Six-year-old solar power plant partially repowered with new trackers and bifacial solar modules


At the end of 2018, there were 690 ground mounted utility-scale solar power plants totaling greater than 25GWac in commercial operation in the United States. These projects represented tens of billions of dollars of installation costs and hundreds of millions of ongoing annual operations and maintenance work.

And now, a $20 billion revenue stream is arising — upgrades of racking, inverters, and solar modules that maximize the amount of electricity that can be delivered through already existing interconnection approvals.

OCI Solar Power has repowered a portion of its 39.2MWac/49.4MWdc Alamo 1 solar power plant in Bexar County, Texas. The plant has been upgraded to Array Technologies trackers and bifacial solar modules. Existing inverters, manufactured by Kaco New Energy, concrete foundations, and balance of system gear were left in place.

The facility came online in December of 2013, and sits on 445 acres of land on the southside of San Antonio. Originally, the plant was built with 167,680 Yingli solar modules, 295 watts each, on 2,260 single-axis and 1,932 dual-axis trackers manufactured by ERCAM Trackers.

ERCAM dual axis trackers at OCI Solar’s Alamo 2 solar farm, maintenance crew

Image: pv magazine

The work took nine months to complete. Jason Thompson, Construction Manager for OCI, said the new block of trackers and bifacial modules “will be used for field testing and data-gathering.”

RES Americas Inc. was the original engineering, procurement and construction (EPC) firm, with Swinerton Renewable being contracted for the recent work.

In August of 2016, the facility added 1MW/250KWh of energy storage to provide fast response frequency stability.

Inverter manufacturer SMA launched its SMA Repowering department in January of 2019 where it offers engineering services to support system upgrades of this nature. Spanish company TSO recently patented drone based O&M software that supports repowering in its O&M algorithms. The older European solar market has been talking about repowering for a few years now, with 40GW of solar power plants greater than 100kW and older than five years of age.

Hardware manufacturer Alencon makes a piece of hardware that allows for upgrades of this nature called the “String Power Optimizers and Transmitters” (SPOT for short). It allows for connection of hardware with varying voltages to each other, easing the upgrade process. Alencon also offers an engineering service surrounding the repowering, a very different process from the original design route.

Modules and racking aren’t the only upgrades. In 2018, almost half of the utility scale solar + energy storage installations were energy storage upgrades to already existing solar plants.

OCI claimed it was able to do the upgrades without powering down the whole of the facility, and that due to the success of this upgrade they’re now looking for new facilities to similarly redevelop.

Here’s a clip of the original panels being installed.

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