Hoymiles 4020S HiBattery 4kWh Stackable Battery Module - Free delivery
Hoymiles HiBattery 4020S — 4kWh Stackable Battery Expansion Module
Ran out of storage before you ran out of sun? The HiBattery 4020S adds another 4.02kWh to your existing Hoymiles HiBattery 4020 X or 4020 AC. It stacks straight onto the unit you already own — no rewiring, no extra cabling, no electrician callout. Add up to three and you'll be running 16.08kWh of LiFePO4 storage.
Note: the 4020S is an expansion module. It needs a HiBattery 4020 X or 4020 AC base unit to work, and cannot be used on its own.
Key features
4.02kWh of extra LiFePO4 capacity — roughly a full evening of household load for most homes
Stacks without cables — sits directly on the base unit, connections made through the stacking interface
Up to 2,000W charge and discharge per module
Expand to 16.08kWh with up to three 4020S modules on one base unit
IP66 rated for indoor or outdoor installation
Automatic charge balancing across the stack, managed by the system BMS
Wide operating range — rated from −20°C to 55°C, so a garage or exterior wall is fine
Why add a 4020S
More of your own solar, less of theirs
Most homes with a single 4020 unit fill the battery by mid-afternoon in summer and then export the rest for a few pence a unit. A second module gives that energy somewhere to go. The extra capacity typically pays back fastest for households with evening-heavy consumption — EV charging, electric heating, or anyone on a time-of-use tariff who wants to buy overnight and coast through the peak.
Buy capacity when you need it, not before
The point of a modular system is that you don't have to guess your future consumption on day one. Start with the base unit, live with it for a winter, and add a 4020S when you know what you're short by. A heat pump, an EV, or a new home worker all change the maths — the stack changes with them.
Genuinely a DIY job
Hoymiles designed the 4020 series around stacking rather than cabling. The 4020S locates onto the base unit and the system recognises it and rebalances state of charge across the modules by itself. Do bear in mind it weighs 35kg, so it's a two-person lift.
Built to outlast the payback period
The 4020 series uses automotive-grade LiFePO4 cells rated beyond 8,000 cycles, with cell-level balancing, low-temperature self-heating, aerosol fire suppression and a pressure relief valve. LiFePO4 chemistry is the reason these can sit in an unheated garage and still be working in fifteen years.
Technical specifications
ModelHB-4020-S
Usable capacity4.02 kWh
Cell chemistryLiFePO4 (lithium iron phosphate)
Max charge / discharge power2,000 W
Compatibility HiBattery 4020 X,
HiBattery 4020 AC Max modules per system3 (16.08 kWh total)
Dimensions (W × D × H)520 × 275 × 199 mm
Weight 35 kg
Ingress protection IP66
Operating temperature −20°C to 55°C
Cycle life 8,000+ cycles
Standalone operation Not supported
In the box: 1 × Hoymiles HiBattery 4020S expansion module
FAQs
Can I use the 4020S on its own?
No. It has no inverter or control electronics of its own and must be paired with a HiBattery 4020 X or 4020 AC base unit.
How many can I add?
Up to three per base unit, taking total system capacity to 16.08kWh.
Do I need an electrician?
The module stacks onto the base unit without additional AC or DC wiring. It's a 35kg lift, so plan for two people. Any work affecting your existing installation should still go through a qualified installer.
Does it work with both the 4020 X and the 4020 AC?
Yes — the same module fits the PV-coupled 4020 X and the AC-coupled 4020 AC.
Can I install it outside?
Yes. The IP66 rating covers dust and water jets, and the module is rated down to −20°C.
Will mixing an older and newer module cause problems?
No. The system balances state of charge across modules automatically, so a module added later settles in with the existing stack.
Hoymiles HiBattery 4020S — 4kWh Stackable Battery Expansion Module
Ran out of storage before you ran out of sun? The HiBattery 4020S adds another 4.02kWh to your existing Hoymiles HiBattery 4020 X or 4020 AC. It stacks straight onto the unit you already own — no rewiring, no extra cabling, no electrician callout. Add up to three and you'll be running 16.08kWh of LiFePO4 storage.
Note: the 4020S is an expansion module. It needs a HiBattery 4020 X or 4020 AC base unit to work, and cannot be used on its own.
Key features
4.02kWh of extra LiFePO4 capacity — roughly a full evening of household load for most homes
Stacks without cables — sits directly on the base unit, connections made through the stacking interface
Up to 2,000W charge and discharge per module
Expand to 16.08kWh with up to three 4020S modules on one base unit
IP66 rated for indoor or outdoor installation
Automatic charge balancing across the stack, managed by the system BMS
Wide operating range — rated from −20°C to 55°C, so a garage or exterior wall is fine
Why add a 4020S
More of your own solar, less of theirs
Most homes with a single 4020 unit fill the battery by mid-afternoon in summer and then export the rest for a few pence a unit. A second module gives that energy somewhere to go. The extra capacity typically pays back fastest for households with evening-heavy consumption — EV charging, electric heating, or anyone on a time-of-use tariff who wants to buy overnight and coast through the peak.
Buy capacity when you need it, not before
The point of a modular system is that you don't have to guess your future consumption on day one. Start with the base unit, live with it for a winter, and add a 4020S when you know what you're short by. A heat pump, an EV, or a new home worker all change the maths — the stack changes with them.
Genuinely a DIY job
Hoymiles designed the 4020 series around stacking rather than cabling. The 4020S locates onto the base unit and the system recognises it and rebalances state of charge across the modules by itself. Do bear in mind it weighs 35kg, so it's a two-person lift.
Built to outlast the payback period
The 4020 series uses automotive-grade LiFePO4 cells rated beyond 8,000 cycles, with cell-level balancing, low-temperature self-heating, aerosol fire suppression and a pressure relief valve. LiFePO4 chemistry is the reason these can sit in an unheated garage and still be working in fifteen years.
Technical specifications
ModelHB-4020-S
Usable capacity4.02 kWh
Cell chemistryLiFePO4 (lithium iron phosphate)
Max charge / discharge power2,000 W
Compatibility HiBattery 4020 X,
HiBattery 4020 AC Max modules per system3 (16.08 kWh total)
Dimensions (W × D × H)520 × 275 × 199 mm
Weight 35 kg
Ingress protection IP66
Operating temperature −20°C to 55°C
Cycle life 8,000+ cycles
Standalone operation Not supported
In the box: 1 × Hoymiles HiBattery 4020S expansion module
FAQs
Can I use the 4020S on its own?
No. It has no inverter or control electronics of its own and must be paired with a HiBattery 4020 X or 4020 AC base unit.
How many can I add?
Up to three per base unit, taking total system capacity to 16.08kWh.
Do I need an electrician?
The module stacks onto the base unit without additional AC or DC wiring. It's a 35kg lift, so plan for two people. Any work affecting your existing installation should still go through a qualified installer.
Does it work with both the 4020 X and the 4020 AC?
Yes — the same module fits the PV-coupled 4020 X and the AC-coupled 4020 AC.
Can I install it outside?
Yes. The IP66 rating covers dust and water jets, and the module is rated down to −20°C.
Will mixing an older and newer module cause problems?
No. The system balances state of charge across modules automatically, so a module added later settles in with the existing stack.