The modern solar power industry in the United States turns 50 years old in 2023, and though few electric cooperatives have used the technology at scale for that long, early co-op adopters of photovoltaic generation can look back at a decade or more of lessons learned.

There’s broad agreement that the current solar movement in the U.S. traces its roots to Solar One, a demonstration home built at the University of Delaware in 1973 that generated power using cadmium sulfide photovoltaic film. About 25% of the energy absorbed from sunlight was converted to electricity and stored in batteries.

Solar One and Delaware’s four-season coastal climate contributed to research that helped move solar technology from laboratory demonstrations to full-scale production.

It would be another few decades and multiple technological breakthroughs before generation-scale photovoltaics would catch on, but electric co-ops were among the first to take up the challenge and build large installations.

Green Power EMC was one of the pioneers. Created in 2001 by Georgia co-ops, its mission was to analyze and source renewable generation for the cooperative energy portfolio.

By 2012, a growing interest in solar drove the renewable energy cooperative to help some of the state’s co-ops plan and design several 1-megawatt demonstration projects and build community solar arrays. Their first utility-scale project— a 20-MW array near Hazlehurst, Georgia—was built under a power purchase agreement with independent power producer Silicon Ranch in 2015.

Since then, Georgia co-ops have added 900 MW of utility-scale solar to their collective renewable energy portfolio, said Green Power EMC President Jeff Pratt.

And by the end of 2024, they’ll have “more than 1,600 MW of solar generation spread across more than 40 sites in Georgia,” said Nicholas Ham, Green Power EMC’s manager of engineering and operations. “We serve 38 of the state’s 41 distribution co-ops, so we’ve learned a lot about getting sustained value out of solar generation.”

Here are some of Green Power EMC’s key improvements, adaptations and lessons learned in its decade of solar experience.

Better Technology

Green Power EMC’s earliest arrays were fixed-mounted panels connected in series to inverters.

“For our utility-scale solar installations, we now use single-access tracker systems that follow the sun from east to west, which improves power production,” said Ham. “We have also switched to an inverter bank design that clusters essential equipment in strategic locations on the sites, so they are easier to access and maintain.”

Silicon Ranch also equips its solar installations serving Green Power EMC with monitoring equipment and sensors that, coupled with periodic visual inspections by its field staff and predictive analytics by its performance engineers, help to recognize hotspots, detect panel failures or identify signs of potential inverter problems. Some newer installations also utilize bifacial panels that capture energy from sunlight reflected off the ground by collecting it on the bottom side of the panel.

Monitoring and Maintenance

Community and utility-scale solar developments are constantly monitored both on and off-site, and the data is analyzed to proactively identify potential or existing issues. When a degradation of equipment performance is detected, trained repair crews can respond quickly, or local co-op personnel can conduct assessments to pinpoint problems.

While solar panels are relatively robust, rocks, tree limbs and hail can pose hazards. Pollen and dirt, water spots and surface oxidation can reduce output.

“Our cleaning program is currently based upon a five-year cycle, but we are considering reducing that time window to improve overall performance and extend the life expectancy of our panels,” said Ham. “Ultimately, the site’s performance, as relayed by the monitoring equipment, should inform our decision-making process on the most appropriate time to perform cleaning and other maintenance activities.”

Many sites have been seeded with low-growing grasses and flowering plants, and some allow livestock grazing to reduce the need for mechanical mowing and chemical fertilizers or pesticides that erode topsoil and destroy soil health.

“Through their Regenerative Energy® platform, our solar energy partners at Silicon Ranch are introducing a new sheep industry here in Georgia that will, over time, provide locally grown grass-fed meats at local and regional markets and grocers,” said Pratt.

Battery Storage

Battery storage is expanding the overall value of renewable energy, including solar, but the technology is still evolving.

Green Power EMC worked with Jefferson-based Jackson EMC to develop a 1-MW solar array with a 250-kilowatt battery/548-kilowatt hour energy storage system (BESS), Pratt said, noting that the project is helping a commercial member achieve its energy sustainability goals.

“We’re using the Jackson EMC project to conduct research and develop potential use cases and applications for the systems,” said Pratt. “Our findings can help us determine ways to use the BESS technology on a larger scale in the future.”

Disposal Practices

Most solar panels are designed to operate for 25 to 30 years, and depleted units need to be removed for disposal. The International Renewable Energy Agency projects that around 78 million tons of raw materials from solar arrays, valued at $15 billion, could be recycled worldwide by 2050.

While Georgia’s electric co-ops purchase the full output of Green Power EMC’s utility-scale solar arrays, the majority of those projects were developed and are owned by Silicon Ranch, which contracts with module recyclers including SolarCycle and First Solar.

“That’s provided us with a high-recovery recycling platform that recovers up to 95% of a solar panel’s value,” said Pratt. “It’s allowing for the return of essential materials that make up these panels including glass, silicon, silver, copper, and aluminum, to the supply chain where they can be used to manufacture new panels.”