--- title: "SolarEdge SE66.6K (K66.6SE) - Secondary unit Grid-tie Inverter: Specs & Datasheet | ComparePV" description: "SolarEdge SE66.6K (K66.6SE) - Secondary unit 66.6 kW grid-tie inverter. Specs: 98.0% European efficiency, 1000 V max DC input, 45.0 kg." source: "https://comparepv.com/inverter/solaredge-solaredge-se66-6k-k66-6se-secondary-unit" updated: 2026-01-16 --- # SolarEdge SE66.6K (K66.6SE) - Secondary unit ## Identity - **Manufacturer:** SolarEdge - **Model:** SolarEdge SE66.6K (K66.6SE) - Secondary unit - **Series:** SolarEdge K100SE / K66.6SE - **Rated AC power:** 66.6 kW - **Type:** Grid-tie - **Phases:** Three-phase ## How it compares Compared against 243 inverters from 30 to 100 kW. Ranks are within that class. | Measure | This inverter | Class median | Standing | Rank in class | | --- | --- | --- | --- | --- | | European efficiency | 98.0% | 98.2% | Typical | 99 | | MPPT trackers | - | 4 | | | | Max DC input voltage | 1000 V | 1100 V | Typical | 125 | | Weight per kW | 0.7 | 1.1 | Strong - top 7% | 15 | | Warranty | - | 5 yrs | | | ## Specification ### AC output - **Rated AC power:** 66.6 kW - **Max apparent power:** 66.60 kVA - **Phases:** Three-phase - **Nominal AC voltage:** 480 V - **Max AC current:** 80.0 A - **Grid frequency:** 60 Hz ### PV input - **Max DC input power:** 90.00 kW - **Max DC voltage:** 1000 V ### Efficiency - **European efficiency:** 98.0 % - **Max efficiency:** 98.1 % ### Physical - **Dimensions:** 540 × 315 × 260 mm - **Weight:** 45.0 kg - **Enclosure:** IP65 - **Cooling:** forced-air - **Noise:** 60 dB - **Operating temperature:** -40 to 60 °C ### Connectivity and protection - **Interfaces:** Ethernet - **Protocols:** RS485, Ethernet, GSM (optional plug-in) - **Protection:** AFCI, DC switch, Surge protection ### Warranty and certificates - **Certifications:** IEC 62109, AS 3100, VDE-AR-N 4105, G59/3, EN 50438, EN 4777, CEI 0-16, CEI 0-21, CEI 0126-1-1, BDEW, IEC 61000-6-2, IEC 61000-6-3, IEC 61000-3-11, IEC 61000-3-12, RoHS ### Pros - **Modular Synergy Architecture - Higher System Availability** - The system consists of a Synergy Manager and independent power units (2-3 units depending on the model), ensuring that a failure of a single unit does not shut down the entire installation. In practice, this translates to a higher uptime compared to monolithic inverters from competitors (Huawei SUN2000-100KTL-M2, SMA Sunny Tripower CORE2), where a single fault takes an entire 100 kW block offline. - **Peak Efficiency of 98.3% and European Efficiency at Premium-Class Level** - A peak efficiency of 98.3% (confirmed in the official EU datasheet) places the series among the top performers in the commercial 66.6-100 kW segment. For reference, the Huawei SUN2000-100KTL-M2 achieves 98.4%, representing a negligible difference within a comparable price range. - **3 Independent MPPT Trackers, 12 String Inputs** - Three independent MPPTs capable of handling 12 strings allow flexible PV array design with varying orientations and tilt angles within a single commercial installation, eliminating the need for additional combiners - an uncommon feature in this power class. - **Module-Level Monitoring and Shade Compensation** - Integration with SolarEdge power optimizers enables per-panel performance data collection (module-level monitoring) and eliminates partial shading losses. For commercial installations with complex roof layouts and obstructions, this provides a tangible energy yield advantage. - **Commissioning via SetApp - No LCD Display Required** - Mobile app-based commissioning through SetApp reduces startup time and minimizes configuration errors during installation, which is particularly valuable in large commercial installations with multiple inverters. ### Cons - **Counterparty Risk - SolarEdge Financial Health** - Between 2024 and 2025, SolarEdge conducted 4 rounds of mass layoffs (totaling >1,800 positions), replaced its CEO (Shuki Nir, December 2024), reported a 64% year-over-year revenue decline in Q3 2024, and shut down its energy storage division. For commercial projects backed by 12-20-year manufacturer warranties, this represents a significant risk factor when evaluating long-term service support and parts availability. - **Mandatory Power Optimizers - Higher CAPEX** - The full feature set of the series (module-level monitoring, shade compensation, RSD) requires a power optimizer on every panel. For a typical 100 kW commercial installation (approximately 170-200 modules), this adds a cost of approximately 15,000-25,000 PLN compared to string solutions without optimizers (e.g., Huawei SUN2000 with Smart Power Sensor), potentially increasing total project CAPEX by 5-10%. ## About this series SolarEdge K100SE / K66.6SE are three-phase grid-tie inverters designed for large commercial and industrial installations, where rapid installation, high availability, and easy servicing are key. What sets them apart is their **Synergy modular architecture** - the device consists of a manager and independent power units, simplifying installation tasks and potential component replacements, thereby reducing downtime. In practice, this also enhances resilience against failures, as the system is not entirely dependent on a single unit. These inverters work with power optimizers, enabling **module-level monitoring** and improved performance under partial shading. Independent MPPT tracks facilitate the design of PV fields with varying orientations and diverse irradiance conditions. Their high **European efficiency** translates to significantly better energy yields under typical operating conditions in Poland, not just in laboratory settings. For communication, Ethernet (and other interfaces, depending on configuration) is used, while configuration and startup can be performed via the service application. This series is tailored for investors seeking advanced safety features, grid compliance, and a reasonable manufacturer’s warranty. ## Questions ### What is the standard warranty on the SolarEdge K100SE and K66.6SE inverters? The SolarEdge K100SE and K66.6SE inverter series come with a standard manufacturer's warranty of 12 years. SolarEdge does, however, offer the option to extend the warranty to 20 years, which is a significant consideration when planning commercial and industrial installations where continuous operation has a direct impact on return on investment. The scope of the warranty extension should be agreed upon with an authorized SolarEdge installer. ### What is Synergy Technology in the SolarEdge K100SE series and what does it mean in practice? Synergy Technology means that the inverter consists of a manager unit and independent power units that can be replaced without shutting down the entire system. In practice, this reduces potential repair downtime and simplifies the transport and on-site installation of heavy 100 kW equipment at industrial facilities. The system is not dependent on a single block, so a failure in one power unit does not bring the entire installation to a halt. ### Does the SolarEdge K100SE require power optimizers, and what does that change about the installation? The K100SE series is designed to work in conjunction with SolarEdge power optimizers. The optimizers enable per-module performance monitoring and significantly reduce losses under partial shading of individual modules. For large commercial installations, this also facilitates rapid fault diagnostics without the need for manual inspection of each string. ### What installations is the SolarEdge K66.6SE suited for, and when is the K100SE the better choice? The SolarEdge K66.6SE, rated at 66.6 kW, is well suited for medium-scale commercial installations - for example, on manufacturing facilities or warehouses with limited roof space or lower energy demand. The K100SE variant, rated at 100 kW, is dedicated to larger industrial sites where minimizing the number of inverters and simplifying the wiring layout is a priority. The independent MPPT inputs on both models allow PV arrays with different orientations or tilt angles to be served within a single installation. ### What is the European efficiency of the SolarEdge K100SE series inverters and what does it mean for energy yield in Poland? SolarEdge inverters from the Synergy Technology series achieve a European efficiency of approximately 98.1%. European efficiency is calculated taking into account the typical solar irradiance distribution across Europe, and therefore more accurately reflects real-world energy yield under Polish conditions than peak laboratory efficiency. A higher European efficiency figure translates directly into greater annual energy production, particularly on overcast days and during periods of low irradiance. ### How does commissioning and configuration of the SolarEdge K100SE proceed at a commercial site? Commissioning of the K100SE series is performed via the dedicated SolarEdge service application, eliminating the need to operate a physical panel in hard-to-reach locations. The inverter features an Ethernet interface for integration with site-level energy monitoring and management systems. The modular Synergy architecture also accelerates the commissioning process itself, as power units are validated automatically during the pre-handover procedure. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/inverters/5cda3a11aceec-814c5717843c.pdf) ## Alternatives | Inverter | Rated AC | Euro efficiency | MPPT | Weight | Difference | | --- | --- | --- | --- | --- | --- | | [SolarEdge SE66.6K (K66.6SE)](https://comparepv.com/inverter/solaredge-solaredge-se66-6k-k66-6se) | 66.6 kW | 98.0% | | | Similar on paper | | [SolarEdge SE66.6K (K66.6SE) - Primary unit](https://comparepv.com/inverter/solaredge-solaredge-se66-6k-k66-6se-primary-unit) | 66.6 kW | 98.0% | | 48.0 kg | 3.0 kg heavier | | [SolarEdge SE66.6K (Synergy, 277/480V)](https://comparepv.com/inverter/solaredge-solaredge-se66-6k-synergy-277-480v) | 66.6 kW | 98.0% | | | Similar on paper | | [SolarEdge SE66.6K (Synergy) – secondary unit (physical)](https://comparepv.com/inverter/solaredge-solaredge-se66-6k-synergy-secondary-unit-physical) | 66.6 kW | 98.0% | | 45.0 kg | Similar on paper | | [SolarEdge SE66.6K (400V grid)](https://comparepv.com/inverter/solaredge-se66-6k-400v-grid) | 66.6 kW | 98.0% | | | Similar on paper | | [SolarEdge SE66.6K (Synergy, 380/400V)](https://comparepv.com/inverter/solaredge-se66-6k-synergy-380-400v) | 66.6 kW | 98.0% | | 32.0 kg | 13.0 kg lighter | | [SolarEdge SE66.6K (IL00IBNQ4)](https://comparepv.com/inverter/solaredge-se66-6k-il00ibnq4) | 66.6 kW | 98.0% | | | Similar on paper | | [Growatt MAC 66KTL3-X MV](https://comparepv.com/inverter/growatt-mac-66ktl3-x-mv) | 66 kW | | 3 | 52.0 kg | -0.6 kW, 7.0 kg heavier | --- Source: https://comparepv.com/inverter/solaredge-solaredge-se66-6k-k66-6se-secondary-unit