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

Puerto Rico recovery: This solar + storage microgrid helps power off-grid school hurt by hurricane

A solar + battery storage microgrid at S.U. Matrullas, a K through 9 school that educates over 150 students in the remote town of Orocovis, Puerto Rico was commissioned via collaboration with Pura Energía and energy storage provider sonnen. This project serves as a model for the resiliency created by solar + storage technologies, as it represents a fully off-grid site deep in the mountains of Puerto Rico.

sonnen solar storage puerto rico

The school has been completely off-grid since Hurricane Maria and is not expected to have power for many months to come. sonnen has donated two smart energy storage systems, an eco 8 (4kW / 8kWh) and eco 14 (8kW / 14kWh), to be paired with a 15-kW rooftop solar system provided by Pura Energía. The microgrid will provide enough energy to keep the school open, enabling the facility to use clean and renewable energy to keep classes going instead of relying on a noisy, gas fueled generator. During sonnen’s most recent visit to the site in February, students were using the sonnen system to charge their laptops for an upcoming technology lesson.

Orocovis is known for its breathtaking beauty and is one of the highest peaks in Puerto Rico, with the ocean visible on both the north and south shores of the island. However, the remote area is difficult to reach due to road and bridge wash-outs along the single-lane road that winds throughout the mountains. With the installation of the microgrid, S.U. Matrullas currently does not plan to reconnect with the Puerto Rico Electric Power Authority (PREPA), even once power is restored to the area. Further, the school will soon be off-water, as Por Los Nuestros – an organization with ties to local TV star Jay Fonseca as well as Manuel Cidre and others in the private sector – has helped facilitate recovery efforts and plans to donate a water collection and filtration system to bring the school to 100% sustainability.

Case study: Prepping solar tracker systems in advance of a hurricane

S.U. Matrullas is the site of the ninth and tenth microgrid systems that sonnen and Pura Energía have installed on the island since Hurricane Maria struck in September 2017. Other microgrids have included community and relief centers, washing machines and laundromats, food distribution centers and a school for behaviorally challenged children in Aguadilla. All efforts and technology were donated by sonnen and Pura Energía via the del Sol Foundation for Energy Security, thus far exceeding $350,000.

“We have witnessed first-hand not only a collaborative humanitarian effort that has aided critical recovery efforts in Puerto Rico, but one that has fostered forward-thinking strategies leveraging an integrated renewable energy capable of providing power to a large group of people,” said Adam Gentner, sonnen’s Director of Business Development, Latin American Expansion. “These microgrids effectively form the blueprint for more than just recovery, but for preparation for islands and regions around the world that are susceptible to natural disasters and power outages. As sonnen continues its global expansion, we will maintain our focus on bringing clean and affordable energy to all.”

— Solar Builder magazine

Florida Power and Light debuts solar-plus-storage strategy at a major power plant

Florida Power & Light Co. unveiled a new solar-plus-storage system last week that they say will be the first in the country to fully integrate battery technology with a major solar power plant in a way that increases the plant’s overall energy output. By incorporating this new technology into the FPL Citrus Solar Energy Center, a solar power plant that was built in 2016, FPL expects to increase the amount of solar energy that the plant can deliver to the electric grid by more than half a million kilowatt-hours a year.

Florida Power Light Wildflower Commissioning Battery Storage

DeSoto County Commission Chairman Jim Selph (left), Florida Power & Light Company (FPL) President and CEO Eric Silagy and DeSoto County Commissioner Terry Hill discuss the company’s new battery storage technology at the FPL Citrus Solar Energy Center in DeSoto County, Fla., Feb. 9, 2018. During the commissioning of the company’s third and newest solar power plant in DeSoto County – FPL Wildflower Solar Energy Center – the company unveiled what is believed to be the country’s first-of-its-kind solar-plus-battery storage system that increases the amount of energy a solar plant delivers to the grid. Photo credit: Alex Menendez for FPL. (PRNewsfoto/Florida Power & Light Company)

The new system features a 4,000-kilowatt/16,000-kilowatt-hour storage capacity comprised of multiple batteries integrated into the operations of the FPL Citrus Solar Energy Center. In addition to enabling the plant to provide more solar energy to the grid, the battery system is capable of storing the energy and dispatching it to the grid at a later time.

This technology has the potential to harness millions of kilowatt-hours of solar energy a year that would normally be lost and improve the predictability of solar energy, which naturally fluctuates with the sun’s availability. Increased predictability enables FPL to more efficiently dispatch other power plants, helping save customers on fuel costs.

How the new system works

The new solar-plus-storage system unveiled today is the first large-scale application of “DC-coupled” batteries at a solar power plant in the U.S.  An advantage of DC-coupled batteries is the ability to harness extra energy that a solar plant generates when the sun’s rays are the strongest.

During these optimal operating periods, a solar plant may generate more power than its inverters can process, resulting in some energy inevitably being lost – or “clipped” by the inverter. Unlike other batteries, a DC-coupled system can capture this extra clipped energy, thereby increasing the amount of energy the plant delivers to the grid.

The additional solar energy and the increased predictability afforded by battery storage can enable FPL to more efficiently dispatch other power plants, helping save customers on fuel costs.

For several years, FPL and other NextEra Energy companies have been researching and testing battery-storage technologies to study a variety of potential benefits ranging from grid stabilization to improved solar integration. Currently, NextEra Energy companies operate approximately 130 megawatts of batteries with more than 100 megawatt-hours of storage capacity.

RELATED: Why mass customization works in utility scale solar solutions 

FPL’s solar plans

FPL is in the midst of one of the largest solar expansions ever in the eastern U.S. with more than 520 megawatts – 3.5 million new solar panels – added in the last two years alone and nearly 300 megawatts more scheduled to enter service by March 1. From 2016 to 2023, FPL expects to install a total of more than 10 million solar panels. These advancements continue to improve FPL’s carbon emissions profile, which is already approximately 30 percent cleaner than the U.S. industry average.

Moreover, FPL’s eight newest solar plants combined are projected to generate more than $100 million in net savings, over and above the cost of construction, for FPL customers. Investments like these help FPL keep rates low for customers over the long term. Today, FPL’s typical 1,000-kWh residential customer bill is lower than it was more than 10 years ago and approximately 25 percent lower than the latest U.S. average. (FPL rates are decreasing again on March 1.)

FPL is the largest generator of solar energy in Florida with 10 major solar power plants and numerous other universal solar installations, totaling more than 635 megawatts of capacity, including:

  • FPL Horizon Solar Energy Center, Alachua and Putnam counties
  • FPL Coral Farms Solar Energy Center, Putnam County
  • FPL Indian River Solar Energy Center, Indian River County
  • FPL Wildflower Solar Energy Center, Desoto County
  • FPL Babcock Ranch Solar Energy Center, Charlotte County
  • FPL Citrus Solar Energy Center, DeSoto County
  • FPL Manatee Solar Energy Center, Manatee County
  • FPL Martin Next Generation Clean Energy Center (hybrid solar/natural gas), Martin County
  • FPL DeSoto Next Generation Solar Energy Center, DeSoto County
  • FPL Space Coast Next Generation Solar Energy Center, Brevard County
  • FPL Solar Circuit at Daytona International Speedway, Volusia County
  • Solar research installation at Florida International University, Miami-Dade County
  • Numerous FPL SolarNow arrays in local communities

Also, four more new solar power plants are on track to enter service by March 1, 2018:

  • FPL Barefoot Bay Solar Energy Center, Brevard County
  • FPL Blue Cypress Solar Energy Center, Indian River County
  • FPL Hammock Solar Energy Center, Hendry County
  • FPL Loggerhead Solar Energy Center, St. Lucie County

— Solar Builder magazine

How JLM Energy’s Phazr microstorage system helps combat California utility rates

JLM Energy Phazr

California’s new utility rates undercut the value of rooftop solar. To help customers combat this dynamic, JLM Energy has deployed more than 2,000 Phazr MicroStorage units and is successfully managing residential time-of-use charges for customers in all three major utility territories from San Diego to the Oregon border. Time-of-use rates are designed to charge a premium for electricity during late afternoon and evening when the utility grid is stressed by heavy use.

Phazr is a distributed energy storage platform that uses the unique concept of ‘microstorage.’ It pairs a single solar panel with a battery pack in a one-on-one ratio. Its plug-and-play design eliminates the need for skilled installation, driving costs down. Phazr charges directly from the renewable energy generated by the solar panel so it completely qualifies for the Federal Investment Tax Credit.

Erin Clark, JLM Energy’s chief operating officer said, “By storing solar energy in batteries until the evening when it is needed most, homeowners can save money and create efficiencies. The combination of solar plus storage future-proofs the customers’ investment as tariff rates are changed by the utilities.”

New guide shows strategies for pairing community solar with storage

William Cotter of SunStor, a Solar installer in PG&E territory said, “JLM’s Phazr gives us a competitive advantage. It is a streamlined, adaptable and smart solution that provides solar customers with peace of mind, enhanced efficiency and guaranteed savings on their utility bill.”

Phazr uses JLM Energy’s patent-pending Symmetric DC Regulation, the only technology available that enables a solar panel to charge a battery and send power into the home simultaneously. Excess energy from the solar panel is stored in Phazr for use later in the day to achieve time-of-use shifting, or solar self-supply in the evening. Because Phazr only charges from solar, it qualifies for the 30 percent federal investment tax credit.

By taking this module-level approach, JLM’s Phazr is advancing DC coupled storage applications and spurring widespread adoption of storage. Phazr maximizes solar generation to provide the most optimized solution, ensuring the customer achieves the highest possible savings and a rapid return on investment.

— Solar Builder magazine

NEXTracker’s NX Drive storage solution selected for project in Ontario

Leclanché, an Ontario, Canada-based global integrator of energy storage, has selected NEXTracker to supply its NX Drive energy storage system (ESS) for battery solutions the company is installing at commercial and industrial businesses in Ontario, Canada. NX Drive is a standardized battery enclosure system for generation-plus-storage and stand-alone storage applications. In this installation, NX Drive ESS will be utilized as a stand-alone system, incorporating a storage inverter and entire ESS within the enclosure to help power several small businesses in metropolitan Toronto. Selected for its long-term value, intelligent design and quality components, each ESS unit has a capacity of approximately two MWh.

“NEXTracker’s NX Drive ESS technology exceeded our safety and aesthetic design requirements while reducing the required footprint,” said Thom Reddington, Leclanché Sr. VP North America. “They were able to design the solution to incorporate the entire PCS (power control system) which includes not just a battery in the container, but also a fully integrated inverter and entire ESS system.”

“By partnering with Leclanché on this innovative program, we can help commercial and industrial customers minimize their energy demand costs with our NX Drive ESS,” said Dan Shugar, NEXTracker CEO. “With the Canadian power supply relying more on renewable but intermittent power sources, NX Drive takes the pain out of these grid management challenges by providing an integrated and reliable storage system.”

NX Drive provides a flexible, pre-engineered balance-of-system (BOS) solution for virtually any generation-plus-storage or stand-alone storage application. NX Drive consists of a standard ISO form-factor enclosure with pre-engineered and integrated electrical, mechanical and thermal management safety features. Customers can also upgrade battery modules as technology evolves, and integrate photovoltaic and/or storage inverters, depending on design preference. Using advanced, patent-pending technologies to ensure safe operation and optimized performance, the NX Drive system infrastructure supports standard customer-supplied or NEXTracker-sourced Tier 1 lithium-ion batteries.

These Leclanché energy storage projects support the larger trend in Ontario towards clean, reliable energy generation and grid resiliency. In 2010, Ontario launched the Long-Term Energy Plan which has phased out coal-fired electricity generation and built a clean system that is more than 90% free of greenhouse gas emissions. Now the Energy Plan is focused on ensuring there is a robust supply of electricity to power homes and businesses across Ontario by increasing the renewable mix on the grid using energy storage applications.

— Solar Builder magazine