India’s RFID Solar Mission

By Mary Catherine O'Connor

As part of a national strategy to increase the amount of energy generated via solar power, the Indian government is mandating that all solar modules be tagged and tracked.

In 2009, the government of India, through its Ministry of New and Renewable Energy (MNRE), approved the Jawaharlal Nehru National Solar Mission, a national strategy to increase the amount of energy generated via solar power. The goal is to have solar power become cost-competitive with other types of energy generation by 2022, as part of the country's National Action Plan on Climate Change.

As part of this strategy, the government mandated that each solar—or photovoltaic (PV)—module placed into use must carry an RFID tag, so that it can be easily identified and tracked throughout its useful life. The objective is to link PV module manufacturers to solar power deployments—which, in some cases, will contain many hundreds of modules. "Different manufacturers will sell panels into a big deployment," says Chandrasekar Sanikop, practice head for AvID, an Indian IT services firm specializing in identification systems and radio frequency identification, which is helping PV module manufacturers meet the tagging mandate. A module is a collection of PV (solar) cells built into a single board. A panel is two or more modules wired together and ready to be fitted into a power system.

Finished solar module without panel (left), followed by final finished product with panels fitted to the module (the white boundary is the panel).

"Say you have a big field of panels," Sanikop explains. "One goes down. Who will know where the panel comes from, what its specifications are, etc.?" According to the MNRE mandate, each RFID tag must be encoded with the name of the module manufacturer and the solar cells; the month, year and country of manufacture for the module and the cells; the module's technical characteristics, such as its wattage and expected performance statistics; and a serial number that uniquely identifies the module.

The power companies that purchase the modules—and the MNRE agents who will periodically inspect the solar farms—will be able to quickly access this information by reading a module's RFID tag, to determine whether panels are operating at peak performance, and to locate and replace modules that are outdated or recalled. The tags will also provide an efficient and accurate method for tracking modules that need to be removed from installations for repair.

RFID service providers throughout India are scrambling to capture the business of the country's solar energy companies, which are working to fulfill the production goals. PV manufacturers are looking for complete, end-to-end solutions that will enable them to both comply with the government mandate, and improve their internal operations. Providers are taking different approaches to meeting the mandate, which could require up to ten million tags, says Tirthankar Kshetrimayum, the deputy general manager for Switzer Instrument Ltd., an Indian RFID solutions provider.

Beyond the Mandate

Waaree, a Mumbai-based solar module manufacturer, got an early jump on the tagging requirement. In 2010, the company deployed an RFID system that not only complies with the government mandate, but also provides a number of internal benefits, including greater inventory visibility and management, improved manufacturing and shipping efficiencies, and reduced inventory levels.

Previously, in order to track its production, Waaree, like most PV manufacturers, attached a bar-code label to each module. Now, RFID allows the company to significantly improve its ability to track each module and associate technical data to each module, as required by the government mandate.

Chandrasekar Sanikop, AvID's practice head

After partnering with IAITO, a Mumbai-based provider of RFID tracking solutions, in June 2010, Waaree conducted a detailed RFID study—including site surveys of its manufacturing facilities—and established two use cases. Both involved tagging the PV module at the manufacturing plant, rather than at a later point along the supply chain, such as at a distribution center, to maximize the technology's benefits.

In one case, an RFID tag would be embedded within the PV module during its manufacturing process. In the second scenario, an RFID adhesive label would be attached to a module after it is produced. Each scenario presented unique challenges. To be embedded, the tag would need to measure no more than 400 microns (0.016 inch) in thickness, and would need to withstand extremely high temperatures and pressures. A tag attached to the panel's exterior would need to withstand exposure to outdoor elements and extreme temperatures.

Waaree and IAITO worked together to conduct tests of both use cases, says Anand Shenoy, IAITO's founder and CEO. The two companies found that attaching the RFID tags to each module was preferable for two reasons. While IAITO had developed a customized, heat-resistant RFID tag that could be embedded, the tag could still be damaged during the manufacturing process. If that happened, he says, it would be impossible to remove the tag, or to embed another one inside the module. In addition, the embedded tags must withstand higher temperatures than those attached to a panel's exterior, and thus cost more.

Powering Up the Tagging Process

Currently, an RFID tag is attached to each module that Waaree produces for an Indian solar power plant. After being manufactured, the module is subjected to a "flash" test, using a sun simulator. As it is exposed to this intense light, the power produced by the solar cells is measured and recorded. This data is captured by the PV Tracker software platform, developed by IAITO for the tagging application. The software associates the flash test results with a unique serial number, as well as the other information required by the government mandate.

All of this information is encoded to the memory of the PV Tracker tag, which complies with the EPC Gen 2 standard. IAITO sources the RFID chips used in the tag from three vendors: Alien Technology, Impinj and NXP Seminconductors. The tag, which has a strong adhesive backing, is manually attached to the module by hand. The tag and the adhesive are designed to withstand temperatures as low as -20 degrees Celsius (-4 degrees Fahrenheit), and as high as 150 degrees Celsius (302 degrees Fahrenheit), and are encased in a clear film that protects the tag from rain, as well as from the Sun's ultraviolet rays.

Tirthankar Kshetrimayum, Switzer Instrument Ltd.'s deputy general manager

The amount of memory required to save all of the data required by the mandate exceeds the memory on the tag's chip, so IAITO developed a special algorithm that condenses this information. To read the tag, the power companies that purchase the modules, as well as the MNRE inspectors, will require an RFID reader equipped with the IAITO PV Tracker software, which will uncompress the data.

To improve its internal processes, Waaree installed RFID readers throughout its factory, in order to track the each module's location once it has been tagged. This information is used to ensure that the inventory of its finished modules is accurate. As each panel is shipped to a customer, the tag attached to each module on that panel is interrogated, and Waaree's order system is updated to associate the data saved to each RFID tag with the original work order. If a module used in a PV installation is found to be underperforming, or if it completely malfunctions, that module will be removed for repair or replacement, and the tag will be used to track the device throughout the shipping and repair or disposal process.

Different Approaches to the Same Goal

Beyond the information that each tag must contain, the Indian government has yet to set any standards regarding the tagging process, or the types of RFID tags used. This could change in time, Sanikop says. "As of now, the specs of RFID tags and equipment are not standardized," he states, "but down the line, things might get uniform across the mandate guidelines."

AvID offers both high-frequency (HF) and ultrahigh-frequency (UHF) tags for module tracking, Sanikop says, but most of the tags it has sold to PV manufacturers contain NXP's passive HF (13.56 MHz) Icode chips. The high-memory capacity of these chips allows manufacturers to save all of the tag data required to the chips, without having to compress the data, as Waaree does.

A third option, Kshetrimayum says, is to use high-memory EPC Gen 2 tags, such as the 512-bit tags produced by UPM Raflatac that Switzer Instrument sells to its PV manufacturing customers. These tags, he adds, have sufficient room to save all mandated data.

And while Waaree chooses to attach RFID tags externally, both AvID and Switzer are currently working with other PV manufacturing firms that have decided to embed their tags directly into the modules during the manufacturing process.

What matters most, according to the RFID solution providers, is that the transition from bar codes to RFID be seamless and easy—and that the RFID systems provide internal benefits for manufacturers. Some PV manufacturers are tagging all of the modules they produce, Kshetrimayum says—even those being exported, and thus not subject to the government mandate—in the hope that this will benefit them in other ways, such as allowing the modules to be tracked and inventoried more easily, and providing a means for authenticating where and when the modules were made.