Yaskawa-Solectria says PVI 50, 60 TL inverters now meet California Rule 21

Yaskawa – Solectria Solar, a U.S. commercial PV inverter manufacturer, announced that their PVI 50 TL and PVI 60 TL inverters are now fully compliant with California Public Utility Commission (CPUC) Rule 21 – UL1741 SA.

Yaskawa solectria inverters

Achieving compliance two months prior to the deadline demonstrates Yaskawa – Solectria Solar’s dedication to remain at the forefront of cutting-edge technology and innovation.

“We are committed to providing grid-support enabled utility-interactive inverters to meet our Nation’s needs to ensure a stable grid,” said Miles Russell, Director of Product Management. “Yaskawa – Solectria Solar is continuously working to lead the market with the highest quality and reliability, while keeping up with the latest requirements.”

Rule 21 describes newly defined needs by utilities for grid stabilization as PV generation in California continues to grow. The Rule describes interconnection, operating and metering requirements for inverters to allow the grid to accept increased capacity as California adds more GWs to its grid. Rule 21 will allow inverters to actively interact with the grid and contribute to system-wide stability and reliability. UL1741 SA prescribes testing methods to qualify smart inverters for compliance with Rule 21.

California’s Rule 21 decision finalized, IREC considers it a ‘big win’

— Solar Builder magazine

Yaskawa-Solectria Solar inverters now fully compatible with Tigo optimizers

Yaskawa – Solectria Solar announced full compatibility of its three-phase string inverters with Tigo’s module optimizers, fully complying with the 2014 and 2017 National Electric Code (NEC) 690.12 Rapid Shutdown Requirements.

Yaskawa-Solectria Solar extends its string inverter line“We are pleased to offer our customers a solution that complies with the upcoming module-level rapid shutdown requirements,” said Miles Russell, Director of Product Management at Yaskawa – Solectria Solar. “Tigo’s integration with Yaskawa – Solectria Solar inverters allow us to stay at the forefront of the latest technology and code changes, while keeping costs low. This solution gives customers the reassurance they are looking for when it comes to safety.”

Tigo’s UL and IEC-certified optimizers TS4-L and TS4-O discharge the capacitors in the inverter to ensure zero voltage at shutdown. In addition, the built-in automatic over-current and over-temperature features reduce liability and provide safer conditions for installers, customers and first responders in case of emergency.

System design

Tigo conducted extensive testing to validate the effective performance of the systems together in standard operating environments. Yaskawa – Solectria Solar’s three-phase string inverters, PVI 23/28/36TL, can be used successfully in combination with the following TS4 product families from Tigo:

• TS4-B models –D, -M, –S, -O, -L
• TS4-R models –M, -S , -O

“Tigo is distinguished in the industry as being the sole company to offer a certified modular platform so customers can cater their system needs by simply replacing the TS4 functional covers,” says Gal Bauer, Director of Training and Development at Tigo. “By combining our innovative technologies with tier 1 companies like Yaskawa – Solectria Solar, Tigo is providing the solar market with the safest solar energy generation products and management systems.”

RELATED: 2017 Solar Inverter Buyer’s Guide 

 

— Solar Builder magazine

Sunworks to start installing co-branded Yaskawa – Solectria inverters

Yaskawa – Solectria Solar formed a partnership with Sunworks, which means Sunworks will be installing co-branded PVI 50/60TL transformerless three-phase string inverters that are a part of Yaskawa – Solectria Solar’s top-selling commercial string inverter line.

Sunworks says it chose Yaskawa – Solectria Solar inverters based on their reliability, Yaskawa – Solectria Solar’s support, and the ongoing successful relationship between both companies.

sunworks yaskawa solectria inverter

“Sunworks has initiated its ‘Powered by’ program, which is tailored to exceed customer expectations, reduce installation time and enhance production. Yaskawa – Solectria Solar was chosen after extensive evaluation to be our partner of choice for this program,” said Robert Lopez, VP Procurement of Sunworks.

The alignment of the two solar companies will create new opportunities for customers who can benefit from both company’s service and increased flexibility.

RELATED: 2017 Solar Inverter Buyer’s Guide 

First project lined up

Sunworks will begin installing Yaskawa – Solectria Solar inverters in a 2.8-MW ground-mount project located in Buttonwillow, Calif.. Yaskawa – Solectria Solar’s PVI 60TL provides the best solution to optimize BOS, reduce labor costs, and maximize energy harvesting for customers.

Sunworks will continue to utilize other Yaskawa – Solectria Solar commercial products in addition to the PVI 50/60TL depending on project needs.

— Solar Builder magazine

1,500-volt systems to trend in 2017: Here’s what you need to know

SolarBOS-cutline

SolarBOS combiner

Large-scale solar projects are heading into yet another sea change: the 1,500-volt PV system (Vdc). The idea behind the voltage increase is the same now as it was during the move from 600 volts to 1,000 volts — further reduce installation costs and increase profitability by reducing the number of inverters and other BOS components required.

“But there is a difference this time,” notes TJ Kanczuzewski, president of Inovateus Solar located in South Bend, Ind. As a solar EPC and distributor, Inovateus Solar was one of the first solar companies to be introduced to 1,000 Vdc from 600 Vdc and has seen these types of technology transitions before. “Today’s 1,500 Vdc are more sophisticated systems than we’ve ever had before.”

Advanced Intelligence

Kanczuzewski relays his experience designing projects with Schneider Electric’s new Conext SmartGen 1,500-Vdc inverters, which can record and store operations and service history, as well as upload all of this data and self-diagnostics to the cloud.

“The Conext system also offers 30-year service life and a minimum of 15 years before the first major service,” he says. “So, this time, these systems are very intelligent as well as powerful.”

And this is just the beginning as all of your favorite inverter brands start to launch and ramp up production on their product lines. At the 2016 Solar Power International, Yaskawa-Solectria Solar, one of the most widely installed brands, pre-announced its 1,500-Vdc, utility-scale string inverter, the SLX 1500 line. These inverters will be available at various power levels and AC voltages, but adding in its Wireless Mesh network eliminates the need for communication wiring, reducing communications and BOS cost.

“In addition, the Wireless Mesh proves to simplify commissioning, has robust/secure networking, advanced grid functionality, superior asset management and improves response time,” says Natalie Holtgrefe, senior marketing manager for Yaskawa-Solectria Solar.

RELATED: How optimizers bridge the gap to 1,500-volt PV systems 

But is it safe?

Regardless of ancillary benefits, being an early adopter to such a step up in voltage carries risk.
“There is a lack of understanding in the industry concerning incident energy and arc flash risk. This is true for 1,000-Vdc systems and clearly becomes more important in 1,500-Vdc systems,” says SolarBOS CTO Coel Schumacher.

BOS equipment provides overcurrent protection and disconnecting means used for system operation and maintenance and must be accessible to personnel. Due to the nature of photovoltaic installations, there are a significant number of sources that aggregate in BOS equipment, and a series of devices are typically used to achieve this.

“While it is possible to isolate these devices, the long runs between them make it inconvenient as well as difficult to isolate a device by a means within line of sight,” Schumacher continues. “If the device is not completely isolated, portions of the equipment remain energized. This poses an arc flash risk and yet there is no consensus on how to evaluate that risk, much less how much risk there truly is.”

SolarBOS offers BOS equipment including combiners and recombiners with various options for circuit count, current ratings, OCPD and disconnecting means. On the AC side of the inverter, SolarBOS offers configurable switchgear that is necessary for string inverter implementation.

Yaskawa-Solectria Solar’s DISCOM 1500 string combiners offer various options that make design and safety easier for installers, including MC4/H4 connectorized wire whips, compression lug studs and heavy gauge bus bars.

Eaton, which has extensive experience in managing DC circuits in other high voltage DC environments such as battery storage systems, rail systems and steel mills, reminds us that the call for 1,500-volt safety extends to the equipment, too.

“At 1,500 Vdc, there is substantially higher voltage stress on the solar modules, which can make modules more susceptible to potential induced degradation (PID),” says John Vernacchia, segment manager for renewable energy at Eaton. “Only a few years ago, PID had a disastrous effect on many solar projects. As developers look at using this higher voltage technology, caution should be taken to use PID-resilient solar modules and to use grounded arrays. Past experience has shown that floating arrays are significantly more sensitive to PID due to the negative voltage bias placed on the solar modules.”

Eaton’s 1,500-Vdc inverters will employ a new proprietary DC design concept that replaces manual DC disconnects with DC contactors to improve both control and enhance operator safety.

Eaton’s 1,500-Vdc inverters will employ a new proprietary DC design concept that replaces manual DC disconnects with DC contactors to improve both control and enhance operator safety.

Reducing BOS costs

As dazzling as the new capabilities are, the potential BOS cost reductions are just as enticing for an industry constantly having to prove its economic worth. GTM Research estimates that overall project costs can be reduced by three to five percent by moving to 1,500-Vdc systems, realized mainly through reduced installation time and fewer components.

SolarBOS’s Schumacher says the 1,500-Vdc projects they’ve done are acting as flagship installations to prove the benefits of higher voltage systems. In general, he says, BOS equipment becomes more energy dense and cost effective at 1,500 Vdc.

“In addition 1,500-Vdc systems lend themselves to higher AC voltages [600 Vac or more], which helps to reduce AC conductor and switchgear cost,” Schumacher says.

Eaton developed its Crouse-Hinds series DC collection system, Sunnector, to reduce costs and installation time in these utility-scale solar projects. This system can help reduce labor and material costs by 15 percent on average, according to Vernacchia, in 5 MW and larger-scale, grid-tied solar projects that use fixed-tilt ground-mount racking designs.

A key here is using aluminum for long-distance runs, but still incorporating copper connections to the PV modules. This way contractors are able to use standard copper connectivity and tools, while project owners are able to reduce costs by taking advantage of lower cost aluminum wire.

Yaskawa-Solectria’s SLX 1500 line and Wireless Mesh network eliminates the need for communication wiring, reducing communications and BOS cost.

Yaskawa-Solectria’s SLX 1500 line and Wireless Mesh network eliminates the need for communication wiring, reducing communications and BOS cost.

So, where are we?

Holtgrefe says Yaskawa-Solectria Solar is seeing considerable demand for 1,500 Vdc in utility-scale projects. However, 95 percent of demand in the C&I space is still for 1,000-Vdc products. Her expectation is for the C&I space to move toward 1,500-Vdc systems at a slower rate of adoption than utility-scale.

“We’ll need to educate our customers about this new offering and help them understand the value,” Kanczuzewski says. “Code standards will need to be revised in some areas, and different utilities may have their own guidelines, so installers will need to make sure that 1,500 Vdc is compliant or show how 1,500 Vdc is becoming the new standard. We can always go back to 1,000-Vdc systems if our customers require it, but we hope we’ll be able to transition quickly.

“Inovateus went through the same type of customer education and standards review with the transition to 1,000 Vdc, but we expect that 1,500 Vdc will overcome any hurdles and become the norm within the next two to three years.”

Chris Crowell is the managing editor of Solar Builder.

— Solar Builder magazine

Inverter experts explain how to best calculate levelized cost of energy

APsystems

Photo courtesy of APsystems.

Levelized cost of energy (LCOE) is one of the most important metrics used for judging the value of a PV system. It is also less easily understood and seemingly open to interpretation. How am I really calculating this figure? What is sitting outside this calculation?

Ask five inverter companies, and you might get five answers. So, we asked them all to get all of the answers.

Factor for Failure

A recurring theme when calculating LCOE for a PV system is getting a full understanding of its potential for failure and its ability to mitigate those losses: How many components are there? How likely are they to fail? When and how often could they fail? How much production will be lost during those failures? How much work is involved in getting it running again? This means keeping in mind variables like inverter replacement cost, system engineering cost, interconnection updates (adoption of new codes) and re-inspection cost.

Fronius Diagram

Fig. 1: Courtesy of Fronius USA.

Fronius did a study, examining the costs associated with replacing or repairing inverters 15 to 20 years from the present to account for that full PV system cost of ownership. An example they gave: If the original system cost is $10,000 and the extended cost factor is 1.10, then the total cost of the system over its lifetime is $10,000 x 1.10 = $11,000. Within this study, its SnapInverter resulted in 1.05 cost factor, while a generic string inverter hit 1.19 and a microinverter hit 1.26. The important variable in this calculation was mean time between failure (MTBF), defined in this study as the failure rate during the intrinsic failure period (see Fig. 1).

“Since the industry has grown so rapidly in recent years, the majority of PV systems in the United States are less than five years old, with typical standard inverter warranties being five to 10 years in length,” says Brian Lydic, senior standards and technology engineer at Fronius. “The majority of inverters installed in the field are still under warranty, and the industry has not needed to address large numbers of inverter replacements or repairs due to end of lifetime, though this will become commonplace.”

Yaskawa – Solectria Solar notes the correlation between the number of components and a higher MTBF, which makes sense intuitively. This makes the MTBF discussion a big part of the operations and maintenance (O&M) and LCOE calculation.

“The capability to service your inverter efficiently and in the most effective manner is crucial to keeping uptime high and calculating LCOE,” says Danielle Kershner, channel sales representative, Yaskawa – Solectria Solar, which keeps component count low by integrating AC/DC disconnects and integrates modular power stages to minimizes time and cost for service. The company has also revamped its customer service department to reduce downtime.

Another way to look at this is operational expenditure (Opex). The question answered here is “How much value am I losing during downtime?” So, Opex would include equipment failure, maintenance, repairs, materials and labor lead-time, restructuring, capacity change and so on. This analysis can favor microinverters in certain applications as any failures will only affect small portions of a system in a single moment, versus the entire system in the case of a string inverter failure. As mentioned in our feature on service on page 20, web-based monitoring services can be crucial for improving timeliness and efficiency of O&M functions.

“Since downtime is tied to the loss of generation, this variable must not be taken lightly when trying to maximize the LCOE,” says Frank O’Young, associate VP for Darfon. “The LCOE may be lowered by as much as 20 percent if the system uses equipment that is easy to maintain, quick to troubleshoot and requires minimal repair time.”

Look at Lifetime

Establishing all of the variables that add and subtract from the economic value of a PV system is step one. Establishing a timeframe is step two. Is your LCOE calculation really looking at the broad picture?

“When you compare two systems with a calculated LCOE, be sure the warranties are equivalent because the cost to replace a major component like a string inverter can have a serious impact on that calculation, particularly when those needed replacements occur once, or often twice within a 25-year period,” says Jason Higginson, senior director of marketing, APsystems, which has 10- and 25-year warranty options for its microinverters.

Adjacent to the warranty is service recovery speed. Ed Heacox, GM of CPS America, a leading commercial inverter company, says a key for them is having ready-to-go spares or RMA inverters available. “We are offering service speed commitments as well as onsite spares to help customers reach nearly zero downtime. Innovation of these commercial programs is a big part of our work on LCOE for customers,” he says.

Pika Energy Diagram

Example of “future-proofing” an install with a Pika Energy inverter.

Max Efficiency

Enough of all of this failure talk. Most of the time the system is going to be on and working, and when it is, it needs to be kicking ass and improving LCOE.

“One of the potential drawbacks is that LCOE calculations do not effectively differentiate between upfront and variable costs,” says Peter Mathews, North American general manager for SolarEdge.

His example: The fixed cost of a system, including customer acquisition, permitting and design, are realized regardless of the size of the PV system. Each added module can be installed for a much smaller variable cost.

“The trade-off between fixed and variable costs is more advantageous for systems with more PV modules since they can generate a disproportionately greater amount of energy versus the initial upfront costs,” he says. “LCOE calculations are therefore only part of the financial return. The calculation for return on investment (ROI) should also factor in the revenue generating potential of any site to generate cash from the PV system. The LCOE only calculates the expense. The returns can also vary based on region, rate structure or the ability to switch rate structures. Having a highly flexible PV solution that can add more modules onto projects is a powerful tool in maximizing the return on PV projects.

SolarEdge’s philosophy is to allow for the installation of modules in shaded areas and on roofs with varying angles. This degree of design flexibility means more modules per roof.

Marv Dargatz with HiQ Solar recommends stacking string powers high enough to maximize ROI while the system is up and humming. To do this right, he cautions to be wary of STC ratings.

“STC ratings for modules tend to be optimistic, partly because they are measured with a cell temperature of 25° C. In the real world, cell temperatures in direct sunlight are more likely to be at 60 or 70° C, yielding less power,” he says. “Overall, when orientation to the sun, temperature, time of year, soiling and aging are taken into account, strings put out a lot less power than STC leads you to expect. It’s therefore important to stack the inverter to make sure it is operating as near to its max output as possible to maximize ROI.”

He also says having a single MPPT per string rather than paralleling helps maximize harvest.

RELATED: How to achieve low LCOE utility-scale solar without cutting costs 

Seriously, Really Look at Lifetime

Pinpointing the lifetime of a system at 25 years from 2017 puts you into 2042. We did the math three times just because that number looks insane. We might all be in an Escape from New York post-apocalyptic future, but those PV systems will still be kicking, and one has to assume energy storage is going to be in a completely different position than it is now. And assuming that, you must assume your customers are going to want to move to upgrade to solar+storage, if they haven’t already, which throws all of your previous LCOE forecasting out the window of your 2042 flying car.

So yes, understanding cost and performance metrics for batteries is an important factor to consider today. Batteries introduce multiple new variables into the financial model and can have a positive or negative impact on LCOE depending on the technology used and how it is sized relative to the PV array and loads.

“A battery has both an instantaneous power rating [in watts or kilowatts] and an energy capacity rating [in kilowatt-hours] and they both factor into the financial model,” says Paul Dailey, director of product management, OutBack Power. “In addition, battery life is often expressed either in cycles or calendar life, but you need both metrics to determine the value of the battery in your application over time.”

The future of energy storage is why Chip Means, director of sales development, Pika Energy, says DC voltage is by far the most underrated and under-appreciated variable in LCOE.

“Too many solar inverter products use a low voltage range, typically 48 volts. Solar is rapidly changing to require the addition of battery storage behind the meter. Using 48-volt equipment simply doesn’t make sense for this evolving reality,” he says. “Low-voltage inverters are typically AC-coupled to add a battery to grid-tied solar, which requires using two inverters. This clunky, 48-volt arrangement means the customer’s roundtrip efficiency will be typically around 80 percent.”

Pika Energy’s products use an internal bus voltage of nominally 380 Vdc, and all of its components — PV Link solar optimizers, Islanding Inverters and Pika-compatible smart batteries — use this bus voltage to connect, communicate and transmit power. This results in a system with roundtrip efficiency of closer to 90-92 percent. That 12 percent increase on roundtrip efficiency pays major dividends in terms of LCOE.

Magnum Energy’s MicroGT inverter also comes ready to talk to the MS-PAE inverter/charger, to ease that solar-plus-storage transition.

“Installing storage-ready PV systems now will save significant time and resources when returning in the near future to add energy storage,” says Mike Dixon, sales and marketing director, Magnum Energy. “Not only considering current equipment investments, but future equipment investment — which doesn’t fall under the O&M umbrella — can save on the most expensive part of the solar formula.”

Unless all of these lifetime costs and realistic max output calculations are included and explained clearly to customers, a backlash will occur once they are surprised by replacement costs or any other unforeseen variable. And no one wants a line of customers wielding lightsabers outside their door in 2042, demanding satisfaction. 

This feature is from our March/April “Inverter Issue.” Get your FREE subscription to print here or digital versions here.

— Solar Builder magazine