Leading energy storage provider E22 and power electronics manufacturer Alencon Systems have partnered to offer a unique, integrated DC-coupled Solar + Storage solution. The Alencon BOSS™ bi-directional DC-DC converter serves as the link between the battery racks and the DC-bus in the E22 DC POWER OPTIMISER™

Hatboro, PA and Madrid, SpainEnergy Storage Solutions (E22), a leading global battery storage integrator and manufacturer, and Alencon Systems, the leading U.S. manufacturer of galvanically isolated DC-DC converters and optimizers, have partnered to offer a unique, turnkey DC-coupled Solar + Storage solution. The integrated solution, offered by E22, is called the DC POWER OPTIMISER™. Both E22 and Alencon will officially launch the solution at SPI 2019.

The DC POWER OPTIMISER™ consists of a DC to DC bidirectional converter, Alencon’s Bi-Directional Optimizer for Storage Systems – the BOSS™, connected to a battery, packaged in a single 2m (W) x 1m (D) x 2.3m (H) IP65 (NEMA 3/4X) containerized package. This container includes control and communication equipment, a battery management system, and cooling and safety systems as well as Alencon’s BOSS. The unit is compliant with UL1741 and designed to UL9540A. These distributed systems can connect with string inverters sized up to 150kW and 1,500 volts DC. The system is controlled via E22’s ETER software, a proprietary energy management and system control software platform developed by E22.

Alencon’s BOSS bi-directional DC-DC optimizer along with E22’s solutions will be on display in Alencon Booth #2629 at SPI.

E22’s DC POWER OPTIMISER offers a truly turnkey DC-coupled Solar + Storage solution which provides users a number of powerful benefits over traditional AC coupled systems while eliminating the system configuration challenges and deployment limitations of other DC-coupled solutions. The DC POWER OPTIMISER offers greater round-trip efficiency, while firming intermittent solar output to both extend solar production and turn solar into a truly dispatchable energy resource. By DC-coupling the battery to the solar, the DC POWER OPTIMISER also captures solar energy that would otherwise be clipped during times of overproduction. DC-coupling solar and storage with the DC POWER OPTIMISER also allows for favorable IRS tax treatment of the system, further improving the economics offered by E22’s solution.

Including Alencon’s BOSS galvanically isolated, rack-level DC-DC converter in this container provides a myriad of benefits to project owners. The DC POWER OPTIMISER can be easily connected to the grid via a string inverter, the first DC-coupled system to offer such a feature. This will allow PV plant owners to easily integrate storage into existing PV plants using string inverters. The inclusion of the BOSS also allows for superior system safety and maximum battery rack utilization by isolating each battery rack. By controlling the charge of the system at the rack level, the BOSS assures maximum utilization of each battery rack while at the same time improving system safety by minimizing the risk of fault currents and other safety risks. The battery rack level charge approach provided by the BOSS also greatly simplifies battery rack augmentation that will invariably need to occur over the life of a Solar + Storage project.

“Using Alencon’s BOSS DC-DC platform with the DC POWER OPTIMISER allows us to offer the market a truly unique, flexible and integrated DC-coupled Solar + Storage solution,” states E22 Managing Director Daniel Fernandez de Salamanca. “The DC POWER OPTIMISER solves a number of challenges in the market, including the ability to couple solar and storage on the same DC bus while using transformerless string inverters. At the same time, the solution can easily be scaled up to the multi-megawatt scale to work with more centralized systems.”

“In addition to mapping the PV voltage to the battery, the Alencon BOSS provides galvanic isolation to the DC POWER OPTIMISER, thus allowing grounded PV to be coupled onto the same DC-bus as the battery,” states Alencon President Hanan Fishman. “This feature means E22’s solution can be deployed in either new solar + storage installations or as a storage retrofit into an existing PV plant.”


Each DC POWER OPTIMISER can be sized to include up to 240kWh of energy storage. Based on the C-Rate chosen, the duration of discharge of the battery is between two to four hours. The DC POWER OPTIMISER contains all cooling, control, safety and isolation in the same unit. E22’s proprietary ETER software controls the interfaces with PV inverters to manage MPPT while providing control over the rest of the system. E22’s ETER software also communicates with the battery management system. For new deployments, the PV Inverter may be mounted on or next to each DC POWER OPTIMISER minimizing additional hardware.

For larger PV installations, the DC POWER OPTIMISER can be housed in a central container configuration to reduce parts count and simplify O&M.