SOFAR Hybrid Inverters with Second-Life EV Batteries

The SOFAR HYD KTL-3PH series is a three-phase hybrid inverter line spanning 3 kW to 20 kW with a 180–800 V DC battery input. It talks CAN using the BYD Battery-Box HVM/HVS frame set, which BMS-EV emulates for used EV packs.

What SOFAR hybrid inverters do. SOFAR Solar HYD 3-20KTL-3PH is a three-phase hybrid inverter that manages PV MPPT, battery charge/discharge and grid interaction in one unit. The battery port accepts 180–800 V DC (nominal window 350–650 V for optimal efficiency). Battery communication is CAN 2.0B at 500 kbps using a BYD Battery-Box protocol frame set. Compatible second-life packs include Tesla Model 3/Y, BMW i3, VW MEB (ID.3/ID.4), and Hyundai/Kia 400 V variants (Kona EV, Niro EV).

About SOFAR

Shenzhen SOFAR Solar Co., Ltd. is a Chinese inverter manufacturer. SOFAR publishes battery communication documentation as an installer PDF ("SOFAR HYD Battery Communication Protocol Rev. 3.x"); the frame set is a subset of the BYD Battery-Box protocol.

Supported models

Model	Phase	AC output	Battery DC	MPPT	Comms
HYD 3000-KTL-3PH	3P	3 kW	180–800 V	2	CAN 500k (BYD)
HYD 4000-KTL-3PH	3P	4 kW	180–800 V	2	CAN 500k (BYD)
HYD 5000-KTL-3PH	3P	5 kW	180–800 V	2	CAN 500k (BYD)
HYD 6000-KTL-3PH	3P	6 kW	180–800 V	2	CAN 500k (BYD)
HYD 8000-KTL-3PH	3P	8 kW	180–800 V	2	CAN 500k (BYD)
HYD 10KTL-3PH	3P	10 kW	180–800 V	2	CAN 500k (BYD)
HYD 15KTL-3PH	3P	15 kW	180–800 V	2	CAN 500k (BYD)
HYD 20KTL-3PH	3P	20 kW	180–800 V	2	CAN 500k (BYD)

DC voltage ranges

Battery port operating window: 180 V minimum (below this the inverter opens the battery contactor and stops), 800 V maximum (charge limit).
Three battery voltage ranges to distinguish: (1) Absolute range — 180–800 V DC (charge/discharge allowed); (2) Full-power range — depends on inverter model (5/6 kW: 180–800 V; 10 kW: ~200–800 V; 15 kW: ~300–800 V; 20 kW: ~400–800 V); (3) Efficient window — 350–650 V (highest DC/AC conversion efficiency). Below 300 V discharge power derates linearly with voltage; above 700 V charge current is reduced.
MPPT range: 180–1000 V (600 V nominal). PV strings and battery port are electrically separate.
Minimum start voltage: ≥200 V required at battery port to complete precharge sequence.

Communication protocol

SOFAR HYD uses CAN 2.0B at 500 kbps with 120 Ω termination. The frame set follows the BYD Battery-Box HVM/HVS specification. BMS-EV re-encodes vehicle BMS data into these frames.

CAN ID	Direction	Content
0x151	Inverter → Battery	Wake-up / handshake
0x250	Battery → Inverter	Handshake response, protocol version
0x290	Battery → Inverter	Charge/discharge V and I limits
0x2D0	Battery → Inverter	Manufacturer / serial ASCII
0x210	Battery → Inverter	SOC, SOH, pack V, I, T
0x110	Battery → Inverter	Alarms, protection flags
0x150	Battery → Inverter	Cell min/max V, min/max T

Handshake sequence is mandatory: SOFAR sends 0x151 on power-up and expects 0x250 within 5 s. Miss the handshake and the inverter enters "BAT COM ERR" state and will not retry until reboot.

Battery compatibility

Tesla Model 3/Y — 50/60/75/82 kWh, 315–403 V. Full window; charge target 396 V, discharge floor 300 V.
BMW i3 — 22/33/42 kWh, 260–402 V. Full window.
VW MEB (ID.3/ID.4/Skoda Enyaq) — 55/62/77/82 kWh, 288–418 V. Full window.
Hyundai/Kia 400 V E-GMP variants — Kona EV, Niro EV, Soul EV: 320–400 V.
Renault Zoe R135 52 kWh — 300–400 V.
Not supported: Native 800 V packs at full charge (Porsche Taycan, Audi e-tron GT, Hyundai Ioniq 5, Kia EV6) exceed the 800 V ceiling. Low-voltage Nissan Leaf 24/30/40 kWh re-configured as 48 V blocks — SOFAR HYD is HV-only, use SolaX X1 LV instead.

Wiring architecture

┌───────────────────┐ ┌────────────────┐ ┌──────────────────┐ │ EV battery pack │ │ BMS-EV │ │ SOFAR HYD KTL │ │ (Tesla / i3 / │ HV DC │ Controller │ CAN │ Battery port │ │ MEB / Kona EV) │──────►│ (precharge + │──────►│ 180–800 V │ │ │ │ translator) │ │ │ │ Vehicle BMS kept │ CAN │ BYD Battery- │ │ PV MPPT × 2 │ │ alive by 12 V │◄─────►│ Box HVM │ │ 180–1000 V │ │ from BMS-EV aux │ │ frame emu. │ │ │ └───────────────────┘ └────────────────┘ └────────┬─────────┘ │ │ AC 400 V 3-phase ▼ Grid + loads

Wiring is identical in topology to a native BYD Battery-Box install. The BMS-EV controller bridges the vehicle CAN bus (native EV protocol at 500 kbps) and the SOFAR battery CAN bus (BYD-frame 500 kbps). Precharge is handled by the BMS-EV controller on the pack side because SOFAR expects a "ready" pack.

Common integration guides

Known limitations

Handshake is strict. If the BMS-EV controller boots slower than the inverter's 5 s handshake window, HYD locks out until inverter reboot. Wire the controller so it boots before or with the inverter.
Only one battery bank. SOFAR HYD has one DC battery port. Parallel packs require external paralleling with matched voltage — not recommended.
800 V native packs not supported. Above 800 V full-charge voltage, HYD opens the contactor and cannot be reset without lowering pack voltage.
Firmware update path. Battery protocol versions changed between HYD firmware v2.0 and v3.x. Verify inverter firmware ≥ v3.00 before commissioning — the frame IDs above assume v3.x.
Single-phase not offered. HYD-KTL-3PH is three-phase only. Single-phase properties should use SOFAR HYD 3000ES/6000ES (a different, LV-only product line, not covered by BMS-EV).

FAQ

Is SOFAR HYD compatible with the Tesla Model 3 battery?

Not directly. Tesla uses a proprietary BMS protocol; SOFAR expects BYD Battery-Box frames. The BMS-EV controller sits between the two and translates in both directions.

What is the maximum battery voltage on HYD KTL-3PH?

800 V charge target. Charge should be capped 20–30 V below this ceiling for cell-imbalance headroom.

Does SOFAR need a specific battery firmware from BMS-EV?

Yes. BMS-EV ships pre-configured for SOFAR HYD firmware ≥ v3.00 with the BYD HVM frame set. Older SOFAR firmware (v2.x) uses different frame IDs — verify and update the inverter before commissioning.

Can SOFAR run without an internet connection?

Yes. The battery communication is local CAN — no cloud dependency. SOFAR's WiFi/4G dongle is monitoring-only and can remain disconnected.

What happens on grid loss?

HYD KTL-3PH supports off-grid backup with the AC backup port. Battery discharges to the backup AC bus while grid is isolated. Autonomous switchover is ≤20 ms per SOFAR spec.

Which grid codes are supported?

EN 50549, VDE-AR-N 4105, CEI 0-21, G98/G99, RD 1699, plus regional codes for AU, ZA, TH. Selected in installer menu at commissioning.

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Last updated: 2026-09-18

Current firmware: 15.0.14

Technical author: BMS-EV engineering team (Clima Boost sp. z o.o., Poland)

Reviewer: Jakub Lipiński, founder/lead engineer BMS-EV

Revision: 2026-09-18 — aligned with firmware 15.0.14, SOFAR 180–800 V DC verification, Kia EV6 + SOFAR HYD 15KTL case study reference

Parameter	Value	Source
HYD 5-20KTL-3PH battery voltage range	180–800 V DC absolute	SOFAR HYD 5-20KTL-3PH datasheet V5.2 (2024)
Two independent battery input channels	25 A each, ~10 kW each	SOFAR datasheet + Wattuneed HYD20KTL-3PH product page
Full-power range by model	5/6 kW: 180–800 V; 10 kW: 200–800 V; 15 kW: 300–800 V; 20 kW: 400–800 V	SOFAR datasheet section 4 (Battery Data)
BYD Battery-Box HVS protocol emulation	ARM V010 / DSP V010 minimum firmware	SOFAR HYD Battery Communication Protocol Rev. 3.x (installer PDF)