The bus voltage of a home battery is set by the inverter, not by the brochure. A low-voltage system runs a 48 V-class DC bus — 51.2 V nominal on our modules. A high-voltage system stacks modules in series into a string, rated up to 1000 VDC in our HV configuration. The two are not interchangeable, and the capacity figure in kWh tells you nothing about which one a site needs.
The order of decisions is therefore: inverter first, DC bus second, capacity third. What follows is what actually differs between the two buses, which Woolii systems sit on which one, and the checks that belong on the quote.
Start with the inverter's battery voltage window
An inverter datasheet specifies a battery voltage range, not a battery part number. That window is the constraint the storage has to fit:
- A low-voltage inverter expects a 48 V-class battery. Our storage modules are 51.2 V nominal — 48 V on the 2.56 kWh IP65 model.
- A high-voltage inverter expects a series string: a few hundred volts, up to 1000 VDC on our stacked HV configuration.
- A 51.2 V pack cannot serve an HV input, and an HV string cannot serve a 48 V input. No setting in the monitoring app bridges that gap.
That is why the pairing question comes before the capacity question. If the customer's inverter is already on the wall, the bus is already decided. If the inverter is still open, the bus is a choice you make with the site — not after it.
What actually differs between the two buses
| Low-voltage (48/51.2 V class) | High-voltage (series string, up to 1000 VDC) | |
|---|---|---|
| How modules combine | In parallel — add modules alongside | In series — stack modules to raise the bus |
| DC current for a given power | Higher | Lower |
| DC cabling and protection | Heavier cable, higher current per run | Thinner cable, lower current |
| Battery management | Module-level BMS; a module can be added or swapped | String-level BMS with high-voltage insulation and safety design |
| Typical fit | Wall retrofits, single-family homes, modest power | Floor or cabinet installs, higher power, longer DC runs |
Both are LiFePO4. Chemistry is not the variable here — the bus is.
The cable difference follows from one relationship: power is voltage multiplied by current. For the same kilowatts, a higher bus voltage draws lower current, which is why an HV string can use thinner conductors and loses less over the run, and why a low-voltage system needs more copper for the same job. Neither is "better". HV pays off where power and distance are large; LV pays off where the job is a straightforward wall retrofit and modules may need to be added or replaced over the years.
Which of our systems sits on which bus
Storage Wall series — low-voltage, wall-mounted
The wall line runs a low-voltage architecture across four capacities from 2.56 kWh to 14.34 kWh, at 48 V or 51.2 V, with CAN/RS485 communication to the inverter and parallel expansion. The 2.56 kWh model is the IP65 outdoor option, and the series lists up to three units on a wall run. Full detail is on the Storage Wall series page.
Stacked storage series — one module, two bus options
The floor-standing tower is built from 5.12 kWh modules, two to six per system (10.24–30.72 kWh). The same module is offered in two configurations: SN-ST-LV51100 for a low-voltage bus, and SN-ST-HV51100, which builds a series string up to 1000 VDC. This is the clearest illustration of why a module's own voltage is not the system's bus voltage — see the Stacked Storage series page.
Rack storage series — 19-inch, scaling into a high-voltage system
Rack modules of 5.12 kWh in a standard 19-inch format, one to twelve per system (5.12–61.44 kWh), scaling into a roughly 60 kWh high-voltage system for cabinets, equipment rooms, larger residential backup and light-commercial work. Specifications are on the Rack Storage series page.
The inverters we integrate
We integrate Huawei SUN2000 and Deye SG-series hybrid inverters: single-phase 230 V, 5 kW to 10 kW, two to three MPPT trackers, CAN/RS485 battery communication, parallel operation up to six units. The Huawei models are built for high-voltage battery stacks; the Deye SG-series supports low-voltage LiFePO4 and off-grid operation. Which battery model we confirm against which inverter is documented on the verified compatibility list, and it ships with a quote — details on the hybrid inverter page.
What to confirm before a battery goes on the quote
- The inverter's battery voltage window — the single check that decides the bus.
- The BMS protocol — CAN or RS485, and whether the inverter expects one specific battery model rather than any compliant pack.
- Charge and discharge current limits — match them to the module rating, not only to the kWh.
- Expansion headroom — how many modules the bus supports, and how many units the inverter accepts in parallel.
- Backup behaviour, if outages matter to the customer — whether the inverter runs islanded without the grid.
- Phase count at the connection point — a separate question from the DC bus. It affects what can stay powered during an outage, and the network operator's technical connection rules for that address govern it. Do not promise a backup scope before checking them.
Two published guides cover the neighbouring ground: how to read a home battery datasheet for the parameters themselves, and inverter compatibility for the protocol questions worth putting to any supplier.
Three pairings that go wrong
- Reading the module voltage as the system voltage. A 51.2 V module appears in both our LV and HV stacked systems. The module number describes the module; the bus describes the system.
- Buying on capacity and ignoring the bus. "10 kWh" says nothing about whether the unit will connect. Quote volts and kilowatt-hours together.
- Treating high voltage as the premium tier. It is a fit decision, not a ranking: HV for cabinet installs, higher power and longer DC runs; LV for wall retrofits and simple module swaps.
The bus you pick decides how you expand
Expansion is set by the bus as much as by the capacity. Adding kilowatt-hours is a different job on a parallel low-voltage bank than on a series high-voltage string, and the inverter's parallel capacity is the other half of the limit. If growth is likely — an EV charger, a heat pump, a second living unit — settle the bus and the inverter headroom before the first module goes on the wall. Our expansion planning guide sets out that sequence, and wall vs stacked vs rack covers the physical format decision that usually runs alongside it.
Tell us the inverter and the job
Send us the inverter make and model — or, if the inverter is not chosen yet, the site and what the battery has to do — and we will confirm which bus fits, which of our modules sits on it, and send the datasheet for that configuration before you quote. The verified inverter compatibility list comes with it.
Start with a specification enquiry or browse the full storage range.
Questions installers ask us
Can I use a 48 V battery with a high-voltage inverter?
No. The inverter's battery voltage window decides what it will accept, and a 51.2 V-class pack sits below an HV input's range while an HV string sits above a 48 V input's. Confirm the window on the datasheet before you specify either side of the pairing.
Is a 51.2 V module always a low-voltage battery?
No. Our stacked series uses the same 5.12 kWh module in two configurations — SN-ST-LV51100 for a low-voltage bus and SN-ST-HV51100, which builds a series string up to 1000 VDC. The module's own voltage is only one of the numbers on the sheet.
Which inverters do you pair batteries with?
We integrate Huawei SUN2000 and Deye SG-series hybrid inverters — single-phase 230 V, 5 kW to 10 kW, CAN/RS485 communication, parallel operation up to six units. The Huawei models are built for high-voltage battery stacks; the Deye SG-series supports low-voltage LiFePO4 and off-grid operation. The verified model list, and the battery each one pairs with, is available on request.
Does a higher bus voltage mean more usable energy?
No. Usable energy is the kWh figure. The bus voltage changes the current drawn for a given power, the DC cabling, and which inverters the battery can connect to. A 5.12 kWh module is 5.12 kWh on either bus.
Can I decide the battery first and the inverter later?
Only if the inverter is still open. Once an inverter is installed, its battery voltage window and BMS protocol fix what the storage can be, so the bus belongs in the first site conversation rather than in the procurement list.