Solar Energy Storage Equipment for Grid-Tied Residential Projects

New high-density lithium-ion battery technologies, innovative software and power electronics designs, and changes to incentive programs, such as California’s storage-centric Self-Generation Incentive Program (SGIP), are ushering in a new era for grid-connected, customer-sited energy storage projects. This article profiles 15 manufacturers that design and build inventive equipment for residential-scale solar-plus-storage systems. I highlight power electronics, as well as some current lithium-ion battery products that may be less familiar to solar professionals than the more-established lead-acid battery brands and models. In some cases, the equipment detailed is also suitable for small-commercial projects that have an energy storage requirement. While US markets for residential-scale grid-connected PV storage systems are still limited, the continued advancement of product designs and falling storage costs will speed the opening of new markets and opportunities.

Adara Power

Founded in 2013 as JuiceBox Energy and rebranded under its current name in 2016, Adara Power was an early developer of products integrating lithium-ion battery technology with power electronics for residential-scale solar-plus-storage systems. In addition to providing solutions for backup power during grid failures, Adara focuses on energy storage systems layered with monitoring and control software for peak shift, load shave and self-consumption applications. Its flagship product is the 8.6 kWh residential Energy Storage System (ESS), which deploys Samsung lithium nickel manganese cobalt oxide (NMC) cells, configured to operate at 50 Vdc nominal. The system’s battery is certified to UL 1642, and has a specified minimum life of 10 years. The Adara ESS is compatible with the Schneider Electric XW+ inverter-chargers. Designs can dc- or ac-couple solar arrays with the Adara system. Integrators have successfully ac-coupled inverters from vendors including SMA America and SolarEdge with Adara’s first-generation system.

In April 2017, Adara announced its second-generation system, the Adara Pulse. The modular system is driven by Adara's iC3 Controller and expandable to 20 kWh of storage. The Adara Pulse supports ac coupling for off-grid and grid-tied applications. Adara’s peak-shifting, solar-charging and self-consumption, and nonexport algorithms ensure compliance with the federal investment tax credit and adaptability for a wide range of energy storage applications. The monitoring and control system is designed to optimize storage utilization in regions subject to time-of-use rates and supports net-metering programs such as California’s Net Energy Metering 2.0. The Adara iC3 Smart Controls offer cellular connectivity and support out-of-the-box communication between lithium-ion batteries such as LG Chem’s 48 Vdc RESU10, Schneider Electric XW+ inverters and a cloud-based software platform.

Adara Power • San Jose, CA • 888.692.3272 • adarapower.com

Enphase Energy

When Enphase Energy launched in 2006, it created the modern microinverter product class. Since then, it has continued to refine its microinverter and monitoring systems, as well as their installability. Enphase developed its AC Battery, initially announced in October 2015, to support self-consumption and energy time-of-use optimization across global markets. The company first introduced the battery in Australia, and announced US availability in February 2017. The AC Battery, a scalable, modular energy storage system, is a component of Enphase’s Home Energy System, which includes the company’s microinverters, Envoy networking hub and gateway, and module-level Enlighten monitoring software.

The Enphase AC Battery uses lithium iron phosphate (LiFeYPO4) chemistry from Eliiy Power with cell safety certifications from TÜV Rheinland and UL, including UL 9540. The cells provide 1.2 kWh of capacity at a nominal voltage of 25.6 Vdc. The AC Battery can discharge to 100% of rated capacity and has a round-trip cell efficiency specification of 96%. Weighing only 55 pounds, the AC Battery is designed for single-person installation and interconnection with standard household wiring. Its enclosure is NEMA 2 rated for indoor installation in an unoccupied space. The AC Battery carries a 10-year or 7,300-cycle warranty for greater than 80% of its initial rated capacity.

Enphase Energy • Petaluma, CA • 877.797.4743 • enphase.com

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