PPC Group has constructed an enormous 550-megawatt solar array covering the abandoned opencast lignite mines of Ptolemaida in Northern Greece.
The power station utilizes about 950,000 bifacial solar panels placed on innovative single-axis solar tracking mechanisms covering many acres of flattened land.
The solar trackers have the ability to move in response to the position of the sun all through the day.
The substitution of depleted lignite mines with photovoltaics helps speed up the transition towards renewable energy in Western Macedonia.
Converting open-pit coal mines into solar foundations
The Ptolemaida basin produced soft brown coal to feed regional thermal power plants for more than six decades.
Decades of heavy open-cast mining left behind vast terraced craters, loose soil, and unstable terrain that required extensive civil engineering before installation could begin.
Heavy construction equipment regraded millions of cubic yards of loose overburden and compacted dirt foundations to anchor steel mounting posts securely.
Surveyors used specialized ground-penetrating radar to identify subsurface voids and ensure long-term structural stability across the entire project perimeter.
Repurposing existing high-voltage transmission lines and electrical substations from the decommissioned coal plants drastically reduced grid interconnection expenses.
Industrial land reclamation converts environmental liabilities into productive, utility-scale clean energy assets.
Capturing ground reflections with bifacial solar glass
Six decades of heavy mining operations resulted in huge terraced mines, loose soils, and unstable ground.
Heavy machinery had to regrade millions of cubic yards of loose overburden and compact soil to ensure that the steel mounting columns were installed firmly on the ground.
Ground-penetrating radars were used to locate underground cavities for long-term structural stability.
Utilization of existing high-voltage electricity lines and substations from the closed-down coal plants saved costs of grid connection.
Industrial reclamation transforms an environmental hazard into energy-producing facility.
Following the sun with motorized tracking rows
However, fixed tilt panels suffer from efficiency losses when the sun is at a lower angle during early mornings and late afternoons.
The Ptolemaida plant utilizes the Nextracker single-axis trackers with tilting systems, which move the panel rows in a continuous manner along the north-to-south rotational axis.
Electric motors supply power to the connected torque tubes made of steel in order to ensure that the modules remain perpendicular to the sun rays.
Optimal angles are calculated by the software in real time to ensure that no shadowing occurs between rows of panels when the sun’s angle is low.
This helps achieve maximum megawatt output through optimal tilt of the panels every operating hour of the day.
There is an automatic flat stowing function activated by wind sensors in severe weather, as reported by the PPC Group.
Stabilizing regional power grids with co-located storage
Renewable energy production becomes highly intermittent as thick clouds pass above Western Macedonia or at night.
The injection of 550 MW of peak capacity PV energy into the high-voltage grid system calls for accurate management of the grid.
A battery energy storage system is also being developed.
The large capacity lithium-ion batteries store excess energy produced in the middle of the day so as to avoid grid curtailing as a result of low local demand.
Battery energy discharge takes place during the period of high evening demand, thereby ensuring smooth energy delivery to the national grid.
Fast-acting inverter controls kick in almost immediately as a way of stabilizing any voltage irregularities.
Lowering utility generation costs through massive scale
Construction of such large-scale renewable projects demands a large capital outlay for specific equipment, logistics, and site preparation activities.
Funding of the project through European recovery programs and financial institutions reached hundreds of millions of dollars, according to Completion, Nextracker, PPC Group reports.
Centralizing almost a million solar panels to create a single project decreases the operating and maintenance expenses per megawatt.
Production of environmentally friendly energy for local industry increases the resilience of the region while at the same time helping Greece achieve its long-term decarbonization objectives.
Creation of utility-scale solar farms on abandoned coal mines represents an example of how to develop reclamation projects around the world.
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