Context Clues: Know where to find the value when selling commercial solar solutions

magnifying glass

Land in any airport, and the view tells the story. Commercial buildings with fresh paint and no solar panels on them yet. Residential customers may commit to solar for a variety of personal and ethical reasons, but nonresidential property owners tend toward the pragmatic.

They make business decisions based on profits.

This historically lagging solar segment is starting to come around though. In the Q3 2017 U.S. Solar Market Insight report from GTM Research, which showed a 22 percent decline for the overall industry year over year, also showed that nonresidential solar grew 22 percent, installing 481 MW.

The business is out there. The installers who present solutions based on a clear understanding of nonresidential energy costs can build momentum in what may turn out to be the largest solar segment of all.

Utility tariff structures

Commercial and industrial customers have complex energy needs that go far beyond a simple “go / no-go” decision for a solar project. In particular, these customers pay much of their electricity bill in the form of demand charges. These charges can be quite complex, featuring “ratchets” and other calculations resulting in very high charges that can last for many months after a simple error in operations. In many utility service territories, demand charges comprise more than one-third of the customer’s electricity bill; in a few, it’s more than one-half.

In addition to rising demand charges, changes in time-of-use (TOU) rate structures in many states have customers scrambling for solutions. While there is no doubt that solar can deliver significant energy savings to a nonresidential customer, a traditional solar installation provides little or no reduction in demand charges for most accounts, nor any control over the time of day when energy is consumed.

A solar installation that delivers big energy savings may result in little or no demand savings. As shown in Figure 1, a single cloud at the wrong time on the wrong day can wipe out a month’s worth of savings. Without appropriate demand management technology, net load can “spike” to create a new monthly peak demand.

solar storage

Figure 1: Solar Plus Demand Management, Office Building, July 2015

Solar providers are increasingly finding that when they propose new projects to their nonresidential customers, these customers are more informed and sophisticated about their energy needs. Odds are good that a storage provider has already come calling to see if a battery system could help with TOU rates and demand charges, but batteries are still very expensive, and in states without significant subsidies, they often don’t pencil out on their own, either.

In our interviews with solar professionals this past summer, we were told over and over that because of changes in the market, “it’s time to get off the roof and come inside.” Until a solar provider has a more complete picture of a customer’s energy needs — their energy usage patterns and the business needs driving those patterns — that provider is competing at a disadvantage. In reality, any solar solution needs to be presented in the context of these usage patterns and needs.

From Tesla cars to Gigafactories, there is a lot of news about battery storage, and as battery costs continue dropping, some smart solar providers are exploring becoming solar-plus-storage providers. In some states with high incentives for batteries (and with some clever use of the Investment Tax Credit), this can be a good combination. In many cases, load flexibility is both more valuable and less expensive than batteries. Simple changes in operation (undetectable to building occupants in commercial buildings and easy to manage in many industrial facilities) can offset the variation in solar output and eliminate spikes that cause high demand charges, but only with the right tools. Such load flexibility can actually complement storage solutions. With the right analysis, taking advantage of flexible loads can help a customer to right-size energy storage subsystems for a more cost-effective total package. The solar triple play — solar plus storage plus load flexibility — can be a potent solution to a variety of customer energy challenges.

RELATED: Our Project of the Year for 2017 is a great example of finding value

Expanding the comfort zone

There are no serious technical impediments to delivering nonresidential solar solutions that bring both energy and demand charge savings. The trends are all in favor of such solutions:

  • Storage devices (both batteries and thermal storage) are declining in price quite rapidly; new announcements from both established and new storage vendors appear weekly.
  • Building and industrial controls are becoming more sophisticated and more standardized.
  • Sensors and data networks are increasingly affordable and more universally deployed.
  • Big data analytics are becoming more widespread, powerful and accessible.
  • Software solutions taking advantage of machine learning and advanced control algorithms will soon be widely available for application in real-world customer energy solutions.

As with many new major shifts, the technology outlook is bright, but the biggest change required is cultural. Solar providers with a high comfort level matching panels and inverters to customer roofs and electrical systems may face a steep learning curve when moving into the less-familiar world of building and industrial operations. Inside the facility, it’s a whole different world, but one that every complete customer energy solutions provider must understand.

The good news is that many of the initial fact-finding steps are the same as those required for solar installations everywhere. The customer billing data, load profile data and utility tariff information remain the foundation of any good proposed solution. Creating a complete energy solution, however, requires a more complete supplier ecosystem than most current solar providers can deliver alone.

Some of the most fruitful conversations we had last year at Intersolar and Solar Power International were about the development of that bigger ecosystem. Numerous battery vendors, many of whom originally came out of the market for small, off-grid applications, began to describe how their offerings could be adapted for commercial building applications in demand-charge reductions. Software startups, many of whom got their start from DOE SunShot awards, contributed ideas for better data visualization and control. And while control vendors have not even been present at past solar events, a few are starting to recognize the synergies between solar and load flexibility.

The future is promising for innovative solar providers who are willing to broaden their offerings and embrace a total energy solution approach for commercial and industrial customers. We invite feedback and conversation with any solar providers with insights into how the nonresidential market is changing, and how to strengthen the emerging ecosystem of nonresidential energy solution providers.

John T. Powers is founder and CEO of Extensible Energy. An energy economist with more than 30 years of experience in consulting and technology development for the electric utility industry, Powers has worked in energy efficiency, demand response and renewables for most of his career. He currently serves as project officer for the Community Solar Value Project, a DOE SunShot project helping utilities to develop better community solar programs.

— Solar Builder magazine

DC decisions: Large-scale PV wiring trends are leaving behind DC combiners, cables

inverter pad

Closer to the grid connection, interrupt ratings are higher, which is why SolarBOS recommends fuses instead of breakers.

All large-scale PV projects will involve a ton of modules and only one grid connection, so all of the aggregation decisions made in between comprise a big chunk of a profitable project pitch. We asked two major eBOS suppliers for the trends leading the way in large-scale PV wiring in 2018, and both of them point to huge reductions in traditional DC wiring and an emphasis on fuses.

Goodbye DC combiners

The most significant DC wiring trend for Jason Whitaker, president of Shoals, has been the migration away from the traditional combiner paradigm to harness assemblies, which is a big step toward simplification and reducing the amount of DC cable needed. The Big Lead Assembly (BLA) is a prime example.

“What previously had been the feeder cable, running from the inverter to the combiner, has now become the entire solution in itself: The BLA, a large conductor, tailored for each site, in which all the PV circuits are combined as they branch off from the BLA at the optimal electro-mechanical positions within the array,” he says. “This allows for a streamlined, plug-and-play installation.”

Pre-paralleling PV strings and incorporating in-line fuses can further reduce the amount of cabling needed.

“If the ILF [in-line fuse] saves more than 25 ft of PV cable, it has paid for itself,” Whitaker says. “ILFs can significantly reduce both the amount of cable required within a PV array and the number and/or size of combiners deployed.”

On a typical tracker installation with combiners and component harnesses (ILFs), a 39 percent reduction in DC string wiring can be expected. Then, factor in the BLA, and that number moves to about a 51 percent reduction. Note: Shoals also recently partnered with Array Technologies on a solution tailored to its tracker system, which improves those economics even more.

“Optimization of the electrical and mechanical systems together will result in a decreased installation time while simultaneously increasing system reliability,” Whitaker says.

All that, coupled with significant labor savings will result in the lowest installed cost solution. The BLA not only provides value from a CAPEX perspective, it also offers significant savings in OPEX when you consider the increased reliability and the elimination of components that require operations and maintenance (O&M).

Shoals’ Big Lead Assembly

Diagram of the streamlined design of Shoals’ Big Lead Assembly combined with in-line fuses.

Hello AC combiners

The philosophical shift in the industry from central inverters to string inverters in larger-scale applications has big implications for eBOS decisions. What was typically all DC aggregation is a big mix of DC and AC. Coel Schumacher, CTO of SolarBOS, sees this as a chance to install fused AC combiners and recombiners instead of breakers.

“Breakers are great for applications with variable loads — plugging too many devices into an outlet, a hair dryer in a bathroom. In a solar application there aren’t any variable loads or hair dryers, so if an overcurrent protective device [OCPD] trips, there is a real problem, and resetting the OCPD is the least of your concerns,” he says. “Breakers degrade with every use, so the more times they are used as a disconnect, the more likely they are to nuisance trip at some later time when they shouldn’t.”

Four trends leading ground-mounted solar in 2018 from IHS Markit

As you get closer to the grid connection, interrupt ratings are higher. Fuses offer higher interrupt ratings and are more cost effective at these higher ratings than breakers.

“When a fuse is replaced, it will operate as it did when the original was new. A breaker on the other hand, after being reset, may not,” Schumacher says. “Breakers can also be more difficult to replace when they do eventually fail.”

Remember that every connection in a design is a source of contact resistance which generates heat, so one way to reduce potential for failure is to reduce those contact points. An example: Some systems are designed to connect the output lug to the copper bus bar using neutral bars attached with fasteners. This would mean one or more connections than is necessary and relies on small fasteners. Instead, SolarBOS uses a distribution block that directly connects to the incoming string wires and the output lug.

“Similarly, our positive bus bar typically connects to the next component directly with a bolted connection rather than using additional busbars or unreliable clamps,” Schumacher says. “Not only do all of these connections perform better, but there are fewer of them, which reduces the number of connections that need to be checked in maintenance efforts.”

— Solar Builder magazine

PV Pointer: How to optimize PV system structural design for environmental hazards

snow-covered solar panels

According to a recent study by SolarPower Europe, new solar photovoltaic (PV) capacity installed worldwide in 2016 reached more than 76 gigawatts. This was largely due to dramatic growth led by the United States and China, with both countries almost doubling the amount of solar added from 2015. Globally there is now more than 305 GW of solar capacity, and with the increase of solar projects around the world, different climates, topography and other geographic considerations are making design for the environment increasingly important to ensure the integrity of the system over its lifetime.

PV plants are subject to a multitude of threats from the physical environment over the span of their lifetime. These threats must be taken into consideration during structural design in order to mitigate the risk to the system. With PV plants now being installed all over the world, the applicable risks will vary greatly depending on the geographic location. Therefore, the design of each plant must be thoroughly evaluated for its unique set of potential environmental hazards.

Environmental Loads

The first decision to make in determining the environmental loads on a plant is to identify the appropriate risk category for the plant. Building codes around the world use this categorization to determine the probability of occurrence of the design loads, or in other words, how extreme the design loads are. More critical solar project facilities can be designed for a higher risk category, and therefore, for loads with a lower probability of occurrence and a larger magnitude. For example, a rooftop system at a hospital that is required to remain operational after a design level event will be designed to higher loading conditions than a utility-scale facility behind a fence that is not supplying critical power to the grid.

Check out all of our PV Pointers here

Evaluating Different Types of Environmental Loads

When designing a PV plant, the environmental loads that usually first come to mind are wind and snow loads. However, certain architectures or geographical locations will necessitate consideration of seismic, ice or thermal loads as well.

Due to the large surface area and low weight of PV arrays, wind loads are often the most critical environmental forces. Consideration must be taken for both the potential wind magnitude at the site as well as surrounding topographic features that may amplify or weaken the wind as it approaches the PV plant. In many designs, wind tunnel test data is used to most accurately predict the resulting loads on a particular architecture. More accurate prediction of the wind loads allows for optimized structures that still meet the desired levels of performance and reliability.

Snow is another common critical design load on many PV plants. Rooftop and fixed-tilt ground-mounted systems are particularly vulnerable due to the relatively shallow slope of the modules. In addition to the snow’s weight on the tables, the designer must consider snow accumulation between tables, drifting and the potential need for an elevated system to allow for snow shedding. Tracker systems allow for some mitigation of the snow loads by tracking to maximum tilt to shed a large portion of the snow.

Seismic loads are less discussed in the solar industry, but they can be a significant concern in locations with high snow load and moderate to high seismic risk. Since the snow weight is considered part of the seismic mass, the resulting loads can be significant as snow accumulates (force = mass x acceleration). Many PV plants use wide flange post sections which have significantly lower strengths in one direction than the other. As earthquakes act in all directions, this is a vulnerability that needs to be expressly accounted for in design.

Ice, temperature and flooding are additional environmental risks that need to be examined for PV plants in some locations. Ice can add weight to a table and can be a concern for freezing up moving parts. Temperature becomes a concern with systems like trackers where there are long continuous members such as torque tubes. Thermal swings such as those found in desert climates can cause enough expansion or contraction of the steel along a row to result in non-trivial forces on the system. Finally, systems in floodplains must take the expected flood levels into account in the architecture and evaluate whether to design an elevated system.

Designing for these potential load effects helps to mitigate the risk to a PV plant from environmental hazards, thus increasing the overall reliability of the system throughout its lifetime and providing better value to the plant owner.

Lauren Busby Ahsler is a structural engineering manager at SunLink. She works on project engineering as well as tracker product development for SunLink.

— Solar Builder magazine

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


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