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

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

Recommending a battery to a customer in a solar + storage project 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. We dove into choosing among all of those options in this article. Now, here’s a roundup of four of the top solutions on the market.

1. SimpliPhi


The SimpliPhi High-Output Battery, launched to the market in 2015, was designed to address the Marine Corps requirements for a high-output battery that could provide a sustained peak power output of 10 to 15 minutes without any risk of overheating, thermal runaway, fire or shutting down, as well as longer duration base power delivery over 20 or more hours. The battery architecture creates minimal electrical impedance, so SimpliPhi’s batteries do not have a thermal profile that requires temperature management or cooling and have never suffered dangerous thermal runaway or fires. This design allows for one unit to provide both peak and long duration power, while also being modular, scaleable, non-toxic and safe.

2. Crown Battery


Eco-friendly Crown1 batteries are optimized for renewable energy and the widest array of configuration options. According to the U.S. EPA, Crown1 batteries are 99 percent recyclable — more recyclable than an aluminum can or any other battery technology. Crown1 combines robotic assembly in Fremont, Ohio, with the industry’s heaviest plates and most active materials to enhance performance and lifespan. Proprietary Cast-On-Strap systems are 100x more precise than manual welding, for greater reliability and longevity. Automated testing and vision systems maximize precision, power and uniformity. Crown1 features 6-, 8- and 12-volt models with 33-390 Ah (20-hour rating) capacities.

3. U.S. Battery

US batter

U.S. Battery RE Series deep cycle batteries use the company’s exclusive XC2 formulation and Diamond Plate Technology to create highly efficient battery plates to deliver greater watt-hours per liter and watt-hours per kilogram than other flooded lead-acid battery in the market. In addition, U.S. Battery RE Series batteries reduce mossing and sulfation conditions by incorporating the company’s Defender moss shields and Outside Positive plate battery design. Defender moss shields are effective in preventing mossing shorts caused when positive active material particles dislodge from the battery plates and collect under the plate connectors. Also, unlike chemical carbon additives that are intended for use in AGM batteries, the Outside Positive (OSP) battery design mitigates the effects of positive and negative plate sulfation and further increases battery life, overall capacity and stable performance.

4. Trojan Battery

trojan battery

The Trojan Battery Solar product line features both true deep-cycle AGM and flooded batteries which are specifically designed for solar and other renewable energy applications. Trojan Solar AGM features a non-spillable, maintenance-free design which enables installers to customize the use and position of the batteries in various applications. Trojan’s Flooded Solar batteries leverage its 90 years of deep-cycle flooded technology expertise and are engineered to provide the best cycling in the industry. Both solar flooded and AGM batteries are manufactured in the U.S., and Solar AGM is certified for non-hazardous shipping per U.S. DOT/IATA regulations and tested to an eight-year design life under the IEC 61427 standard for solar batteries.

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

— Solar Builder magazine

Distributor PROINSO adds Trojan batteries to microgrid solutions


PROINSO, a global distributor, integrator and technology company in the solar market, has supplied over 2.7 GW of projects and has operations in over 20 countries across 6 continents. The company says is adding the full range of Trojan batteries to its micro-grid and mini-grid solutions.

Trojan’s new solar deep-cycle AGM batteries are an area of particular focus. These non-spillable, maintenance-free batteries are engineered for best value in solar and storage applications. All Trojan batteries are produced at its U.S. manufacturing plants, which employ the latest technology, testing and quality control standards in the industry.

“Expanding Trojan’s distribution network with the addition of PROINSO enables us to readily meet customer demands in the region for deep-cycle batteries to power a variety of renewable energy applications,” said Michael Grundke, General Manager for EMEA for Trojan Battery. “PROINSO also will provide the high level of service our customers have come to expect from Trojan Battery.”

Solect Energy launches commercial energy storage division

PROINSO has both the experience and a proven track record with back-up power supply, diesel hybrid and off-grid systems, working with components such SMA Sunny Island and SMA Diesel Hybrid. PROINSO aims to increase its position as a leading provider of mini-grid and micro-grid solutions, which was formally recognised with the 2016 Solar+ Power Rural Electrification Award for its off-grid project in Kepulauan Riau, Indonesia.

According to Pablo Gonzalez of PROINSO: “PROINSO is committed to working with products which offer the highest return on investment over a project’s life cycle. Through our well established global operations, logistics and engineering expertise we have excellent growth in this sector. Now, by adding Trojan Batteries we are able to offer a one-stop-shop complete solution for mini-grid and micro-grid projects.”

Later this year PROINSO will launch its tracker-based micro-grid, using its TURNSOLE Powered by OMRON solution.

— Solar Builder magazine

Enersys offers new line of thermally managed outdoor battery bank enclosures

Valutflex enersys

EnerSys offers a complete line of modular, thermally managed VaultFlex outdoor enclosures for telecommunication, cable, Uninterruptible Power Supply (UPS) and utility applications. VaultFlex outdoor enclosures provide a selection of heating and cooling options designed to maintain the proper operating temperature for backup battery systems in the most extreme environments. Designed to provide protection from weather and other outdoor conditions, VaultFlex outdoor enclosures help contribute to extended life, reduced maintenance and less frequent replacement of batteries.

VaultFlex outdoor enclosures also include passive ventilation that mitigates hydrogen gas, and are constructed to protect the battery backup system from earthquakes. VaultFlex outdoor enclosures also feature security and intrusion prevention measures including concealed interior door hinges, multi-point captive latching mechanisms and door intrusion alarms that can send a distress signal out in the case of unauthorized or unscheduled entry.

— Solar Builder magazine

On the Scene: We went to the Eaton Experience Center to see the grid’s future

Eaton Xperience center

Eaton is one of those companies that does everything without you realizing it, with innovations for industries as diverse as aviation, data centers, food and beverage, rail and, of course, utilities, just to name a few. The company recently expanded its Experience Center in Pittsburgh to show the latest advances in electrical power quality, energy management and safety in a real-world, hands-on setting for interested customers, electrical contractors, consultants and builders in need of training.

In other words, it is a playground for engineers. Everything around the building, except maybe the coffee maker, is labeled, which isn’t just useful for novices like me.

eaton experience center“We’ve had engineers come in here and we’ve asked them to identify a transformer, and they couldn’t do it. They could easily point to the symbol on a design, but they don’t always see them in real life,” noted Dan Carnovale, Power Systems Experience Center manager for Eaton, which again shows the practicality and importance of the Experience Center.

The Solar Builder team stopped by to take it all in, and believe me, it was a lot to take in. Full disclosure: I was showed a lot of stuff and took a lot of notes as fast as I could. That notepad contains in-depth info on super capacitors that aid in solar smoothing, substation vs. pad-mounted transformers, balancing voltage regulation on a larger scale, aggregating string inverters in larger applications and more. The formula for cold fusion might be in there somewhere, but we will never know because they are illegible and incoherent. But that’s OK because the Experience Center isn’t about relaying those details, it’s about the experience, duh.

chris crowell at eatonExperiencing the Experience

The facility includes a functioning microgrid demonstration. There is a 24-kW solar canopy in the parking lot, 86 panels on the roof, 30 kWh in battery storage and a 100-kW generator, all of which are controlled by Eaton’s Power Xpert Energy Optimizer controller. The intersection of all those assets and optimizing their usage is at the core of advancing energy resiliency, so that Eaton’s Experience Center can operate even when the local utility grid may be impacted by an outage.

The standout display plays out two fault scenarios on a small grid that involves three local controllers and one master controller: You enter into an artificial neighborhood, complete with fake squirrels in fake trees. Suddenly, the room gets dark, a thunder rumble is heard and lightning strikes a tree that topples into an electric pole.

Scenario one plays out with no automation. The fault is triggered and the recloser fires and keeps closing, but power won’t be restored until a truck is rolled. Scenario two plays out with automation and is able to isolate the fault and restore power to the critical loads on the microgrid downstream.

Trust me, it was cool.

Animatronic show aside, it feels like we are looking at the future of the grid, not just in terms of the technology, but the mindset needed for deploying and managing distributed energy resources in ways that are much more efficient and economical than how things are done today.

— Solar Builder magazine