Apogee SQ-522-SS | Full-Spectrum Quantum PAR Sensor with Modbus Output

Apogee SQ-522-SS — Full-Spectrum Quantum PAR Sensor with Modbus Digital Output The Apogee SQ-522-SS is a professional-grade, full-spectrum quantum PAR sensor designed for accurate and continuous PPFD measurement across all light sources — including narrow-band LEDs. Built for commercial growers, researchers, and greenhouse engineers who need data they can trust, the SQ-522-SS outputs a digital signal via Modbus RTU protocol over RS-232 or RS-485, making it ideal for integration with dataloggers, controllers, and building management systems. With a spectral range of 389–692 nm (±5 nm), the SQ-522's full-spectrum response significantly outperforms traditional quantum sensors when measuring LED grow lights — giving you accurate readings rather than misleading estimates. Key Features 🌱 Full-spectrum quantum sensor — spectral range 389–692 nm ±5 nm for accurate LED PAR measurement 📡 Modbus RTU digital output — RS-232 or RS-485 compatible, PPFD returned in digital format 🏗️ Rugged self-cleaning housing — anodized aluminium body with cast acrylic diffuser 🔌 Pre-tinned pigtail leads — easy connection to dataloggers and controllers 📏 NIST-traceable calibration — sensor-specific calibration coefficients programmed at the factory 💧 Suitable for aquatic environments — including salt water aquariums and coral growing ☀️ Minimal azimuth error — typically less than 0.5% Typical Applications PPFD measurement over plant canopies in greenhouses, growth chambers, and outdoor environments Reflected and under-canopy (transmitted) PPFD measurement Commercial and research greenhouse facility monitoring (e.g. Syngenta, Embrapa-scale installations) Multi-zone PAR measurement integrated with dataloggers and environmental controllers Aquatic PAR measurement — coral growth, saltwater aquariums Technical Specifications Output: Modbus RTU (RS-232 / RS-485) Spectral Range: 389–692 nm (±5 nm) Housing: Anodized aluminium with acrylic diffuser Calibration: NIST-traceable, factory-programmed sensor-specific coefficients Azimuth Error: <0.5% Cable: High-quality, pre-tinned pigtail leads Mounting: Compatible with Apogee AL-120 solar mounting bracket (sold separately) What's in the Box Apogee SQ-522-SS Quantum Sensor Cable with pre-tinned pigtail leads Protective blue cap Datalogger, mounting bracket, and controller sold separately. Requires a Modbus-compatible measurement device supporting the Read Holding Registers (0x03) function. Why Buy From The Hydro Bros? We supply professional-grade horticultural equipment to commercial growers, research facilities, and serious hobbyists across the UK and internationally. Need a quote for multiple units or a commercial project? Get in touch with our team directly and we'll put together a tailored quotation for you.