NEC 2017 Primer for Solar Installers: Manufacturers explain how their products meet the updated code

NEC 2017

Jan. 1, 2019, is almost upon us, which means the National Electric Code (NEC) 2017 is almost in effect. Not all jurisdictions will be up to speed (hell, some aren’t even up on NEC 2014 yet), but around 24 states will require compliance immediately. We asked a variety of manufacturers about their NEC 2017-ready products, how they work and any advice they have for solar installers to meet the new code.

This section is from our Nov/Dec issue of Solar Builder magazine. Subscribe for free right here.

Code to know

690.12 Rapid Shutdown of PV Systems on Buildings

PV system circuits installed on or in buildings shall include a rapid shutdown function to reduce shock hazard for emergency responders in accordance with 690.12(A) through (D).

(A) Controlled Conductors. Requirements for controlled conductors shall apply to PV circuits supplied by the PV system.

(B) Controlled Limits. The use of the term, array boundary, in this section is defined as 305 mm (1 ft) from the array in all directions. Controlled conductors outside the array boundary shall comply with 690.12(B)(1) and inside the array boundary shall comply with 690.12(B)(2).

1. Outside the Array Boundary. Controlled conductors located outside the boundary or more than 1 m (3 ft) from the point of entry inside a building shall be limited to not more than 30 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.

2. Inside the Array Boundary. The PV system shall comply with one of the following:

(1) The PV array shall be listed or field labeled as a rapid shutdown PV array. Such a PV array shall be installed and used in accordance with the instructions included with the rapid shutdown PV array listing and labeling or field labeling.

(2) Controlled conductors located inside the boundary or not more than 1 m (3 ft) from the point of penetration of the surface of the building shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.

Know your signs

solaredge

SolarEdge’s SafeDC technology is embedded in its DC optimized solution and as such meets NEC 2017 without any additional components. The existing PV system AC disconnect is used as the initiator. Whenever the inverter or grid is turned off (i.e. AC power), then the DC voltage and current fall below the NEC 2017 thresholds within 30 seconds — each power optimizer is responsible for lowering its output voltage to 1 volt during rapid shutdown activation. This happens both in and outside the array boundary.

“New signs are required to inform emergency responders of the equipment meeting NEC 2017. NEC 2017 requires that equipment used as rapid shutdown devices be listed for rapid shutdown and evaluated according to stringent standards. Installers should check to ensure all equipment is properly listed. For example, inverters and combiners that are used inside or outside the array boundary as rapid shutdown devices must be listed for rapid shutdown in the event that they are used for that purpose,” says Lior Handelsman, founder, VP of marketing for SolarEdge.

HellermannTyton Don’t skimp on labels

HellermannTyton offers a line of NEC 2017 code compliant labels that have been tested to actual real-world conditions for over seven years and through accelerated aging tests, which show the labels will survive decades of exposure [see example of one that did not on the right]. Because of the extensive testing of these solar-compliant labels, HellermannTyton offers a seven-year warranty on all adhesive labels that include the HT check mark and a 25-year warranty on any aluminum labels.

“Many municipalities are very concerned about label life. In this age of OSHA and ANSI compliance, there is increased liability on installers and inspection services. If a label only remains visible for a few years, and if someone gets injured or killed in the process of interacting with the equipment, there can be substantial fines or costly litigation that can affect on-going business,” says Todd Fries, product category manager – identification for HellermannTyton.

Watch for SunSpec certification

sunspec

If you’re unfamiliar with the SunSpec Alliance, it’s time you became familiar. This trade alliance of more than 100 solar and storage stakeholders has been working on information standards for plug-and-play PV system interoperability, but its communication solution for meeting module-level power control and safety (rapid shutdown) with any panel and inverter combination might be its crowning achievement. Look for the logo to the left to find products certified to the SunSpec RSD Specification. Here’s a list of early adopter companies involved in the collaboration and rollout.

• ABB
• Adesto Technologies
• Canadian Solar
• Celestica Inc.
• Chint Power Systems –
North America
• Delta Products
• Enphase Energy
• ER Solar
• Fronius International
• Ginlong-Solis
• Hansol Technics Co.
• HiQ Solar
• Itek Energy
• Ingeteam
• JA Solar
• LERRI Solar Technology
• Maxim Integrated
• Mersen Electrical Power
• Midnite Solar
• Neo Solar Power
• Omron Global
• OutBack Power
• Phoenix Contact
• SMA
• Samil Power
• Seraphim Solar USA
• Semitech Semiconductor
• Silfab Solar
• Solartec
• ST Micro
• Sungrow
• SunPower
• Sunrun
• Sunpreme
• Suntech Power
• Talesun Tesla
• Texas Instruments
• Tigo Energy
• UL LLC
• Yaskawa Solectrica
• Yingli Solar

sunspec

This is a diagram of how the SunSpec Communication signal for module-level rapid shutdown works.

froniusCompliance doesn’t mean cost

“It is important to know what the actual requirement is and then getting to code compliance in the simplest, most cost-effective way to not put extra financial burden on the customer. We believe that industry standards and innovation will drive down cost and allow customer choice,” says Richard Baldinger, head of marketing for Fronius.

The Fronius Symo Advanced three-phase inverter combines the benefits of the Fronius Symo with the convenience of an open industry standard. Featuring 10 models ranging from 10 kW to 24 kW, the Fronius Symo Advanced meets NEC 2017 compliance in conjunction with the Tigo TS4-F cover via the integrated Power Line Communication (PLC) transmitter that uses the SunSpec communication signal for rapid shutdown. This eliminates the need for any additional communication hardware and provides the most cost-effective option for code compliance.

tigoTigo Energy’s TS4-F (Fire Safety) is a UL-certified multivendor rapid shutdown solution for commercial PV systems that complies with NEC 2017. The TS4-R-F is a simple add-on that retrofits a regular standard solar module with a module-level rapid shutdown device and is compatible with the power line-based SunSpec communication signal for rapid shutdown. Using the existing DC wires between the inverter and module-level electronics as a communication channel significantly reduces installation time.

midnite solarMidnite Solar’s MNLSOB line, in both 600-volt and 1,000-volt models, utilize one transmitter and multiple receivers per system. This product can be used for string or module-level shutdown by using one receiver per string or one per module. They plug directly into the MC4 connectors on your module and, because the MNLSOB transmitter induces a PLC signal into the PV Positive line, there is no additional or new wiring to be done between the transmitter and the receivers. Midnite Solar will be introducing a new SunSpec-compliant MNLSOB by January.

Make no compromises

“There are no additional design requirements to implement shutdown functionality. A designer can build a project for maximum energy harvest, optimal ROI, or with any other goal in mind and simply choose the most cost-effective MLPE to address his or her needs. The shutdown functionality is built into these solutions and does not impact other project considerations. Installers should also be aware of the upcoming release of UL Standard 3741 as another way to comply with NEC 201 690.12 without requiring module-level shutdown by using equipment listed as ‘PV Hazard Control Arrays,’” says Brad Dore, director of marketing for SMA America.

SMA’s Sunny Tripower CORE1 meets the shutdown requirements of NEC 690.12 when paired with a TS4-R-F module-level device. The inverter and MLPE retrofit unit operate on the new SunSpec Power Line Communication (PLC) signal for module-level rapid shutdown. This solution is the most cost-effective way to achieve module-level shutdown. The solution operates on a simple “stay alive” signal broadcast from the inverter over the existing DC wires. The TS4-R-F units will operate while AC power is present, and if AC power is cut via the AC disconnect, the MLPEs lose the “stay alive” signal and de-energize in accordance with code.

Streamline to ground

Section 690.43 states that “Exposed noncurrent-carrying metal parts of PV module frames, electrical equipment, and conductor enclosures of PV systems shall be grounded in accordance with 250.134 or 250.136(A), regardless of voltage.”

brilliant rack

Brilliant Rack racking systems feature mounting connections with serrated bolts that ensure the most effective metal-to-metal contact for proper bonding connections. These connections are essential for dispersing any electrical charge, providing multiple pathways to soil in compliance with Section 250.92 B. This reduces the danger of equipment damage or human injury should the rack become electrically charged through equipment malfunction, human error or lightning strike. Independent testing has demonstrated Brilliant Rack systems are capable of dispersing higher currents through the system into soil, and that the serrated bolt and nut are likely to maintain this connection better over a long period of time than WEEB clips.

sunmodo

SunModo’s ground lug, self-bonding clamps and self-bonding rail splices meet the requirements found in NEC 2017. The basis of the self-bonding system is its patented stainless-steel floating bonding pin, which is designed to be captive in the mounting components and provides a bonding path from the PV panel frames to the rails and rail splices and finally to the ground lug. The Ground Lug is compliant with both UL 467 and the equipment grounding requirements 690.43. The self-bonding system is for use with PV modules that have a maximum series fuse rating of 30A.

 

 

Rooftop Adder Table removed

quick mount pv

“The Rooftop Adder Table that has affected the ampacity calculations for conductors that are run at a specified distance above a rooftop has been deleted. This table generally hasn’t been well accepted by electrical personnel since its addition to the NEC several years ago. Because of the deletion, if raceways are kept at least 7/8 of an inch above the rooftop, there should no longer be a need for upsizing conductors and increasing costs,” says Randy Barnett, safety compliance professional for the NFPA.

Quick Mount PV has two NEC 2017-ready products in its classic conduit mount and conduit mount for tile. When used in conjunction with a standard off-the-shelf conduit hanger, the conduit is raised in excess of the minimum 7/8-in. off the roof surface, which is new in NEC 2017. These mounts are designed to lift electrical conduit off the roof to protect wiring from overheating. These mounts use Quick Mount’s proprietary waterproofing technology to seal the roof penetrations, and aluminum and stainless steel parts are used to secure the electrical conduit for the life of the system.

— Solar Builder magazine

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.

sb-econference-web-post

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)

Fronius_Symo

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