“Solar power makes sense for Walmart, and it makes sense for Massachusetts,” said David Ozment, Walmart director of energy.

“Walmart’s solar installation commitment is a game-changer for renewable energy in Massachusetts,” said George Bachrach, president of the Environmental League of Massachusetts. “This is the largest business customer to see the economic and environmental benefits of solar power, and I hope others follow in Walmart’s footsteps.”

At a press conference in Boston, sustainability executives outlined the economic and environmental benefits of solar power.

“We are committed to increasing the use of renewable energy resources, including solar panels, at our stores in Massachusetts and, over time, throughout the country,” said Ozment. “In a state like Massachusetts, we expect the solar systems to produce enough power to provide 10-15 percent of each store’s energy needs. This will also reduce our use of Greenhouse Gases and help to provide energy expense savings and long term price certainty.”

Massachusetts currently has almost 100 MW of solar power, up from less than 4 MW in 2007. The Walmart solar installations will bring the state closer to the Commonwealth’s goal of generating 250 MW of solar power by 2017.

Walmart’s goal is to be powered 100 percent by renewable energy. The United States’ EPA Green Power Partnership program ranks Walmart as the second-largest onsite green power generator in the U.S. Renewable projects provide 1.1 billion kilowatt hours annually, or about 4 percent of electricity for Walmart buildings globally. The grid supplies another 18 percent, for a total of 22 percent renewable electricity as of 2010. Walmart has 180 renewable energy projects in operation or under development, and continues to test solar, fuel cells, microwind, offsite wind projects, green power purchases and more.

In Massachusetts, Walmart is partnering with Greenskies of Connecticut to install the thin-film panels. “Walmart’s commitment to solar power deployment plants a stake in the ground for other large energy users,” said Andrew Chester of Greenskies.

Today, Scottsdale Unified School District and SunPower Corp. are celebrating the installation of 5.5 MW of high efficiency SunPower solar power systems at 11 district schools. The systems are expected to reduce the district’s electricity costs by $25 million over the next 25 years.

The historic Blue Plate mayonnaise factory has been converted into energy-efficient apartments for artists. Powered by a 63kW system with MAGE POWERTEC PLUS modules the tenants are enjoying reduced utility costs. © MAGE SOLAR

More than 3,300 MAGE POWERTEC PLUS US-modules supply 1.4 GWh of clean, reliable energy per year to six housing projects that were part of the revitalization plan. Among the converted buildings are the iconic American Can and Blue Plate buildings in New Orleans, the latter being on the National Register of Historic Places. Other segments include the city’s River Garden Apartments and the Bonne Terre Apartments in Houma with a combined 564-kW of solar energy spread out over 69 individual rooftop applications and 26 parking canopies.

The project was designed, engineered and executed by Pontchartrain Mechanical of New Orleans, one of the largest mechanical contractors in the Gulf coast region and leading provider of environmental systems. MAGE SOLAR has been working closely with PMC’s chief system designer and solar department manager Micah Galy to develop optimal solutions for each of the individual installations included in the project: 2,000 black MAGE POWERTEC PLUS modules were chosen to provide a sensible, integrated solution on the historical building portion of the project, and sophisticated power optimizers are installed to avoid power losses due to shading from trees, light poles or buildings.

The project’s developer, HRI Properties, has been pioneering innovative methods for building neighborhoods and creating entire communities. MAGE SOLAR’s maximum-efficiency modules with their industry leading 30-year power output guarantee have been integrated into the project by HRI as a vital part of the company’s sustainability mission and long-term energy cost projection.

“We congratulate both HRI Properties and Pontchartrain Mechanical to this remarkable accomplishment,” said Joe Thomas, CEO and President of MAGE SOLAR USA. “To see the vision of both partners to create sustainable, vibrant metro communities executed so perfectly and with such craftsmanship will attract not only many happy residents but also inspire others to follow their pioneering example. Additionally, the system owner and tenants can enjoy on the financial benefits of low operating and utility costs our highly efficient modules are producing for the next three decades.”

“We were privileged to work in partnership with HRI to carve out this megawatt of solar systems within its portfolio of properties.  It has been an amazing introduction into what can happen when innovative, talented people have a vision and will not stop until the vision becomes reality.  MAGE was very supportive in the process and helped us meet a very tight construction schedule,” commented Chuck Sardi, CEO and owner of Pontchartrain Mechanical Company. “We look forward to the next challenge as we continue to grow green.”

Funding for the project was made possible through the American Recovery and Reinvestment Act and the EmPower Louisiana initiative administered by the Louisiana Department of Natural Resources. Net metering arrangements have been made with the local electric utilities.

“Clean energy helps us fulfill the ‘sustainability’ part of our mission, which is to revitalize cities by creating diverse, vibrant and sustainable communities. The need for clean energy will only dramatically grow in the future,” said HRI co-chairman and co-founder Pres Kabacoff.

The new test demonstrated that under heavy shading conditions the use of microinverters instead of typical string inverters can help mitigate the impacts of shade by improving system performance by more than 12 percent.

“Photovoltaic (PV) Shading Testbed for Module-level Power Electronics” was co-authored by NREL senior engineers Chris Deline and Jenya Meydbray, as well as Jason Forrest and Matt Donovan of PV Evolution Labs of Davis, Calif. The research was paid for by DOE.

Shade significantly impacts PV performance, and is considered in PV system design. The effects of shade can vary depending on the configuration of the PV modules, the extent of the shade, and the use of shade mitigating power electronics in the system. The industry currently lacks representative, repeatable test procedures for evaluating the annual effect of shade on different PV systems equipped with different shade mitigation devices.

The new report details a repeatable test procedure for simulating shaded operation of a PV system and an analysis model for converting these measurements into annual performance forecasts.

Shade measurements from more than 60 residential installations provide the basis for the shading conditions employed during the test, which are analyzed for three typical shade scenarios: “light”, “moderate”, and “heavy” shading. The relative performance of a system using shade mitigation devices is compared against an identical system equipped with a reference string inverter for these three shade scenarios, providing an annual performance improvement score.

Combined with additional derates like annual shade loss and inverter CEC efficiency, this annual shade improvement score can allow performance modeling software such as PV Watts and System Advisor Model  to better predict annual performance for PV systems that use shade mitigating power electronics. It also allows an accurate comparison between different devices.

An initial application of the test protocol was conducted by PV Evolution Labs, showing the shaded performance benefit of microinverters compared with a typical string inverter on identical 8-kW solar arrays. The microinverter was found to increase system production by 3.7 percent under light shading, 7.8 percent under moderate shading, and 12.3 percent under heavy shading, relative to the reference string inverter case. Additional detail is provided in the report to allow duplication of the test method for different power electronics devices and test installations.

Standard test methodologies using applicable test conditions should provide value to the PV community, since products can be compared by a common metric and accurate information can be collected about devices’ annual performance benefit.

This is a major step in establishing new and realistic testing standards for PV power electronics,” said David Briggs of Enphase Energy, a microinverter manufacturer.

To download the study, go to http://www.nrel.gov/docs/fy12osti/54876.pdf.  DOE funded NREL’s participation in the study. Enphase Energy paid PV Evolution Labs to run the experiment.

Even big-box stores like to save money, and retailers have been turning to solar power more frequently in the last few years as panel and overall system prices have dropped. Knowing electricity prices for the next 20 years can help stores prepare more realistic budgets and become more competitive in their markets. Two companies approach solar projects for retailers differently, but the outcome is the same — significant savings for the store.

Building Big
Costco, Fresh & Easy Neighborhood Market, IKEA, Kroger and Safeway have all found their electricity prices drop after partnering with REC Solar on rooftop installations.

“Energy costs are usually the second expense behind fuel for most retailers,” says Ben Collinwood, director of national accounts for REC Solar. “By improving the energy costs or reducing energy costs by 10 percent, you can influence the net profit margins of public companies by one percent just because the energy costs represent so much of the expense of a company.”

REC Solar designs, builds, constructs and services all of its solar electric installations. Starting as a residential installer in 1997, REC has grown in the commercial market within the last five years. Its first retail customer was Costco Wholesale nearly four years ago, and REC’s retail portfolio has expanded to include many more.

An REC Solar employee finishes up a 39-kW installation on top of a Fresh & Easy Neighborhood Market in Phoenix. REC installed similar systems on 10 other Fresh & Easy stores throughout the Phoenix area.

IKEA has turned to REC Solar for a large majority of its 15 completed energy projects (most in the 1-MW range) in the United States and 20-plus projects in planning stages. The Swedish home furnishings retailer specifically went with roof-mount systems since its stores were so large. Collinwood says some stores had the capacity to offset 100 percent of their loads just because the rooftop area was so vast.

“Many retailers focus on roofs. They’re unused space,” he says. “Being able to turn that into a revenue-producing asset is something very helpful to them. Also, it doesn’t typically affect the look and feel of their stores. These retailers have gone out of their way to make a good brand for themselves and to produce a public image for themselves with their storefront and their marketing. Adding a carport/solar canopy to a lot of these sites could affect the look and feel of their stores.”

Retailers aren’t trying to hide the fact that they’ve “gone green” either. REC Solar has a great partnership with Costco to not only install solar systems on top of its stores, but to also sell solar products to customers within the stores.

“It’s a surprising trend. I think it’s a fantastic thing to do. It helps stores increase revenue,” Collinwood says. “They can walk up, purchase a solar system at the checkout counter and then we would go in and install it for them later on. That has generated tens of millions of dollars in additional revenue for [Costco].”

Extra Incentives
Tioga Energy works differently to bring solar energy to retailers. The company focuses exclusively on solar power purchase agreement (PPA) development. Projects are built, financed, owned and operated by Tioga on customer properties and the electricity is sold to the customer at a set price. Marc Roper, Tioga vice president of sales and marketing, says the PPA option is attractive to retailers that are just looking at cheaper electricity prices and not interested in the upkeep.

Tioga is headquartered in San Francisco but has satellite offices in Canada and the Northeast. The company tries to be involved in markets that have decent incentives and create viable project economics for customers.

“We’re able to build a solar power system, finance it at a cost including incentives that allows us to sell the electricity to our customers at typically less than what they would otherwise pay to buy electricity from their utility,” Roper says.

Most customers come through Tioga via its direct sales force that reaches out to companies promoting the value of a long-term electricity contract.

“Unlike buying from your utility on a month-to-month basis, where rates go up and you can’t really control it, with a solar PPA you’re essentially signing up for 15 to 20 years at a fixed price,” Roper says. “There is a lot of value to our customers just in that sort of hedging against future rate increases.”

BJ’s Wholesale Club has worked with Tioga on five new projects, commissioning the fifth in March. BJ’s had originally been involved with solar PPAs in the early ’00s through a different company that recently got out of the solar game. Tioga came in and acquired the old systems, and more new installs are in the works.

“BJ’s is committed to sustainability, and they like the green aspect of electricity,” Roper says. “They’re also a very competitive retailer. They couldn’t afford to enter into agreements that ended up costing them money.”

Roper says discount stores are great to work with because they already understand the value of saving a dollar.

“A company like BJ’s is very good at procurements. That’s what they do. They buy large quantities of stuff at very low prices. They work on thin margins,” he says. “They know with today’s natural gas prices, those rates are very low and attractive. But they also know that they’re signing up for short-term contracts. When natural gas prices inevitably rise, those electricity rates are going to go up. So the security of a low fixed-price for them really strengthens their portfolio. You could consider it a long-term hedge against future rate increases as well as a good deal today.”

Tioga completed this 344-kW system on the roof of BJ’s Wholesale Club in South Attleboro, Mass., in 2010. BJ’s only pays for the electricity produced by the system.

Although BJ’s has close to 200 retail facilities, they’re not all great candidates for solar. Tioga finds the best locations with respect to viable incentive programs. BJ’s two Tioga installations in New Jersey and two in Massachusetts had great incentives at the time. The most recent project Tioga completed for BJ’s was on Long Island in New York. Tioga applied for a grant two years previously with the New York State Energy Research and Development Authority (NYSERDA), and a new BJ’s store on Long Island ended up being the perfect grant recipient.

“It worked out well for BJ’s,” Roper says. “Whenever there is an opportunity to make something work, we’ll jump on it and talk to them about it.”

Win-Win Situation
The retailers aren’t the only ones benefitting from turning to solar. REC Solar has found that one installation in a community that hasn’t been introduced to solar before can really turn heads.

“We typically do 1-MW projects in states that haven’t done a lot of solar or at least not to this scale,” Collinwood says. “These projects generate new interest from people. For example, the IKEA store in West Chester, Ohio, generated already five additional commercial inquiries. It’s a new area because you have the new, early adopters checking out solar and getting excited about a new option for themselves.”

In January and February 2012 alone, REC Solar quoted 10 times more projects than in 2011. These aren’t necessarily secured contracts, but at least the interest is there. Collinwood believes that as long as retailers are competitive, there will be interest in solar and other renewable energies.

“There’s a little bit of a keeping up with the Joneses mentality going on,” he says. “Retailers are seeing other retailers locking their energy rates for the future. They’re probably thinking they should do the same so they don’t become uncompetitive in the future.”

Q: Why is it important in large commercial and utility-scale applications to ensure integration of solar products?

A: Integration of equipment is critical to maintain high energy output with highest efficiency at a low overall capital cost over the lifetime of the project. Every component integrated together needs to work at its highest efficiency for that specific project. When integrated solutions are configured, the solar panel characteristics are used to fine tune the inverter performance. The high efficiency inverter output of AC energy is transformed to higher voltages to be distributed or delivered to the utility grid, and carefully integrated solutions will maintain the high energy efficiencies.

The opposite is true if solar products are not carefully integrated. The solar panel energy will be lost in inefficient utilization of the inverter, transformer and connections to the grid, resulting in high-cost solar PV projects which may stop a project at the design phase.

Q: How do Siemens inverter products work for large commercial and utility-scale applications?

A: The Sinvert PVS solar inverter converts the DC from the PV generators into a three-phase current. This three-phase current is then fed into the connected power grid. The inverter design is optimized for the lowest possible losses and thus the greatest possible efficiency. 

The integrated DC and three-phase distribution makes the system compact and inexpensive to integrate.

Q: When is using a large inverter most appropriate?

A: A larger inverter is used when a PV installation is generating energy to deliver to the utility grid.

Q: What are the advantages of using a large inverter?

A: The PVS inverters receive large amounts of DC energy from a PV field, accumulate this DC energy and feed it into the appropriate quantity of internal system inverters to ensure the highest efficiency of DC-to-AC energy is produced in the shortest amount of time.

Other large inverter manufacturers do not utilize the PVS technology which results in their efficiencies being reached later in the day, which comparatively is a reduction of energy harvest. Larger inverters allow portions of the inverter to be shut off during the day depending upon the amount of irradiation energy available at that moment. This increases the life of the components and keeps the efficiency output high.

Because our PVS inverters accumulate the DC energy on a common DC bus, the large PVS inverters are able to help prevent energy losses. Smaller inverters will only be able to handle small amounts of energy being fed directly to that inverter.

With the common DC bus, areas of a DC solar field experiencing high amounts of irradiance will deliver high amounts of energy. Other areas of the same DC field which are not experiencing the same high amount of irradiance will still be delivering energy to the common DC bus. The DC bus then accumulates and averages the DC energy prior to this DC energy being inverted to AC power. This will help prevent energy loss (clipping) and increase the energy harvest.

Other smaller inverters do not average or “load share” the incoming DC energy. When a project uses larger inverters, you have less inverters and equipment in the field. This results in less labor, installation and capital costs. This also results in fewer systems to maintain over the lifetime of the project.

Mark Loeser had seen it all in New Jersey solar energy systems — shoddy frameworks, careless installs and just overall bad planning. While the state was creeping closer to overtaking California as the top PV installer, Loeser says he was seeing many more inspection failures in his former job as technical director for the New Jersey Clean Energy Program (NJCEP).

“We were failing an inordinate amount of PV projects for numerous reasons, but there was a significant number of failures due to poor installation practices,” he says. “From that experience it has been my firm belief that in order to have a sustainable PV industry, education would have to be one of the cornerstones.”

Now CEO of Krannich Solar East, Loeser took his experiences and has turned Krannich into a training outlet for solar professionals. He believes there should be a minimum mandatory installation training to ensure quality design and installation practices are employed in the solar industry.

“If our industry is to continue to expand acceptance into the American lexicon, then we’ll need to train people from all walks of life on the importance of this industry and the positive environmental impacts it has,” he says. “This training should start with the youth and infiltrate every profession that designs and builds almost everything. This includes professional like architects, engineers and all the way to the tradesman crafts like carpenters and electricians.”

Open to everyone
Krannich Solar started in 1995 as an installation company working out of a house in Europe. Kurt Krannich’s first office was his living room, and his three employees worked out of the garage. Eventually, they transitioned from a small installation company to a worldwide wholesaler and system designer with 19 locations. The U.S. branch was founded by Kurt’s brother in 2005, and 2012 saw the operation reorganized into six companies, a training division and a projects division.

Training became an intense focal point of the U.S. division in New Jersey. Mark Stevens, director of technical and sales support for Krannich Solar USA, says training isn’t new to the company, but its dedication to improving the American industry is a welcome addition.

“Krannich Solar has been fulfilling these roles in Europe for more than a decade,” Stevens says of the company’s training program. “Now, Krannich Solar is bringing its vast experience by expanding its presence in the United States. By supporting the solar industry with value-added services [like] training, engineering, project development and procurement where we highlight customer service, Krannich serves as a one-stop shopping experience.”

Before October 2011, there was a small training room rarely utilized by Krannich, Loeser says. Today the company offers one-day introduction courses and multiple-day seminars across the country, with a large majority taught at its New Jersey headquarters. The courses were chosen after careful market research and direct feedback from customers, says Dessie Kirilova, director of training and business development. Krannich offers comprehensive solar PV training that encompasses classes from entry level to intermediate and advanced, including project management training, product training and skill development.

An instructor introduces a class to “Solar PV Technical Sales” at Krannich’s training center in New Jersey.

“We have quite a diverse audience because our classes are approved for ‘continuing education’ by a number of institutions,” Kirilova says, mentioning state electrical boards, the North American Board of Certified Energy Practitioners (NABCEP), the Interstate Renewable Energy Council (IREC) and the American Institute of Architects (AIA). “We cater to people who are interested in solar photovoltaics and want to get into the industry to professionals who want to develop specific skills and want to stay current with industry updates and new technologies.”

Vincent O’Grady has taken several courses with Krannich, including “Solar PV Technical Sales” and “PV Conductor Sizing.” He works for GeoPeak Energy, a renewable energy contractor and SunPower Elite Dealer in New Jersey, which recently won SunPower’s “Commercial Top Producer of the Year” award.

“I come from a renewable energy and green building public policy background, so all the technical aspects I have learned about solar PV have been through lessons learned in the field, from training classes at places like Krannich and from colleagues with whom I share skills and knowledge they may lack,” O’Grady says.

Planning for the Future
Krannich’s aim with its training courses is to be a competitive force in the market.

“Our objective for providing training is twofold. The first is obviously to train the solar PV installer community to be the most professional and efficient in all aspects of system design and installation. The second objective is to provide high quality products at very competitive prices and value added services to our clients,” Loeser says. “We are focused on our customers’ success.”

Even in the short time the courses have been offered, Krannich has already started revamping its approach to teaching.

“Seminars/classes definitely evolve as the market shifts focus. Currently in the United States, classes are being attended by people interested in the commercial side of the industry, project development, specific skill development and new product trainings,” Kirilova says. “The same applies to the change in the student audience. The entry-level market is saturated, and we see a shift in training to cater to the professionals that already have certain experience in the field.”

Through discussion courses and hands-on opportunities, students learn the best installation practices as recognized by industry groups and standards. Those at Krannich believe they’re taking the right steps to improving the U.S. market.

“Training is one of Krannich’s main focuses in our plan to support our customers — together with very competitive pricing, unmatched customer support [and] rigorous quality control,” Kirilova says. “We believe in an educated solar PV installer base to promote the benefits of solar energy and instill trust and quality on the solar market.”

By Jeff Seagle

The sun is Earth’s most basic life-giving force, but its destructive forces can wreak havoc on solar power systems trying to harness its output. Solar projects are cost intensive and require many years before yielding a solid return on investment. It is imperative that systems produce flawlessly from the time the installation first goes online. The proper selections of components that support the longevity and durability of the installation become critical choices in the process.

Electrical enclosures are designed to protect equipment, and the material of choice becomes the primary defense against the long weathering impact of most solar installations. Both local environments and damaging ultraviolet (UV) radiation must be taken into account. UV energy attacks materials and works to break apart their substrates. This degradation can lead to the structural breakdown in certain materials and potential failure over time. The right enclosure material can help boost the performance of a solar power system.

A Stahlin enclosure was chosen to house solar inverters on a rooftop installation in California.

Types of Enclosures
There are three different enclosure types: metal, plastic or composite. Common metal enclosure choices include carbon steel, stainless steel and aluminum. Metals are usually low in cost and have a long service life, corrosion resistance and weatherability. Plastic enclosure choices include thermoplastics, such as polycarbonate, polyester and PVC.

Thermoplastics are more susceptible to UV radiation and weathering degradation over time. Composite enclosures, like those made with polyester combined with glass, have a backbone of unique fiber-reinforced plastic (FRP) that is exceptionally durable and weather-resistant.

Environmental Considerations
Corrosive environmental conditions can act as accelerants for corrosion just as gasoline does for fire. The factors that determine the level of corrosion in an environment include extreme weather conditions such as moisture, UV radiation, dust and temperature (spread between the daily high and low temperatures as it influences condensation and evaporation of moisture).

► Moisture: The level of corrosion typically increases with moisture content. Common atmospheric sources of moisture are rain, dew and condensation. Rain can have a beneficial effect in that it washes away contaminants from exposed surfaces. If rain collects in pockets or crevices however, it can be very detrimental. When relative humidity exceeds 70 percent, a thin film of moisture will form on a metal surface, providing an electrolyte. This dew or condensation can become very corrosive if it is saturated with a contaminant like sea salt or acid compounds from industrial sources.

► UV Radiation: UV has been a concern with non-metallic manufacturers for many years. The rate at which the UV degradation occurs will vary depending on heat, humidity and latitude with which the product is installed. There are also differences in the way UV breaks down differing non-metallic materials. For instance, the effects of UV light become critical more quickly with thermoplastics than with thermosets of similar chemical structure because thermosets have a heavier mass and therefore take longer for UV energy to break it down.

► Dust: Dust particles can cling to surfaces and retain moisture. Typical sources for dust include: soil/sand, smoke and soot particles or salts. Depending on the chemical composition of the dust, it may contribute to the corrosive attack or may act as a catalyst.

► Temperature: Increasing the temperature of a corrosive media will generally increase the rate of corrosion. Temperature gradients on the same piece of metal can create a basic corrosion cell. The part of metal with the higher temperature will become anodic to the area with a lower temperature.

Material Selection
If you have the opportunity to select the material, ensure you have investigated the material and that it is the most appropriate for the type of environment. Every application has its unique demands, and many capabilities are considered to be inherent in certain material choices.

Composite enclosures provide a long life and maximum reliability when it comes to all environment types. They’re a great answer to corroding stainless steel enclosures in marine environments. Composite materials are also not conductive, so they’re safer than metal enclosures.

Those building large-scale PV applications must carefully evaluate all factors to ensure an enclosure made of any material type will withstand its environment. The process for proper material and enclosure selection begins with a detailed consideration of the PV application. Each environment is unique, and all possible applications should be identified for the intended enclosure application. Contractors should start with a simple list of needs and ask plenty of questions. Failure of an enclosure can’t be an option when everyone is relying on the solar industry to help reduce the planet’s dependence on fossil fuels.