NMS Inverters: Equipment Upgrade Guide for Aging PV Power Plant Renovation
With the global push for carbon neutrality and the gradual aging of early-stage photovoltaic (PV) power plants, the renovation and upgrade of aging facilities have become a critical task in the renewable energy industry. A large number of PV power plants built 8-15 years ago are now facing issues such as reduced inverter efficiency, component degradation, outdated control systems, and non-compliance with new grid standards. Among these, inverter obsolescence is the primary bottleneck restricting power generation efficiency and operational stability. As a core equipment for aging PV plant renovation, NMS inverters offer tailored solutions to address these pain points. This guide systematically elaborates on the necessity, assessment methods, upgrade advantages of NMS inverters, implementation procedures, and key considerations for aging PV power plant renovation, providing actionable guidance for plant operators and maintenance teams.
Aging PV power plants, typically those in operation for over 7 years, suffer from cumulative performance decay of core components. According to industry data, traditional inverters lose 10%-15% of conversion efficiency after 5-8 years of operation, while PV modules may experience attenuation of up to 65% in severe cases. Additionally, early inverters lack compatibility with modern energy storage systems and intelligent management functions, failing to meet updated grid connection requirements for frequency modulation and voltage regulation. These issues lead to a 20%-30% drop in annual power generation, increased maintenance costs, and even potential safety hazards. The National Development and Reform Commission of China has explicitly promoted PV equipment renewal, emphasizing the replacement of inefficient inverters to enhance power generation capacity and system stability—a policy backdrop that further highlights the urgency of inverter upgrades.
Pre-Renovation Assessment: Laying the Foundation for Inverter Upgrade
A comprehensive pre-renovation assessment is essential to ensure the compatibility and effectiveness of NMS inverter upgrades. This process involves three core steps, focusing on equipment status, grid compliance, and upgrade goals.
1. Equipment Status Diagnosis
First, conduct a full inspection of the existing system, focusing on inverter performance, PV module attenuation, and wiring conditions. For inverters, test key indicators such as DC-AC conversion efficiency, MPPT (Maximum Power Point Tracking) response speed, and fault rate. If the conversion efficiency drops below 85% or the annual fault rate exceeds 5%, replacement is recommended. For PV modules, use professional equipment to measure attenuation rate—modules with attenuation exceeding 20% should be replaced or rearranged to match the new NMS inverter’s input parameters. Meanwhile, inspect cables and connectors for aging, corrosion, or overheating, as these can affect the new inverter’s operation.
2. Grid Compliance Check
Verify whether the existing system meets current grid connection standards, including requirements for low-voltage ride-through (LVRT), reactive power regulation, and data monitoring. Early PV plants often lack LVRT capability, which is mandatory under new grid codes. NMS inverters are designed to comply with global grid standards (e.g., IEC 61727, IEEE 1547), but pre-assessment ensures that the upgrade plan addresses specific grid requirements of the plant’s location.
3. Upgrade Goal Definition
Clarify upgrade objectives based on operational needs, such as improving power generation efficiency, reducing maintenance costs, integrating energy storage, or achieving intelligent management. For example, plants aiming for efficiency improvement can prioritize NMS inverters with high conversion efficiency, while those targeting smart operation can opt for models with integrated cloud monitoring.
Core Advantages of NMS Inverters for Aging Plant Renovation
NMS inverters are specifically optimized for aging PV plant renovation, offering four key advantages that address the unique challenges of legacy systems.
1. High Compatibility with Legacy Components
Unlike conventional inverters that require matching new PV modules, NMS inverters feature a wide DC input voltage range (40V-580V) and flexible MPPT configuration, compatible with most early-stage monocrystalline and polycrystalline modules. They support both series and parallel connection of old modules, eliminating the need for large-scale module replacement and reducing renovation costs by 30%-40%. Additionally, NMS inverters are compatible with existing transformers and switchgear, minimizing structural modifications to the plant.
2. Industry-Leading Conversion Efficiency & Attenuation Resistance
Equipped with advanced MPPT algorithms and high-efficiency power circuits, NMS inverters achieve a maximum conversion efficiency of 98.5%, significantly higher than the 80%-85% efficiency of aging inverters. Their low attenuation design ensures that efficiency remains above 96% after 10 years of operation, effectively offsetting power losses from aging modules. In practical applications, replacing old inverters with NMS models can increase annual power generation by 15%-20%.
3. Intelligent Management & Remote Maintenance
NMS inverters integrate a centralized intelligent platform that supports real-time monitoring of PV generation, inverter status, and grid interaction. The platform uses AI algorithms to predict component failures and optimize MPPT strategies, reducing manual inspection needs by 60%. Remote maintenance functions allow technicians to diagnose faults, upgrade firmware, and adjust parameters online—critical for aging plants in remote areas where on-site maintenance is costly and time-consuming. This addresses the common pain point of discontinued after-sales service for early inverter brands.
4. Grid Compliance & Energy Storage Integration
NMS inverters are pre-equipped with LVRT, reactive power compensation, and frequency regulation capabilities, fully complying with the latest grid standards. They also support seamless integration with lithium-ion energy storage systems (100kWh-500kWh), enabling peak-shaving and valley-filling to further improve revenue. For aging plants, adding energy storage alongside NMS inverters can stabilize power output and enhance grid connection stability, extending the plant’s operational lifespan by 10-15 years.
Step-by-Step Upgrade Implementation with NMS Inverters
The upgrade process should prioritize safety, efficiency, and minimal downtime. Follow these five steps to complete the NMS inverter installation and commissioning.
1. Preparation & Safety Measures
Shut down the entire PV system and disconnect grid connection to ensure zero voltage in the circuit. Prepare tools such as torque wrenches, multimeter, and insulation testers, and verify that the NMS inverter model matches the system’s power rating (e.g., 50kW, 100kW) and input/output parameters. Conduct a safety briefing for the construction team, emphasizing compliance with electrical operation standards.
2. Removal of Old Inverters
Carefully disconnect cables from the old inverter, label each wire to avoid misconnection, and remove the unit. Inspect the mounting bracket for corrosion or deformation—replace if necessary to ensure stable installation of the NMS inverter. Dispose of old inverters in accordance with environmental regulations, as some components contain recyclable materials.
3. Installation of NMS Inverters
Mount the NMS inverter on the bracket, ensuring proper ventilation (minimum 30cm clearance around the unit) to prevent overheating. Connect DC cables from PV modules to the inverter’s input terminals, following the polarity marking, and fasten connections to the specified torque. Connect AC cables to the grid-side switchgear, ensuring insulation resistance meets standards (≥2MΩ at 500V DC).
4. Commissioning & Testing
Power on the NMS inverter and use the built-in LCD screen or mobile app to configure parameters, including grid voltage, frequency, MPPT mode, and communication settings. Conduct no-load testing to verify inverter startup, voltage output, and self-diagnostic functions. Then perform on-load testing by connecting to the PV array and grid, monitoring indicators such as conversion efficiency, reactive power output, and grid connection stability. Test fault response capabilities by simulating grid fluctuations or module failures to ensure the inverter shuts down or adjusts automatically.
5. Post-Upgrade Monitoring & Optimization
After commissioning, monitor the system for 72 consecutive hours to collect data on power generation, efficiency, and fault records. Use the NMS intelligent platform to optimize MPPT parameters based on local irradiance patterns, further improving energy utilization. Train on-site staff to operate the monitoring platform and perform basic maintenance tasks, such as firmware updates and fault troubleshooting.
Key Considerations for Successful Upgrade
To avoid operational risks and ensure long-term stability, pay attention to the following considerations during the upgrade process.
1. Compatibility Verification
Before installation, confirm that the NMS inverter’s input voltage/current range matches the existing PV array. For plants with mixed old and new modules, use the inverter’s flexible MPPT channels to separate arrays with different attenuation rates, avoiding mutual interference.
2. Grid Connection Approval
Submit upgrade plans and NMS inverter technical specifications to the local power grid company for approval before commissioning. Ensure compliance with grid codes for connection, disconnection, and power quality to avoid rejection or penalty.
3. Maintenance & Service Guarantee
Choose NMS inverters with reliable after-sales service, including on-site support, remote diagnosis, and firmware upgrades. Given the 25-year operational lifespan of PV plants, select a supplier with long-term business stability to avoid service discontinuity—a lesson learned from early plants where 4 out of 5 inverter suppliers exited the market, leading to costly replacements.
Case Study & Benefit Analysis
A 20MW aging PV plant in Northern China, built in 2011, faced severe efficiency decay with annual power generation dropping by 28%. The original inverters had a conversion efficiency of 82% and lacked LVRT capability, failing to meet new grid standards. The plant opted to upgrade all inverters to NMS 100kW models, following the guide’s assessment and implementation steps.
Post-upgrade results showed a 19% increase in annual power generation, reducing grid electricity reliance by 18%. Maintenance costs decreased by 65% due to the NMS inverter’s remote monitoring and low fault rate. The plant also integrated 2MWh energy storage with the NMS inverters, enabling peak-shaving revenue and grid compliance. The investment return period was 5.8 years, extending the plant’s operational lifespan by 15 years. This case demonstrates the tangible economic and operational benefits of NMS inverter upgrades for aging PV plants.
Conclusion
Inverter upgrades are the most cost-effective way to revitalize aging PV power plants, and NMS inverters stand out as the optimal solution with their compatibility, efficiency, intelligence, and grid compliance. By following the pre-assessment, implementation, and post-maintenance steps outlined in this guide, plant operators can maximize upgrade benefits, restore power generation capacity, and extend operational lifespan. As green energy policies deepen, NMS inverters will play a pivotal role in promoting the sustainable development of aging PV assets, turning legacy facilities into high-efficiency, reliable contributors to the low-carbon economy.
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