Connecting batteries — parallel vs series
Parallel connection increases capacity at the same voltage. Series connection increases voltage at the same capacity. For home systems with a 48V hybrid inverter, parallel is needed 90% of the time — to add more kWh without changing voltage.
Parallel connection: more capacity
Two 5.12 kWh LiFePO4 modules in parallel = 10.24 kWh at 51.2 V. Voltage stays at 51.2 V — the inverter sees one large battery.
How to connect in parallel: step by step
- Check compatibility: both modules same brand, same model, preferably same batch
- Equalize charge: difference no more than 1 V before connecting
- Connect power cables: positive to positive, negative to negative. Cable cross-section from 16 mm²
- Connect communication cables: CAN or RS485 in daisy-chain
- Power on: batteries first, then inverter
Maximum parallel modules by brand:
- Deye BOS-G: up to 32 modules
- Veichi: up to 16 modules
- Felicity Solar: up to 16 modules
Safety rules
- Each module gets its own DC fuse or breaker
- Cable lengths from each module must be equal (±10 cm)
- Never connect modules with charge difference over 5 V
Series connection: more voltage
Two 51.2 V modules in series = 102.4 V. Required for powerful inverters at 96V or higher.
When series connection is needed
- Three-phase inverters 10+ kW
- Industrial systems with high DC bus voltage
For single-phase home systems (3-6 kW) — not needed.
How to connect in series
- Positive of first module → negative of second module
- Free negative of first + free positive of second → to inverter
- Identical modules, same capacity, same charge level
Combined connection: series-parallel
For 96V systems with large capacity: pairs of modules in series, then pairs in parallel. Requires qualified installation.
Common mistakes
- Different brands in parallel: BMS systems conflict. We have seen this at least 15 times
- Different capacity in series: smaller module gets overcharged
- Different cable lengths: uneven current distribution
- Did not equalize charge: surge of equalizing current → BMS damage
Tools needed
- Power cables 16-25 mm²
- Communication cable RJ45/RS485
- DC breakers or fuses
- Torque wrench (8-12 Nm)
- Multimeter
Browse the LiFePO4 battery catalog. For matching with your hybrid inverter, contact our team.
Frequently Asked Questions
How many modules can be connected in parallel?
Depends on model. Deye BOS-G — up to 32, Veichi — up to 16. For a home, 2-4 is usually enough.
Can I add a module after a year?
Yes, same model and brand. Charge to the same level before connecting.
What happens with different brand batteries?
BMS systems conflict, one battery takes all current. After a year — failure.
Does each module need its own fuse?
Yes. Each module must have its own DC fuse or breaker. This is a safety requirement.
Does parallel connection increase maximum current?
Yes. Two modules in parallel = double the discharge current.
Summary
Parallel for capacity, series for voltage. Same modules, same charge, same cables. Battery catalog for inverters is on our website.
