Short answer: The Somfy 12V power supply for battery shades is the 12V DC Plug-in Power Supply (1870940). It plugs into a standard 120V outlet and powers Somfy WireFree external-battery motors, such as the Roll Up 28 WireFree RTS V2 and the Cord Lift TLW25, with no batteries to reload or recharge. Somfy lists ten compatible motors and backs it with a 5 year warranty.
Somfy builds WireFree motors in two forms. One carries its lithium-ion cell inside the tube and recharges from a charger. The other draws 12V DC through an external lead, and the installer picks the source at the end of that lead. The Somfy 12V DC Plug-in Power Supply (1870940) is the wall-outlet source for that second group. Somfy describes it as a convenient power source for compatible WireFree motors, one that takes batteries off the job for good. This guide covers the motors it runs and the shades where plug-in power beats a battery.
Somfy motors the 1870940 powers
Somfy's product page for the 1870940 names ten compatible motors. Each one is a 12V WireFree design with an external power lead:
- The Somfy Roll Up 28 WireFree RTS V2 (External Battery) (1241162), a 1.1 Nm, 20 rpm roller shade motor for tubes with a 1.05 in minimum inside diameter. Somfy also lists the earlier Roll Up 28 WireFree RTS (1240292).
- The Somfy Cord Lift WireFree CL32 RTS (External Battery) (1002422), a 0.34 Nm, 72 rpm headrail motor.
- The Somfy Cord Lift WireFree TLW25 RTS (External Battery) (1003294) and its Zigbee twin, the TLW25 Zigbee (1241780), plus the Cord Lift WireFree TLV25 Zigbee (1246811).
- The Somfy Tilt 50 WireFree Through-Shaft RTS (1240276) and the Tilt 50 WireFree Through-Shaft Zigbee (1241783).
- The Sonesse 28 WireFree external-battery motors in RTS and Zigbee versions.
RTS and Zigbee motors share the list. The supply delivers power and carries no control signal, so each motor keeps its own radio and answers its own remote or hub.
Embedded-battery motors sit outside the list. A Sonesse ULTRA 30 WireFree RTS (1003310) holds its cell inside the tube and recharges through the Somfy Lithium-ion Charger (V2 Head) (9025166). Wired 24V DC motors such as the Sonesse 30 RTS need a 24V source, covered in our guide to Somfy power supplies for 24V motors. Match the voltage on the motor label to the supply before ordering.
Somfy 12V power supply specs
The figures below come from the 1870940 product pages on somfypro.com and somfysystems.com and from Somfy's WireFree Power Supply Compatibility Matrix (01/2025).
| Somfy name | 12V DC Plug-in Power Supply |
| Somfy reference | 1870940 |
| Output | 12V DC |
| Input | Standard wall outlet, 120V AC (Somfy matrix: 120 to 230V AC) |
| Motors served | WireFree external-battery motors, RTS and Zigbee |
| Compatible motors on Somfy's list | 10 |
| Applications | Interior blinds and shades |
| Finish | White |
| Approval | UL |
| Warranty | 5 years |
Somfy's compatibility matrix marks the 1870940 as mandatory for cULus certified products. A project that has to carry that certification should run its external-battery motors on this supply. The 5 year warranty matches the coverage on Somfy's motors.
Plug-in power or a battery source
An external-battery motor gives the installer a choice at the end of its lead. Somfy offers two battery sources beside the plug-in, and its product pages name the Roll Up 28 WireFree RTS V2 (External Battery) for all of them.
The Somfy Reloadable 12V DC Battery Wand (9018685) holds eight AA lithium cells in a 17.76 in tube that mounts behind the shade. Somfy approves AA lithium cells for it and rules out alkaline and rechargeable AA. Reloading means a ladder and a fresh set of cells.
The Somfy Rechargeable Lithium-ion Battery Pack (9021217) carries a 2600 mAh cell and recharges from the 9025166 charger. Somfy allows up to 16.5 ft between the pack and the motor, which lets the pack sit somewhere easier to reach than the headrail.
The 1870940 removes the battery from the maintenance list. The cost is an outlet within reach of the shade and a lead routed to the motor. A shade that cycles several times a day, or a window behind furniture where a ladder visit is a chore, gains the most. A tall shade with no outlet nearby stays a battery job.
Fit and setup notes installers ask about
- Read the motor label and Somfy reference first. The 1870940 belongs on a 12V WireFree motor with an external power lead, and Somfy's product page for the 1870940 is the authority on fit.
- Mark the outlet before the shade goes up. An outlet close to the headrail or roller bracket keeps the lead short and out of sight.
- Power the motor before pairing. RTS motors then pair to a remote with the steps in our guide to pairing a Somfy RTS remote, and Zigbee motors join their hub.
- Mixed jobs work. Plug-in power on the windows near an outlet and a pack or wand on the rest keeps every shade on genuine Somfy power.
Somfy's battery, charger and cable choices for every WireFree generation sit in our guide to WireFree batteries, chargers and cables. Motor manuals, the WireFree Databook and the power supply matrix live in the Somfy spec library.
Ordering the 1870940 with your motor
Order one Somfy 12V DC Plug-in Power Supply (1870940) for each external-battery motor you want on wall power, then add the control part the motor's radio calls for: an RTS remote or a Zigbee hub. Battery wands, rechargeable packs, chargers and the 24V transformers sit together in our Somfy power supplies, batteries and chargers collection.
FAQ
Does the 1870940 charge a Sonesse ULTRA 30 WireFree motor?
No. The Sonesse ULTRA 30 WireFree carries its lithium-ion cell inside the tube and recharges through the Somfy Lithium-ion Charger (V2 Head) (9025166). The 1870940 serves external-battery motors, such as the Roll Up 28 WireFree RTS V2 (External Battery) and the Cord Lift TLW25, and replaces the battery source on those shades.
Can I run a 24V Somfy motor on the 1870940?
No. The 1870940 delivers 12V DC for WireFree external-battery motors. A wired 24V DC motor such as the Sonesse 30 RTS takes the Somfy 24V DC 1.67 A Wall Mount Power Supply (1822209) or a Somfy Power Distribution Enclosure. Check the voltage on the motor label before you order power.
Is the Somfy 12V power supply approved for UL projects?
Yes. Somfy lists UL approval on the 1870940 product page, and its WireFree Power Supply Compatibility Matrix marks the 1870940 as mandatory for cULus certified products. The supply carries a 5 year warranty, and Somfy rates it for interior blinds and shades.
Does the 1870940 work with Zigbee WireFree motors?
Yes. Somfy's list includes the Cord Lift WireFree TLW25 Zigbee, the Cord Lift WireFree TLV25 Zigbee, the Tilt 50 WireFree Through-Shaft Zigbee and the Sonesse 28 WireFree Zigbee external-battery motor. The supply provides power alone, so each motor still joins a Zigbee hub such as the Somfy TaHoma Switch.
Sources: Somfy product pages for the 12V DC Plug-in Power Supply 1870940 on somfypro.com (compatible products, 120V input, UL, white, 5 year warranty, interior blinds and shades) and somfysystems.com; Somfy WireFree Power Supply Compatibility Matrix 5158703B, 01/2025 (cULus footnote, 120 to 230V AC input); Somfy WireFree Databook 2026.07.01 (WireFree power accessories); somfypro.com and somfysystems.com pages for 1241162, 1002422, 9018685 and 9021217.
Shade Motors Direct is an authorized source for genuine Somfy motorized window shade, blind, and drapery parts.
