Independent Power Producer
Independent Power Producer




In 2013, a major solar farm was installed in Texas. OCI Solar Power decided to look at incorporating energy storage into the mix and turned to a local expert, Younicos, to launch its first energy storage initiative. The Younicos track record includes the construction of the first battery storage system in Texas, the 36 MW Notrees Energy Storage System, which is still the largest renewables-integrated storage facility in North America and was instrumental in proving the benefits of fast-responding storage assets to the Texas market. The customer was confident that this record of successful performance meant that Younicos was the premier choice for delivering a storage solution tailor-made for the Texas market.






Performance, reliability and ease of installation and maintenance were key considerations for the project team. Younicos’ compact Y.Cube solution was the ideal system to meet all requirements. Two 3 x 3 m Y.Cube enclosures were installed side-by-side on a 90-square-meter concrete slab next to the solar farm control house and tied into the existing 34.5 kV bus. Both Y.Cubes, along with the transformer and other electrical equipment, were installed by a single forklift in a cost-effective and speedy installation. Each Y.Cube enclosure contains the LG-Chem battery racks, two Y.Converters 250, Younicos’ proprietary power electronics solution, along with HVAC, fire suppression and auxiliary load equipment, all managed by the Younicos control platform. The unique configurability of the Y.Cube solution, which allows the user to build the system with more granularity than offered by a standard ‘one-size-fits-all’ 40-foot container, enabled the customer to optimize both the operational size and footprint of the storage system.

“The nice part about the Y.Cube is that it’s really an all-in-one-enclosure. Easy to install, easy to maintain.”


John Huffaker, Vice President of Commercial Development, OCI Solar



A number of product features within the Y.Cube helped to improve the overall investment case: a thermal management system in each Y.Cube minimizes parasitic loss and battery degradation by maintaining battery temperatures within more consistent limits than in a conventional 40-foot container, hence reducing operating costs and extending battery life; adding a distribution panel connecting the four converter units enables individual units to be isolated if necessary, while the other units continue to operate and the compact size of the system provides very easy access for performing any manual checks or maintenance. In real-time operation, the Y.Cube is guided by a web Battery Temperature user interface. This secure, multi-user interface was (Y.Cube) (3rd party BESS) developed on the basis of our experience in energy storage operations in Texas. It is programmed to enable multiple services, while complying with all ERCOT reporting and second-by-second telemetry requirements. Following final commissioning of the Y.Cube in Q2 2016, this system is ready to track and report on system performance in today’s market, while providing its user the flexibility to incorporate future services in the years to come.




energy storage system, installed alongside a solar farm.



of commissioning the Y.Cube battery farm in Texas.



of capacity to provide grid services such as fast frequency response.




The customer wanted to install the storage system alongside its solar farm, taking advantage of existing equipment and interconnection facilities. In order to preserve the versatility of the system, it was important to select a chemistry that could reliably participate in the markets for energy storage today, namely Fast-Frequency-Regulation-Service (FRRS). Younicos was also required to provide other services, such as solar power ramping, to smooth the intermittency of the co-located solar farm output, as well as future services such as Firm Frequency Response (FFR). The team selected the LG-Chem JP1 batteries. Since this was the first time of this high-power battery chemistry was deployed in the Texas market, the technology was put through rigorous performance tests in Younicos’ Technology Center in Austin to validate the selection.