| Rated AC Power | Typically 1–20 kW per inverter, commonly used with small turbines and distributed generation. | Typically 20–500 kW per inverter, often installed in parallel for higher-capacity projects. | Commonly 500 kW–3.5 MW or more per converter unit, depending on turbine architecture. | Confirm continuous output, overload capability, and whether the rating is based on apparent power or active power. |
| Conversion Efficiency | Approximately 94–98% peak efficiency; system efficiency is lower after cabling and protection losses. | Approximately 96–98.5% peak efficiency for modern power-electronic designs. | Approximately 97–99% peak efficiency, with annual energy yield depending on the efficiency curve. | Compare maximum efficiency, European or weighted efficiency, partial-load efficiency, and standby consumption. |
| Maximum DC or Generator-Side Voltage | Often below 1,000 V DC, depending on the turbine generator and system design. | Commonly 1,000–1,500 V DC in higher-power systems. | Frequently 1,500 V DC on the converter side, while medium-voltage output may be provided through a transformer. | Verify compatibility with generator voltage, turbine insulation, local electrical rules, and service tools. |
| MPPT or Variable-Speed Operating Range | Designed for a broad variable-speed turbine input; the usable range is model-specific. | Usually supports a wide generator speed and voltage range to increase energy capture at changing wind speeds. | Typically uses advanced converter control for variable-speed operation, reactive-power control, and grid support. | Request the actual input-voltage, frequency, and torque-speed operating envelope rather than only the nominal rating. |
| Grid Voltage Compatibility | Common low-voltage outputs include 120/240 V or 230/400 V, depending on the market. | Common low-voltage outputs include 400 V, 480 V, or other regional three-phase configurations. | May use low-voltage converter output with a step-up transformer to medium-voltage collection systems. | Check nominal voltage, frequency, phase configuration, transformer requirements, and permitted voltage tolerance. |
| Grid Frequency | Usually configured for 50 Hz or 60 Hz operation. | Usually configured for 50 Hz or 60 Hz operation with region-specific protection settings. | Must comply with the project grid code, including frequency ride-through and active-power control requirements. | Ensure the firmware and protection settings support the target country without unauthorized configuration changes. |
| Reactive Power Capability | Often limited or optional; basic units may operate close to unity power factor. | Commonly supports adjustable power factor and reactive-power control. | Normally expected to provide dynamic reactive-power control, voltage regulation, and power-factor operation across the required range. | Compare the P-Q capability curve, reactive-current limits, response time, and performance at low active power. |
| Grid Support Functions | May include anti-islanding, voltage protection, frequency protection, and controlled reconnection. | May include low-voltage ride-through, high-voltage ride-through, ramp-rate control, and frequency response. | Typically requires low- and high-voltage ride-through, frequency ride-through, fault-current contribution, ramp-rate control, and active-power curtailment. | Match the inverter functions to the grid operator’s connection code, not only to the inverter’s generic feature list. |
| Harmonic Performance | Total harmonic distortion is commonly designed below 5% at rated conditions, subject to the grid and installation. | Modern systems commonly target low current distortion, often below 5% under specified operating conditions. | Project-level harmonic compliance may require filters, transformer selection, and verification at the point of common coupling. | Ask for measured harmonic-current data, test conditions, switching-frequency information, and point-of-common-coupling limits. |
| Protection Functions | Anti-islanding, overcurrent, overvoltage, undervoltage, overfrequency, underfrequency, and ground-fault protection. | Includes the small-system functions plus more configurable protection and communication interfaces. | Includes coordinated protection, breaker interface, synchronization, fault recording, and plant-level protection integration. | Verify protection coordination, trip settings, reconnection delays, arc-fault requirements where applicable, and local certification. |
| Cooling and Environmental Rating | Natural or forced-air cooling; common outdoor protection levels include IP54–IP65 depending on enclosure design. | Forced-air cooling is common; liquid cooling may be used in higher-power systems. | Forced-air or liquid cooling is selected according to power density, ambient temperature, altitude, and maintenance strategy. | Check operating temperature, derating curve, humidity, salt mist, dust, altitude, corrosion protection, and ingress rating. |
| Operating Temperature | Common design ranges are approximately −20°C to +50°C, with power derating at high temperature. | Common design ranges are approximately −20°C to +50°C, depending on enclosure and cooling system. | Project-specific designs may cover approximately −30°C to +50°C or wider ranges, usually with thermal derating. | Compare the full-power temperature range, derating start point, cold-start behavior, and heating requirements. |
| Altitude Capability | Many units are rated around 1,000 m without derating, with reduced power at higher elevations. | Often rated around 1,000–2,000 m before derating, depending on insulation and cooling design. | High-altitude projects may require special insulation coordination, cooling design, and derating calculations. | Confirm the altitude correction curve for power semiconductors, insulation, cooling airflow, and transformer equipment. |
| Communication and Monitoring | Common interfaces include RS-485, Ethernet, Wi-Fi, or cellular gateways. | Commonly supports Modbus RTU/TCP, remote monitoring, event logs, and power-control commands. | Usually requires SCADA integration, time synchronization, remote dispatch, disturbance recording, and plant-controller communication. | Check open protocols, data points, cybersecurity controls, remote firmware policy, and compatibility with the project SCADA system. |
| Applicable Standards and Grid Codes | Typical references include IEC 62109 safety requirements, IEC 61727 utility interface requirements, and applicable national rules. | May require IEC 62109, IEC 61400-21 power-quality measurement, IEEE 1547, EN 50549, or equivalent regional standards. | Must comply with the specific transmission or distribution grid code, plant-control requirements, and power-quality standards. | Request current certificates and test reports for the target market; generic CE marking alone does not prove grid-code compliance. |
| Reliability and Serviceability | Fewer components and modular replacement can simplify field service. | Replaceable fans, surge protection devices, control boards, and power modules can reduce downtime. | Modular power stacks, condition monitoring, redundant controls, and local spare-parts support are especially important. | Compare warranty terms, expected service life, mean time between failures, spare-parts availability, and technician training. |
| Energy Yield at Low Wind Speeds | Highly dependent on the generator curve, startup speed, control algorithm, and inverter standby losses. | Broad operating range and low night-time consumption can improve annual yield at moderate wind sites. | Advanced control and partial-load efficiency are important because turbines spend substantial operating time below rated power. | Use the turbine power curve and inverter efficiency curve together; do not select solely by peak efficiency. |
| Best-Fit Selection | Best for Small distributed wind projects where simple installation, local certification, and low service complexity matter most. | Best for Commercial and community projects requiring scalable capacity, remote monitoring, and flexible grid control. | Best for Large wind farms where grid-code performance, availability, plant control, and lifetime energy yield dominate the decision. | The best inverter is the one that satisfies the site’s grid code, turbine operating envelope, climate conditions, annual energy model, and service plan at the lowest lifetime cost. |
