SMA Storage M 4.09 kWh LFP High-Voltage Battery
SMA Storage M STM-BM-4.09-10: lithium iron phosphate battery module with 4.09 kWh usable capacity for the SMA Storage M high-voltage storage system, designed for the Sunny Tripower Hybrid X three-phase hybrid inverters.
It is stacked in a tower with the STM-BMS-10 BMS unit (sold separately): 3 to 12 modules, i.e. 12.3 to 49.1 kWh usable. IP66, suitable for outdoor installation, 36 kg. 10-year warranty when registered within 30 days of commissioning.
The SMA Storage M STM-BM-4.09-10 is the building block of SMA's new high-voltage storage system: 4.09 kWh usable (4.33 kWh nominal) in lithium iron phosphate cells, stacked in a tower together with the STM-BMS-10 management unit. It is the native battery for the Sunny Tripower Hybrid X three-phase hybrid inverters and is also compatible with the single-phase Sunny Boy Smart Energy.
The number of modules sets the power, not just the kWh
Each module adds about 57.6 V to the tower voltage, and charge and discharge current with the Sunny Tripower Hybrid X is limited to 50 A. The power the battery can actually deliver is therefore voltage times current: 3 modules (172.8 V nominal) give about 8.6 kW, 6 modules (345.6 V) about 17 kW, and 12 modules (691.2 V) exceed the rating of any Hybrid X.
In practice, a short tower becomes the bottleneck on a large inverter: a Hybrid X 15 only reaches full discharge power from 6 modules upwards, and as the battery approaches empty the voltage drops towards the bottom of its window (50.4 V per module), taking available power down with it. Size the system on the evening power you need, not only on energy.
STM-BM-4.09-10 technical specifications
| Usable / nominal capacity | 4.09 kWh / 4.33 kWh per module |
| Technology | Lithium iron phosphate (LFP) |
| Configurations | 3 to 12 modules per tower, with 1 STM-BMS-10 BMS unit |
| System usable capacity | 12.28 kWh (3 modules) to 49.12 kWh (12 modules) |
| System nominal voltage | 172.8 V (3 modules) to 691.2 V (12 modules) |
| Charge and discharge current | 50 A with Sunny Tripower Hybrid X; 30 A with Sunny Boy Smart Energy |
| Depth of discharge | Usable capacity at 94.5% DoD, 0.2C, +25 °C |
| Round-trip efficiency | 93.5% at 0.2C |
| Guaranteed energy throughput | Up to 7.2 MWh per installed kWh, depending on the country of installation |
| Degree of protection | IP66, indoor and outdoor installation |
| Operating temperature | -20 °C to +50 °C, optimum 15-30 °C; natural cooling |
| Connections | DC MC4 Evo 2, CAN communication via RJ45 |
| Certifications | CE, UN 38.3, IEC 62619, IEC 62477, VDE 2510-50 |
| Dimensions (W x H x D) | 530 x 133 x 405 mm |
| Weight | 36 kg |
| Warranty | 2 years standard, 10 years when the product is registered within 30 days of commissioning |
How much battery each inverter can take
- Sunny Tripower Hybrid X 5-15: up to 9 modules, 36.8 kWh usable
- Sunny Tripower Hybrid X 20-30: up to 12 modules, 49.1 kWh usable
- Sunny Boy Smart Energy: up to 28.7 kWh, with current limited to 30 A
The minimum is always 3 modules: SMA specifies configurations from 3 to 12 modules, each with its own BMS unit, and a single module is not an approved configuration. A first installation therefore starts with one BMS plus three modules.
What it means in everyday life
A home with a heat pump typically uses 6 to 10 kWh between sunset and morning. Three modules, 12.3 kWh usable, cover a winter night with margin; four or five modules (16.4-20.5 kWh) make sense when an electric car also charges in the evening. Taller towers, from 8 modules upwards, suit farms, small businesses and workshops where evening loads are continuous and the battery cycles more than once a day.
Frequently asked questions
Can I use a single module?
No. The manufacturer specifies SMA Storage M in configurations of 3 to 12 modules, always with the STM-BMS-10 BMS unit. A single module is not an approved configuration.
Can it be installed outdoors?
Yes. It is rated IP66 and declared for indoor and outdoor use, operating from -20 °C to +50 °C. Best capacity and lifetime are reached between 15 and 30 °C, so a shaded wall or a ventilated plant room is preferable to direct sunlight.
Is it compatible with SMA Home Storage?
They are two separate systems. Storage M uses 4.09 kWh modules and its own BMS unit, Home Storage uses 3.28 kWh modules: modules from the two systems cannot be mixed in the same tower. The Sunny Tripower Hybrid X is compatible with both families.
Is the warranty really 10 years?
Only if the product is registered through SMA's product registration within 30 days of commissioning. Without registration the standard 2-year warranty applies. Instead of a cycle count, SMA guarantees an energy throughput of up to 7.2 MWh per installed kWh, with values depending on the country.
How many modules does a 10 kW Hybrid X need?
Delivering 10 kW requires around 200 V of battery voltage, so at least 4 modules (230.4 V nominal, about 11.5 kW at 50 A). With 3 modules the inverter works, but discharge tops out at around 8.6 kW and drops further as the battery nears empty.
