Battery chemistry matters: What to know before installing solar + storage systems

battery

The days when a residential or commercial solar installer did not need to know the difference in performance between lead-acid and lithium-based batteries are over. Battery storage has emerged as an unavoidable complement to solar, slashing peak charges and outwitting utility time-of-use charge games, not to mention saving microgrids from outages.

Recommending battery chemistry to a customer is no less complicated than recommending a particular solar array solution. Depending on customer goals of low initial cost, ease of maintenance, frequency of use, depth of discharge, source of recharge energy, longevity and warranty, however, choices narrow down rapidly. Lowest life-cycle cost, or total cost of ownership calculations, performed for site-specific use, also help customers understand the variations in side-by-side options.

“There are some applications where lead-acid still presents the lowest cost of ownership, so if you are just doing peak shaving or off-grid backup, you can use lead-acid as long as your usage is tightly controlled and meets the requirements of a lead-acid system,” says Jason Zerbe, the systems marketing manager at Enersys. “In other cases the most important function of the battery is that it has 100 percent up-time. There, lithium starts to make sense because it can do more in a partial state of charge and because it is not necessary to fully recharge the battery periodically without affecting the lifetime of the battery, unlike with lead-acid.”

Historic leader: Lead-acid

Lead-acid battery solutions are far from antiquated, still capturing over a third of the global battery market. While it is true that lead-acid batteries are heavier than alternatives, charge more slowly and generate hydrogen gas as they age, lead-acid still provides a solid value at a low cost, and can disprove criticism of poor longevity in some configurations.

Deep-cycle lead-acid batteries can last as long as a solar array, with designed use. Trojan Battery recently branded a line of batteries specifically for the solar industry to prove this point. At the high end, Trojan’s Industrial grade lead-acid batteries can last up to 17 years, delivering 3,600 charge/discharge cycles at an average 50 percent depth of discharge (DOD). In comparison, Trojan’s solar absorbed glass mat (AGM) lead-acid battery lasts eight years, delivering 1,700 cycles at a 50 percent DOD.

Top 5 battery installation issues for solar installers

You need to consider how much your customer wants to participate in the storage process. Less-expensive flooded lead-acid batteries — costing from $100/kWh to $200/kWh — provide between 600 and 1,200 cycles and require water refilling maintenance, but AGM or gel chemistry lead-acid batteries, which are 20 percent more expensive, can provide about 1,700 cycles without requiring the extra maintenance, according to Erguen Oezcan, senior sales director for renewable energy at Trojan Battery.

The safety and environmental story of lead-acid is tricky. On the one hand, flooded batteries carry the extra costs of a venting system needed to draw off the hydrogen gas that is formed over time as well as a containment basin to guard against spills (a code requirement). But, on the plus-side, lead-acid batteries are 99 percent recycled — one of the most recycled products in industry today. Lithium batteries are not yet recyclable.

There are some relatively new additions to basic lead-acid chemistry to consider. Carbon-enhanced anodes limit the formation of sulfate deposits, which hamper performance and decrease battery life. Other innovations include the use of metallic agents to enhance the electrolyte, layered insulating wrappings for AGM mesh and so-called moss shields that limit internal shorts.

JLM Energy

JLM Energy recently installed more than a dozen residential Phazr MicroStorage plus solar projects in locations throughout the greater Phoenix metropolitan area to shave peaks when demand spikes.

Up and comer: Lithium-iron phosphate

When lithium-ion batteries came into common use, they seemed destined to capture the bulk of the battery market. But high prices — which thankfully are falling rapidly — combined with fire concerns have encouraged manufacturers to experiment with a variety of other lithium chemistry variations. One that’s emerging is lithium-iron phosphate (LiFePO4 or LFP), which exhibits fast discharge, long life and greater operating safety than other variations.

LFP is a nontoxic, thermally stable material and is much safer — from fires and explosions — than the standard cobalt-containing lithium-ion (LiCoO2) chemistry. The difference in chemistry also makes the LFP less expensive than the lithium-ion battery.

The cost of LFP batteries is down to about $400 per MWh and should drop further as more large-scale production comes onto the market. “LFP battery costs have dropped 25 to 30 percent over the last two years,” says Catherine Von Burg, the CEO of SimpliPhi.

Still, commercial and industrial customers are seeing a return on investment for LFP in four years or less, when targeting problems like peak shaving, says Von Burg. Her company routinely installs LFP battery banks on C&I rooftops.

A host of local regulations have arisen to mitigate the fire risk from lithium-ion, which adds cost to both residential and commercial applications installed indoors. This is where LFP’s chemistry can make a difference — at the point of installation completion.

LFP performance can beat lithium-ion, with LFP batteries generally providing about 2,000 charge/discharge cycles, compared to about 1,000 for lithium-ion batteries, according to one industry source.

Because of its safety, rooftop battery solution provider JLM Energy also uses LFP in its Phazr battery system, which is mounted underneath each panel in a rooftop solar array.

One forward-looking advantage of using LFP battery systems is the growth of community solar, microgrids and other aggregated forms of distributed energy resources. As utilities become more capable of interacting with these DER systems, more smart, fast battery systems will be called upon to support the grid, if not also enabling some form of private-sector energy arbitrage, suggests Von Burg.

New standards

Comparing battery lifetime has become more standardized with the advent of the International Electrotechnical Commission’s (IEC) standard 61427 test, which provides performance criteria that all batteries for PV applications should be measured against. It offers a common, internationally accepted platform to compare and contrast batteries from different manufacturers.

Warranties are also widely variable, so trust in solid companies unless a reliable third-party warranty policy has been issued on the product. “There is a trend among battery companies with a limited reputation to give unbelievable warranty terms. Then the owner has to prove a lot of things to collect on the warranty, which is really tricky and in-transparent,” Oezcan says.

Battery showcase: Four solar + storage solutions for your next project

To aid in the information battle, independent energy certification body DNV GL just developed Battery XT, the first testing-based verification of battery lifetime for lithium-ion batteries. The independent verification tool compiles battery lifecycle data and predicts battery degradation under different conditions and duty cycles, providing renewables stakeholders with an objective way to compare the value and reliability of types and brands of energy storage technology as well as provide consulting on battery size and chemistry selection.

“As the storage market continues to expand, the ability to manage risk at the point of purchase is becoming increasingly important,” says Rich Barnes, executive vice president and regional manager for DNV GL Energy in North America. “Battery XT will empower stakeholders to make better purchasing decisions based on objective, third-party testing.”

This section was featured in the January/February 2018 issue of Solar Builder magazine. Sign up for a FREE subscription here.

 

— Solar Builder magazine

The LONGi-term play: Get familiar with this record-breaking Chinese manufacturer

solar panels in flowers

Even amid the tariff uncertainty, China-based LONGi Solar is ready to establish a bigger presence in the U.S. and intrigues us in the (ahem) long-term. Wholly owned by LONGi Group, there was speculation that in a punitive tariff scenario the company might consider establishing its own U.S. manufacturing line, but when we asked about it, the leadership team had no news of that kind to reveal. Just know that they are watching the U.S. market and Trump’s decision closely, weighing a lot of scenarios.

“The United States will continue to be one of the major PV markets in the world, and we are fully committed to the U.S. PV market,” the company told us. “With PV system cost continuing to drop, more and more states will reach grid parity. We are actively assessing the trade case and keep all options open to serve the U.S. market.”

Some numbers for context:

  • For the last 17 years, LONGi has been in mono products development, committing about 5 to 7 percent of its annual revenue to R&D on high-efficiency mono c-Si ingot, wafer, cell and module technology.
  • LONGi is the largest supplier of mono-crystalline silicon wafers in the world with more than $2.7 billion in total assets in 2016.
  • LONGi Solar shipped more than 3 GW mono modules by 2016, and will ship approximately over 4.5 GW high efficiency mono modules in 2017.

Focus on PERC

The main area of focus for LONGi is its PERC cell development. In this year’s DNV-GL module extended reliability scorecard, both of its conventional mono and mono PERC modules were among “top performers” for all testing categories — the latter of which has been a big focus since releasing its PERC module, Hi-MO 1, in 2016.

“We are seeing more and more customers realizing the benefit of mono PERC modules,” the LONGi team told Solar Builder. “Just two years ago, PERC cell capacity accounted for about 5 GW of the market. But the drive for higher efficiencies in the world’s largest solar market, China, has turned the tables.”

Mono PERC modules bring a new economic advantage to the solar market. Due to the higher conversion efficiency associated with mono PERC technology, solar developers can use fewer modules and less equipment to achieve a desired energy output for a project. This, in turn, saves money due to lower area-dependent balance-of-system costs for items including racking and mounting hardware, cabling and wiring as well as mechanical and electrical installation. PERC cell capacity is expected to reach about 35 GW in 2017, or roughly one-third of all PV module production, according to GTM Research.

Bifacial upgrade

Last year, LONGi Solar upgraded Hi-MO 1 to Hi-MO 2, capturing the best features of LONGi’s Hi-MO 1 technology platform — low-degradation, high-power PERC technology — and combining them with bifacial technology. In mass production, the efficiency of the front side exceeds 21.2 percent. Light reception of the backside can bring significant additional energy yield. If the backside power yield increases the overall module efficiency by 10 percent, the power of bifacial PERC module can reach 330 watts for a 60-cell module (300 watts from the front side), and 396 watts for 72-cell module (360 watts from the front side). Combined with low degradation mono PERC technology, Hi-MO 2 offers first-year degradation below 2 percent, and the average annual degradation below 0.45 percent for 30 years — significantly better than conventional modules.

Meanwhile, the bifacial PERC modules come with double-glass lamination, which improves PID resistance and can extend the module life beyond 30 years.

Bifaciality isn’t a new idea, but LONGi’s version is setting records: The National Center of Supervision and Inspection on Solar Photovoltaic Products Quality (CPVT) issued an independent test report showing that LONGi Solar’s bifacial PERC monocrystalline cells achieved a world record bifaciality of 82.15 percent. For comparison’s sake, the bifaciality of bifacial PERC cells in the market is about 75 percent.

“Bifacial mono PERC inherits all of the advantages of mono PERC, including high power and higher energy yield,” the company says. “In addition, it can harvest energy from the rear side of the module, making system economics even better and delivering significantly lower LCOE. Right now, we are in the product introduction phase and have already seen strong interest from customers. If bifacial PERC modules can consistently demonstrate significant rear side gain (10 to 15 percent or even higher), the market will react quickly and favorably.”

LONGi Solar thinks its high efficiency mono PERC modules would be a fit for EPC contractors and developers in all different applications, including utility, C&I and residential rooftops.

“In particular, the system cost savings with high efficiency mono PERC modules could be much more significant on C&I and residential rooftop projects,” the company says.

More broadly, it sounds like there is an even lower LCOE to be achieved through continued PERC development.

“In the near future, we think mono PERC (including bifacial mono PERC) will be the best solution to deliver lower LCOE,” the company says. “Current HVM production PERC cell efficiency is 21.5 percent. We have demonstrated well over 23 percent for mono PERC cell efficiency on our R&D line, and further improvements will likely continue. In parallel, we are working on a few technologies on the module side: multi-busbar, half-cut cells, as well as shingling process. With these advancements, we think 400 watts can be achieved on 72-cell format in the next couple of years.”

 

— Solar Builder magazine

Rapid Shutdown and Beyond: Inside NEC 2017 and the effort to streamline PV design

collaboration illustration

New codes and regulations are notorious for raising prices and halting innovation in industries, but the new rapid shutdown requirements facing the solar industry are having the opposite effect. Thanks to a coalition of manufacturers and interested parties across solar, the solutions being developed to meet NEC 2017 Module Level Rapid Shutdown requirements will achieve something solar technology has long needed: common language.

“The intent is to create an open protocol for any manufacturer to apply,” says Michael Mendik, head of solution management, Solar Energy Division at Fronius USA. He has been an active member of the SunSpec Alliance, the group that has developed these standards. “Inverter manufacturers can build and design their own transmitters and then the rapid shutdown boxes will also be tuned to that language and can receive the signal. There is no proprietary stuff.”

“The current systems were designed to meet the previous rapid shutdown requirements using mostly proprietary communication systems,” says Mario Thomas, product manager at ABB. “Future system design will be vendor independent, allowing a better choice for the customer and the installer.”

“The solar industry is experiencing significant growth with new requirements, so we welcome the vendor coordination efforts and the wide adoption by many vendors working to improve the safety of clean energy production,” says Danny Eizips, VP of engineering at Tigo. “This is a great opportunity for multivendor support.”

This standard protocol has ramifications beyond the context of rapid shutdown, but let’s start there.

NEC 2017 changes

The 2017 edition of the National Electrical Code (NEC 2017) includes an update to section 690.12 Rapid Shutdown of PV Systems on Buildings. The update pushes the requirement to “module-level” rapid shutdown instead of the “array level” that was listed in NEC 2014. Effective Jan. 1, 2019, this requires conductors inside the array boundary to be discharged to 80 volts or less within 30 seconds of initiating a rapid shutdown event. This requirement comes in addition to the outside the array boundary voltage being limited to 30 volts or less.

At first glance, the changes didn’t require such a collaborative effort. Module-level electronics could have done the trick and piecemeal proprietary products and one-off collaborations from various manufacturers could have continued as usual. Luckily, that wasn’t the case.

The SunSpec solution

Formed in 2009, the SunSpec Alliance is a trade alliance of more than 100 solar and storage distributed energy industry participants, together pursuing information standards to enable plug-and-play system interoperability.

After nearly two years of intense technical collaboration, the Communication Signal for Rapid Shutdown Interoperability Specification was published in September 2017 as a method to comply with NEC 2017. This spec defines a communication protocol that uses the cabling of the solar array to transmit messages over the DC power lines between the PV modules and a master control device located near the inverter.

In addition, PV module manufacturers can implement the protocol on intelligent devices embedded in the junction box of each PV module. A master control device associated with the inverter communicates with the PV modules. Altogether, the specification enables plug-and-play interoperability and any-to-any rapid shutdown solutions.

“This open standard delivers multiple benefits to the distributed energy industry, most notably lower integration costs and the freedom to choose from an array of interoperable products,” saysTom Tansy, chairman of the SunSpec Alliance.

What’s this mean for me right now?

  1. If you are a big fan of installing microinverters, you’re already meeting these rapid shutdown requirements.
  2. As mentioned earlier, the implementation date for NEC 2017 is Jan. 1, 2019. Depending on the Authority Having Jurisdiction where you do business, you may not even be held to the NEC 2014 requirement right now, let alone NEC 2017 when it arrives. The Northeast portion of the country will be the earliest adopters, followed by California.
  3. If you are going to be held to NEC 2017 — or just generally would like to comply on your own — sit back and wait for these SunSpec-certified products to hit the market and design systems the way you always have.

“The complexity here is not on the installer end,” Mendik says. Manufacturers had to develop a transmitter that’s hooked to the DC line and puts in the signal.

Some of these solutions are already available, like the Fronius Symo. Other companies announcing immediate plans to incorporate the technology into their product lines include ABB, Maxim Integrated, Omron, Outback, SMA and Tigo. You can expect to see most of these around Q2 this year. There is no UL testing protocol yet to certify these products, but UL is part of the SunSpec Alliance, and you can expect this to happen soon.

Why else is this a big deal?

Not to be flippant about the importance of safety, but this protocol opens the door for way more impactful product developments. There’s an opportunity here to make your life even easier and bring the costs of a system down even more.

1. Proprietary boundaries will come down.

For starters, the array-to-rapid-shutdown-box-to-inverter architecture is more flexible. Prior to any updates, you had to procure the rapid shutdown box and the inverter from the same manufacturer. No more.

“The installer can install the systems as before and doesn’t have to worry about matching inverters of rapid shutdown boxes,” Mendik says.
So, that’s cool, but that flexibility goes way beyond the rapid shutdown, inverter pairing. “There’s no specific [module-level electronics] on the roof,” Mendik continues. “If there are different panels, they will be working with different rapid shutdown boxes. If one type of inverter in a system breaks, it can be replaced with another, and it will still work. A distributor can have different inverter types in stock for replacement, and everything will still be in line with the protocol.”

2. System designs will be streamlined.

Today, that rapid shutdown box is just an added expense, even now, after the protocol. This is why many installers prefer module-level electronics like microinverters, which meet rapid shutdown module-level requirements while also adding optimization, monitoring and design flexibility.

In the not-too-distant future though, this rapid shutdown box will be gone completely, even in a string inverter design. Soon, using this common language, module manufacturers will be including supped up junction boxes or chips from a company like Maxim instead of diodes. These will meet NEC 2017 and provide MLE performance with a string inverter design. This will keep costs and industry part counts down.

“An integrated module in the future, where the installer doesn’t have to buy and wire a specific rapid shutdown box … it’ll be like going back in time to when he didn’t have to worry about that,” Mendik says. “This also means you won’t have complex electronics on the roof. The standard forces you into more complexity for rapid shutdown, but the solution we’re looking at is simple electronics, not power electronics and doesn’t convert power from DC to AC.”

Thomas sums it up: “The customer in the end has a choice. I think that’s a big benefit. Customers don’t want to get stuck with one vendor and want the right to choose between different manufacturers. Having this choice and competition will reduce costs in the end.”

— Solar Builder magazine

This is Certifiable: Ecolibrium Solar walks us through the UL 2703 testing process

ecolibrium solar

Look at all of these. Installers often change modules based on availability, so being able to test in-house is a big time savings.

Simplification is one of the key objectives of the solar industry, but the path to get there, ironically, is super detailed. Removing components to simplify a racking system, being compatible (and compliant) with a broad range of suppliers and just generally re-thinking what’s already been established is a deliberate and labor-intensive trial-and-error process.

The Ecolibrium Solar office in Boulder, Colo., is a monument to the relentless process of simplification, and maybe it’s just the immediate proximity of craft breweries and, um, agricultural entrepreneurs, but the Ecolibrium team seems cool with it. On its face, there is nothing remarkable to see here, just a standard office tucked in the back of an office park, (save all of the tables and cornhole boards made of PV), but located in the warehouse is its product development and testing facility that is a certified partner lab of TÜV Rheinland Group. This partnership is a boon for simplification. Ecolibrium is able to test and certify modules for UL 2703 compliance in seven days and make a priority of the modules that need immediate certification. Without in-house testing, a company must wait until a lab can test the module, which can take up to several weeks or more.

“It’s a big deal and enables us to be very responsive to our customers’ needs,” says Chris Berg, engineering manager. “Installers often change modules based on availability. Being able to test quickly means we can certify modules as needed. Our UL 2703 listings enable customers and plan reviewers to see if the module specified is approved with our products.” In just the last six or seven months alone, Ecolibrium added around 109 modules to its UL 2703 certification listings.

This is what I’m talking about: Being a certified lab for TÜV Rheinland and testing UL compliance is so much work. To maintain the partnership, Ecolibrium must submit reports that prove its testing tools are calibrated properly. These calibration certificates require cross checking and validation of every tool used — covering everything from torque wrenches to tape measures. Yes, even the tape measures must be independently measured to assure validity of results. I’m exhausted just writing about it. Let’s turn this into a series of pictures to make it simpler for an editor like me.

load test

Load Test: The Ecolibrium lab tests modules to this minimum and beyond — for 30 minutes each — checking for any amount of deformation or slippage. They do this with hundreds of pounds of sandbags, depending on target loads, taking photos of each component before and after each test.

Temperature Test

Temperature Test: There is a temperature test that sends the module through several hundred cycles of extreme temperature changes to see if drastic humidity, cold and heat and constant expansion and contraction will affect the bonding.

Grounding and Bonding Test

Grounding and Bonding Test: The electrical part of the grounding and bonding test had the promise of sparks and excitement — sending 5,000 amps into the panel and blowing a fuse to test the resistance between the clamp and the frame in the event of a worst case electrical fault — but the test is still mostly a checklist to prove the accuracy of the testing conditions and the safety of the testers. A panel must pass this twice in a row.

Got all that? In addition to UL testing, Ecolibrium employs an in-house machinist to streamline the development of new prototypes for its racking product portfolio. Once a prototype is ready, it is handed to Jonah Coles, product solutions manager, who was an installer for seven years before joining Ecolibrium, to test from the installer point of view. Again, the trial and error R&D process is labor intensive, but keeping it all in house truncates the timeline from idea to implementation.

“From a prototyping standpoint, we can move from idea generation, to prototype, to optimizing the design, to a finished product much faster,” Coles explains. “Since we’re focused on continual innovations that simplify and improve racking, the ability to machine and test in house makes a huge difference.”

The latest creation to emerge from this laboratory is the EcoFoot5D High Density Ballasted solution that decreases tilt from 10 degrees to 5 degrees and cuts inner row spacing in half, boosting power density on a roof by 18.4 percent, which is a big industry trend these days. Other simplifications nearing completion are reducing the skirt SKUs for EcoX Rail-less from four to two, while increasing the number of module frame thicknesses that are compatible.


Solar Builder Buzz: Rail-less installation

For a solar installer, a new system, however simple, is just another thing to learn. The old “don’t fix what ain’t broke” principle. But Jonah Coles, product solutions manager for Ecolibrium, believes once installers overcome the learning curve for rail-less installation, they won’t go back to using railed systems. That was just one point of discussion with Coles and Chris Berg, engineering manager at Ecolibrium, during episode three of our Solar Builder Buzz podcast. Head to www.blubrry.com/solar_builder_buzz to listen and subscribe.

— Solar Builder magazine

Ask a Distributor: We ask distributors for their purchasing advice, products to watch in 2018

solar distributors

Solar is now the No. 1 new source of capacity being added to the grid, according to the U.S. Energy Information Administration, and solar installer is the fastest growing job in the country according to the Bureau of Labor Statistics. And what’s the reason for the rise of this new era? The impending doom of the ice caps melting? Hardly. The advancements in technology? Getting warmer.

Really, things just got cheaper.

This is to say that purchasing plays a large, perhaps outsized, role in the value proposition of the industry and your business. Given that reality, we wanted to kick off the year by polling a handful of solar distributors for their purchasing advice.

You’ll be hearing from:

purchasing

Here’s the No. 1 way to avoid purchasing problems

What are the common problems distributors see when it comes to purchasing systems to install? There are a few quick, solvable issues — stuff like reviewing the details of an order before signing off on it or avoiding last minute purchases.

“Plan ahead and inspect shipments to avoid/mitigate mix ups and ensure fast and timely solutions when needed,” McShea says. “Waiting three weeks until install to say something is missing and you need it now is not effective.”

But all of that feeds into the advice that resonated with us the most: Seeing the distributor relationship as a two-way street that adds value to your business. According to the distributors we talked to, the more often you communicate, the more the distributor knows about your business, the easier it is for them to help.

“Valuing price over loyalty and the quality of the relationship with a distributor, I think, is a mistake,” Schoder from Civic notes.

A simple step up in communication will not only solve a bunch of issues but could create additional value for your business.

“Good communication and transparency are always the best remedies for doing good business and mitigating potential errors,” Dufrenne says. “Everyone is busy and going to make mistakes, including distributors and shipping companies. When all parties pay attention to detail and plan accordingly, deliveries and installations seem to go more smoothly.”

And it’s not just an exercise in mistake avoidance. Keeping everyone on the same page, forecast-wise, can only make the ordering process smoother for everyone.

“At least one call a week to plan upcoming jobs would help avoid supply chain issues,” Kyler says. This ensures all orders and forecasting align with expectations.

There’s also the training aspect. “Manufacturers are constantly offering training, quite often through their distributors,” Bailey notes. “Yet we still see many installers deal with headaches for hours which they could have learned to avoid by going through some quick training on the product features and installation.”

Think about kits

Ordering from multiple suppliers for a given residential job can leave more room for error, such as damage during shipping, incorrect parts arriving or a delayed delivery, all of which lengthens install time and increases costs.

“The best solution I’ve seen yet for lowering soft costs is to have one to two standardized kits which the sales team and installation crew are both very familiar with,” says Leone with Civic. “This mitigates both sales and labor costs. We recommend having multiple kits to protect against upstream challenges such as availability.”

“Ordering from one supplier and having the experts kit the equipment per job before shipping to the jobsite or warehouse can reduce most mistakes that cause delays and additional labor/mobilization costs,” Dufrenne says.

Sticking with brands also avoids the hassle of resubmitting permits with different equipment types or brands.

4 soft cost reduction tips

Schoder: “Utilizing online software programs like Helioscope and Energy Toolbase to drastically reduce the amount of time and effort that goes into a respectable customer proposal.”

Bailey: “Smaller installers like to use microinverters for [lowering soft costs]. In many cases they don’t have the in-house expertise to properly design a string inverter system which can maximize production. Microinverters are flexible, and the installers can design in the field by adding modules as they see fit.”

Dufrenne: “Good operations management [from lead generation to final completion]. Use software, like ENACT.”

Kyler: “Installers should keep at least one administrator dedicated to handling all incoming and outgoing paperwork such as permits, SREC registrations and contracts. This would help reduce soft costs and avoid any confusion or dilemmas later on.”

Truck these rolls

For starters, it helps to have a mini-inventory of small accessories (L-feet, clamps, wire), but stocking extra parts for the rest of the system is always a good idea.

“A common purchasing mistake I see installers make is purchasing just enough for their project instead of calculating for inevitable adjustments when they get on the roof,” Kyler says. “Mostly when it comes to racking, I recommend keeping spare parts in each truck.”
Dufrenne laid it out like this: “Not ordering extra parts for racking and attachments ends up costing much more than you’d think, once you have to roll another truck and pay for overnight shipping charges for parts that are usually less than $10.”

When it comes to the inverter (and we will get into this more on page 28) MLPE or string inverters could each offer a route to reduced truck rolls, if handled correctly. But for now, we just note what Kyler recommends: “Select products that allow remote updates or choose manufacturers that provide service programs.”

“Carry spare parts and get your system up and communicating with your gateway and online account before leaving the site,” Bailey says. “Installers who use gateways can track performance as soon as the system lights up. They can coordinate with technical support and determine within a few minutes that all modules and inverters are performing to spec.”

Head to page 2 for advice on system purchasing

— Solar Builder magazine