The SOL40B3E125 is a Schneider Electric EasyPact Solar MCCB — a 3-pole molded case circuit breaker rated 125 A at 40 °C, built for distribution in solar and general 800 V AC applications. Breaking capacity hits 25 kA at 800 V AC, which puts it in the B performance tier — enough for most downstream panel feeds on a solar combiner or distribution board. The 1250 V AC rated insulation voltage (Ui) gives headroom above the operating voltage, and it's certified to EN/IEC 60947-2 with isolation suitability, so you can use it as a disconnect.
Pollution degree 3 (IEC 60664-1) means it's rated for conductive pollution, typical in industrial panels where dust and humidity are present. Electronic trip means thermal memory is built in — it tracks past heating events, so a series of overloads won't sneak past. That matters for solar strings where partial shading or cloud-edge transients can stack. The LSI protection functions let you coordinate with upstream breakers for selective tripping. Power dissipation runs 5 W per pole, so three poles dump 15 W into the enclosure — factor that into your thermal budget if the panel is sealed. IP20 means finger-safe terminals but no water ingress; keep it inside the cabinet.
Fixed backplate mount, screw terminals front-connected top and bottom. Connection pitch is 40 mm, which matches standard busbar spacing for panelboard feeders. Accepts horizontal or vertical orientation, so you can lay it in a tight enclosure. Dimensions: 120 mm wide, 205 mm high, 105 mm deep.