Apogee Instruments SP-110 User manual

APOGEE INSTRUMENTS, INC. 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] FAX: [phone] WEB: APOGEEINSTRUMENTS.COM
Copyright © 2013 Apogee Instruments, Inc.
OWNER’S MANUAL
PYRANOMETER
Model SP-110 and SP-230

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TABLE OF CONTENTS
DECLARATION OF CONFORMITY……………………………..……………………. 3
INTRODUCTION…………………………………………………………………………….. 4
SENSOR MODELS....................................................................... 5
SPECIFICATIONS……………………………………………………………………………. 6
DEPLOYMENT AND INSTALLATION……………………………………………….. 9
OPERATION AND MEASUREMENT……………………………………..…………. 10
MAINTENANCE AND RECALIBRATION………………………………….......... 14
TROUBLESHOOTING AND CUSTOMER SUPPORT…………………………… 16
RETURN POLICY AND WARRANTY…………………………………………………. 17

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DECLARATION OF CONFORMITY
CE and ROHS Certificate of Compliance
We Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
Declare under our sole responsibility that the products:
Models: SP-110, SP-230
Type: Pyranometer
are in conformity with the following standards and relevant EC directives:
Emissions: EN 61326-1:2013
Immunity: EN 61326-1:2013
Safety: EN 61010-1:2010
EU directive 2004/108/EC, EMC
EU directive 2002/95/EC, RoHS (Restriction of Hazardous Substances)
EU directive 2011/65/EU, RoHS2
Please be advised that based on the information available to us from our raw material suppliers, the
products manufactured by us do not contain, as intentional additives, any of the restricted materials
including cadmium, hexavalent chromium, lead, mercury, polybrominated biphenyls (PBB),
polybrominated diphenyls (PBDE).
Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end
products for the presence of these substances, but rely on the information provided to us by our material
suppliers.
Bruce Bugbee
President
Apogee Instruments, Inc.
June 2013

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INTRODUCTION
Solar radiation at Earth’s surface is typically defined as total radiation across a wavelength range of 280 to
4000 nm (shortwave radiation). Total solar radiation, direct beam and diffuse, incident on a horizontal
surface is defined as global shortwave radiation, or shortwave irradiance (incident radiant flux), and is
expressed in Watts per square meter (W m-2, equal to Joules per second per square meter).
Pyranometers are sensors that measure global shortwave radiation. Apogee SP series pyranometers are
silicon-cell pyranometers, and are only sensitive to a portion of the solar spectrum, approximately 350-
1100 nm (approximately 80 % of total shortwave radiation is within this range). However, silicon-cell
pyranometers are calibrated to estimate total shortwave radiation across the entire solar spectrum.
Silicon-cell pyranometer specifications compare favorably to specifications for World Meteorological
Organization (WMO) moderate and good quality classifications and specifications for International
Organization of Standardization (ISO) second class and first class classifications, but because of limited
spectral sensitivity, they do not meet the spectral specification necessary for WMO or ISO certification.
Typical applications of silicon-cell pyranometers include incoming shortwave radiation measurement in
agricultural, ecological, and hydrological weather networks, and solar panel arrays.
Apogee Instruments SP series pyranometers consist of a cast acrylic diffuser (filter), photodiode, and
signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor
to a measurement device. Sensors are potted solid with no internal air space and are designed for
continuous total shortwave radiation measurement on a planar surface in outdoor environments. SP series
sensors output an analog voltage that is directly proportional to total shortwave radiation from the sun.
The voltage signal from the sensor is directly proportional to radiation incident on a planar surface (does
not have to be horizontal), where the radiation emanates from all angles of a hemisphere.

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SENSOR MODELS
Apogee SP series pyranometer models covered in this manual are un-amplified versions that provide a
voltage output, models SP-110 and SP-230. Amplified models, which provide larger voltage signals, and
models that provide a current output, 4-20 milliamps, are also available; see manuals for SP-212 and SP-
215 pyranometers or SP-214 pyranometers.
Sensor model number, serial number,
production date, and calibration factor are
located near the pigtail leads on the sensor
cable.

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SPECIFICATIONS
Power Supply:
SP-230 integrated heaters: 12 VDC with a nominal current draw of 15 mA
Sensitivity:
0.20 mV per W m-2
Calibration Factor:
5.0 W m-2 per mV (reciprocal of sensitivity)
Calibration Uncertainty:
± 5 % (see Calibration Traceability below)
Measurement Repeatability:
< 1 %
Non-stability (Long-term Drift):
< 2 % per year
Non-linearity:
< 1 % (up to 1750 W m-2)
Response Time:
< 1 ms
Field of View:
180o
Spectral Range:
360 nm to 1120 nm (wavelengths where response is 10 % of maximum; see Spectral
Response below)
Directional (Cosine) Response:
± 5 % at 75ozenith angle (see Cosine Response below)
Temperature Response:
-0.04 ± 0.04 % per C (see Temperature Response below)
Operating Environment:
-40 to 70 C
0 to 100 % relative humidity
Can be submerged in water up to depths of 30 m
Dimensions:
2.40 cm diameter and 2.75 cm height
Mass:
90 g (with 5 m of lead wire)
Cable:
5 m of shielded, twisted-pair wire.
Additional cable available in multiples of 5 m
Santoprene rubber jacket (high water resistance, high UV stability, flexibility in cold conditions)
Pigtail lead wires
Calibration Traceability:
Apogee Instruments SP series pyranometers are calibrated through side-by-side comparison to the mean
of four Apogee model SP-110 transfer standard pyranometers (shortwave radiation reference) under high
intensity discharge metal halide lamps. The transfer standard pyranometers are calibrated through side-
by-side comparison to the mean of at least two ISO-classified reference pyranometers under sunlight
(clear sky conditions) in Logan, Utah. Each of four ISO-classified reference pyranometers are recalibrated
on an alternating year schedule (two instruments each year) at the National Renewable Energy Laboratory

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(NREL) in Golden, Colorado. NREL reference standards are calibrated to the World Radiometric
Reference (WRR) in Davos, Switzerland.
Spectral Response:
Temperature response:
Mean temperature response of ten
Apogee silicon-cell pyranometers (
errors
bars represent two standard
deviations above and below mean ).
Temperature response measurements
were made at 10 C intervals across a
temperature range of approximately -10
to 40 C in a temperature controlled
chamber under a fixed, broad spectrum,
electric lamp. At each temperature set
point, a spectroradiometer was used to
measure light intensity from the lamp
and all pyranometers were compared to
the spectroradiometer. The
spectroradiometer was mounted
external to the temperature control
chamber and remained at room
temperature during the experiment.
Spectral response estimate of Apogee
silicon-cell pyranometers. Spectral
response was estimated by multiplying the
spectral response of the photodiode,
diffuser, and adhesive. Spectral response
measurements of diffuser and adhesive
were made with a spectrometer, and
spectral response data for the photodiode
were obtained from the manufacturer.

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Cosine Response:
Mean cosine response of eleven Apogee
silicon-cell pyranometers ( error bars
represent two standard deviations
above and below mean
). Cosine
response measurements were made
during broadband outdoor radiometer
calibrations (BORCAL) performed during
two different years at the National
Renewable Energy Laboratory (NREL) in
Golden, Colorado. Cosine response was
calculated as the relative difference of
pyranometer sensitivity at each solar
zenith angle to sensitivity at 45° solar
zenith angle. The blue symbols are AM
measurements, the red symbols are PM
measurements.
Directional, or cosine, response is defined
as the measurement error at a specific
angle of radiation incidence. Error for
Apogee silicon-cell pyranometers is
approximately ± 2 % and ± 5 % at solar
zenith angles of 45°and 75°, respectively.

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DEPLOYMENT AND INSTALLATION
Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure total
shortwave radiation incident on a horizontal surface, the sensor must be level. An Apogee Instruments
model AL-100 leveling plate is recommended for this purpose. To facilitate mounting on a cross arm, an
Apogee Instruments model AM-110 mounting bracket is recommended.
To minimize azimuth error, the sensor should be mounted
with the cable pointing toward true north in the northern
hemisphere or true south in the southern hemisphere.
Azimuth error is typically less than 1 %, but it is easy to
minimize by proper cable orientation.
In addition to orienting the cable to point toward the nearest pole, the sensor should also be mounted
such that obstructions (e.g., weather station tripod/tower or other instrumentation) do not shade the
sensor.
Once mounted, the green cap should be removed from the sensor.
The green cap can be
used as a protective covering for the sensor when it is not in use.

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OPERATION AND MEASUREMENT
Connect the sensor to a measurement device (meter, datalogger, controller) capable of measuring and
displaying or recording a millivolt (mV) signal (an input measurement range of approximately 0-250 mV is
required to cover the entire range of total shortwave radiation from the sun). In order to maximize
measurement resolution and signal-to-noise ratio, the input range of the measurement device should
closely match the output range of the pyranometer.
SP-110: The sensor is self-powered and applying voltage will damage the sensor.
SP-230: Only apply voltage to the integrated heaters. The sensor is self-powered and applying
voltage will damage the sensor.
All Apogee un-amplified pyranometer models have a standard calibration factor of exactly:
5.0 W m-2 per mV

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Multiply this calibration factor by the measured mV signal to convert sensor output to shortwave radiation
in units of W m-2:
Calibration Factor (5.0 W m-2 per mV) * Sensor Output Signal (mV) = Total Shortwave Radiation (W m-2)
5.0 * 200 = 1000
Spectral Errors for Measurements with Silicon-cell Pyranometers:
Apogee SP series pyranometers are calibrated under electric lamps in a calibration laboratory. The
calibration procedure simulates calibration under clear sky conditions at a solar zenith angle of
approximately 45°. However, due to the limited spectral sensitivity of silicon-cell pyranometers compared
to the solar radiation spectrum (see graph below), spectral errors occur when measurements are made in
conditions that differ from conditions the sensor was calibrated under (e.g., the solar spectrum differs in
clear sky and cloudy conditions, thus measurements in cloudy conditions result in spectral error because
sensors are calibrated in clear sky conditions).
Example of total shortwave radiation
measurement with an Apogee SP-110
pyranometer. Full sunlight yields total
shortwave radiation on a horizontal plane at
the Earth’s surface of approximately 1000 W
m-2. This yields an output signal of 200 mV.
The signal is converted to shortwave
radiation by multiplying by the calibration
factor of 5.0 W m-2 per mV.
Spectral response of Apogee SP
series pyranometers compared to
solar radiation spectrum at Earth’s
surface. Silicon-cell pyranometers,
such as Apogee SP series, are only
sensitive to the wavelength range
of approximately 350-1100 nm,
and are not equally sensitive to all
wavelengths within this range. As a
result, when the spectral content
of solar radiation is significantly
different than the spectrum that
silicon-cell pyranometers were
calibrated to, spectral errors result.

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Silicon-cell pyranometers can still be used to measure shortwave radiation in conditions other than clear
sky or from radiation sources other than incoming sunlight, but spectral errors occur when measuring
radiation with silicon-cell pyranometers in these conditions. The graphs below show spectral error
estimates for Apogee silicon-cell pyranometers at varying solar zenith angles and varying atmospheric air
mass. The diffuser is optimized to minimize directional errors, thus the cosine response graph in the
Specifications section shows the actual directional errors in practice (which includes contributions from
the spectral shift that occurs as solar zenith angle and atmospheric air mass change with time of day and
time of year). The table below provides spectral error estimates for shortwave radiation measurements
from shortwave radiation sources other than clear sky solar radiation.
Spectral error for Apogee SP
series pyranometers as a function
of atmospheric air mass, assuming
calibration at an air mass of 1.5.
Spectral error for Apogee SP
series pyranometers as a function
of solar zenith angle, assuming
calibration at a zenith angle of 45°.

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Spectral Errors for Shortwave Radiation Measurements with Apogee SP Series Pyranometers
Radiation Source (Error Calculated Relative to Sun, Clear Sky)
Error [%]
Sun (Clear Sky)
0.0
Sun (Cloudy Sky)
9.6
Reflected from Grass Canopy
14.6
Reflected from Deciduous Canopy
16.0
Reflected from Conifer Canopy
19.2
Reflected from Agricultural Soil
-12.1
Reflected from Forest Soil
-4.1
Reflected from Desert Soil
3.0
Reflected from Water
6.6
Reflected from Ice
0.3
Reflected from Snow
13.7

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MAINTENANCE AND RECALIBRATION
Moisture or debris on the diffuser is a common cause of low readings. The sensor has a domed diffuser
and housing for improved self-cleaning from rainfall, but materials can accumulate on the diffuser (e.g.,
dust during periods of low rainfall, salt deposits from evaporation of sea spray or sprinkler irrigation
water) and partially block the optical path. Dust or organic deposits are best removed using water or
window cleaner and a soft cloth or cotton swab. Salt deposits should be dissolved with vinegar and
removed with a soft cloth or cotton swab.
Never use an abrasive material or cleaner on the diffuser.
The Clear Sky Calculator (www.clearskycalculator.com) can be used to determine the need for
pyranometer recalibration. It determines total shortwave radiation incident on a horizontal surface at any
time of day at any location in the world. It is most accurate when used near solar noon in spring and
summer months, where accuracy over multiple clear and unpolluted days is estimated to be ± 4 % in all
climates and locations around the world. For best accuracy, the sky must be completely clear, as reflected
radiation from clouds causes incoming radiation to increase above the value predicted by the clear sky
calculator. Measured values of total shortwave radiation can exceed values predicted by the Clear Sky
Calculator due to reflection from thin, high clouds and edges of clouds, which enhances incoming
shortwave radiation. The influence of high clouds typically shows up as spikes above clear sky values, not
a constant offset greater than clear sky values.
To determine recalibration need, input site conditions into the calculator and compare total shortwave
radiation measurements to calculated values for a clear sky. If sensor shortwave radiation measurements
over multiple days near solar noon are consistently different than calculated values (by more than 6 %),
the sensor should be cleaned and re-leveled. If measurements are still different after a second test, email
[e-mail] to discuss test results and possible return of sensor(s).

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Homepage of the Clear Sky
Calculator. Two calculators
are available: One for
pyranometers (total shortwave
radiation) and one for
quantum sensors
(photosynthetic photon flux).
Clear Sky Calculator for
pyranometers. Site data are
input in blue cells in middle of
page and an estimate of total
shortwave radiation is returned
on right-hand side of page.

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TROUBLESHOOTING AND CUSTOMER SUPPORT
Independent Verification of Functionality:
Apogee models SP-110 and SP-230 pyranometers are self-powered devices and output a voltage signal
proportional to incident shortwave radiation. A quick and easy check of sensor functionality can be
determined using a voltmeter with millivolt (mV) resolution. Connect the positive lead wire from the
voltmeter to the red wire from the sensor and the negative (or common) lead wire from the voltmeter to
the black wire from the sensor. Direct the sensor diffuser toward a light source and verify the sensor
provides a signal. Increase and decrease the distance from the sensor head to the light source to verify
that the signal changes proportionally (decreasing signal with increasing distance and increasing signal
with decreasing distance). Blocking all radiation from the sensor should force the sensor signal to zero.
The heaters inside Apogee model SP-230 are designed to mitigate effects from snow, frost, and dew by
warming the sensor body temperature approximately 3 C above ambient air temperature, while under
conditions of no solar loading or radiant heating. A quick and easy check of heater functionality can be
accomplished with an ohmmeter. Connect the lead wires of the ohmmeter to the white and green wires
from the sensor. The resistance should read approximately 780 Ω ± 1%.
Compatible Measurement Devices (Dataloggers/Controllers/Meters):
Models SP-110 and SP-230 pyranometers are calibrated with a standard calibration factor of 5.0 W m-2 per
mV, yielding a sensitivity of 0.2 mV per W m-2. Thus, a compatible measurement device (e.g., datalogger
or controller) should have resolution of at least 0.2 mV, in order to provide shortwave radiation resolution
of 1 W m-2.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee
webpage at http://www.apogeeinstruments.com/content/Pyranometer-Unamplified.CR1.
Effect of Cable Length:
When the sensor is connected to a measurement device with high input impedance, sensor output
signals are not changed by shortening the cable or splicing on additional cable in the field. Tests have
shown that if the input impedance of the measurements device is 1 mega-ohm or higher then there is
negligible effect on the pyranometer calibration, even after adding up to 100 m of cable. Apogee model
SP series pyranometers use shielded, twisted pair cable, which minimizes electromagnetic interference.
This is particularly important for long lead lengths in electromagnetically noisy environments.
Modifying Cable Length:
See Apogee webpage for details on how to extend sensor cable length
(http://www.apogeeinstruments.com/how-to-make-a-weatherproof-cable-splice/).

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RETURN AND WARRANTY POLICY
RETURN POLICY
Apogee Instruments will accept returns within 30 days of purchase as long as the product is in new condition (to be determined by
Apogee). Returns are subject to a 10% restocking fee.
WARRANTY POLICY
What is Covered
All products manufactured by Apogee Instruments are warranted to be free from defects in materials and craftsmanship for a period
of four (4) years from the date of shipment from our factory. To be considered for warranty coverage an item must be evaluated
either at our factory or by an authorized distributor.
Products not manufactured by Apogee (spectroradiometers, chlorophyll content meters) are covered for a period of one (1) year.
What is Not Covered
The customer is responsible for all costs associated with the removal, reinstallation and shipping of suspected warranty items to our
factory.
The warranty does not cover equipment that has been damaged due to the following conditions:
1. Improper installation or abuse
2. Operation of the instrument outside of its specified operating range
3. Natural occurrences such as lightning, fire, etc.
4. Unauthorized modification
5. Improper or unauthorized repair
Please note that nominal accuracy drift is normal over time. Routine recalibration of your sensor/meter is considered part of proper
maintenance and is not covered under warranty.
Who is Covered
This warranty covers the original purchaser of the product or other party who may own it during the warranty period.
What We Will Do
At no charge we will:
1. Either repair or replace (at our discretion) the item under warranty.
2. Ship the item back to the customer by the carrier of our choice.
Different or expedited shipping methods will be at the customer’s expense.
How To Return An Item
1. Please do not send any products back to Apogee Instruments until you have received a Return Merchandise Authorization (RMA)
number from our tech support department by calling [phone] or by submitting an online RMA form at
www.apogeeinstruments.com/tech-support-recalibration-repairs/ . We will use your RMA number for tracking of the service item.
2. Send all RMA sensors and meters back in the following condition: Clean the sensor’s exterior and cord. Do not modify the sensors
or wires, including splicing, cutting wire leads, etc. If a connector has been attached to the cable end, please include the mating
connector – otherwise the sensor connector will be removed in order to complete the repair/recalibration.

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3. Please write the RMA number on the outside of the shipping container.
4. Return the item with freight pre-paid and fully insured to our factory address shown below. We are not responsible for any costs
associated with the transportation of products across international borders.
5. Upon receipt, Apogee Instruments will determine the cause of failure. If the product is found to be defective in terms of
operation to the published specifications due to a failure of product materials or craftsmanship, Apogee Instruments will repair or
replace the items free of charge. If it is determined that your product is not covered under warranty, you will be informed and given
an estimated repair/replacement cost.
Apogee Instruments, Inc.
721 West 1800 North Logan, UT
84321, USA
OTHER TERMS
The available remedy of defects under this warranty is for the repair or replacement of the original product, and Apogee
Instruments is not responsible for any direct, indirect, incidental, or consequential damages, including but not limited to loss of
income, loss of revenue, loss of profit, loss of wages, loss of time, loss of sales, accruement of debts or expenses, injury to personal
property, or injury to any person or any other type of damage or loss.
This limited warranty and any disputes arising out of or in connection with this Limited Warranty ("Disputes") shall be governed by
the laws of the State of Utah, USA, excluding conflicts of law principles and excluding the Convention for the International Sale of
Goods. The courts located in the State of Utah, USA, shall have exclusive jurisdiction over any Disputes.
This limited warranty gives you specific legal rights, and you may also have other rights, which vary from state to state and
jurisdiction to jurisdiction, and which shall not be affected by this limited warranty. This warranty extends only to you and cannot by
transferred or assigned. If any provision of this Limited Warranty is unlawful, void or unenforceable, that provision shall be deemed
severable and shall not affect any remaining provisions. In case of any inconsistency between the English and other versions of this
Limited Warranty, the English version shall prevail.
This warranty cannot be changed, assumed, or amended by any other person or agreement.
APOGEE INSTRUMENTS, INC. 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] FAX: [phone] WEB: APOGEEINSTRUMENTS.COM
Copyright © 2013 Apogee Instruments, Inc.