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’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


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.

• 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
• Samil Power
• Seraphim Solar USA
• Semitech Semiconductor
• Silfab Solar
• Solartec
• ST Micro
• Sungrow
• SunPower
• Sunrun
• Sunpreme
• Suntech Power
• Talesun Tesla
• Texas Instruments
• Tigo Energy
• Yaskawa Solectrica
• Yingli Solar


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’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

Blue light special: Retail is struggling, but solar can be a ray of hope

Francis Scott Key Mall

The 2-MW solar rooftop system at Francis Scott Key Mall in Frederick, Md., is Safari Energy’s eighth in the state, bringing the total capacity of Safari Energy’s commercial rooftop solar systems in Maryland to nearly 10 MW.

As we enter the holiday season, the retail industry is facing challenging times. Business Insider reported that electronics, grocery stores, department stores and drug stores are among the sectors threatened by online retailers such as Amazon. Businesses that were considered “too big to fail” such as Toys ‘R’ Us and Payless are among the 300 plus companies that filed for bankruptcy within the last year. This makes it more important than ever to control operating expenses, find ways to drive additional revenue and create a competitive difference. One of the ways that many businesses are achieving these goals is with renewable energy initiatives, and even more specifically, solar.

The United States has added more solar power than any other type of electricity in 2018. A recent SEIA report noted that non-residential solar, a category used when companies like AT&T and Nestle switch their electricity source to commercial solar power, was the second largest area of growth. Fortune 500 companies have increased their demand for renewable energy, fulfilling sustainability goals and taking advantage of lower solar panel prices, stronger financial incentives and ambitious state-level clean energy programs and mandates. This has trickled down, where now many smaller- to medium-sized retailers are embracing solar energy.

Retailers have a lot to gain by switching to solar energy. In New Jersey, Solar Renewable Energy Credits (sRECs) allow businesses to sell energy to electric generators that can translate into significant sums of money for building owners. Plus, companies are eligible for income tax credits and a bonus on system depreciation. Other states, including New York, offer strong solar rebate programs.

A great tool for selling more C&I solar is aerial imagery. Learn more in our free Webinar this week: Using HD Aerial Imagery to Bid Smarter, Design Faster and Win More Solar Business

In some states (New York, Massachusetts and soon New Jersey), malls and large retailers with significant roof space have the opportunity to generate additional revenue by selling excess energy to the community via a community solar program. Malls are uniquely positioned to benefit even further, given the ability to strike owner/tenant deals, selling excess power to its retail tenants at a discount to market rates. Under all structures, going solar gives the property owner a competitive and promotable advantage to attract new tenants. In addition, retailers have a great brand story to tell the public, attracting positive press regarding their sustainability initiatives. The greening of the property is a newsworthy upgrade that sets a business apart from local and global competitors.

Is solar my solution?

Solar energy isn’t necessarily the best fit for every retailer. The ideal property will have a larger roof space, typically 15,000 sq ft or more. If roof size is an issue, another option is to install the panels in a large, adjacent field or unused parking area. Installing a solar system is also a good time to replace HVAC units and even the entire roof.

But solar panel pricing is low, there are the aforementioned financial incentives and ambitious state-level clean energy programs and mandates, along with new laws for system depreciation.

The switch to solar can be time-consuming, so retail building owners will need solar advisers that can help navigate the process from start to finish. Solar brokers are agnostic when it comes to vendors and help to avoid delays and anticipate installation issues.

We see a crack in the brick and mortar with a glimmer of light coming through, and that ray of light is solar.

Yaniv Kalish is the co-founder and CEO of SolarKal.

Cool C&I rooftop innovations seen at SPI


Available for the first time in the U.S., Holland-based ESDEC debuted its slick Flat-Fix commercial rooftop mounting system. The same lightweight design can be laid out in south-facing or east-west configurations and is built with one tool, keeping the SKUs at a minimum. The feet are adhered with glue (or a bolt if needed) and an optional ballast tray. The system is already proven but the team needed to make a few tweaks to launch in the U.S., mostly relating to cable management, all of which were cleverly designed like the rest of the system.



Sunflare is a light, thin, rugged solar system that is changing the residential solar roof and ready to do the same for existing parking structures. Sunflare modules are lighter than silicon, so they can go where other solar can’t. That means there’s no need for new heavy steel carports. The net result is minimal disruption or displacement of tenants, customers and employees. The additional benefit of not having to construct a new parking structure is that there’s no potential hassle with new code compliance, which sometimes requires changes to parking lots.



Remote C&I system design has never been easier thanks to Nearmap’s updates. Its digital surface and line of sight analysis produces a jaw-droppingly clear picture for 71 percent of the U.S. population that is updated three times per year. You can really tell the difference between obstruction or dirt, as well as accurately measure the pitch and dimensions of any surface. When combined with the newest version of Aurora Solar’s software, Aurora estimates 10 times performance upgrades for multi-megawatt, commercial-scale solar projects with the added ability to simulate the solar energy production of a PV system as you are designing.

You can learn all about how to use aerial imagery as part of your solar business during our free webinar this week. Sign up here.



— Solar Builder magazine

PV Pointer: Three tactics for better solar designs under time of use rates

The promise of lower utility bills is a key motivator for most prospective solar customers, but time of use (TOU) rates — which charge different electricity prices depending on the time of day — add complexity to finding the best deal for the customer. Luckily, there are several strategies solar contractors can use to design the optimal PV system under specific TOU rates that will increase a customer’s solar savings and make your proposals more competitive.

olar design and financial analysis software

Solar design and financial analysis software example.

1. Start with integrated system design and financial analysis tools

One of the first considerations for finding the best design for TOU rates is to make sure you’re using software tools that will let you easily and accurately determine how different design choices will impact the financial returns of your project.

The structure of TOU rates varies, with important differences in the time periods when different pricing applies. TOU rates can be very favorable for solar customers if peak price hours coincide with when PV systems produce the most. In other cases, like when peak price hours occur in the evening, TOU rates can reduce solar savings.

To get an accurate understanding of your customer’s savings, your financial modeling tools must take into account how much the PV system will produce at different times, combined with the exact structure of your customer’s TOU rate. Beyond that, integrated solar design and financial analysis software will allow you to quickly see how system design changes or alternative utility rates affect project economics.

2. Get smart about post-solar rate choices

A second consideration for saving your customer the most money with their solar installation is to familiarize yourself with their utility rate choices and the financial implications of different rates. In some cases, the solar customer only has one potential rate that they are eligible for, but other times (like for some PG&E customers) there are multiple options. If your customer has a choice between rates, make sure to explore the financial implications of different options.

Choosing the best rate can significantly improve the economics of the project. In a case study of a solar design for a medium-sized office building in PG&E territory in California, Aurora Solar found that choosing a different post-solar rate resulted in over $42,000 in additional savings over the lifetime of the project. In addition to the increased savings making your proposal more compelling, this kind of expertise can distinguish your company in the sales process.

3. Explore alternative azimuths for your PV design

Finally, contractors can also experiment with different azimuths (orientations) to adjust the timing of some of the array’s production. For example, if a system is facing west, it may produce less overall but have more production later in the day. In cases where peak hours are late in the day, there may be times when this makes sense.

Again, using an integrated program for solar design and financial analysis makes assessing the merit of these kinds of design changes a lot easier because you’ll more easily be able to compare the value of the solar energy produced, overall system production and other financial metrics like payback period.

Even if TOU rates have not arrived in your area yet, they are likely to be more common in the future. Getting smart about how to maximize your customers’ savings under TOU rates can help you stay ahead of the curve.

— Solar Builder magazine

The case for solar as resilience from natural and economic disasters

solar jobs

Resilience is a hot topic in solar industry conversations these days because of how it and other distributed energy strategies can protect critical infrastructure from natural disasters. Resilience can be hard to quantify, but solar industry leaders and regulators should extend the valuation of energy resilience to man-made disasters too, like what often befalls the brittle local economies of middle class and lower income communities around the country.

Consider news today that General Motors is closing its Lordstown, Ohio, plant. Less than an hour drive from the Solar Builder offices, Lordstown is like any other Rust Belt city you won’t see on the map. Instead of a hurricane, it was basically built on the shaky foundation of a labor industry. And like many of these cities, when that industry (or one big company) downsizes or dies, the city goes right along with it. Basically, whether it is through tax breaks or not, tying a region’s success to the whims of a specific market or the success of a handful of companies leaves communities vulnerable.

There’s no fixing the ebbs and flows of the market to keep all jobs safe, but solar and other renewable energy sectors right now do present an opportunity for leaders at the local or state level (especially in middle and low-income communities) to proactively cultivate an emerging sector that will define the next century and is less reliant on job creators to support it.

We already know the job reports continue to show how renewable energy dwarfs all other industries in jobs added and in economic impact. Our Project of the Year for 2018 is one shining example of how solar development (in Ohio) can aid all sorts of stakeholders from construction workers to small business owners while also lowering bills for taxpayers and city operations. Added to that quantity is quality — renewable energy is literally the future of the grid and inextricably linked to the future of society. If a city smartly builds distributed generation into its core, the jobs themselves will be as inherently self-sustaining as the energy created.

This is why we harped on the power of local initiatives to grow or stifle the solar industry in our Sept/Oct cover feature because what’s at stake isn’t just the flourishing of another random industry. There is a huge public service component at stake, and in addition to jobs, this new paper in Energy Policy shows how state influence directly correlates to the drop in solar PV panel prices. Thus, state incentives drive the price indicators that further spur private investment and innovation.

For something like solar PV, an industry that is up and running, future cost declines are most likely to be found in a balance of accelerated deployment (continuing to drive down the costs of existing technology) and ongoing R&D (hedging against the possibility that existing technology could level off prematurely).

In summation of our two cents per kWh: Solar is now a proven commodity and a stable growth sector of huge societal importance that inherently needs local labor. Over time it will also save taxpayers, businesses and cities a considerable amount of money, which can all be infused in the economy in other ways. Local and federal government should be salivating at the opportunity to lead the charge purely on the grounds of resilience from both natural and economic disasters.

— Solar Builder magazine

Poll results show utilities losing ground to third-parties in consumer preference for new energy services

consumer preference

Customer demand for new energy technologies like electric vehicle (EV) charging and solar power has more than doubled since 2017. Utilities across the country, with an eye on creating new revenue streams, are increasingly launching EV charging and solar power offerings to meet this growing demand. While many consumers view utilities as natural providers for these offerings, utilities are quickly losing preferred provider status to non-utility third parties.

Overall customer preference for the utility as a solar power provider among interested customers has fallen from 68% last year to 47%. While preference for utilities as a provider of EV charging offerings remains flat, preference for third-party providers has increased by 66%. If preference for third-party providers continues to increase at this rate, they will overtake utilities in consumer preference in three years.

“Utilities are on the verge of one of the greatest marketing and revenue opportunities they have ever had,” said Chris Oberle, senior vice president at Market Strategies International-Morpace. “If they want to capture significant EV charging and solar power market share, utilities need to quickly build and defend their brands as trusted providers of new energy technologies.”

The energy industry research shows customers with low brand trust in their utility have a very high preference for third-party providers, while the utilities with the strongest preference tend to have higher Brand Trust scores as well as strong support for being “trusted energy advisers.”

Provider Preference by Offering Category and Brand Trust

(Brand Trust is measured on a scale of 1–1,000)

Solar power offerings – prefer utility

  • Low brand trust: 38 percent
  • High brand trust: 47 percent

Solar power offerings – prefer third party

  • Low brand trust: 29 percent
  • High brand trust: 7 percent

Solar power offerings – no preference

  • Low brand trust: 33 percent
  • High brand trust: 46 percent

EV charging – prefer utility

  • Low brand trust: 38 percent
  • High brand trust: 58 percent

EV charging – prefer third party

  • Low brand trust: 28 percent
  • High brand trust: 19 percent

EV charging – no preference

  • Low brand trust: 44 percent
  • High brand trust: 33 percent

Nationwide, 14% of utility customers say that they are likely to adopt rooftop solar, community solar, solar hot water or home battery storage within the next six months. While western states like California and Arizona are perceived to be the hottest solar markets, the greatest demand for solar offerings is actually in the South—stretching from Texas to Virginia. Similarly, customers in the South indicate the greatest interest in home or public EV charging offerings.

The study

These and other findings can be found in the Cogent Reports 2018 Utility Trusted Brand & Customer Engagement: Residential study by Market Strategies International-Morpace. The study measures the market dynamics of over 65 offerings and customer shopping behaviors of 18 customer segments.

Market Strategies-Morpace conducted surveys among 52,486 residential electric, natural gas and combination utility customers of the 130 largest US utility companies (based on residential customer counts). The sample design uses a combination of quotas and weighting based on US census data to ensure a demographically balanced sample of each evaluated utility’s customers based on age, gender, income, race and ethnicity. Utilities within the same region and of the same type (e.g., electric-only providers) are given equal weight in order to balance the influence of each utility’s customers on survey results. Market Strategies-Morpace will supply the exact wording of any survey question upon request.

— Solar Builder magazine