48V combis for cabin and backup power
When to choose Vulcan combi inverter-chargers over separate charger and inverter — sizing for ESS and critical loads.
Off-grid cabins, farm outbuildings and critical backup installs often start as “a charger and an inverter” — then grow into overlapping AC paths, duplicate transfer switching and unclear priority when grid or generator returns.
A 48V combi inverter-charger such as the Vulcan or Pro Combi S consolidates invert and charge in one platform, sized for ESS banks rather than single 12V leisure batteries.
Combi vs separate units
- One chassis — shared firmware, single transfer logic, fewer external AC interlocks
- 48V native — pairs with AMPS RB48100 / RB48150 racks and parallel VT48500 strings
- Shore or generator AC in — charges the bank while supplying pass-through to loads
- Invert on battery — when grid drops, combi inverts from ESS without a separate switchover box
Sizing framework
- Continuous AC load
- Size inverter/combi output above running watts (not just surge)
- Runtime
- Bank kWh = load kW × hours required at depth-of-discharge limit
- Charge rate
- Match shore/gen input to acceptable bank charge current
- Critical loads
- Separate essential circuits if whole-site backup is not required
- Sterling range
- Vulcan V485500 / V486200 · Pro Combi S · AMPS rack ESS
Cabin vs farm backup
Seasonal cabins prioritise quiet operation and simple owner use — combi transfer should be automatic with clear status. Farm and workshop backup may need higher continuous power and longer runtime; parallel racks and higher-power Vulcan models become relevant.
“Off-grid customers rarely regret oversizing the combi for continuous load — they regret undersizing charge rate and living with a bank that never reaches full before the next outage.”
Sterling Power product team
Solar and DC inputs
Many off-grid sites add solar MPPT on the DC side while the combi handles AC charge from generator or occasional grid. Specify DC and AC charge paths together so the BMS sees coherent limits — our team can review combined layouts.
Next step
Send location, critical load list and any existing shore/gen supply. We’ll suggest Vulcan or Pro Combi S model and AMPS rack count for your runtime target.