • Jack’s partnered with Sprout City Farms, which will manage crop production under the solar array as well as train the first agrivoltaic farmers in Colorado. • The farm donates 2 percent of its energy production to low-income households in Boulder County. • Jack’s has an Artist on the Farm program to support local creatives. • Students and community members have an opportunity to tour Jack’s to learn about agriculture, solar power and land use management through their new non-profit arm, the Colorado Agrivoltaic Learning Center.
Solar arrays on farms can be dual-use beyond crops too: “We have worked with several farms to develop solar solutions that serve a dual-purpose of energy production and livestock shade,” Dooling tells us. “This helps maximize the efficiency of the farm real estate, where often the need for livestock yards and operational buildings competes with the priority placed on tillable cropland, leaving little room for solar without sacrificing space for other needs. Using solar to serve a dual-purpose over livestock makes overall space use more efficient.”
All of these results are profound. Farming is a tough, fickle business as it is, and climate change has only made it tougher and more fickle. Water shortages, extreme weather and increasing global temperatures require new measures to protect plants and soil from negative environmental (human) influences. Solar arrays are proving to be one of those measures, while also being a source of additional income and community resilience. The more solar developers we have planting agrivoltaics into the core ethos of the industry, the more dual-use ideas are bound to blossom.
“We see it as the most responsible way to develop,” Nichols says. “To reach any of the goals we have as an industry and country, we have to be great at ground-mount development, and responsible development becomes a competitive advantage. We see the benefits immediately.”
Chris Crowell is managing editor of Solar Builder.
S-5!'s PVKIT 2.0 is one such direct-attach solar mounting solution for metal roofs.
Rooftop rail-less solar PV systems have been around for many years, and year-over-year, continue to be a growing part of the solar market. Yet hesitancies still exist with both the technology and with learning new methodologies. One of these hesitancies is wire management.
We recently sat down with Doug Claxton, owner of The Solar Revolution and consultant with TSR Energy based in Boulder, Colo.; Mark Gies, solar expert and director of solar business with S-5!; and Shawn Haddock, senior field applications specialist with S-5!, to discuss wire management on low-slope rail-less PV systems.
Module preparation
Module preparation on the ground means less work on the roof.
Prepping modules is one of the highly critical steps that must be planned, designed and executed to minimize installation time on the roof.
“Every project is unique, and there are many different methods for wire management and different combinations of products when it comes to home runs — but it can always be figured out before you get on the roof. That’s what I've seen helps installers the most” Haddock says. “I have shown up at jobsites, looked at their wire management design and thought, ‘this is crazy’. Then, we end up back at the office and spend the day working with the designers to come up with a better diagram that will now make the project days go faster.”
“On site, we typically have one or two people on the ground with a string diagram so they know how to properly prep the leads,” Claxton adds. “One of the first things we do is figure out how we are going to manage all the optimizer conductors because that is a challenge, but that challenge exists whether you have rail or not.”
Strategic string design
Strategic string design like this minimizes labor and material.
Take the time to strategically design your string layouts. This will enable you to minimize wire length, reduce the time it takes to clip up wires and plug in jumpers and also provide easy access to string ends, optimizers or microinverters. A few hours at the desk optimizing string design can save many hours or even days on the roof.
“On the front end, the system designer can make or break the job for installers on the roof, as well as for future O&M activities,” Claxton says. “We have always been big on cleaning up designs through logical string layouts and grouping home runs. I have seen layouts that tee up the installers for failure and make troubleshooting and diagnostics more difficult. I understand that sometimes the goal is to get as many Watts on the roof as possible, but I think you eventually pay the price for doing that as opposed to getting really clean layouts.”
Benefits of direct attaching solar modules to metal roofs
Far fewer parts
Huge reduction in freight cost
Labor reduction
Reduced handling/logistics
Reduced dead load to the roof
25 percent better load distribution
Speed of system installation
Better wind resistance
Correction gaps
Correction gaps can be as small as 1 inch or large enough to create a narrow walkway to access all modules.
Although sometimes correction gaps are necessary (between pairs of modules) to align with metal roof seams, there is a clear benefit to creating a narrow walk space (shown above), which provides speeds access during installation and makes future O&M much easier and safer. The net loss of module space is usually below 3 percent (often it is zero).
“With correction gaps, you have easy access to every module on that project without having to walk on modules or worry about damaging them,” Haddock says. “You can quickly pull up a module, fix connections, and/or replace them. These gaps are essentially buffered spaces that allow for modules to be tweaked, improving the alignment and squareness of the array vs. the squareness of the roof. The gap can be as little as 1 in. or as large as 8 or 10 in., in which case it can be used as a walk space. Correction gaps can make the solar array more aesthetically pleasing from the ground.”
“This style works especially well when you have rooftops that have two-foot on-center seam spacing, which is common on low-slope commercial roofs,” Claxton says. “The gap provides the ability to walk between those twin module columns and not on top of the modules. This also facilitates wire management and MLPE replacement. In my opinion, the correction gap is well worth the small reduction in system size.”
Gies has worked with solar companies that design arrays with the number of rows or columns equaling the string sizes. “That is the ultimate design since all connectors, optimizers and microinverters are easily accessible from the array’s edge,” he says.
Trunk and branch wire management
Trunk and branch method saves installation time. Wire trays minimize effort to route jumpers to home runs.
As sub-arrays get bigger and bigger, even with careful string and layout design, string ends may be located deep inside the module array. Wire trays can be installed underneath the modules to save significant time that would otherwise be needed to tie or clip up jumper wires on a direct path from the string ends to the home run (shown above).
“Wire jumpers can be routed to the wire tray, bundled inside it without any need for clips and then routed directly to the home run,” Gies says. “This method can also keep wires better organized.”
“When you are truly getting large, this would be a way to go,” Claxton adds. “But, a lot of times with a 100-kW system, with careful planning, you probably don’t need this. And, even with more than 100 kW, you are probably doing multiples of 100-kW blocks. This is certainly a good method if you have no choice but to bring a lot of jumpers to home runs or back to one central point.”
MLPE considerations
Both types of MLPE, optimizers and microinverters, have continued to gain traction in the solar market and are now more commonplace in rooftop projects of all sizes. MLPE can usually be installed by mounting to the module frame (shown on right) or directly to the roof. For some, there are specific reasons to mount to the roof, such as manufacturer requirements, but in most cases, mounting to the module frame is easier and most economical.
“I have heard various cases for both, but I am a big proponent of mounting MLPE right onto the modules,” Claxton says. “It allows for clean wire management that can be prepped in advance, making it easy for the installers who are setting the mods.
“Now, microinverters are another story, but I still think they are great to mount directly onto the modules,” he continues. “You can put a microinverter onto the module creating something similar to a true AC module. Then, it is a matter of managing the trunk cable, which can be accomplished with several wire management products intended for this purpose. From there, it’s just plug and go.”
Some installers may prefer to mount microinverters to the roof. Since a microinverter’s AC branch circuit is a single-trunk cable, both the microinverter and trunk cable cannot be installed together during the module prepping process. Others may prefer to mount microinverters to the metal roof using clamps and connecting them all to the AC trunk. This way, the modules are plugged in as they are set in place.
Additionally, other logistics such as the weight or size of the MLPE, or even local codes, may hinder or prevent direct attachment to the modules.
Tying it together
Strategically designing module and string layouts, prepping modules in staging areas and performing repeatable installation procedures overcomes all hurdles to installing rail-less solar. Even first-time installers of S-5’s new rail-less system have reported time savings of up to 50 percent.
Claxton concludes: “Start with the design; know all of the products at your disposal to achieve good wire management; use all of the products to mock it up; make sure that your configuration is actually what is going to work with the module, and then execute it with robotic repetition.”
This carport at a city building in Montgomery County, Md., was built by RBI Solar.
Solar carports, or canopies, are becoming a dual-purpose component of more microgrids that protect critical services locations from grid shortcomings. While both carports and microgrids individually have long been gaining ground among adopters, the combination of the two enables more site-constrained critical facilities to add solar reliability to microgrids, especially where little open ground exists for standard ground-mounted solar solutions.
The basic purpose of a microgrid is to island the user facility — be it a hospital or fire station — from the utility grid when brown-outs or black-outs are at play (which are becoming more common). While the regulated utilities claim a need for state approval for billions of dollars worth of grid improvements to avoid these outages — both planned and unplanned — such improvements, if approved, are not likely to be evenly distributed.
Utility grid “investments are unlikely to be made in areas with low population density but that are likely high risk for outages. This type of situation could be aptly addressed by DER (distributed energy resources), within microgrids or as standalone resources,” observes a February 2021 report from the California Energy Commission on DER planning.
The paired solar carport + microgrid solution is finally coming of age. “We now have some decent traction with solar carports and microgrids for critical services, including hospitals, fire stations and water plants,” says Raphael Declercq, executive VP of distributed solutions at EDF Renewables. “We also see the potential for the use of EVs for vehicle-to-building solutions. In a few years, there will be some bi-directional charging with EVs that can smooth the load at home, or in a building, as a resource on top of a backup stationary battery.”
EDF defines microgrids as “innovative systems that integrate batteries, renewable generators, load control and traditional onsite generators with intelligent componentry to create a system that ensures continuity of operation during power outages.”
The integration of EVs to solar carport microgrids may come to be the tail wagging the dog. “Solar carports are now part of the integrated solution for greenhouse gas reduction,” Declercq says. “Carports and microgrids hit the bull’s eye for resiliency even before popular talk emerged about the goal of reducing climate change.”
State mandates for microgrids have helped blaze the trail for solar carport installations being added to the mix. Over the past few years, microgrids have gained traction among utilities, commercial customers and local governments, according to a September 2020 report from Guidehouse Insights, by Jared Leader, the manager of industry strategy at Smart Electric Power Alliance (SEPA), and Peter Asmus, research director at Guidehouse Insights.
The authors identified 1,639 microgrids in the United States, representing 11,496 MW of total capacity. “Given the anticipated increased frequency of natural disasters due to climate change, the value of microgrids as a resilience solution is growing,” the authors opine. “Over the past few years, policy makers in the U.S. — especially on the West Coast, Hawaii and Northeast — have proposed (and often enacted) legislation promoting microgrids. All told, lawmakers in 18 different states have proposed or enacted 112 bills over the past 5 years.”
For example, in 2018, the California Energy Commission approved $72 million for microgrids including systems for state military bases, ports, Native American tribes, and disadvantaged communities, among other locations. Funding for the grants come from the Electric Program Investment Charge (EPIC), which taps customer charges levied by the state’s three investor-owned utilities, Pacific Gas & Electric, San Diego Gas & Electric and Southern California Edison.
Medical facilities
Hospitals and other medical facilities are a primary target for solar carports + microgrids. One medical facility to recently adopt solar carports is the Department of Veterans Affairs at the Biloxi VA Medical Center in Biloxi, Miss. The system includes a 550-kW solar PV parking canopy, and a separate PV parking canopy for electric service vehicles, developed by Hannah Solar Government Services.
Similarly, M Bar C Construction recently installed a 412-kW solar carport at Vista Community Clinic, north of San Diego. The system consists of five solar carports installed throughout ground-level parking, as well as a full-cantilevered solar carport installed atop an existing parking garage.
Larger solar carports also are becoming more mainstream. For example, KDC Solar recently turned on a massive 1.6-MW solar carport at CentraState Medical in Freehold, N.J. The new system will generate approximately 2.1 million kWh of solar electricity per year, which covers 70 percent of the campus, the highest percentage of solar electricity of any hospital in New Jersey.
Fire and police stations
Fire stations typically have little extra ground space for fixed-tilt or single-axis solar, but they do have limited parking space ripe for solar carports.
Mass.-based Cape & Vineyard Electric Coop is planning microgrids for four fire stations, including some solar carports, within its jurisdiction covering 20 towns in state. The plans for the district include integrated EV charging, and solar carports may be extended to a water treatment plant and to golf courses.
In the same way, the city of Portland last year voted to adopt a fire station microgrid with financial support from Portland General Electric (PGE). The system consists of a 30-kW solar array, a 30-kW/60-kWh battery bank, and a 125-kW diesel generator, with a microgrid controller designed by Ageto.
The City of Woodland, Calif., adopted a solar carport for the city police headquarters, developed by PCI Solar, that is expected to generate approximately 636,012 kWh per year.
Maritime projects
Maritime ports, too, are a type of critical service infrastructure where solar microgrids are being adopted that have ample open parking lots. The Port of Long Beach is adopting a $7.2 million microgrid project including a solar carport, energy storage systems and advanced system management controls at the port’s security headquarters. The solution may spread to other state ports through the cooperation of students at the University of California at Irvine’s Advanced Power and Energy Program, which will analyze a year’s worth of data from the project.
Charles W. Thurston is a contributor for Solar Builder.
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GAF Energy’s solar roofing manufacturing is coming to the United States 
