S3-20
Modular and expandable energy storage covering home, balcony and small residential energy applications.
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Key data at a glance
Explore the key specifications below. Contact our team to discuss your application and configuration.
Specifications
- Battery chemistry
- Rechargeable Lithium-ion (LiFePO4)
- Battery capacity
- 2010 Wh
- Maximum charging power
- 2400 W (maximum with expansion packs)
- Cycle life
- 6,000 rated cycles
- Operating temperature
- -20°C to +55°C
- Connectivity
- Wi-Fi / Bluetooth
- Dimensions / weight
- 350 × 174 × 225 mm / 20 kg
- Expansion capability
- Supports 2–10 kWh modular expansion
Technical Overview
Quick answer: The S3-20 is a 2.01 kWh balcony micro DC energy storage system with 2,400 W PV input across two MPPT channels, 99.9% MPPT efficiency, and expandability to 10 kWh via up to four SE-20 expansion batteries—delivering 40%+ volume reduction and 88.2% higher energy density in an IP65, 20 kg package.
What Is the S3-20?
The S3-20, from Kunlu Electronic Technology (Shanghai) Co., Ltd., is a micro DC-coupled energy storage system (ESS) for balcony solar installations. It sits between the PV panels and a microinverter, storing surplus solar energy in a LiFePO₄ (LFP) battery instead of exporting it. Its compact enclosure measures just 350 × 174 × 225 mm and weighs 20 kg—lighter and smaller than conventional balcony batteries, with a 15-year design life.
Key Technical Specifications (S3-20)
| Parameter | Value |
|---|---|
| Battery type / capacity | LFP, 2.01 kWh @ 51.2 V (43.2–57.6 V range) |
| Expandable capacity | Up to 10 kWh |
| PV input power | 2,400 W max, 2 channels |
| MPPT voltage range | 20–54 V per channel (13–60 V operating, 60 V max) |
| Max input current / Isc | 32 A / 40 A per channel |
| Recommended module power | 300–600+ W, up to 2 modules per channel |
| DC output | 1,200 W max, 30 A, 20–45 V |
| MPPT efficiency | 99.9% |
| Charge–discharge efficiency | 94.0% |
| Protection / temperature | IP65 / −20 °C to +55 °C |
| Communication | Wi-Fi (Bluetooth) + RS485 |
| Certifications | CE, WEEE, UN38.3, RoHS, REACH, IEC 62619 |
How Does Expansion Work?
The S3-20 pairs with the SE-20 expansion battery pack (2.01 kWh, 350 × 174 × 182 mm, 18 kg). Up to four SE-20 units daisy-chain to the master unit for a total of 10 kWh, with an easy plug-in connection supporting a 2.5–15 kWh system range across configurations. Expansion raises maximum charge power to 2,400 W.
Why DC-Coupled Storage?
By storing energy before inversion, the S3-20 achieves 99.9% MPPT tracking efficiency and 94% battery charge–discharge efficiency. Its high-voltage cell boost technology increases energy density by 88.2% while cutting enclosure volume by more than 40% compared with previous-generation balcony ESS units—critical for rail-mounted balcony installations where weight and space are limited.
Safety and Reliability
The system uses LiFePO₄ chemistry, IP65 dust and water protection, natural convection cooling (no fans, no noise), and 6,000-rated cycles. It operates from −20 °C to +55 °C at up to 2,000 m altitude and 0–95% relative humidity (non-condensing).
Monitoring and Control
The iEnergy app provides real-time monitoring and control of charging, discharging, and expansion status over Wi-Fi or Bluetooth; RS485 is available for integration.
FAQ
What solar panels suit the S3-20? Any module of 300–600+ W within the 13–60 V per-channel window; up to two modules per channel, two channels total.
Can it work in winter? Yes, it operates down to −20 °C.
Is it certified for Europe? Yes—CE, RoHS, REACH, WEEE, UN38.3, and IEC 62619.