Fronius launches inverter with integrated SunSpec rapid shutdown transmitter

Fronius rapid shutdown inverter

String inverter manufacturer Fronius launches the new Fronius Symo Advanced, a three-phase string inverter with an integrated Power Line Communication (PLC) transmitter based on the SunSpec Rapid Shutdown communication standard. In conjunction with the Tigo TS4-F cover, solar installers get a simple and cost-effective solution for Module Level Shutdown.

Jurisdictions with National Electrical Code (NEC) 2017 adoption require module level shutdown functionality in new solar systems starting January 1st of 2019. This requires all conductors within 1 foot of an array to be de-energized to 80V or less within 30 seconds of rapid shutdown initiation. This new requirement can potentially cause challenges and additional cost for solar installers, if the industry does not innovate.


To provide solar installers with cost-effective, simple and innovative solutions, multiple members of the SunSpec Alliance defined an open industry standard for communication between modules, inverters and string combiners to support module level rapid shutdown requirements. This multi-vendor industry standard was published in September of 2017.

Fronius has been a driving force in developing this industry standard and was among the first ones to announce a product based on the standard. “We not only believe that industry standards have economic advantages for distributors and installers, but that they also ensure better safety. Since solutions based on a standard are known throughout the entire supply chain, we can achieve more safety and reliability. This is beneficial for the entire industry”, says Adrian Noronho, CEO of Fronius USA. “Furthermore, open standards give customers more choice”.

The new Fronius Symo Advanced three-phase inverter has an integrated Power Line Communication (PLC) transmitter based on the SunSpec Rapid Shutdown communication standard. This allows for plug & play connection with SunSpec based module electronics directly via the DC wires. In a first step the Tigo TS4-F cover is available. The solution eliminates the need for any additional communication hardware and provides the most cost-effective option for code compliance today.

This new inverter combines the benefits of the Fronius Symo with the convenience of an open industry standard. Featuring ten models ranging from 10 kW to 24 kW, the Fronius Symo Advanced is the ideal compact three-phase inverter for commercial applications. The light weight design, the SnapINverter mounting system and true field-serviceability allow for easy installation and highest reliability over the lifetime of a system.

In states with NEC 2014 requirements, the Symo Advanced can be mounted next to the array, eliminating the need for rapid shutdown boxes, since the inverter itself acts as rapid shutdown device. Thus, the Fronius Symo Advanced inverter provides a solution that adapts easily to the different requirements in different states – all with the same stock keeping unit (SKU).

Fronius starts shipping the Fronius Symo Advanced in January 2019.

— Solar Builder magazine

How to Increase your Competiveness with Adaptive System Design

Stand out from the competition

As solar markets are getting more established, the competition between installation companies increases. More players, both regional and national, are entering the market. While this is good for solar shoppers and the overall growth of the solar industry, installers might face tougher competition. As a result, differentiation becomes more important. This article shows how installers can stand out from their competition. Learn more.

— Solar Builder magazine

Meet the new Fronius Commercial Rooftop Solution (inverter, MC4 connectors, shade cover)


The commercial and industrial (C&I) space is one of the most challenging environments for solar installations because of high ambient temperatures, high irradiance, obstructions, setbacks or pathways add to the complexity and cost of design. But the segment increased 20 percent in the third quarter of 2017 and may be ready to boom, according to CEOs at Solar Power Northeast. Fronius, one of the top string inverter manufacturers, is ready to kick start that demand with a new solution for simple and cost-effective commercial rooftop installations, including easy NEC 2014 and 2017 compliance. The new Fronius Rooftop Solution consists of a Fronius Symo 24.0 string inverter, the MC4 Connector option and the Fronius Shade Cover.

Mount at any angle

The Fronius Rooftop Solution provides a comprehensive solution for commercial rooftops. The lightweight Fronius Symo 24.0 inverter allows for mounting at any angle from vertical to completely flat. The 24 kW size facilitates both optimal inverter distribution and string length for space limited commercial rooftops. The collective design approach of the solution applies to both inverter and system design to provide a high reliability, right features, and right size, resulting in best return on investment for both installers and system owners. Low labor requirements, design flexibility, and the Fronius O&M advantages of this truly field serviceable inverter combine to provide best Levelized Cost of Energy (LCOE).

In rooftop applications, the easiest and most cost-effective way to fulfill NEC 2014 and 2017 requirements is to mount the inverter next to the array, within the boundary for NEC rapid shutdown requirements. This way the inverter acts as a rapid shutdown device and eliminates the need for additional equipment – reducing the number of components and Balance-of-system (BOS) cost.

Shade cover

Fronius symo shade cover

Many rooftop installations are unique in design and to ensure the highest inverter performance throughout the lifetime of a system, Fronius offers a shade cover as part of the Fronius Rooftop Solution – keeping the inverter’s temperature low and performance high even in sunny and high temperature mounting locations. The cover is simple and quick to install, taking just five minutes. Due to the increased energy production, the Fronius Shade Cover pays for itself. The Fronius Shade Cover can also be retrofitted to existing installations.

MC4 Connectors

MC4 Connectors

The MC4 Connector option for the Fronius Symo 24.0 simplifies the installation of the Fronius Symo inverter even further. By simply connecting the DC wires through MC4 connectors, multiple installation steps are eliminated, such as wire management inside the inverter, installation and sealing of conduits, or pull tests of torqued conductors. This not only reduces installation and commissioning time, which is crucial for bigger projects, but also simplifies ongoing preventive maintenance and improves technician safety.

“As a string inverter leader we are striving for rooftop excellence and with the Fronius Rooftop Solution we take our offering for commercial rooftops even further”, says Michael Mendik, Head of Solutions Management at Fronius USA. “Customers have always asked for cost-effective installation options and a low-cost solution to protect the inverter from heat when installed next to the array. With the Fronius Rooftop Solution we provide a comprehensive solution for commercial rooftop applications.”

— Solar Builder magazine

PV Pointer: Find the hidden value in ‘oversizing’ inverters

Fronius oversizing inverters

While inverter oversizing is not new to the solar industry, there are still inverter manufacturers that do not offer an attractive DC:AC ratio for their inverters. This highly impacts cost and profitability of a solar system. Therefore, it’s important for system designers and solar installers to have a closer look on the oversizing capabilities of inverters, and to tap into their hidden power.

Inverter oversizing refers to adding more DC power to an inverter than it is rated for. For example, if you connect 6 kWp of DC power to a 5 kW inverter, you oversize the system by 20%. This makes total sense, because the peak power of 6 kWp will only come up in very few and short moments – so using a 6 kWp inverter (no oversizing) would be unnecessary and therefore a waste of money. In situations where the system actually generates more than 5 kW, the inverter would clip are so rare and so short, that it is negligible. The advantages you gain by oversizing clearly outweigh the effects of clipping.

Modern, high-quality inverters like Fronius SnapINverters can handle DC power of up to 150% of the inverter’s nominal output power, which would be for example 7.5 kWp on a 5 kW inverter, which is a lot of hidden power. Let’s have a closer look on the advantages of oversizing.

Cost savings

A main advantage of oversizing are the initial cost savings. For the price of a 5 kW inverter, you get to support a 7.5 kWp system – benefitting from 2.5 kW of hidden power in your 5 kW inverter (for free). Inverters with a poor DC/AC ratio, or no oversizing capability whatsoever, do not provide this cost saving, increasing the cost per Watt significantly.

In commercial, rooftop or ground mount systems, oversizing reduces the number of inverters needed to support the available array size and its kWp on a given roof. This not only reduces the initial cost, but also the O&M expenses – both resulting in a better return on the investment.

More DC power without an AC panel upgrade

Residential AC panels only allow a certain amount of solar power (AC) being connected to them. For example, 3.8 kW AC is the highest power that is possible on a 100 A service panel, 7.6 kW on a 200 A service panel and 11.4 kW on a 300 A panel. As the cost of upgrading a service panel can be very high, it is useful to fit the largest system possible on the existing AC panel. Inverter oversizing helps to maximize the DC power of your solar system. If you have a 200 A panel and a 7.6 kW AC inverter with 50% oversizing, you can actually get 11.4 kWp of DC power. If you were to choose an inverter without oversizing capability, you would be stuck with only 7.6 kWp, or you would have to invest in an expensive panel upgrade.

Higher yields

While the efficiency of high-quality inverters is quite stable over the whole power range, it’s still getting higher the closer the inverter operates to its nominal power. By oversizing a system, the operating point of the inverter is at a higher power, closer to its AC rating, and reaches its capacity earlier in the morning and stays there until later in the afternoon. This not only improves the inverter’s efficiency, but also maximizes the overall energy yield, while keeping inverter cost low – for maximum return on investment.

Conclusion: Look twice when choosing inverters. Make sure to take their oversizing capabilities into account and to tap into the hidden power of high-quality inverters. Fronius SnapINnverters, for both residential and commercial, are capable of 50% oversizing (DC:AC ratio of 1.5:1) – which is a lot of hidden power, so system designers can really maximize the above advantages of oversizing.

— Solar Builder magazine

NABCEP hat trick: Fronius’ William Burkert first to earn these three PV certifications


After becoming a NABCEP Certified PV System Inspector, William Burkert, Solar Application Engineer of Fronius USA, became the first and only person to be a NABCEP certified PV System Inspector, PV Installation Professional and PV Technical Sales Professional.

“Receiving NABCEP’s PV Solar Inspector Certification is personally very satisfying,” Burkert said. “More important it means I can offer customers the added confidence of knowing that their photovoltaic system installations will be inspected to the highest standards in the solar industry.”

NABCEP is the most well established national certification organization for renewable energy professionals. Designation as a NABCEP PV System Inspector is widely recognized to be the most important and meaningful certification of its kind in the solar industry.

To earn his NABCEP certification, Burkert was required to first document relevant education and experience related to PV system installations. Then he had to pass a rigorous exam that covers the breadth of the multi-craft knowledge, skills, and abilities required to competently design, install, inspect and maintain PV systems. The exam assesses knowledge on subjects as diverse as electrical and mechanical system design, job site safety, the National Electrical Code, roofing and construction techniques, and system maintenance and troubleshooting.

“Anyone who makes the considerable effort required to earn NABCEP certification has documented their training and experience as part of the eligibility process,” said Richard Lawrence, Executive Director of NABCEP. “They have also made a very real commitment to upholding high standards of ethical and professional practice. I am delighted to again welcome William Burkert of Fronius to the ranks of the industry’s leading solar professionals.”

To earn his NABCEP PV Technical Sales Professional certification, Bill was required to first document relevant education and experience. Then he had to pass a rigorous exam that covers the breadth of the knowledge, skills, and abilities required to competently perform a solar site assessment, conduct performance and financial analysis, develop a preliminary system design, and prepare a detailed sales proposal for the customer. The exam assesses knowledge on subjects as diverse as financial incentives, utility bills and rate structures, electric load analysis, fundamentals of electrical and mechanical system design, and PV system types and components.

— Solar Builder magazine