Energy storage installations for homes and businesses — involving battery technology — are on the rise in areas where extreme weather threatens the electric power grid, such as flood-prone Houston, wildfire-stricken California and hurricane-ravaged Puerto Rico.

Energy storage installations for homes and businesses — involving battery technology — are on the rise in areas where extreme weather threatens the electric power grid, such as flood-prone Houston, wildfire-stricken California and hurricane-ravaged Puerto Rico.

A sustained power outage can lead to serious consequences, such as loss of income and even death. Because of climate change, the frequency of these extreme weather events and outages will climb.

Traditionally, buildings would rely upon gas-powered diesel generators during outages. These generators have their own problems and do not necessarily help the electric grid become more resilient.

With recent technological changes, could batteries become the new generators?

Tracking sharp growth in the past year
Small-scale, so-called behind-the-meter energy storage accounted for 60% of battery capacity in the United States during the first quarter of this year.

Deployments grew 138% in the past year, driven in part by families and business leaders who are seeking resilience against power disruptions in our increasingly volatile climate.

When properly designed, electric energy storage can not only provide additional grid resilience, it can further minimize greenhouse gas and local air emissions compared with the conventional gas generators.

The EU’s latest Clean Energy Package (CEP) is “undoubtedly positive” for energy storage, with the technology expected to play a key role in meeting the legislation’s ambitious “32% by 2030” renewables target, Brittney Elzarei, senior policy officer at trade organisation EASE has said.

In an article for Volume 20 of PV Tech Power, the quarterly technical journal from our publisher Solar Media, Elzarei takes a close look at the CEP, noting that recognition by EU policymakers of the value of energy storage has greatly evolved in just the past decade since its third iteration in 2009.

“The CEP is undoubtedly positive for the storage sector. By establishing a binding renewables target of 32% by 2030 – along with targets for renewables in transport, heating and cooling – the package sets a high level of ambition that can only be achieved with the widespread deployment of flexibility solutions such as storage.”

Barriers still exist to the market, Elzarei argues, with so-called ‘double-charging’ – levying energy storage systems grid fees when both ‘consuming’ or ‘generating’ power from and to the grid – still in place and the lack of investment certainty that still exists when brokering contracts for services from energy storage, due to the limiting in duration of balancing services set out in the CEP.

Nonetheless, progress has been made, the EASE senior policy officer writes, taking a deep dive into the role of transmission network and distribution network operators, the scope for deploying non-battery energy storage technologies including hydrogen, and other topics. The article also takes a look further ahead to plans for full decarbonisation across the EU by 2050 and the Commission’s own analysis of the various different types and amounts of energy storage that will need to be deployed to meet 80% greenhouse gas (GHG) emissions reductions by that year.

Utility Ameren Missouri is planning three grid-scale solar facilities with energy storage, marking what is claimed will be the first ever instance of an energy company in the US Mid-West state powering its customers’ homes with batteries.

A release from the utility, a subsidiary of Ameren Corporation, said that it filed plans today with the Missouri Public Service Commission (MoPSC) for the building of three power plants, for which Ameren Missouri said it will invest around US$68 million.

The plants will be built in Green City, Richwoods and Uticah, dotted around the mostly-rural state, with each plant of 10MW solar PV capacity and an unspecified output and capacity of battery energy storage. Via Twitter, the company released a short publicity film which said the plan to build the solar capacity with batteries is an “innovative, cost-effective solution to help maintain reliable energy service in rural communities.”

“If an outage is detected, solar energy stored in batteries will help keep your lights on,” the video said.

The company just launched its first ever community solar facility mid-way through August, allowing customers to sign up to buy solar energy generated in 100kWh blocks at Ameren Missouri Lambert Community Solar Center. Meanwhile, it has also launched a Smart Energy Plan.

In addition to beefing up energy security with upgrades on transmission networks to cope with severe weather, the plan includes a reduction of carbon dioxide emissions by 80% from 2005 levels by 2050, with interim targets for 2030 (35%) and 2040 (50%).

The California Energy Commission (CEC) Oct. 30 will release two energy storage solicitations totaling $31 million to support the state’s goal under SB 100 of attaining 100% fossil-free electricity by 2045.

The commission wants to get the word out now because preparing energy storage projects and proposals can be time consuming, said Mike Gravely, CEC research program manager.

“We are doing this to bring new technologies that are cheaper and better performing to meet SB 100,” he said, adding that existing technology isn’t capable of meeting the requirements of the legislation.

Among the new technologies the commission focuses on are microgrids — and energy storage plays an important role in them, he said.

“Microgrids help integrate these clean technologies. These are the solutions we need to reverse the impacts of climate change.” Gravely noted that the focus on energy storage will help move microgrids along. All the microgrids that have received commission funding include energy storage.

Details on energy storage solicitations
Proposals for the energy storage projects will be due by the end of the year, and the commission will issue the awards between April and June, he said.

The first of the two energy storage solicitations is for $20 million and seeks technology demonstration projects in four categories.

“This is for projects that are maybe on the second generation of design,” said Gravely.

The solar power panel–level energy storage developer Yotta, based in Austin, Texas, has received $1.5 million in funding to continue work on SolarLEAF, the company’s energy storage solution. (Several hundred thousand dollars in grant money has also been obtained.) The funding will be used to continue with technological development and commercialization.

Additionally, the company hired former SunPower employee Phil Gilchrist to be the Director of Mechanical Design Engineering. Yotta’s CEO, Omeed Badkoobeh, answered some questions about the SolarLEAF technology for CleanTechnica.

What is the capacity of each panel-level energy storage unit, how much does a unit weight and what are the dimensions?

Each unit has 1kWh of capacity, weighs 52.6 lb, and has dimensions that are approximately 15” x 26” x 4”.

What are the advantages of using panel-level storage?

Panel-level storage shares a lot of the advantages that other module-level power electronics — microinverters, DC optimizers, etc. — bring to the industry, such as the simplification of design, power efficiency, and power optimization. Unlike other large stationary ESS systems, the SolarLEAF™ simply integrates with the same racking system as the solar module and uses the same balance of system. This is advantageous in situations with limited space or where the placement of stationary storage may add significant trenching costs. Additionally, the distributed design of the SolarLEAF™ with lithium-iron-phosphate technology is the safest way to integrate storage, as there is no risk of a cascading thermal runaway. In commercial rooftop systems with ballast racking, the SolarLEAF™ offsets the additional weight needed, which is typically accomplished with concrete ballast blocks.

Where are your energy storage units located in relation to the solar panels in a solar power system?

SolarLEAF™ is designed to be mounted directly behind the solar module that is powering it. The SolarLEAF™ can install electrically between the PV modules and the inverter because it can work with microinverters, string inverters, and battery inverters.

Can your storage units be used with ground-mounted solar?

Yes, Yotta is developing attachment brackets for various ground-mount racking solutions.

Could they be used on motorhomes, travel trailers, or mobile homes?

The SolarLEAF™ is generally not recommend for moving vehicles unless the installation is completed via a professional attachment process.

What battery chemistry do your storage units use?

Lithium-Iron-Phosphate.

As battery owners and operators seek to maximise the returns from their assets, they simultaneously face the Herculean challenge of managing degradation. This remains one of the most prominent challenges in the industry, where assets are expected to last around 15 years before reaching End-of-Life (EoL).

Degradation manifests itself in several ways leading to reduced energy capacity, power, efficiency and ultimately return on investment.

Put simply, battery degradation is a serious economic problem which will vary according to how the battery is used. It is therefore essential to monitor factors which drive degradation. These include temperature, ramp rate, average State of Charge (SoC) and Depth of Discharge (DoD).

Analysing the impact of these factors is vital to assessing the cost-benefit of decisions to charge or discharge a battery in response to different market signals.

This is especially important as single/multi-service batteries have the option of participating in a variety of markets, such as frequency regulation or the Balancing Mechanism (BM), and each market can have a different risk level according to the asset’s load profile and cycling behaviour.

Back to basics: what ‘exactly’ is a charge cycle?
Unfortunately, and confusingly, the industry has different definitions for what ‘a cycle’ actually is. In commercial documents, such as warranties, a cycle is calculated via energy throughput. This tallies the energy going in/out of the battery and divides total energy throughput by capacity. Even though this is a relatively simple calculation, it actually only tells you the number of ‘Equivalent Full Cycles’, or EFCs.

EFCs do not quantify DoD, which factors how deep charge cycles are. As can be seen below, EFCs would be unable to distinguish 1 cycle of 100% DoD vs 2 cycles of 50% DoD vs 10 cycles of 10% DoD. Cycle depth is completely ignored in EFCs! For this reason, KiWi Power utilises the Rainflow algorithm as a tool for profiling each ‘real cycle’ in terms of DoD.