®
SQ-521 PAR Sensor
Request a Quote

SQ-521 PAR Sensor
Continuous PAR Measurement Made Easy

undefined
Quality—guaranteed

If you need high-quality, continuous PAR measurements over the long term, the rugged SQ-521 PAR Sensor has got you covered. It’s backed by an industry-leading four-year warranty and is considered THE gold standard for simple, accurate indoor/outdoor PAR measurements. Plus, it’s compatible with ZENTRA Cloud for easy remote data access, so you can see your data anywhere, anytime.

Measure photosynthetically active radiation (PAR)

Get accurate and cost-effective measurement of photosynthetically active radiation (PAR) from all light sources used to grow plants. 

 

Use it absolutely everywhere

The SQ-521 is a full-spectrum quantum sensor that measures the Photosynthetic Photon Flux Density (PPFD) in μmol m-2 s-1 from a field of view of 180 degrees. Get superior, continuous PPFD measurements over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) measurements in the same environments. 

 

Best full-spectrum sensor on the market

The SQ-521 PAR Sensor is so accurate, it’s considered the best sensor on the market for difficult-to-measure indoor environments. It has an incredible spectral range of 389 to 692 nm ± 5 nm, which means superior performance under variable sky conditions and increased accuracy under LED and other artificial light sources. Sensors are cosine-corrected to maintain their accuracy even when radiation comes from low zenith angles. Each sensor is carefully pre-calibrated for all light sources in controlled conditions and traceable to NIST reference standards. 

 

Rugged, self-cleaning housing

The SQ-521 PAR Sensor is designed with a patented domed-shaped sensor head (diffuser and body) to facilitate runoff of dew and rain. This keeps the sensor clean and minimizes errors caused by dust blocking the radiation path. Sensors are housed in a rugged anodized aluminum body, plus each sensor comes with a special mounting bracket and leveling plate.

 

Easy setup. Easy data access.

The simple-to-set-up SQ-521 is plug and play with the ZL6 data logger, which self-identifies each sensor and includes a tilt sensor so you can see remotely if your quantum sensor is off level. Get instant and continuous data from the cloud wherever you are. See your data on computer, tablet or smartphone. 

Quality—guaranteed

If you need high-quality, continuous PAR measurements over the long term, the rugged SQ-521 PAR Sensor has got you covered. It’s backed by an industry-leading four-year warranty and is considered THE gold standard for simple, accurate indoor/outdoor PAR measurements. Plus, it’s compatible with ZENTRA Cloud for easy remote data access, so you can see your data anywhere, anytime.

Specifications

Input voltage    5.5 to 24 V DC 
Current Draw 1.4 mA (quiescent), 1.8 mA (active)
Calibration uncertainty ± 5% (see calibration traceability below)
Measurement range 0 to 4000 μmol m-2 s-1
Measurement repeatability Less than 1% (Up to 5000 μmol m-2s-1)
Lon-term drift (nonstability) Less than 2% per year
Response time 0.6s, time for detector signal to reach 95% following a step change; fastest data transmission rate for SDI-12 circuitry is 1 s
Field of view 180°
Spectral range 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50%)
Spectral selectivity Less than 10% from 412 to 682 ± 5 nm (see spectral response below)
Directional (Cosine) response ± 2% at 45 ° zenith angle, ± 5% at 75 ° zenith angle (see directional response below)
Azimuth error Less than 0.5%
Tilt error Less than 0.5%
Temperature response -0.11 ± 0.04 % per C (See temperature response below)
Uncertainty in daily total Less than 5%
Detector Blue-enhanced silicon photodiode
Housing Anodized aluminum body with acrylic diffuser
IP rating IP68
Operating environment -40 to 70 °C; 0 to 100% relative humidity; can be submerged in water up to depths of 30 m
Dimensions (serial #3033 and above) 30.5 mm diameter, 37 mm height
Dimensions (serial #0-3032) 24 mm diameter, 37 mm height
Mass (5 m cable)(serial #3033 and above) 140 g
Mass (5 m cable)(serial #0-3032) 100 g
Cable length 5 m
Cable connector types 3.5 mm “stereo” plug
Data logger compatibility (not exclusive) METER Em50/50G, EM60 series, ZL6 series, ZSC

FAQ's

Can PAR be estimated form total shortwave radiation?

 

It is better to measure PAR and total shortwave radiation (PYR); however, PAR can be estimated from total shortwave radiation by using a physically based model.

Downloads

Full-Spectrum Quantum Sensor Manual Manual PDF, 0.957MB
Using Apogee Quantum Sensors With ZENTRA System Manual PDF, 0.997MB

Request a quote

Fill out the form below to help us pair you with the right expert. We’ll prepare the information you request, then contact you as soon as possible.