Parallel battery towers with the Combiner Box-300A
When one battery port runs out of terminals — use Deye's 300 A combiner box to parallel up to four battery towers into one inverter, and chain boxes for larger banks.
Updated 29 June 2026
On bigger residential and C&I battery banks you can run out of battery terminals on the inverter, or simply need to bring a lot of towers back to a single tidy connection point. The Combiner Box-300A is a busbar enclosure that parallels up to four battery towers and feeds the inverter through two outputs — and you can parallel multiple boxes for larger capacity.
📄 Manual: Combiner Box-300A installation manual (PDF) — Deye’s factory instructions (bilingual English/Chinese, diagram-led terminal layout).
What it is
A passive DC combiner — copper busbars in an IP55 enclosure. There are no electronics and no BMS inside: it carries power only, so each battery’s communication wiring still daisy-chains separately per the battery manual.
| Spec | Combiner Box-300A |
|---|---|
| Battery voltage range | MAX. 1000 V |
| Battery inputs | 4 (M8 screws) |
| Battery outputs | 2 (M10 screws) |
| Max. operating current | 300 A |
| IP rating | IP55 |
| Operating temperature | −40 ~ +60 °C (derates above 45 °C) |
| Cooling | Natural |
| Storage temperature | −40 ~ +80 °C |
| Relative humidity | 0 ~ 95% (condensing) |
| Altitude | < 3000 m |
| Dimensions (W × D × H) | 420 × 200 × 250 mm |
| Weight | 15 kg |
How it connects
Each battery tower lands on one of the four inputs; the two outputs run to the inverter’s battery port. For banks larger than four towers, parallel several combiner boxes together and feed the inverter from the combined output:
[towers ×4] → Combiner Box → ┐
[towers ×4] → Combiner Box → ┼─→ Inverter battery port
[towers ×4] → Combiner Box → ┘
Wiring notes
- Size the cable to the load, not just the box. At up to 300 A you need appropriately rated battery cable and protection — work it out the same way as 50K cable & breaker sizing.
- Keep paralleled cable runs equal length between towers so current shares evenly across the bank.
- Observe polarity and torque the M8 input / M10 output lugs to the manufacturer’s spec.
- Comms are separate. The combiner only joins the DC power; battery BMS communication still chains per the battery stacking guide.
- Mind the environment. IP55 and −40 ~ +60 °C make it suitable for a sheltered outdoor location, but derate above 45 °C and keep it out of direct weather where you can.
When you need one
Reach for a combiner box once the number of battery towers exceeds what the inverter’s battery terminals can take directly, or when you’re paralleling enough towers that a single shared busbar is cleaner and safer than stacking lugs. For multi-inverter sites, also see Parallel installation.
