Displaying performance data in a place where many people see it, like the lobby of an office building, is a nice way to enhance system monitoring. The option is available to all Enphase System owners via Enlighten’s Kiosk View setting. Visitors may recognize patterns in the results and provide feedback if they notice something unusual. Ten sets of eyes, or a hundred, are better than one. Anytime a system is underperforming, it’s best to notify a technician as soon as possible. Putting system performance on display also reinforces the environmental and social impact of going solar with Enphase.

Enphase built these display settings into Enlighten in simpler times when it was enough to show pictures of the solar module array, lifetime energy output, and some additional site information. System owners have more urgent needs for performance data now. We’re addressing those needs by automatically updating the summary data shown to visitors every five minutes. The new functionality is included in the latest Enlighten software update.

Enphase maintains a help center to answer frequently asked questions about Enlighten. To learn about turning on display settings and customizing the information that visitors can see, please visit the Enphase Kiosk View page.

Fleet monitoring ensures the reliable performance of residential PV systems, but what happens when the Wi-Fi password changes or the kids unplug the solar gateway to connect their Xbox?

With more than 580,000 systems operating worldwide, Enphase recognizes the importance of reliable networking and the advantages of using cellular networks to transmit data without interruption. Our cellular solutions, Mobile Connect and Mobile Connect+, improve on traditional cable and wireless internet services in several ways.

For technicians, Mobile Connect is easier to set up than a Wi-Fi internet connection. You mount the modem on a wall or a flat surface, then attach the cellular antenna to the modem and connect the modem to the Enphase Envoy with a USB cable. That’s it. The system is preconfigured for a simple, plug-and-play installation.

Installers who provide operations and maintenance can use Mobile Connect to control access to monitoring data. This can mean the difference between monitoring and not monitoring, especially in places where the system owner or the system host hasn’t already set up a local network.

System owners protect their investment with cellular monitoring. When performance data comes through home networks, an Internet service disruption caused by a change in the home router or modem can cut off monitoring at any time. The cause may be something as simple as an unplugged network cable. If the homeowner cannot troubleshoot the problem themselves, the cost of a truck roll for a technician to restore monitoring can easily exceed the cost of cellular monitoring.

Cellular monitoring is an excellent option in locations where internet service is unreliable or nonexistent. It also opens the possibility of monitoring ground-mount systems where it would be too difficult or cost prohibitive to pull cable for a networking connection.

Enphase now offers two cellular monitoring options: Mobile Connect, a 3G service with a 5-year prepaid data plan, and Mobile Connect+, a new 4G LTE service with a 12-year prepaid data plan. Both options come with a 5-year hardware warranty, and both are compatible with residential systems using up to 60 Microinverters and IQ Envoy, IQ Combiner, Envoy-S Metered, AC Combiner Box, or Envoy S-Standard. Cellular coverage for Mobile Connect is provided by AT&T, making reliable, high-speed service available to the US, Puerto Rico, US Virgin Islands, Canada, and Mexico.

November 28, 2016

Two men examine solar modules set up in a field on the NREL campus.

NREL engineers Bill Sekulic (left) and Chris Deline look at the new PV array just north of the NREL parking garage. The new array extends the testing capacity for solar modules at NREL. Photo by Dennis Schroeder

Solar panels at the Energy Department's National Renewable Energy Laboratory (NREL) are ubiquitous to the point of practically being invisible, but new rows of photovoltaic (PV) modules installed on the southern edge of campus are intended to attract attention.

The newest modules are being installed to measure how their efficiency at converting sunlight into electricity changes over time. That change, called the degradation rate, will be posted on NREL's website along with the manufacturers' names. To start, 50 solar modules made by three manufacturers will be deployed in 2017. Then, each year for the following two years, additional sets of 50 modules made by other companies will be added.

"We're going to buy up modules that represent the average cross-section of installed modules each year in the United States and see how they do over time," said Chris Deline, an engineer at NREL who also serves as director for Colorado's two regional test centers: SolarTAC (an 8-acre site near Denver International Airport) and one on NREL's 327-acre campus in Golden. The test centers, funded by the Energy Department, are used to validate new technologies and measure the performance of solar modules over time. Across the NREL campus, solar modules are integrated into the buildings, including the roof of the five-story parking garage near the new array field. Another building, the Outdoor Test Facility (OTF), has an adjacent solar array field but doesn't have much room for more modules on its concrete pads.

"The main difference is this large grassy area gives us the capability of having larger systems," Deline said. "Over at the OTF, because of our space constraints, we can only have 8 or 10 modules for a given system. With this one we're able to do side-by-side comparisons of larger systems."

Workers install PV modules at NREL’s new solar array field.

Workers install PV modules just north of the NREL parking garage. Modules in the first row are part of a small demonstration project for the PV industry to help obtain initial performance validation. The PV modules in the other rows are part of a new Energy Department program called PV Lifetime. The intent is to study, with high accuracy, the initial degradation of PV modules, and to make all of the data publicly available. Photo by Dennis Schroeder

More Modules to be Added Each Year

Once completed, the new solar array field will house four rows of PV modules. The first row, already in place, is for partner manufacturers' modules that NREL is either studying or comparing to similar products. For example, a California company, SolarCity, has NREL testing its modules against those made by a Chinese manufacturer.

Further along the row, high voltage (up to 1,500 V to represent the high voltages used in some PV systems today) is applied to modules of a range of constructions. This helps quantify their susceptibility to degradation associated with the leakage currents that can occur at these high system voltages. How the modules do at NREL will be assessed against the performance of identical setups in Singapore and China.

"This greatly expands our ability to work with commercial partners," Deline said. "The other neat thing is it allows us to get access to some of these cutting-edge products because a lot of this stuff is not commercially available. We're like customer No. 1 for some of these new technologies. It gives us the ability to get in at the forefront."

Although the degradation rates for modules will be made public, the contracted testing done for clients will be kept confidential.

The experiments at the new array field will run for three years on average. At the OTF, some experiments involving the longevity of solar modules have been ongoing for decades. No matter how long the solar panels undergo testing, all of the power they generate will flow into NREL's circuits. About 19% of electricity used on the campus comes from the sun.

Two men stand next to solar modules in a field on the NREL campus.

NREL engineers Bill Sekulic (left) and Chris Deline monitor the progress of the new PV array just north of the NREL parking garage. The new array will be used in part to make more data available to the public. Photo by Dennis Schroeder

Importance of Regular Measurements

Over time, solar modules become less effective at converting sunlight into electricity. NREL researchers examined the results of nearly 200 studies and found this degradation rate ranges from 0.5%-1% a year, depending on the technology used. A high degradation rate means less power will be produced over the lifetime of a PV system, and that increases the per-kilowatt-hour cost of generating solar electricity.

The performance of most PV modules is measured only once: at the factory. For studies reporting degradation rates, frequently, the degradation is calculated from the measured performance at the time of the study (after several years in the field) compared with the nameplate rating, which is the expected output a module will have. Sometimes the degradation rate follows a non-linear path, so a regular measurement will provide more accurate information.

"It is important to determine how the degradation rates vary because a module that maintains its output for many years and then fails on the last day of its life will generate a lot more electricity than a module that degrades 10% in the first year and then is stable," said Sarah Kurtz, an NREL research fellow and co-director of the National Center for Photovoltaics. A weakened solder bond, for example, could break and that would throw off the performance of a module.

Ongoing measurement of the new solar modules is part of the PV Lifetime project, a new effort led by Sandia National Laboratories. In addition to the modules deployed at NREL, similar arrays will be installed at regional test centers at Sandia and in Florida. The data collected will be published on NREL's website.

PV Lifetime is an outgrowth of the SunShot Initiative, launched by the Energy Department in 2011. The original goal of the initiative was to bring the price of solar-generated electricity down to 6 cents a kilowatt-hour by 2020. The initiative last month announced the goal is close, with prices at 90% of the way there. The revised target calls for dropping the price further, to 3 cents between 2020 and 2030.

Learn more about solar research at NREL.

— Wayne Hicks

December 6, 2016

A man looks through a small clear object.

NREL scientist Matt Reese holds a substrate with the solar cells removed to minimize the weight of the solar cell. Photo by Dennis Schroeder/NREL 40800

Two thousand years ago, Roman legionnaires lugged 100-pound packs into battle. A lot has changed since then, but technology hasn't really reduced an infantryman's load. On the battlefield, mobility is critical—but a typical, modern Marine may shoulder an 80-pound backpack containing 20 pounds of back-up batteries for an array of electronics.

When soldiers or supply convoys are forced to move slowly on repeated trips, they can become "targets of choice" for enemy combatants. Because of this, the Energy Department and Department of Defense are looking for ways to ease such heavy burdens, and a team of researchers at the National Renewable Energy Laboratory (NREL) is exploring novel approaches for making renewable power sources lighter.

Photovoltaic (PV) cells are the military's choice to power remote bases, but the ones it uses are not only large and inflexible, they aren't very efficient. Last summer, NREL embarked on a $1.5 million, three-year research and development contract with the Office of Naval Research to explore making lightweight solar cells. In this work, the journey has been marked by fundamental science—and creative thinking.

"What if we could grow solar cells on the same heavy substrate we use in the standard high-efficiency, low-cost polycrystalline processes?" asked Matthew Reese, an NREL staff scientist in PV research. Afterwards, researchers could transfer the high-efficiency cadmium telluride (CdTe) or copper indium gallium selenide cells to lighter-weight packaging—trimming the weight of the cells.

Thin-film solar cells, grown on substrates such as stainless steel, titanium foils, and polyimide, produce flexible products that are ideal for solar blankets and tarps. As such, the thin films are more portable—but they also typically lack the higher efficiency of cells grown on thick-glass substrates. Reese's challenge has been to combine the best of both.

The solution: a novel "lift-off" of a high-efficiency cell that could then be repackaged on thin film.

A soldier stands in front of solar panels in the field.

Marine officer Brandon Newell worked with renewable energy sources such as solar panels in Afghanistan. Photo by Brandon Newell

An En-Lightened Idea is Born

The seed of this idea began around four years ago, when Reese was working with NREL's Teresa Barnes on a research project funded by the Energy Department's Foundational Program to Advance Cell Efficiency (F-PACE). F-PACE supports PV cell efficiency, and the NREL team was making lightweight CdTe solar cells on flexible glass.

"When you grow a CdTe cell, you need to grow it for highest efficiency on a transparent substrate," Reese said. In turn, "the order in which you grow the layers of a cell is critical. For CdTe, the substrate has to be transparent, and that limits choices" because CdTe requires high temperatures. Plastics, therefore, won't work.

Although growing CdTe cells on glass, which can withstand high temperatures, was promising, this approach had a drawback. Even flexible glass can shatter, making it unreliable for certain military applications. But researchers felt that retreating to low-efficiency, flexible cells wasn't an option. The military is interested in high specific power, which means it wants as many watts as it can get out of the minimum amount of weight. To hit that goal, many researchers think of using III-V multijunction solar cells, the most-efficient PV materials. "But those cells are too expensive," Reese said. "Even the military can't afford that option."

A soldier with a PV flexible portable power pack in a field.

Global Solar's lightweight, flexible, and portable power pack is an example of solar in the field; these thin film portable power packs have been field tested by the military. Photo by Global Solar Energy

The Navy Sees a Need

When work finished about a year ago on the F-PACE efficiency project, Reese and his colleagues continued to think about ways to combine high-efficiency PV with robust packaging that was lightweight. After gaining support from NREL through a Fiscal Year 2016 Laboratory Directed Research and Development project headed by scientist Miguel Contreras, the team wrote a follow-up white paper. The project drew interest from the Office of Naval Research—but the Navy wasn't looking for a packaging makeover. Project leaders wanted an approach with the highest efficiency, and therefore, with high specific power.

"We thought for a little bit, and then it occurred to me. We'd done this diagnostic test by delaminating CdTe cells," Reese said, referring to a way of lifting a cell off a substrate to remove it. "Maybe we really could have the best of both worlds." Researchers could do all of the standard higher-temperature processing on the rigid glass substrate, which they know how to process—then they could delaminate the high-efficiency cells and put them in any package. "We could de-couple growth constraints from a package of choice. You could select whatever you wanted as the ideal package at the end," Reese said. This concept was approved, and the project for the Navy began in August.

To launch the exploration, Reese got creative. "I like arts and crafts," he joked.

While there are a variety of ways—excluding razor blades—to remove cells that are a few micrometers thick, Reese and his team chose a method that uses liquid nitrogen. Once that step was completed, they  used a "handle" that attaches to the cell, allowing them to put the cell on a flexible substrate. The team managed to demonstrate clean separation on small areas as part of the initial tests. That showed promise, but there's more work to be done.

Reese and his team are optimistic—the idea of transferring these low-cost, high-efficiency solar cells to the types of flexible backings that could withstand field exposure is encouraging.

"There are a series of different ways we can try to do this," he said. "We are investigating several approaches in parallel. We want to understand what needs to be controlled. What are the knobs we can turn to separate large area samples cleanly at a specific interface? How do we control fracturing in polycrystalline systems? What are the inherent limits to its flexibility?"

If successful, the flexible, lightweight, high-efficiency, and reliable solar power will not only reduce the weight that a soldier needs to shoulder—it could also maximize military operational effectiveness in unmanned aerial vehicles and reduce the number of manned supply convoys. In other words, if this works, the NREL team could ultimately help the military ease burdens and save lives.

Learn more about NREL's solar research.

— Connie Komomua and Ernie Tucker

Major Brandon Newell: Marine Experience Fuels Passion for Renewables

A man on a balcony looks out at a field with a building behind him.

Marine Major Brandon Newell at the National Renewable Energy Laboratory as its first military fellow, looking for ways to leverage the laboratory's research for the military. Photo by Ernie Tucker/NREL

Brandon Newell had been in the Marine Corps only 18 months in 2003 when he found himself on the Kuwait-Iraq border as the United States launched Operation Iraqi Freedom. He saw, firsthand, the difficulty of battlefield logistics and how a lack of efficiency could impact a mission.

"Speed is something the Marines try to achieve," he explained, because the Corps' capabilities are based on agility and mobility.

During those initial days of the Iraq War, there was added urgency because nobody knew whether Saddam Hussein's forces would deploy chemical weapons. The marines were heading from the Kuwaiti border to Baghdad, moving farther and faster than they had ever pushed.

About two weeks into the battle, something unexpected happened. As his unit was setting up communications equipment, they saw armored U.S. vehicles rolling past them toward the rear. "This was odd, because up to this point, everyone was moving north towards Baghdad. About an hour later, we got a call for an operational pause, because we'd outrun our logistics," he said.

Vital supplies such as food, fuel, and batteries couldn't keep up with the attack—so the troops had to pull back and wait for fresh materiel to catch up. "We had stretched lines so thin that we had to take a break from the war," he said. "This actually led the Marine Corps to completely reorganize logistics support. We're better now, but we want to improve more."

That's the motivation Newell brought to NREL in July when he started a one-year term as the National Renewable Energy Laboratory's (NREL's) first military fellow. He wants to help Energy Department efforts in support of the Department of Defense (DOD) and to explore NREL capacities that might benefit the military. But for Newell, who now holds the rank of major, his interest in renewable energy—and NREL—is not new.

A Curiosity about Renewables and NREL

Newell had been intrigued with solar energy since sixth grade when he built a model solar car—and throughout his career, thoughts about renewables remained. For example, while stationed in Kaneohe Bay, Hawaii, for three years starting in 2005, he saw plenty of renewable energy technologies.

Eventually, in 2009, after he connected with John Barnett in NREL's Integrated Applications Center, Newell spent six weeks as what is believed to be NREL's first active-duty military intern. During that time, he and Barnett co-authored a white paper for the Office of the Secretary of Defense, recommending a military liaison officer at NREL and making the internship a regular thing. It was August—just as his NREL stint was ending—and the timing was perfect.

Newell attended the first Marine Energy Summit in Washington, D.C.—a one-day event held then to address the topic of energy, water, and waste on the battlefield. Noting his interest, the Commandant picked him to be part of the Marine Energy Assessment Team, which was deploying to Afghanistan. "I was thrilled. I was actually being given the opportunity to apply what I had been learning to helping Marines on the battlefield," Newell said.

Newell arrived in the Helmand Province of southwest Afghanistan in September 2009 as part of a six-member team, which also included Barnett. Several weeks there allowed Newell to see some of the hardships—but also the potential for renewable energy and energy efficiency alternatives to lighten the 80-100 pound load infantrymen typically carry.

After returning from that fact-finding mission, he helped brief the Pentagon on keeping the foot-mobile Marines agile—and the Marines leveraged his expertise. For example, in 2011, he deployed again to Afghanistan, serving as energy liaison officer to the regional command.

Benefits of Renewables for the Military

Newell's various experiences help him advocate for advances in military capabilities. He wants to assist as the Marines explore variety of technologies to keep them efficient. Newell said he will attempt to translate the realm of the possible by "leveraging the capabilities at NREL for our needs in the military." He admits such a task isn't always easy, but it should help to "have someone who has been on both sides to help imagine what's possible." Furthermore, he'll be looking at technologies that the military is not yet trying, and exploring capabilities within NREL that DOD may not be aware of.

Even after he leaves NREL, knowing he may not return to energy assignments, he expects the investigations in renewable energy technologies will continue—and lessons he's learned on both battlefields and in laboratories will make a difference to future Marine leaders and others in the service of the United States.

— Ernie Tucker