Sofar Solar ESI-9.9K-T1 — The three-phase hybrid inverter that transforms your home
The Sofar Solar ESI-9.9K-T1: three-phase power for large installations and professionals
The Sofar Solar ESI-9.9K-T1 is the 9,900 W three-phase hybrid inverter in the ESI range — the most powerful model in the series. It is designed for large homes of 150 m² and above, farmers, tradespeople and small businesses with a three-phase installation looking to maximise their solar self-consumption. A key advantage for the Belgian market: it is Synergrid-certified, ensuring immediate compliance with the requirements of distribution network operators. Its maximum efficiency reaches 98.2% — the highest in the ESI range — with the capacity to handle up to 20 kWp of panels.
What this inverter actually does
- It converts the energy from your solar panels into three-phase 380/400/415V AC electricity with a maximum efficiency of 98.2% and 3 independent MPPT trackers to optimise each string separately
- It stores surplus energy in Sofar BTS 5K lithium batteries (high-voltage LiFePO4, 350–435 V) for use in the evening, at night or in the event of a grid outage
- It secures your power supply with a switchover to backup power in under 10 ms — imperceptible to your electronic devices, machinery and professional equipment
- It monitors your installation in real time via the SolarMan Smart app (iOS / Android), with built-in Wi-Fi at no extra cost
- It feeds surplus energy back into the grid if your contract allows
With 25 to 45 solar panels (10 to 20 kWp) and a Sofar BTS battery storage system of 10 to 20 kWh, a large house or small business can achieve 65 to 80% self-consumption, representing an estimated saving of between €1,200 and €2,500 per year depending on consumption patterns.
20 kWp capacity: the solution for large roofs and businesses
With a recommended PV input capacity of 20 kWp, the ESI-9.9K-T1 is designed for large rooftops on houses, agricultural sheds or commercial buildings. Its 3 independent MPPT trackers (range 160–950 V, 25 A per MPPT) allow panels to be distributed across multiple orientations or roof sections without any loss of performance — each string is optimised separately, even if one of them is partially shaded.
Synergrid-approved: guaranteed compliance with the Belgian grid
The ESI-9.9K-T1 is Synergrid-approved, meaning it meets the technical standards set by distribution network operators in Belgium. This certification simplifies the connection process and avoids delays associated with exemption requests. A decisive advantage for installers and customers seeking rapid commissioning.
Passive cooling: zero noise, zero maintenance
The ESI-9.9K-T1 relies exclusively on natural convection to dissipate heat — no mechanical fans. Three key benefits:
- Silent operation: no fan noise, even at full load — ideal for installation in a plant room, machinery room or near offices
- Increased reliability: the absence of moving mechanical parts eliminates the main source of failure in inverters
- IP66 protection: suitable for outdoor installation, in agricultural sheds or unheated rooms
Scalable storage: from 5 to 30.72 kWh
The ESI-9.9K-T1 is exclusively compatible with Sofar BTS 5K lithium batteries (LiFePO4, 5.12 kWh per module, 400 V high voltage). Between 1 and 6 modules can be connected in parallel, with a maximum discharge current of 29.7 A:
- 1 module (5.12 kWh): basic backup, small building
- 2–3 modules (10–15 kWh): large house or moderate commercial consumption
- 4–6 modules (20–30 kWh): high consumption, agricultural or light industrial use
⚠️ Important: the inverter operates without a battery in direct self-consumption mode. In the event of a grid outage without a battery connected, it shuts down (standard anti-islanding protection). Storage can be added after installation.
Monitoring: SolarMan Smart
Wi-Fi is built into the inverter — no additional dongle is required for basic monitoring. The SolarMan Smart app (iOS / Android) allows you to:
- View real-time production, consumption and battery status
- Check your daily, monthly and annual savings
- Diagnose faults remotely
- Manage multiple installations from a single account — ideal for installers and fleet managers
Additional connectivity options: LAN (wired), RS485 / CAN (battery and meter communication), optional 4G for sites without Wi-Fi (hangars, remote farms).
Installation
Installation must be carried out by a qualified electrician. Key points:
- Weight: 30 kg — two people are required for wall mounting
- Dimensions: 708 × 440 × 170 mm
- IP66 protection — suitable for outdoor installation, in a shed or unheated technical room
- Passive cooling, silent operation
- PV start-up voltage: 200 V — power generation possible from the first hours of daylight
- Operates without a battery from the moment of installation
- Synergrid-approved — guaranteed compliance with the Belgian grid without any additional steps
SolarMan Smart
SofarSolar is redefining the future of energy with smart inverters. Equipped with advanced monitoring features, our inverters come with a WiFi Stick as standard, paving the way for seamless connectivity. Choose your path to efficiency with options such as Ethernet, GPRS or LTE dongles. Transform every installation into a digital symphony, where solar power becomes a connected, smart and sustainable experience. SofarSolar, your partner for smarter and brighter energy.
Apple Store - Solarman Smart
Android - Google Play - Solarman Smart
Setup steps:
1. After launching the app, register as a new user or enter your current SOLARMAN login details.
2. Create a new system and enter the system data.
3. Scan the barcode on the logger stick to assign an inverter to the system.
4. Go to the newly created system to configure the logger stick (device/logger).
5. Press the button on the WiFi dongle for 1 second to activate the dongle’s WPS mode so that the smartphone can connect to the WiFi dongle.
6. Now select your local WiFi network for internet access and enter your WiFi password.
7. The WiFi dongle is now configured with the access details.
The future of energy in your home
The Sofar Solar ESI-9.9K-T1 is more than just an inverter: it is the heart of your energy self-sufficiency. With its 9.9 kW output, scalable storage and responsiveness, it ensures your home is always powered, more economical and more environmentally friendly.
FAQ – Sofar Solar Tri 9.9 kW Hybrid Inverter – ESI-9.9K-T1
1. What is the Sofar Solar ESI-9.9K-T1 hybrid inverter and what is it designed for?+
The Sofar Solar ESI-9.9K-T1 is a 9,900 VA / 9,900 W three-phase hybrid inverter, Synergrid-approved for installation in Belgium. It converts the solar energy generated by your panels into three-phase 380/400/415 V alternating current, manages storage in lithium batteries and provides an automatic backup power supply in the event of a grid outage. With a maximum efficiency of 98.2% and a European efficiency rating of 97.5%, it is the go-to solution for large family homes, SMEs or farms looking to maximise their self-consumption and energy independence.
2. What is the maximum solar panel capacity that can be connected to the Sofar ESI-9.9K-T1?+
The ESI-9.9K-T1 accepts up to 20,000 Wp (20 kWp) of solar panels at the input, representing a PV oversizing of over 200% compared to its rated power. It features 3 independent MPPT trackers (1 string per MPPT) with an input current of 25 A each, an MPPT voltage range of 160 to 950 V and a maximum input voltage of 1,000 V. This 3-MPPT architecture is particularly advantageous for installations with multiple roof orientations or where partial shading is present, as each panel is managed completely independently.
3. Which batteries are compatible with the Sofar ESI-9.9K-T1 and what storage capacity is possible?+
The ESI-9.9K-T1 is designed to work with Sofar Solar BTS 5K LiFePO4 lithium batteries (5.12 kWh / 100 Ah / 400 V high voltage). It accepts a battery voltage range of 350 to 435 V, with a maximum discharge current of 29.7 A — a higher value than that of the ESI-8K-T1 model (24 A), allowing for faster energy exchange with the batteries. The storage capacity is fully scalable from 5.12 kWh to 30.72 kWh (1 to 6 BTS 5K modules in parallel), allowing you to precisely tailor the runtime to your consumption and upgrade the system over time.
4. Does the ESI-9.9K-T1 work without batteries? Can batteries be added later?+
Yes, the inverter can operate without a battery in direct self-consumption mode: the solar energy produced is consumed immediately by your appliances, and any surplus is fed into the grid or regulated according to your configuration. Storage can be added at any time thanks to the modularity of the BTS 5K system, without replacing the inverter. This allows you to start with a manageable initial investment and gradually increase autonomy according to your needs. However, without a battery, the EPS backup function will not be available during a grid outage.
5. What happens during a power cut? Does the ESI-9.9K-T1 provide backup power?+
Yes. The ESI-9.9K-T1 automatically switches to off-grid mode (EPS) in under 10 ms during a power cut, a delay that is virtually imperceptible to your electronic devices (computers, internet routers, fridge, lighting, heat pump, etc.). With a rated power of 9,900 VA in three-phase mode, it is capable of powering an entire large home or business premises during an outage. This function requires one or more Sofar BTS 5K batteries to be connected and sufficiently charged.
6. How can I monitor and control the system remotely with the Sofar ESI-9.9K-T1?+
The inverter comes with Wi-Fi, LAN (Ethernet), RS485 and CAN as standard. A 4G module is available as an option for sites without a fixed internet connection. Monitoring is carried out via the SolarMan Smart app (iOS & Android), which allows you to view solar production, battery status and consumption in real time, schedule charging during off-peak hours, and update the firmware remotely. The integrated EMS (Energy Management System) automatically optimises energy flows between panels, batteries, the grid and domestic consumption to maximise your self-consumption rate.
7. Is the ESI-9.9K-T1 Synergrid-approved for Belgium? What certifications does it have?+
Yes, the ESI-9.9K-T1 is Synergrid-approved (C10/11 standard), the mandatory Belgian standard for connecting photovoltaic installations with storage to the distribution grid. This approval is particularly important for property owners subject to the prosumer tax in Wallonia, Flanders and Brussels, as it determines the legality of commissioning and eligibility for any grants. The inverter is also VDE-certified (Germany), making it fully compliant for use throughout Western Europe.
8. What are the dimensions, weight and installation requirements of the Sofar ESI-9.9K-T1?+
The inverter measures 708 × 440 × 170 mm and weighs 30 kg — the same dimensions as the ESI-8K-T1 model, making replacement or upgrading easy. Its natural convection cooling (fanless) ensures silent operation and requires no mechanical maintenance. The IP66 rating allows for installation both indoors and outdoors (garage, plant room, sheltered façade). The operating temperature range is -30 °C to +60 °C (derating above +45 °C), with a PV start-up voltage from 200 V for maximised output from the very first hours of sunshine.
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