--- title: "Growatt WIT 40K-A-US L2 / WIT 40K-AU-US L2 Hybrid Inverter: Specs & Datasheet | ComparePV" description: "Growatt WIT 40K-A-US L2 / WIT 40K-AU-US L2 40 kW hybrid inverter. Specs: 120.0 kg." source: "https://comparepv.com/inverter/growatt-wit-40k-a-us-l2-wit-40k-au-us-l2" updated: 2026-01-16 --- # Growatt WIT 40K-A-US L2 / WIT 40K-AU-US L2 ## Identity - **Manufacturer:** Growatt - **Model:** WIT 40K-A-US L2 / WIT 40K-AU-US L2 - **Series:** WIT 28-55kW - **Rated AC power:** 40 kW - **Type:** Hybrid - **Phases:** Three-phase - **Battery port:** yes ## 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 | - | 98.2% | | | | MPPT trackers | - | 4 | | | | Max DC input voltage | - | 1100 V | | | | Weight per kW | 3.0 | 1.1 | Weak - bottom 2% | 221 | | Warranty | - | 5 yrs | | | ## Specification ### AC output - **Rated AC power:** 40 kW - **Max AC power:** 44.00 kW - **Max apparent power:** 44.00 kVA - **Phases:** Three-phase - **Max AC current:** 122.2 A - **Power factor:** -1 ... +1 - **Harmonic distortion (THD):** 3.0 % ### Efficiency - **Max efficiency:** 98.0 % ### Battery - **Battery port:** Yes - **Battery voltage:** 380~450V - **Grid-forming:** Yes ### Physical - **Dimensions:** 820 × 1350 × 501 mm - **Weight:** 120.0 kg - **Enclosure:** IP66/NEMA 4X - **Operating temperature:** -30 to 60 °C - **Max altitude:** 4000 m ### Connectivity and protection - **Interfaces:** Display - **Protocols:** RS485, CAN, USB, 4G/LAN (optional) - **Protection:** Surge protection ### Warranty and certificates - **Certifications:** UL 1741:2021, UL 1741 SA, IEEE 1547:2018, IEEE 1547.1:2020, CSA C22.2 No.107.1, FCC Part 15, CEC, Rule 21, HECO, SRD, PG&E NBT (listed in footnote) ### Pros - **UPS with Black Start - Switchover Time \<20 ms** - The built-in UPS function switches power to selected circuits in under 20 ms (per manufacturer specification), protecting voltage-sensitive loads such as cold-storage units, servers, and production lines from outages. The black-start capability allows the system to restart without grid availability - a rare feature in the C&I inverter segment that sets this series apart from conventional grid-tied inverters. - **Peak Efficiency 98%, European Efficiency ~97%** - Maximum conversion efficiency reaches 98%, with a European efficiency of ~97% - figures that place this series in the upper tier of the 28-55 kW hybrid inverter segment. Over a 20-year system lifetime, this translates into meaningfully higher energy yield under Polish climatic conditions, which are characterized by predominantly partial cloud cover and frequent below-rated irradiance levels. - **DC/AC Ratio up to 2.0 and Multiple MPPT Trackers** - A DC/AC ratio of up to 2.0 allows safe PV array oversizing without clipping risk, boosting morning and afternoon energy harvest. Multiple independent MPPT trackers (input up to 800 V DC) enable strings with different orientations and tilt angles to be handled separately, minimizing partial-shading losses - a key advantage on the complex roofscapes typical of industrial facilities. - **Scalability up to 165 kW via Parallel Operation** - The series supports parallel connection of multiple units, delivering a combined AC output of up to 165 kW within a single system. This allows installations to be expanded incrementally as site demand grows, without requiring inverter replacement - a significant advantage for warehouses and commercial facilities with phased build-out plans. - **Factory-Integrated Type II SPD (DC + AC) and 110% AC Overload Capability** - Factory-fitted Type II surge protective devices on both the DC and AC sides eliminate the cost and installation of additional SPD modules otherwise required under IEC 60364-7-712 for commercial PV systems. Continuous operation at 110% of rated AC load ensures stability during motor start-up transients and momentary demand spikes. ### Cons - **No BNEF Tier-1 Bankable Inverter Status** - Growatt does not appear on the BloombergNEF Tier-1 Power Inverter Manufacturers list (as of Q1 2026 per available publications), which may represent a barrier to project financing by banks and funds that require this classification as a condition of project finance. Competitors such as SMA, Fronius, and Huawei hold Tier-1 status, giving them a structural advantage in institutional tenders and debt financing processes. - **Standard Warranty Only 5 Years** - The base manufacturer warranty is 5 years - below C&I market expectations, where SMA offers 5 years with an extension option up to 20 years (SMA Extended Warranty) and Fronius provides a standard 5-year warranty extensible to 10 years. For commercial sites operating under bankable long-term agreements such as PPAs of 15+ years, a short base warranty period represents a genuine contractual risk. ## About this series Growatt WIT 28-55kW series is a **three-phase hybrid inverter** designed for commercial and industrial installations, where stable network operation and realistic energy self-consumption with energy storage are key. What sets it apart is the **built-in UPS and black start function**, enabling selected circuits to remain powered and allowing the system to start up even after a network outage - a solution particularly useful in service facilities, refrigeration units, or farms. The use of **multiple MPPT trackers** facilitates designing PV fields on different roof sections and minimizes losses due to partial shading, resulting in more stable energy yields throughout the day. The high European efficiency means fewer conversion losses under typical climatic conditions in Poland, thus delivering more energy to consumers or storage. Remote monitoring and communication are available (WiFi, Ethernet modules, 4G solutions, app, and platform), simplifying service and operational control. This series works with high-voltage energy storage systems, features comprehensive safety measures (including SPD type II on both DC and AC sides), and comes with certifications required for target markets and region-dependent, purchase-condition-based warranty. ## Questions ### How many MPPT trackers does the Growatt WIT 28-55kW inverter have, and is that sufficient for a multi-slope roof installation? The WIT 28-55kW series features multiple independent MPPT trackers - up to 10 in the US L2 variant - allowing separate PV strings from different roof slopes or azimuths to be connected independently. Because each tracker operates autonomously, shading on one string group does not degrade the output of the remaining strings. This is particularly important in commercial installations where rooftops are often divided by penthouses, skylights, or HVAC equipment. ### Does the Growatt WIT 28-55kW provide backup power during a grid outage? Yes. The WIT 28-55kW series includes a built-in UPS function and black-start capability, meaning that a designated backup circuit can be powered from the energy storage system even when the grid is unavailable. The black-start feature allows the inverter to restart autonomously after a complete loss of power, without requiring an external trigger. This makes the solution well suited to cold-storage facilities, commercial premises, and agricultural operations where grid interruptions result in measurable financial losses. ### Which energy storage systems are compatible with the Growatt WIT 28-55kW? The inverter is designed for use with high-voltage battery systems, including solutions from Growatt's own portfolio (the APX series). The wide battery voltage range minimises conversion losses and improves both charging and discharging efficiency. Before selecting a specific storage unit, it is advisable to consult the current compatibility list available from your distributor or in the technical documentation, as the manufacturer regularly expands it. ### What is the warranty on the Growatt WIT 28-55kW inverter, and can it be extended? The standard warranty for Growatt inverters is 5 years. The manufacturer offers an extended warranty option that can provide up to 10 years of coverage in total. The exact terms depend on the sales region and the agreement concluded with the distributor. For commercial installations, it is therefore recommended to confirm the scope of service and the guaranteed response time directly with the supplier before purchase. ### How can the Growatt WIT 28-55kW inverter be monitored remotely? The WIT 28-55kW series supports WiFi, Ethernet, and optionally 4G communication modules, enabling connection to the Growatt ShineServer platform and its mobile application. Both the installer and the site owner can track energy production, storage state of charge, self-consumption, and grid parameters in real time. For industrial installations, RS485 and Modbus interfaces are also available, facilitating integration with BMS or SCADA systems. ### Does the Growatt WIT 28-55kW hold the certifications required for the European market, and what efficiency does it achieve? The European version of the inverter carries the certifications required for operation on the Polish and EU power grids. Peak efficiency reaches approximately 98.2%, while the weighted European efficiency - calculated for typical climatic conditions - is marginally lower, resulting in minimal conversion losses throughout the year. Type II SPD surge protection on both the DC and AC sides safeguards the installation against atmospheric and grid-borne overvoltages. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/inverters/WIT-28-55K-AU-US-L2-d1273943caf3.pdf) ## Alternatives | Inverter | Rated AC | Euro efficiency | MPPT | Weight | Difference | | --- | --- | --- | --- | --- | --- | | [GoodWe GW40K-ET-10](https://comparepv.com/inverter/goodwe-gw40k-et-10) | 40 kW | 97.8% | | 62.0 kg | 58.0 kg lighter | | [Ginlong Solis S6-EH3P40K-H](https://comparepv.com/inverter/ginlong-solis-s6-eh3p40k-h) | 40 kW | 97.4% | | 73.0 kg | 47.0 kg lighter | | [Growatt MID 40K-HU](https://comparepv.com/inverter/growatt-mid-40k-hu) | 40 kW | 97.2% | | 48.0 kg | 72.0 kg lighter | | [Deye SUN-40K-SG01HP3-EU-BM4](https://comparepv.com/inverter/deye-sun-40k-sg01hp3-eu-bm4) | 40 kW | 97.0% | | 80.0 kg | 40.0 kg lighter | | [Growatt WT 40K-H-US L2 / WT 40K-HU-US L2](https://comparepv.com/inverter/growatt-wt-40k-h-us-l2-wt-40k-hu-us-l2) | 40 kW | | 2 | 140.0 kg | 20.0 kg heavier | | [Growatt WIT 40K-XHU](https://comparepv.com/inverter/growatt-wit-40k-xhu) | 40 kW | | 4 | 90.0 kg | 30.0 kg lighter | | [PowMr SOLXPOW X4-40K](https://comparepv.com/inverter/powmr-solxpow-x4-40k) | 40 kW | | | 72.0 kg | 48.0 kg lighter | | [Growatt MID 36K-HU](https://comparepv.com/inverter/growatt-mid-36k-hu) | 36 kW | 97.2% | | 48.0 kg | -4.0 kW, 72.0 kg lighter | --- Source: https://comparepv.com/inverter/growatt-wit-40k-a-us-l2-wit-40k-au-us-l2