1stess CM Series Off-Grid Solar Inverter
The 1stess CM Series combines a pure sine wave inverter, built-in MPPT solar charger and AC battery charger in a compact wall-mounted unit. Choose 1.5kW, 2.5kW or 3.5kW models for 220/230Vac indoor solar and battery power projects, with model-specific 12V or 24V battery input, optional WiFi monitoring and one-stop project support.
Compact Solar Power Conversion for Professional Projects
The 1stess CM Series is a range of compact off-grid solar inverters designed for importers, procurement teams, EPC contractors and solar system integrators serving 220/230Vac markets. The series integrates pure sine wave AC output, MPPT solar charging and AC battery charging in one wall-mounted enclosure.
Available Power Classes
- 1.5kW model with 12V battery input
- 2.5kW model with 24V battery input
- 3.5kW model with 24V battery input
Typical applications include residential solar battery systems, rural electrification and appropriately sized small-business backup installations. This series is designed for standalone operation and does not support parallel connection.
Built-in MPPT with Defined Charging Limits
Each CM model features a built-in MPPT solar charge controller with maximum PV open-circuit voltage of 500Vdc and maximum PV array power ranging from 2000W to 4000W depending on model.
Charging Specifications
- Maximum solar charge current: 100A
- Maximum AC charge current: 60A
- Maximum combined AC plus PV charge current: 100A
- Peak conversion efficiency: 96% (PV to output), 93% (battery to output)
Battery-Mode Output Specifications
Battery-mode output power differs from rated power and should be considered during system design:
- 1.5kW version: 1200W in battery mode (12Vdc input)
- 2.5kW version: 2500W in battery mode (24Vdc input)
- 3.5kW version: 3000W in battery mode (24Vdc input)
PV-triggered lithium battery activation is available on S variants only. N variants do not include this function. Lithium battery BMS communication is not supported.
Installation and Monitoring
The CM Series features an IP21 enclosure suitable for indoor installation protected from rain and splashes.
Environmental Specifications
- Operating temperature: -10 to 55°C
- Relative humidity: 5% to 95%, non-condensing
Selectable output priorities include UTL, SOL, SBU and SUB. Optional WiFi monitoring connects through the designated RJ45 WiFi interface.
Technical Specifications
| Specification |
1.5kW |
2.5kW |
3.5kW |
| Model variants |
CM1500-12S / CM1500-12N |
CM2500-24S / CM2500-24N |
CM3500-24S / CM3500-24N |
| Rated power |
1500VA / 1500W |
2500VA / 2500W |
3500VA / 3500W |
| Battery-mode power |
1200VA / 1200W |
2500VA / 2500W |
3000VA / 3000W |
| Surge power |
3000VA |
5000VA |
7000VA |
| Battery input |
12Vdc |
24Vdc |
24Vdc |
| Max. PV array power |
2000W |
3000W |
4000W |
| Max. PV open-circuit voltage |
500Vdc |
500Vdc |
500Vdc |
| Max. PV input current |
15A |
15A |
15A |
| Output voltage |
220/230Vac ±5% |
220/230Vac ±5% |
220/230Vac ±5% |
| Output waveform / frequency |
Pure sine wave / 50-60Hz |
Pure sine wave / 50-60Hz |
Pure sine wave / 50-60Hz |
| Transfer time |
10ms computer / 20ms appliances |
10ms computer / 20ms appliances |
10ms computer / 20ms appliances |
| PV-triggered lithium activation |
S: Yes; N: No |
S: Yes; N: No |
S: Yes; N: No |
| Net weight |
4.0kg |
4.4kg |
4.4kg |
Dimensions: 330 * 278 * 98mm. Operating temperature: -10 to 55°C. Humidity: 5%-95%, non-condensing. Specifications and accessory scope should be confirmed for the ordered model.
Buyer Frequently Asked Questions
Which CM inverter should I choose for a 24V battery system?
The 2.5kW and 3.5kW versions use 24Vdc battery input. Compare battery-mode output as well as rated power: these versions are specified for 2500W and 3000W in battery mode respectively. Check load starting demand and battery discharge capability before selection.
Does the 3.5kW model supply 3.5kW continuously from the battery?
The 3.5kW model is specified for 3500W rated power and 3000W battery-mode power. Use the battery-mode figure when assessing operation from the battery. Request the final manual for operating conditions and applicable limits.
Can this IP21 inverter be mounted outdoors?
Specify a suitable indoor location protected from rain and splashes. Refer to the installation manual for ventilation, mounting conditions and environmental limits. IP21 should not be treated as an outdoor weatherproof rating.
Is lithium battery activation available on every model?
No. PV-triggered lithium battery activation is listed for the S variants. The N variants do not include it. This activation function does not mean the inverter has BMS communication.
Does the inverter communicate with a lithium battery BMS?
Lithium battery BMS communication is not supported. Battery charging limits and protection settings should be checked against the chosen battery's documentation during configuration.
Are WiFi monitoring and parallel operation included?
WiFi monitoring is optional and uses the listed RJ45 WiFi interface. Parallel operation is not supported. Confirm monitoring module inclusion and configuration before purchase.
How much current can AC and PV charging provide together?
The maximum combined charge current is 100A. Separate limits are up to 100A for solar charging and 60A for AC charging; the combined limit remains 100A.
What should an importer or EPC contractor send for a quotation?
Provide the destination market, order quantity, continuous and starting loads, battery voltage and battery data, proposed PV array, monitoring needs and branding requirements. Ask for model-specific documentation and the proposed accessory and delivery scope.
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