Need for Speed: Inside the upgrades to the most powerful microinverter on the market

Today’s solar systems require a more robust communication architecture to manage significantly more data points and in-field software updates, and this need was the driving force behind APsystems’s newest microinverter. Despite being the most powerful microinverter you’ll find on the market, the QS1 debuted rather quietly at Solar Power International last year — a debut that even caught director of marketing Jason Higginson off-guard. But hey, when a product is ready, it’s ready.

Key to the QS1 development was incorporating a high-speed wireless Zigbee connection instead of Power Line Communication (PLC). The difference is measured in speed of both installation (75 percent reduction in installation time) and data transmission.

“With the smart grid, and a very smart inverter, there are a considerable number of data points that need to be communicated back from the microinverters through the gateway and to the monitoring platform in the cloud,” Higginson explains. “This means a steady stream of data is constantly flowing from the inverter to the internet. When systems like the QS1 and YC600 apply remote firmware upgrades, this creates a demanding bidirectional data flow and, for MLPE systems, traditional powerline communication isn’t going to cut it.”

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The QS1 employs high-speed wireless Zigbee, which is up to three times faster than conventional powerline communication (PLC), creating a local 2.4GHz mesh network for fast and reliable data communication between the microinverters and the gateway.

The QS1 is positioned to maximize high output PV panels up to 375 W by providing a higher peak output power (a microinverter-leading 300 W AC output per channel) and a wider MPPT voltage range (22V-48V) that allows for bettering tracking and energy harvest during low light conditions of dawn and dusk.

“It also features four individual MPPT so each PV module is managed and tracked separately, which means things that affect a single panel such as shading or debris do not affect the output from the rest of the panel even if they’re connected to the same microinverter,” Higginson says.

APsystems QS1 Microinverter Datasheet


An APststems calling card is reducing the number of microinverter units needed per project. Only one QS1 unit is needed for every four modules (instead of the standard 1:1 ratio) while still providing four independent MPPT. This means fewer units to stock, transport and install while costing less than the equivalent of four individual microinverters. There are shared components that reduce the overall cost per watt by comparison.

But it’s not all shiny new performance numbers and doodads — APsystems kept the AC trunk cabling common with its dual-module YC600, which adds a hugely important flexible, mix-and-match compatibility on the same circuit to enhance site design capability and maximize circuit capacity.

“Using an even number of PV modules is ideal, however, with the APsystems 4-in-1 and 2-in-1 cost advantages, even if there are an odd number of PV modules in the array, leaving one side of a YC600 unused doesn’t significantly impact the cost per Watt of the system,” Higginson says.

Both microinverters also utilize the same gateways, so installers can choose the ECU-R for single or multi-residential installations or the ECU-C for applications requiring consumption monitoring and advanced contact/relay features.

“Compatibility with the existing YC600 microinverter system gives the QS1 an unprecedented advantage,” says APsystems chief technology officer Yuhao Luo. “Mixing dual and quad microinverters in the same system adds design flexibility while offering a strong inventory and installation labor advantage over conventional microinverters.”

Chris Crowell is the managing editor of Solar Builder.

— Solar Builder magazine

Delta issues recall of Eltek solar inverters due to fire hazard

Delta inverter recall

This recall involves Delta’s Eltek THEIA HE-t string inverters after the company discovered the capacitors can fail and allow heat to build up, causing the cover to eject with force from the unit and posing fire and impact hazards. The recalled inverters measure about 28 inches high by 14 inches wide by 6.5 inches deep. They were sold in four different kilowatt ratings: 2.0 kW, 2.9 kW, 3.8, kW, and 4.4 kW. “Eltek,” and the model designation “THEIA” and “HE-t” are printed on the front display panel of the inverter.

Delta Electronics has received 11 reports of the capacitors failing, including two reports of the cover forcibly ejecting off the inverter units. No injuries have been reported.

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These were sold through various solar installers in Arizona, New York, Tennessee and Washington from March 2012 through May 2017 for between $2,000 and $4,000. This recall effects about 2,600

If you have installed an Eltek string inverter from Delta, you should immediately contact your customers to turn off the switch on the inverter’s front cover, switch off the circuit breaker for the inverter and contact Delta Electronics USA to arrange for a free replacement inverter. Delta Electronics will remove the recalled inverter and install a replacement.

Importer: Delta Electronics USA Inc., of Plano, Texas

Manufactured in: China

— Solar Builder magazine

Delta inverters are now certified for rapid shutdown via Tigo Energy

Delta inverters

Delta Group inverters are now UL certified with Tigo’s rapid system shutdown (RSS) solutions: TS4-F (Fire Safety), TS4-O (Optimization), and TS4-L (Long String). Tigo is currently shipping with Delta and more tier one certified inverter manufacturing partners throughout the U.S. Contact Tigo for more information about RSS for integrated or retrofitted PV installations.

This UL certification is part of Tigo’s multivendor initiative providing customers with the advantages of reliable, safe, and cost-effective solutions. The use of Tigo smart modules and high efficiency inverters allows design flexibility for installers to comply with National Electric Code (NEC) 2017 690.12 RSS regulations. Tigo has also been internationally recognized as the only module-level power electronic vendor with UL-certified RSS with PV module manufacturers.

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The following Delta inverters are newly UL-listed as a Rapid Shutdown System with Tigo’s TS4 units:

TS4-F (Fire Safety). This is the most cost-effective RSS solution with SunSpec-defined power-line communication.

  • M36U
  • M42U
  • M60U
  • M80U

TS4-O (Optimization) and TS4-L (Long Strings). These are the only UL-certified multivendor RSS in the U.S. solar market also include additional features like optimization and long string designs.

  • M4-TL-US
  • M5-TL-US
  • M6-TL-US
  • M8-TL-US

— Solar Builder magazine

World’s largest solar PV peaker power plant uses DC-coupled storage design with Ampt optimizers


The Lāwa’i Solar and Energy Storage Project in Hawaii completed this month became the world’s largest operational solar PV+storage peaker plant and is responsible for delivering 11% of Kauai’s power while providing mission critical grid support during peak demand periods.  The completion of this system allows the utility to deliver up to 40% of the island’s evening peak power using stored solar energy. This record-breaking record-breaking PV peaker power plant has 28 MW of solar PV and 100 megawatt-hours (MWh) of DC-coupled energy storage.

To meet the demanding operational needs of a clean energy peaker plant while being cost competitive, the project developer chose to use a DC-coupled storage architecture based on Ampt String Optimizers for its cost and performance advantages. DC-coupled energy storage systems charge batteries using energy from the DC solar array rather than the AC grid.

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Ampt String Optimizers decrease the total cost of the entire power plant. Ampt’s unique features lower the cost of all the power electronics, including the inverter and battery converter, and save in electrical wiring of the PV array.

Moreover, Ampt String Optimizers maximize the performance of the PV system by managing power on each string of PV modules rather than across the whole array at a central point. This increased granularity mitigates system degradation to deliver more lifetime energy. DC-coupled storage systems based on Ampt operate at a higher efficiency and capture energy that would otherwise be lost.

The power plant includes the wireless communication feature of Ampt optimizers to enhance operations and maintenance (O&M) effectiveness with high-accuracy synchronous string-level data.

“The Lāwa’i project sets the standard for PV+storage system design,” said Levent Gun, CEO of Ampt. “We are pleased that Ampt technology played a key role in achieving this industry milestone and we look forward to being part of follow-on projects in Hawaii.”

— Solar Builder magazine

SunSpec Alliance partners with 7 test labs to certify products for its solar, storage communication standards

sunspec alliance laboratories

SunSpec Alliance, the information standards and certification organization for the Distributed Energy Resource (DER) industry, announced the first SunSpec Authorized Test Laboratory (ATL) partners to provide SunSpec Certified testing services to a global roster of SunSpec Alliance member companies. SunSpec Authorized Test Laboratories represent a foundational service for inverter and other component manufacturers to demonstrate readiness to meet the communications requirements of California Rule 21. They provide testing services, with the SunSpec engineering team responsible for validating results and issuing certification marks.

“Communication-oriented markets leverage certification programs to foster growth, increase stakeholder confidence and lower total system costs. The SunSpec Certified program employs best practices proven by other industries,” said Tom Tansy, Chairman of the SunSpec Alliance. “SunSpec Authorized Test Laboratories provide impartiality and broad market availability of test services for dominant DER communication standards.”

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The SunSpec Certified program culminates 10 years of developing de facto standards that enable solar PV and energy storage systems to interoperate transparently with system components, software applications, financial systems and the smart grid. The program provides DER interoperability, data communications and cybersecurity functionality standards, aligned with international and national protocols, to accelerate industry growth, lower costs and enhance customer confidence.

SunSpec Certified Authorized Test Laboratories announced to date include:
PCTEST Engineering Laboratory Inc.
CSA Group
TUV Rheinland of North America

Initial DER communication compliance programs addressed by SunSpec ATLs include Institute of Electrical and Electronics Engineers Standard (IEEE) 2030.5 / Common Smart Inverter Profile (CSIP), the default communication standard for California Rule 2, and SunSpec Communication Signal for Rapid Shutdown, a de facto standard to achieve compliance with the PV hazard control requirements of the 2017 National Electrical Code.

SunSpec recently upgraded its SunSpec Certified program to fulfill its responsibilities as the compliance authority for California Rule 21 communication requirements (SunSpec test criteria is specifically referenced in CA Rule 21) and to realize the success of the SunSpec Communication Signal for Rapid Shutdown standard, which has been adopted by more than 50 semiconductor, PV module and inverter manufacturers.

— Solar Builder magazine