--- title: "Sofar Solar ESI-9.9K-T1-A Hybrid Inverter: Specs & Datasheet | ComparePV" description: "Sofar Solar ESI-9.9K-T1-A 9.9 kW hybrid inverter. Specs: 97.5% European efficiency, 3 MPPT, 1000 V max DC input, 30.0 kg." source: "https://comparepv.com/inverter/sofar-solar-esi-9-9k-t1-a" updated: 2026-01-16 --- # Sofar Solar ESI-9.9K-T1-A ## Identity - **Manufacturer:** Sofar Solar - **Model:** ESI-9.9K-T1-A - **Series:** ESI-5-12K-T1 - **Rated AC power:** 9.9 kW - **Type:** Hybrid - **Phases:** Three-phase - **Battery port:** yes ## How it compares Compared against 266 inverters from 6 to 12 kW. Ranks are within that class. | Measure | This inverter | Class median | Standing | Rank in class | | --- | --- | --- | --- | --- | | European efficiency | 97.5% | 97.6% | Typical | 104 | | MPPT trackers | 3 | 2 | Strong - top 13% | 6 | | Max DC input voltage | 1000 V | 1000 V | Typical | 59 | | Weight per kW | 3.0 | 2.3 | Typical | 191 | | Warranty | - | 5 yrs | | | ## Specification ### AC output - **Rated AC power:** 9.9 kW - **Max apparent power:** 9.90 kVA - **Phases:** Three-phase - **Nominal AC voltage:** 400 V - **Max AC current:** 15.0 A - **Grid frequency:** 50 Hz - **Power factor:** 0.8 lagging to 0.8 leading - **Harmonic distortion (THD):** 3.0 % ### PV input - **Max DC input power:** 20.00 kW - **Max DC voltage:** 1000 V - **MPPT voltage range:** 160 to 950 V - **Start-up voltage:** 200 V - **MPPT trackers:** 3 - **Max input current per MPPT:** 20.0 A - **Max short-circuit current per MPPT:** 25.0 A ### Efficiency - **European efficiency:** 97.5 % - **Max efficiency:** 98.2 % ### Battery - **Battery port:** Yes - **Battery voltage:** 350-435 Vdc - **Max charge current:** 25.0 A ### Physical - **Dimensions:** 440 × 708 × 170 mm - **Weight:** 30.0 kg - **Enclosure:** IP66 - **Cooling:** natural - **Operating temperature:** -30 to 60 °C - **Max humidity:** 95 % - **Max altitude:** 4000 m ### Connectivity and protection - **Interfaces:** Display - **Protocols:** RS485, CAN (BMS), WiFi (optional), 4G (optional), LAN (optional) - **Protection:** AFCI, DC switch, Surge protection ### Pros - **3× MPPT, 160-950 V Range, 20 A per Tracker** - Three independent MPPT trackers with a wide voltage window of 160-950 V and up to 20 A per tracker allow strings with different orientations or partial shading to be connected without cross-loading losses. This is one of the broadest DC input specifications in the 5-12 kW three-phase residential hybrid inverter class - for reference, the Fronius Symo GEN24 Plus offers only 2× MPPT in this power range. - **Up to 98.2% Efficiency - Top of the Segment** - A peak efficiency of 98.2% places this series in the top quartile of three-phase hybrid inverters in the 5-12 kW range. Under Polish irradiation conditions (approximately 1,050-1,200 kWh/m²/year), every percentage point of efficiency translates to several hundred additional kWh of annual yield on a 10 kWp system. - **IP65/IP66 Rating and -30 to +60°C Operating Range** - High ingress protection against dust and water, combined with a wide operating temperature range of -30 to +60°C, eliminates the need for installation in a heated enclosure. In the Polish climate, where winter temperatures regularly drop below -15°C, this is a practical advantage over inverters with a more limited IP55 rating. - **EPS Switchover in Under 10 ms** - The switchover time to islanding mode (EPS/off-grid) is under 10 ms - on par with UPS-class equipment. This means connected IT devices such as NAS units, routers, and computers do not experience a restart during a grid outage, which is a meaningful advantage for small businesses and remote workers. - **Local Service Center in Poland** - Sofar Solar operates a dedicated service center in Tarnów (ul. Jana Kochanowskiego 30, tel. +48 22 428 50 99) with Polish-language support. A local service point shortens response times and minimizes the risk of extended system downtime compared to brands serviced exclusively from headquarters in China. ### Cons - **Standard Hybrid Warranty - 5 Years** - Sofar Solar's global standard warranty for hybrid inverters is 5 years, compared to the 10-year standard offered by Huawei SUN2000-5K-LT or SMA Sunny Tripower Smart Energy. An extension to 10 years is available, but at additional cost. For a system designed for a 20-25 year lifespan, this represents either an added expense or elevated service risk beyond year five. - **Battery Ecosystem Limited to BTS HV** - Officially certified compatibility covers primarily Sofar BTS high-voltage battery storage units. Integration of third-party batteries (e.g., BYD HVS, Pylontech Force) via CAN/RS485 is not officially confirmed by the manufacturer for this series, which limits flexibility in storage selection and may increase total system cost given the higher price point of the BTS portfolio. ## About this series The **Sofar Solar ESI-5-12K-T1 series** are hybrid three-phase inverters designed for installations where both high self-consumption and flexible energy storage expansion are key. These devices operate in grid-connected mode but can also handle off-grid operation if needed, facilitating the protection of critical circuits in homes or small businesses. A major advantage is the **3x MPPT** - independent trackers allow better utilization of energy from strings with different roof orientations or partial shading, stabilizing yields throughout the day. The high European efficiency translates into significantly lower losses under typical operating conditions in Poland, resulting in more energy delivered for consumption or battery charging. In practice, you’ll also appreciate the **integrated EMS** for intelligent energy management, along with extensive communication and monitoring options - including WiFi, RS485, CAN, plus optional Ethernet and an app. The series is **compatible with BTS energy storage systems** and enables system expansion, while the high IP rating facilitates indoor or outdoor installation. ## Questions ### What is the warranty period for the Sofar Solar ESI-5-12K-T1 series inverters? The manufacturer provides a standard 10-year warranty covering the entire ESI-5-12K-T1 series. The warranty covers manufacturing defects and damage arising under normal operating conditions, in accordance with Sofar Solar's terms and conditions. It is advisable to retain proof of purchase from an authorized distributor, as this document is required when filing a warranty claim. ### Does the Sofar Solar ESI-5-12K-T1 support off-grid operation during a grid outage? Yes, the ESI-5-12K-T1 series supports off-grid (EPS/backup) operation mode. In the event of a grid voltage loss, the inverter automatically disconnects from the grid and supplies selected critical circuits using power from the battery and current PV generation. The switchover time is less than 10 ms, ensuring that most connected devices do not experience any noticeable interruption. ### Which energy storage systems are compatible with the Sofar Solar ESI-5-12K-T1 inverter? The ESI-5-12K-T1 series is compatible with Sofar Solar's high-voltage BTS 5K battery modules (LiFePO4, 5.12 kWh, ~400 V). Between 1 and 6 battery modules can be connected to a single inverter, providing a total usable capacity ranging from 5.12 kWh to 30.72 kWh. This modular design allows the system to be scaled flexibly as energy demands grow over time. ### Why does the ESI-5-12K-T1 series feature 3 independent MPPT trackers, and what are the practical benefits? Three independent MPPT trackers allow PV strings with different orientations or roof pitch angles to be connected and optimized individually. This means that partial shading on one roof section - caused, for example, by a chimney - does not reduce the output of the remaining strings. The MPPT input current reaches 20 A per tracker, providing significant flexibility when sizing the number of panels per string. ### What ingress protection rating do the ESI-5-12K-T1 inverters carry, and can they be installed outdoors? The ESI-5-12K-T1 series inverters are rated IP65, providing full protection against dust ingress and water jets from any direction. This rating makes them suitable for installation both indoors (e.g., garage, boiler room) and outdoors - mounted directly on a wall or support structure. The operating temperature range of -25 °C to +60 °C ensures reliable performance through typical Northern European winter conditions. ### What monitoring and communication options does the Sofar Solar ESI-5-12K-T1 series offer? The ESI-5-12K-T1 series includes Wi-Fi, RS485, and CAN connectivity as standard, with an optional Ethernet port. The integrated Energy Management System (EMS) enables real-time monitoring of PV generation, energy consumption, and battery state of charge via the Sofar Solar mobile application. Data can also be integrated with third-party systems over RS485, which is particularly useful in commercial installations. ## Datasheet [Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/inverters/esi-5-12k-t1-datasheet-2025-06-16-v2-0-en-int-2ac9877fa6a3.pdf) ## Alternatives | Inverter | Rated AC | Euro efficiency | MPPT | Weight | Difference | | --- | --- | --- | --- | --- | --- | | [Growatt SPM 10000TL-HU](https://comparepv.com/inverter/growatt-spm-10000tl-hu) | 10 kW | 96.5% | 3 | 48.8 kg | -1.0 pp efficiency, 18.8 kg heavier | | [SolarEdge SE10000H](https://comparepv.com/inverter/solaredge-se10000h) | 10 kW | 99.0% | | 19.6 kg | +1.5 pp efficiency, 10.4 kg lighter | | [Growatt MOD 10KTL3-XH](https://comparepv.com/inverter/growatt-mod-10ktl3-xh) | 10 kW | 98.1% | 2 | 14.0 kg | +0.6 pp efficiency, -1 MPPT, 16.0 kg lighter | | [Growatt MOD 10KTL3-HU](https://comparepv.com/inverter/growatt-mod-10ktl3-hu) | 10 kW | 98.1% | 3 | 20.0 kg | +0.6 pp efficiency, 10.0 kg lighter | | [Huawei SUN2000-10KTL-M1](https://comparepv.com/inverter/huawei-sun2000-10ktl-m1) | 10 kW | 98.1% | 2 | 17.0 kg | +0.6 pp efficiency, -1 MPPT, 13.0 kg lighter | | [Huawei SUN2000-10KTL-M1 (High current version)](https://comparepv.com/inverter/huawei-sun2000-10ktl-m1-high-current-version) | 10 kW | 98.1% | 2 | 17.0 kg | +0.6 pp efficiency, -1 MPPT, 13.0 kg lighter | | [Huawei SUN2000-10K-MAP0](https://comparepv.com/inverter/huawei-sun2000-10k-map0) | 10 kW | 98.1% | 2 | 21.0 kg | +0.6 pp efficiency, -1 MPPT, 9.0 kg lighter | | [Sungrow SH10RT](https://comparepv.com/inverter/sungrow-sh10rt) | 10 kW | 97.9% | 2 | 27.0 kg | +0.4 pp efficiency, -1 MPPT, 3.0 kg lighter | --- Source: https://comparepv.com/inverter/sofar-solar-esi-9-9k-t1-a