Ask an Expert: Inverter manufacturers give us their best troubleshooting advice

Christopher Barrett

Christopher Barrett

Wi-Fi Can Cause Communication Issues

Christopher Barrett, director of technical services, APsystems

We often see issues our installers are facing related to communication, often due to misplacement of the gateway or an unreliable internet connection. Following best practices recommended by the manufacturer will help installers reduce repeat site visits to fix communication problems. Some of these best practices include installing a gateway in the correct location, which is typically a direct connection to the service panel in which the PV array home-run is landed (often a dedicated PV sub-panel). We also recommend using a wired ethernet connection whenever possible to better ensure reliable communication and minimize returns to the jobsite.

Ryan LeBlanc

Ryan LeBlanc

Double-check those Airways, String Lengths

Ryan LeBlanc, senior applications engineer, SMA America

  1. Over-voltage, strings that are too long, are the fastest way to kill an electrical device.
  2. Blocking airways, installing inverters too close to walls or other inverters, and not inspecting inverters regularly for a blocked air intake are both common. This results in less production, but it’s hard to say if it kills them earlier.
Frank O’Young

Frank O’Young

Pro Tip: Try Different Cable Colors

Frank O’Young, associate VP, Darfon

Our tech team sees that often the polarities of the DC lines from a PV module or string are incorrectly connected to the inverter due to the fact that same color cables (mostly black) are used for the + and – of the module or string. This can be avoided by using different cable colors for different polarities or checking the polarities before inverter connection. Our tech team also sees of that the L1 and L2 lines of the AC circuit are incorrectly wired when tying the inverter to the grid. Caution should be taken when connecting the L1 and L2 and instructions from the inverter manual should be followed.

RELATED: 2017 Solar Inverter Buyer’s Guide 

Mark Cerasuolo

Mark Cerasuolo

Storage is Complex – Get Trained to do it Right

Mark Cerasuolo, director of training and marketing, OutBack Power

Since our products and systems typically either include or interact with batteries, some training beyond what most grid-tie installers have is really necessary to ensure a safe and reliable installation. Even then, we really encourage installers to use pre-wired systems to ensure that the system is complete and wired correctly.

Ed Heacox

Ed Heacox

Top 4 inverter installation issues from CPS

Ed Heacox, GM, CPS Americas

  • “Grid V Out of Limit.” This is when the customer forgot to check that AC switch is on, so the inverter thinks the AC grid voltage is out of limit.
  • String mis-match. An inconsistent number of panels per string on one MPPT.
  • Exceeding DC/AC ratio recommendations. This can lead to occasional intermittent faulting.
  • Installing the DC string from left to right when it would be more ideal to balance the load across two MPPTs. This can lead to one MPPT too far out of balance from other MPPTs (e.g. four strings in No. 1 and one string into No. 2).
Peter Mathews

Peter Mathews

Watch your Connections, System Design

Peter Mathews, North American general manager, SolarEdge

Two very common errors are the improper mating of the connectors or reverse polarity. Other items that relate to the connectors include leaving connectors open during the installation process, which can lead to water penetration, or not fully crimping the wires. Another area in which we see support issues arise is in system design. For example, SolarEdge enables the installation of longer strings, so installers who are used to standard design constraints may out of habit design short strings instead of the 11.25-kWp strings that are available with the SolarEdge solution.

Brian Lydic

Brian Lydic

Inverter Integrity Starts with a Correct Installation

Brian Lydic, senior standards and technology engineer, Fronius USA

The most common installation oversights we see are related to torqueing, inverter location and moisture management. The mounting bracket must be installed on a surface to ensure there is no bowing or warping of the bracket. The wiring compartment must be wired as per guidelines to ensure a flush mating of the inverter body to the mounting bracket chassis. If wire routing or conduit fittings are not considered, there may be a loss of integrity in this seal. Pay special attention to the DATCOM cover. Make sure it “clicks” or “snaps” in place before screws secure it. If the cover is simply screwed in, there may be bowing and slight gaps between the inverter body and DATCOM cover, allowing water ingress.

— Solar Builder magazine

Top 5 battery installation issues for solar installers

Battery Bank

With the right installation, battery banks can provide reliable power for years. In this article, you’ll discover how to avoid costly, hard-to-diagnose battery installation mistakes, and you’ll learn a holistic approach that prevents costly errors long before installation.

1. Not Starting with Efficiency

Each additional kWh of energy demand requires extra solar or wind generation, battery storage and backup generation. Thus, it’s cost-effective to start by increasing efficiency.

First steps include replacing inefficient electronics and appliances with Energy Star models, eliminating vampire loads using switchable power strips and adjusting thermostat settings seasonally.

Next, consider adding blown-in insulation to walls and attics. Since nearly half of household energy is used for space heating and air conditioning, this can drastically reduce heating and cooling demands.

Finally, whole-house fans and nighttime ventilation offer inexpensive comfort. And compressor-less Variable Refrigerant Flow HVAC reduces electricity usage by ~90 percent.

2. Improper Sizing

Oversized panels, turbines and batteries waste money, but undersized systems can make everyday living frustrating — and shorten battery life due to deep discharging. The solution? Calculate accurate electrical loads.

After taking steps to improve efficiency, check the past year’s utility bills to estimate power requirements. Affordable devices like Kill-A-Watt accurately monitor individual appliances’ energy usage and reveal vampire loads. From there, the basic calculation for a system’s power needs is: Watts = amps x volts

For instance, if 1,000 watt-hours (1 kWh) a day are needed, a 12-volt / 84 Ah battery bank (1,008-watt capacity) will not address power demands because the battery would be exposed to 100 percent depth of discharge every cycle.

Experts recommend sizing your system based on a maximum of 50 percent depth of discharge (DoD). In the example above, the battery bank would need to be sized to 12 V / 168 Ah — double the estimated Ah requirements.

Note that some battery manufacturers size systems based on 80 percent or 100 percent DoD. This assumption can provide inadequate reserve power for heavy loads during heat waves and frigid winters or for cloudy or foggy days with low solar production. Batteries discharged by more than 80 percent lack reserve capacity to power high-energy appliances or even keep the lights on.

3. Choosing the Wrong Batteries for the Application

There’s no one-size-fits-all battery. Instead, key factors include ambient temperature, technology, desired voltage, maintenance, sustainability/recyclability and cost.

Lead-acid batteries are the most common for renewable systems. Refined over 100-plus years, they’re longer lasting and 50 to 90 percent less expensive than other technologies. According to the EPA, lead-acid batteries are 99 percent recyclable — more recyclable than an aluminum can.

Options include flooded batteries, which offer the highest ROI but require periodic water adjustment and other preventive maintenance, sealed valve-regulated lead-acid (VRLA) batteries and zero-maintenance options that are more expensive.

RELATED: Is there a PV storage solution between lead-acid and lithium ion? 

Lithium-ion batteries don’t require maintenance and offer the highest power density (and thus, lightest weight). For lithium-ion batteries, battery management systems (BMS) are required to prevent overcharging and to reduce the risk of house fires and explosions caused by thermal runaway. Li-ion’s cost per Ah is the highest and they are zero to 60 percent recyclable.

BMS is not required for lead-acid and many other battery chemistries, but BMS is beneficial because features like temperature-based charging, total and per-cell voltage and DoD monitoring help increase capacity and minimize damage caused by temperature extremes.

Whatever technology you choose, only buy deep-cycle, renewable batteries designed specifically for heavy cycling.

4. Improper Wire Sizing

Wire size varies based on amps carried and how many feet electricity must travel. Often, undersized cables are the hard-to-diagnose cause of system failure.

Just as water needs enough pressure to travel through a garden hose, an electric current must have enough voltage to travel. And much like a garden hose, electrical current must exceed pressure (impedance or resistance) caused by wire shape, thickness, length and other variables.

When cables are too small, voltage drops and makes the load work harder. This can cause lights to flicker, heaters to underperform and motors to burn out early. Worse, undersized cables can generate heat and even start fires. A smaller AWG means a larger cable. To calculate ideal wire size, use a “wire gauge calculator” and specify no more than a 3 percent voltage drop.

5. Improper Storage

Batteries last longest at or around 77˚ F. Every 18° F temperature increase drops available cycles by 50 percent. The cold reduces available capacity exactly when solar production is lowest and energy demands are highest.

The only solution to this problem is protecting batteries, but common storage solutions such as insulated coolers and old refrigerators offer little buffer against the cold, and they trap so much summertime heat that battery temperatures often exceed 140° F.

A better solution is storing batteries in a well-insulated, enclosed structure, either inside the home or in a properly vented box in a garage or shed. To do this, arrange batteries to ensure 1/2-in. air gaps and allow for easy maintenance. Never install breakers, switches or spark-producing devices inside an enclosure — this could cause an explosion.

The best approach uses standalone systems such as EMPUS, an insulated structure that maintains ideal operating temperatures year-round, to maximize the lifespan of batteries and electronics.

John Connell is VP of Crown Battery’s SLI Products Group.

— Solar Builder magazine

How up-steam improvements in module manufacturing could impact the solar industry

Silicor Employees

A simpler method for purifying silicon could cut energy use in purification by two thirds. Photo credit: Silicor Materials.

Lower costs and a better environmental track record benefit the entire solar industry. Yet downstream solar is where cost reduction opportunities often seem the largest and where environmental sustainability pressures appear most acute.

Developers are faced with a range of options for bringing down the cost of solar. They also face pressure from local communities to ensure that solar installations don’t harm the natural environment. In the face of these pressures, it is valuable to remember that cost and sustainability need not be confined to downstream solar — innovations are also ongoing in upstream solar.

New, innovative solar manufacturing techniques can lead to cost reductions and sustainability gains across the entire supply chain, benefiting developers and customers alike.

It’s All Downstream from Here

Recently, I have noticed an industry-wide focus on decreasing balance of systems (BOS) costs and soft costs in solar. This is an exciting area of the industry that sometimes overshadows upstream solar.

In June 2016, GTM Research named soft costs as the biggest opportunity for solar cost reduction, over any other part of the solar supply chain. Attention-grabbing downstream innovations such as drones, new advanced tracking technology and AC panels all show that new solutions abound for bringing down soft costs and BOS costs. Recently, several large companies have articulated their intentions to prioritize BOS and soft cost reductions, with First Solar announcing a plan to bring down soft costs and BOS costs as quickly as possible and an announcement from residential solar company Verengo that it is “focusing on reducing soft costs” going forward.

Interestingly, the excitement within the industry about downstream solar is paired with growing concern about the environmental impacts of solar, particularly the siting of solar projects. Solar development can be delayed by concerns about environmental impacts, from clashes over the habitat of the California desert tortoise to pollination patterns in Minnesota. Based on these headlines, it’s tempting to believe that only downstream solar is responsible for any negative environmental impact and that the production of solar modules themselves is exempt.

RELATED: Thin-film module maker Solar Frontier surpasses 4 GW globally 

Simplicity: The Path Forward for Upstream Solar

Despite popular belief, upstream solar — especially solar module manufacturing — is ripe for cost reduction if upstream solar companies pursue innovation. Additionally, solar manufacturing must also take responsibility for its environmental impacts. Improvements in cost and environmental sustainability on the upstream side can help solar thrive and improve the whole industry’s reputation for sustainability.

There are still cost savings to be had in upstream solar. The costs of manufacturing solar modules contributes about half of the overall PV price per watt of solar, according to GTM Research. Although the cost of multicrystalline silicon photovoltaic modules recently dropped to an all-time low, at 43 cents per watt in 2016 (down from $4 per watt in 2008), the rate of price reduction for solar modules is slowing, and innovation is necessary for continued gains into the future.

One key area where the upstream solar industry can cut costs is in the purification of silicon. Silicon is the most expensive part of a solar module. Today, 90 percent of solar modules are made using electronic grade (EG) silicon, a type of silicon that was originally engineered 50 years ago for use in semiconductors for consumer electronics. This silicon is intensively processed, increasing its costs. However, new technology is now making it possible to purify silicon more simply, in a way that is tailored for use in solar cells. This simple method can reduce capital costs for silicon manufacturers and materials costs for solar module companies, leading to savings across the industry.

The traditional silicon purification processes are also the source of environmental problems in solar. Purifying silicon takes a significant amount of energy. Using traditional methods, it takes up to 125 kWh to make a single gram of EG silicon. The world’s growing silicon market is projected to expand $4.7 billion in 2015 to $8.9 billion by 2021, driven in large part by the growth of solar. Thus, energy savings in upstream solar, and silicon specifically, are important if solar is to be a truly sustainable industry as it grows. Various harmful and toxic
by-products are associated with EG silicon purification: toxic gases, like silane and tetrachlorosilane, and tetrachloride — a toxic and combustible substance. There is a need for continued innovation in upstream solar to reduce the problems of toxics, pollution and carbon emissions.

A simpler method for purifying silicon could cut energy use in silicon purification by two-thirds and avoid the problem of toxics in the process. Silicor Materials, the company I lead, is commercializing such a process now. If more efficient purification processes are adopted and spread quickly throughout the industry, it will lead to lower cost materials and more sustainable manufacturing, which will in turn benefit the entire industry.

Despite all the activity in downstream solar, upstream solar can’t be forgotten in the push for a more efficient, sustainable industry. Solar developers and installers can help accelerate the transition to simpler practices in upstream solar by demanding that manufacturers use the best practices in the industry for the benefit of all.

Theresa Jester is the CEO of Silicor Materials.

— Solar Builder magazine

Keys to inverter service: Data granularity, remote updates, customer relations

Service Provider Training

What support does your chosen inverter include? Fronius Service Provider training, for example, certifies installers to purchase spare parts and field-service inverters to reduce the number of truck-rolls.

Services for solar inverters are improving markedly, from commissioning through replacement, as the flow of panel and string-level data becomes more granular, fueling more sophisticated monitoring systems. From string inverters at a commercial and industrial (C&I) level, to microinverters now dominant in the residential market, manufacturers are embracing dynamic improvements in functionality based on bi-directional communications and firmware adaptability.

“As inverters become more advanced and the best companies advance the market, the distinction between awesome performance and just OK performance is finer than ever,” says Ed Heacox, the general manager of sales and marketing at Chint Power Systems (CPS) America, a commercial inverter manufacturer. “As the variance narrows in product specifications, service becomes a bigger factor than ever.”

Microinverter makers are credited for initially pushing the solar industry data collection standard to a panel-specific level and for providing enough automatic analytics to educate consumers and solve basic performance problems. Now, both micro and string manufacturers are widely including programmable chips and WiFi cards within their inverters that permit periodic upgrades of firmware. And as more frequent passive and active actions in operations and maintenance take place, the benchmarking of performance against manufacturer databases also can optimize predictive functions.

“The main technology to improve service for inverters is communication such as WiFi, which connects the system to the internet and an online monitoring portal,” observes Richard Baldinger, the head of marketing at Fronius. “Through online monitoring like the FroniusSolar.web, users can track the performance of a system and get notified if the system is not performing. Based on state codes and other values, a service truck-roll can be planned.”

RELATED: 2017 Solar Inverter Buyer’s Guide 

Firmware Updates

Two-way communications continue to provide real-time monitoring of micro systems.

“Enphase provides multiple web-based applications for both the installers and homeowners. These applications can be used to verify, in near real-time, that a given system is performing as expected,” says Ilén Zazueta-Hall, the Enphase director of product management for energy management. “Further, solar installers can receive notifications of any significant issues impacting the system, including notifications of when system performance drops below a certain [customizable] threshold.”

But now, firmware is critical to the inverter life cycle. “Firmware is constantly updated, roughly every six months. So being able to refine an inverter is valuable, but not if you have to visit it to do the update,” Heacox says. He notes that this year, CPS is launching remote firmware updates. “We can either give away or provide at a very low cost our Flex Gateway, with ethernet two-way communications. We can do updates with one card supporting dozens of inverters on a site.”

Some installers find microinverters more easily upgradable. “Microinverter monitoring for us has worked so that as the software suit enhances, we have had five or six firmware upgrades at no charge,” says Jeff Mathias, a co-owner of Synergy Solar and Electrical Systems. “I don’t get that with a string inverter company; there is a way to go into the web box to do it, but I don’t.”

SolarEdge inverter

This is a SolarEdge inverter installed on an AllEarth Renewables dual-axis tracker in Grass Valley, Calif. Photo credit: North Coast Solar, Santa Rosa.

Predictive Diagnostics

Failure response has become streamlined thanks to better communications. “If a data monitoring system detects an inverter failure, a technician could arrive on site within 24 to 48 hours with a stock of replacement parts. The repair to the inverter can be done in minimal time in one trip, and the system will resume full power production,” notes Baldinger. “Compare this to a typical scenario where a technician makes a first trip to troubleshoot and determine the exact failure, then orders a replacement. String inverters are often replaced in whole, with wait times of one week typical for the replacement unit to arrive before the technician visits the site again.”

“Microinverters and inverters with optimizers such as SolarEdge make system monitoring and problem diagnosis easier. Receiving an automatic email from Enphase when there is an inverter problem is particularly helpful,” says Brian Hines, the principal at North Coast Solar.

Heacox says that later this year CPS “will roll out remote diagnostics and problem solving, so that we can handle 95 percent of a trouble call from our national support center in Texas.”

Warranty Services Improve

Installers in the past have complained that some inverter makers were slow to replace failed units and that some even insisted on repairing the old one over replacement. That standard is no longer acceptable in the market.

“Before we went to microinverters, we had to go to a site, analyze the string inverter problem and if it was a failure, call the manufacturer and go through their on-telephone de-bugging routine to validate that the unit was bad. Then we’d take it to the shop, put it into box and wait two or three days to a week for the replacement,” Mathias relays. “Now, we just text in an app that we have a bad inverter, and a new one comes in.”

Zazueta-Hall explains: “In cases in which a product is defective, installers are guided through a streamlined return merchandise authorization (RMA) process. Installers can submit a warranty claim or check the status of a pending warranty claim online. Customer support can also authorize an RMA with one call into the support queue to perform remote diagnostics on an inverter. ”

RELATED: LCOE Heroes: How inverters drive down PV levelized cost of energy 

Training Responders

The market has realized that manufacturer training and customer service is integral for inverter maintenance and installer services.

“We offer Fronius Service Provider training, which certifies installers to purchase spare parts [such as PCB boards] and field-service inverters. It also helps reduce the number of truck-rolls in a service case,” Baldinger says.

Inverter design also plays a huge part too because even a well-trained technician working on a complex or cumbersome product is going to run into issues or slowdowns. CPS says it invested in extra engineering and cost into the wire-box and inverter body designs to make them integrated but separable so that when a service event occurs in the inverter body, it can be easily removed and replaced — just four bolts hold the inverter body (top) to the wire-box.

“It takes only 10 minutes to swap the inverter tops for quick uptime recovery,” Heacox says. “It would be several hundred dollars cheaper to make the inverter in one chassis without the separable wire-box, but we know downtime and wasted field service labor and materials can cost much more. We do our best to consider life-cycle service costs when architecting the inverter platform.”

Distributors also play a training roll. “Quality solar distributors can be counted on to provide: short lead times for order fulfillment to installers, in-depth product knowledge and training information,” suggests Jason Higginson, the senior director of marketing for APSystems. “Even if training is offered by the manufacturer, good distributors can often provide basic support and can also coordinate online or live training sessions with a manufacturer for installer customers. Finding a distributor with good relationships with their manufacturers helps to facilitate all the above.”

Microinverter vendors serving the residential market don’t necessarily know where their products are being installed and thus are at a loss to provide support until it is requested. But in the C&I segment, largely equipped with string inverters, the smaller number of devices in field permits more manufacturer-customer familiarity. “In C&I we know where every inverter is going because we go directly to the site ourselves. So we are on a first name basis,” Heacox says. “We also are on a first name basis with our guy in the site region, with the EPC or the developer. So we can directly service the relationship from design to install across full life support.”

Charles W. Thurston is a freelance writer who covers solar energy from Northern California. Reach him at

— Solar Builder magazine

2017 Solar Inverter Buyer’s Guide

Inverters are the brains of the PV system, and if you want to tease out this metaphor (and I do), the comparison is deeper than just “the part that does the thinking.” Really, looking at the latest studies in neuroscience, you could flip the cliché — brains are maybe the inverters of the human body. They are malleable and capable of change (system updates). Concussion research has shown frailties in their design (failure rates). A sleep-deprived brain leads to reduced performance (importance of O&M). And so on.

We don’t really know everything going on in our brains, but inverter manufacturers have all the details on the innards of their products, so we thought it might be handy to corral them all in one place. In this 2017 Inverter Buyer’s Guide, we reached out to every inverter manufacturer to provide us with some key numbers, info on their newest technology and a little advice for buyers.

Sure, inverters fail more than brains do (maybe debatable), but brains don’t have manuals, customer service lines or warranties. So, take advantage of the choice in the market place and choose the inverter and accompanying service solutions that work best for you and your customers.

This complete guide is from our March/April Inverter Issue. Subscribe for free today in print or digital (or both!)

Page 1: Mostly module-level solutions

AP SystemsAPsystems

APsystems was founded in 2009 and is one of the largest microinverter and MLPE solution providers in the world. APsystems serves customers in more than 70 countries through three global business units operating in: Seattle for the Americas region; Lyon, France, for the EMEA region; and Jiaxing, China, for the APAC region. APsystems has hundreds of thousands of units installed around the globe producing over 130 GWh of energy.

APsystems offers installers intelligent, affordable microinverter solutions, plug-and-power features and hassle-free installation. APsystems was the first to offer a dual-module microinverter, the YC500, and then was the first to offer a true three-phase, four-module microinverter for commercial applications, the YC1000. Overall, APsystems microinverters have about 30 percent fewer components than competing brands, which leads to higher reliability and lower costs. APsystems

What’s New?

APsystems extends its advanced microinverter line with the new YC500i with EnergyMax power handling and integrated ground. This EnergyMax technology allows the dual-module unit to produce 274 watts peak output per side (548 watts total), which is nearly a 10 percent increase in peak power output over conventional microinverters and crucial for harvesting the power of today’s high-output PV modules.

The YC500i microinverter builds on the same advanced, FPGA chip-based platform as the popular YC500A flagship model. The YC500i utilizes a trunk cable, offering installers an alternative to the daisy-chain design of APsystems’ YC500A microinverters. This provides a solution for installers who favor trunk cable architecture as well as markets where regulatory bodies prefer an integrated ground.

Advice to Buyers

“When considering inverter solutions, be sure to compare warranties and ask questions about LCOE, determine which solutions will produce the most energy over the life of the system, ask about safety considerations like arc-fault protection and rapid shutdown compliance, consider product reliability and ask about module-level energy monitoring so you can see what each panel is producing,” says Christopher Barrett, APsystems director of engineering and Technical Services.

DarfonDarfon Solar 

Darfon Solar is a division of Darfon Electronics Corp., founded in 1997, and is the world’s leading notebook keyboard and power supply manufacturer with 11 factories and subsidiaries and more than 16,000 employees worldwide. Utilizing its power supply and integrated material expertise, Darfon manufactures off-grid, hybrid and micro inverters, as well as energy storage solutions and a microinverter installation solution. Darfon has more than 10 MW of its products installed worldwide.

What’s New?

The G320 is Darfon’s latest microinverter, capable of handling up to 350 Wdc of power. It offers great flexibility with an operating voltage range of 22 to 60 Vdc and an MPPT range of 24 to 45 Vdc, allowing the use of high-voltage 60- or 72-cell modules. The G320 comes in 208, 240 or 277 (for 480-V three-phase) grid-tied voltages, making the microinverter flexible enough to use in residential, commercial or utility designs.

The G320 offers the increased safety of microinverters but with even more reliability. The G320 features a redundant capacitor design that continues working even if the electrolytic capacitors have problems over time. The G320 also carries an efficiency rating that qualifies for rebates throughout the country. The G320 can also be tied to 10-gauge trunk cables for 30A circuits. This allows more modules on each circuit, a reduction in the number of circuits and a lower BOS cost on larger systems. Finally, Darfon’s G320 comes with a 25-year warranty in the United States.Darfon Solar

Advice to Buyers

“Check the design of the PV system and make sure it matches the inverter specifications,” says Frank O’Young, associate VP for Darfon. “Many people overdesign a PV system with higher voltages and more power than the inverter can handle. Using solar panels with higher voltages than the inverter can handle may result in damaging or burning out the inverter. Using solar panels with higher power output than the inverter can handle will not likely damage the inverter, but it is not cost efficient because you only capture the energy the inverter can handle, not the total energy available.”

Enphase EnergyEnphase Energy 

Enphase Energy, based in Petaluma, Calif., is a global energy technology company focused on bringing smart, connected solar energy to every home, business and community. The company delivers simple energy management solutions that advance the worldwide potential of renewable energy. Enphase has shipped approximately 13 million microinverters, and monitors more than 540,000 Enphase residential and commercial systems have been deployed in more than 100 countries.

What’s New?

The Enphase IQ Microinverter System provides substantial benefits. The Enphase IQ 6+ Micro that supports 60- and 72-cell modules up to 400 Wdc and the Enphase IQ 6 Micro that pairs with 60-cell modules up to 330 Wdc. They are 30 percent lighter than Enphase S-Series microinverters and 40 percent lighter than other microinverters on the market today, partly due to their double insulated, corrosion-free polymeric enclosure. Both offer 97 percent average CEC efficiency.

The two-wire Enphase Q Cable is 50 percent lighter than the previous generation of Enphase trunk cable; the Enphase Q Aggregator offers simple plug-and-play connections for up to three branches on the roof, or the Enphase Q Combiner provides further installation and commissioning efficiency. The Enphase Home Energy Solution with IQ uses a single technology platform for seamless management of the whole solution.Enphase Energy

Advice to Buyers

“It’s always important to think of solar as a long-term investment. What’s going to give you the greatest return over time?” asks Tefford Reed, senior director of the microinverter line. “When considering an inverter for your system, the two most important variables should be reliability and long-term operability. You would the think the two would be synonymous but not so. PV systems are long-term investments and a reliably manufactured inverter is just as critical as an inverter that will be able to accommodate any changes to grid environment.”

HiQ SolarHiQ Solar 

HiQ Solar is an indigenous string inverter company, a rare thing in the United States. The Silicon Valley-based startup focuses on an underserved, but relatively large, niche — the U.S. commercial rooftop and carport segment. Founded in 2009, HiQ has shipped over 40 MW of its TrueString product line.

What’s New?

HiQ has the only string inverter designed to mount under the PV array, making it perfect for commercial rooftops, carports and trackers. The NEMA6 construction and ability to take unequal string lengths makes it a problem solver for difficult installs. The lack of fans or air filters means it requires no maintenance, and at 24 lbs one customer called it “the backpack inverter” because of how easy it was for one person to get them onto a rooftop. The unique combination of features led to it winning the Global Energy News Innovation Award. HiQ Solar

Advice to Buyers

“Check that the environmental rating of the inverter matches the climate of the location of the install. For example, you probably wouldn’t want to use a NEMA3R inverter in a coastal environment,” says Marv Dargatz with HiQ Solar. “People often use terminal blocks for paralleling strings. However, terminal blocks are listed for the number of wires they can accommodate, and many are for one wire. Check the listing to make sure the product is approved for the number of strings you intend to parallel. The TrueString is unique in that it’s a three-phase commercial inverter that doesn’t need paralleling.

Solar EdgeSolarEdge

Founded in 2006, SolarEdge, a global PV inverter company, has a versatile lineup of products — including inverters, power optimizers, storage and smart energy management solutions and a cloud-based monitoring platform — that address a broad range of solar market segments, from residential solar installations to commercial and small utility-scale solar installations. The SolarEdge DC optimized inverter solution maximizes power generation at the module level while lowering the cost of energy produced by the solar PV system. SolarEdge has shipped 3.8 GW of systems, and over 265,000 systems are monitored in 100 countries.

What’s New?

SolarEdge’s HD-Wave inverter uses a novel power conversion topology that significantly decreases inverter size and weight while achieving record efficiency. In fact, SolarEdge won the 2016 Intersolar Award for its new power conversion technology that uses distributed switching and a powerful digital signal processor to create a cleaner sine wave and generate less heat. This technology increases conversion efficiency to a record breaking 99 percent while decreasing product weight by half compared to traditional string inverters. These power packed inverters are designed for reliability through the use of thin film capacitors instead of traditional electrolytic capacitors. HD-Wave inverters offer users greater flexibility through higher DC/AC oversizing (up to 155 percent) and longer string lengths — almost two times longer than traditional inverters (up to 6,000 watts on 7.6-kW model). SolarEdge

Advice to Buyers

“When selecting a PV system, frequently the upfront cost of the system is the determining factor regarding which solution to choose. However, it is important to take into consideration the lifetime value of a system,” says Lior Handelsman, founder and VP of marketing and product strategy at SolarEdge. “Factors that can impact lifetime value include safety features, length of warranties, system uptime, monitoring and future compatibility with storage and smart home solutions. Decisions should not only be based on how much it costs but also include how much value the system can provide throughout its 25-year lifetime.”

On the next page, residential string inverters and solar+storage friendly systems

— Solar Builder magazine