The SI21 is Veichi's mini economic solar pumping series, covering 0.75 to 22 kW across 110 V, 220 V and 380 V voltage classes with MPPT over the whole voltage range and efficiency up to 99.8%. AC/DC power input is supported for continuous operation, and installation is flexible: units mount side-by-side without clearance, on DIN rails or on their side.

Ten PV-specific functions include dry-run protection, dormancy, PQ curve, pump cleaning and constant-pressure control, and the drive handles asynchronous, permanent-magnet synchronous and synchronous-reluctance pump motors. Overload capability is 150% for 60 s, 180% for 10 s and 200% for 0.5 s, with forced air cooling in an IP20 enclosure.