Solar Operations’ myPV ClearSky units help Pine Gate project satisfy interconnection requirements

One of two Solar-Ops myPV ClearSky Interconnection units in the Grissom Solar + Storage facility.

Pine Gate Renewable’s Grissom Solar project went commercial last month. Grissom is a 6.9 MW + 10 MWh solar energy storage facility. Pine Gate has requested support from: Solutions for solar activities (Solar-Ops) to overcome the challenging requirements that emerged during the utility’s interconnection study.

The Grissom project has a single 5MW interconnection to be maintained when solar and battery storage are operated under the supervision of a third-party SCADA system. Both the solar inverters and the battery storage system are independently AC-coupled to the interconnection via two myPV ClearSky units from Solar-Ops.

Each ClearSky provides high-quality metering and recloser protection, while eliminating much of the overhead medium voltage equipment, reducing build time and long-term operating costs.

“AC coupling of battery storage to new or existing solar installations is becoming more common as developers and owner-operators seek to maximize the value of their existing interconnection agreements and PPAs,” said Brad Micallef, president of Solar-Ops. “The ClearSky product line is ideal for these applications because of its small size and built-in ability to meet utility and ITC security and reporting requirements.”

Utilities are concerned about power quality issues due to increased inrush current. Therefore, distribution-coupled generators such as Grissom may face approval issues. When AC-coupled battery storage is added to a solar installation, the extra transformers increase the likelihood that inrush current is a problem.

A distribution grid will experience a rapid drop in voltage due to the sudden demand for power when too many transformers are energized at the same time. This sudden rapid voltage change can cause damage to the power consumer equipment and requires limitation for the utility to operate within IEEE standards.

The Grissom facility, which normally required a special device, was able to reduce inrush current by sequencing the internal medium voltage reclosers of the two myPV ClearSky units. Programming one ClearSky to activate on grid restore and the other to delay energization for a few seconds reduced the arming event to an acceptable level.

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