6.6MW PV Retrofit Project in Italy
Location
Udine, Italy
Commercial & Industrial Solar
Project Information
Project Type：Distributed PV Retrofit
System Capacity：6.6 MW
Inverter Model：Sunways STT-12KTL
Quantity：552 Units
Expected Annual Generation
9.87 GWh
Annual CO₂ Reduction
10,008 Tons
Coal Savings Equivalent
3,849 Tons
Project Overview
Revitalizing Aging Solar Assets in One of Europe’s Most Mature PV Markets
Italy is one of Europe’s leading photovoltaic markets, with a large number of distributed solar power plants installed more than a decade ago. While photovoltaic modules continue to operate efficiently, many older inverters have become a bottleneck, reducing overall system performance and energy yield.
To restore generation efficiency and maximize return on investment, a 6.6MW distributed photovoltaic retrofit project was launched in Udine, Italy. Leveraging its long-standing German engineering heritage and strong presence across Europe, Sunways was selected as the exclusive inverter supplier for this large-scale solar modernization project.
Challenges
Aging Inverters Limiting System Performance
Many photovoltaic systems installed before 2013 were designed with inverter technologies that are now outdated. Although the solar modules remain operational, inverter degradation has led to:
Reduced Energy Yield
Lower conversion efficiency results in significant annual generation losses.
Increased Maintenance Costs
Aging equipment requires more frequent service and replacement.
Limited Grid Adaptability
Older inverter platforms struggle to comply with modern grid requirements.
Lower Investment Returns
Declining system performance reduces overall project profitability.
For plant owners, replacing underperforming inverters has become one of the most effective ways to restore system value without rebuilding the entire solar installation.
Solution
High-Efficiency STT-12KTL Commercial Solar Inverters
Sunways supplied 552 units of STT-12KTL three-phase string inverters to modernize the entire 6.6MW solar plant.
Designed for commercial and industrial photovoltaic applications, the STT-12KTL combines high efficiency, flexible system design and long-term reliability to maximize energy production. The STT series delivers up to 98.6% efficiency and supports flexible PV configurations for commercial rooftop and distributed solar projects.
Key Solution Benefits
Dual MPPT Design
Supports PV arrays with different orientations and layouts, improving design flexibility and maximizing solar harvest.
98.6% Maximum Efficiency
Industry-leading conversion efficiency increases annual energy generation under the same installation conditions.
High DC/AC Ratio
Supports up to 1.6 DC/AC oversizing, enabling greater PV utilization and improved project economics.
Long-Term AC Overload Capability
High-redundancy circuit design allows continuous 110% AC output, maximizing inverter utilization.
Comprehensive Protection Features
Integrated protection mechanisms enhance operational safety and long-term system reliability.
Strong Grid Compatibility
Designed to meet evolving grid requirements across European markets.
Solution Highlights
Why the STT Series Was Chosen：
Higher Energy Production
Advanced MPPT algorithms and high conversion efficiency help extract more power from every solar module.
Lower Levelized Cost of Electricity (LCOE)
Higher inverter utilization and improved energy output reduce electricity generation costs over the project lifecycle.
Simplified Retrofit Deployment
Flexible PV compatibility allows easy replacement of legacy inverter systems without major modifications.
Reliable Long-Term Operation
Industrial-grade design ensures stable performance under demanding operating conditions.
Future-Proof Investment
Supports modern grid standards and helps extend the operational life of existing solar assets.
Project Results
Significant Environmental and Economic Impact
Upon full commissioning, the project is expected to generate approximately:
- 9.87 GWh of Clean Electricity Annually：
Enough to supply thousands of households with renewable energy. - 10,008 Tons of CO₂ Emissions Avoided Each Year：
Supporting Italy’s renewable energy and carbon reduction goals. - 3,849 Tons of Coal Consumption Reduced Annually：
Helping accelerate the transition away from fossil-fuel-based electricity generation.The project demonstrates how inverter modernization can unlock substantial performance improvements without replacing existing PV modules.
Why PV Retrofitting Is Growing in Italy
Italy currently operates one of the largest installed photovoltaic fleets in Europe. A significant proportion of these systems were connected to the grid before 2013 and are now reaching the stage where inverter replacement becomes economically attractive.
As original inverter warranties expire and equipment efficiency declines, PV retrofitting is emerging as a major market opportunity throughout Italy and other mature European solar markets.
For system owners, replacing legacy inverters offers:
- Improved energy production
- Extended plant lifetime
- Better grid compliance
- Higher project profitability
- Faster return on investment
Conclusion
Driving the Next Generation of Solar Performance in Europe
The 6.6MW photovoltaic retrofit project in Udine represents a successful example of how modern inverter technology can revitalize aging solar assets and unlock new value from existing PV infrastructure.
By deploying 552 units of Sunways STT-12KTL inverters, the project significantly improves system efficiency, increases renewable energy generation and strengthens long-term investment returns.
As solar retrofit demand continues to grow across Europe, Sunways remains committed to delivering reliable photovoltaic inverter solutions, advanced grid compatibility and professional local support to help customers maximize the value of their solar investments. Sunways has supplied solar projects across more than 60 countries and regions worldwide through its global network and long-term PV expertise.
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