OTT HydroMet Kipp & Zonen DustIQ User manual

Instruction Manual
DustIQ • Soiling Measurement
Applicable to all models. Please check regularly for updates.
V2105-01

2
Important user information
Dear customer, thank you for purchasing a Kipp & Zonen instrument. It is essential that you read this manual completely
for a full understanding of the proper and safe installation, use, maintenance and operation of your DustIQ.
We understand that no instruction manual is perfect, so should you have any comments regarding this manual we will be
pleased to receive them at:
OTT HydroMet B.V.
Delftechpark 36, 2628 XH Delft, or
P.O. Box 507, 2600 AM Delft
The Netherlands
Tel. [phone]
[e-mail]
www.kippzonen.com
Publication date: May, 05, 2021
Important changes:
•Extra instructions for dealing with small transmission loss offsets
•Advice for not yet locally dust calibrated measurements
•Advice to use 24VDC as power supply to get the best measurements
•Extra attention for the right Modbus command “04 Read Input Registers” to get data from the DustIQ.
•Extra Frequently Asked Questions (FAQs)
December 2019 updates:
•Added advice not to install the DustIQ horizontally when vertical soiling pattern is present.
October 2019 updates:
•Added Tilt and Panel temperature to Campbell examples
January 2019 updates:
•Full Feature version with tilt sensor, PV panel temperature sensor and daisy-chain capabilities added.
•DustIQ height reduced from 40 to 35mm starting with serial number 180094
•Added status and calibration context flags and stored in Modbus® registers
•Increased minimum irradiation for local dust calibration to 800 W/m2
•Added remark that 5% transmission loss for local dust calibration equals 50 ‰ in Modbus register 21

3
Table of contents
Important user information ............................................................................................................................................ 2
Introduction..................................................................................................................................................................... 5
Safety precautions................................................................................................................................................. 5
Waste disposal....................................................................................................................................................... 5
Customer support.................................................................................................................................................. 5
Product overview ............................................................................................................................................................ 6
The DustIQ soiling measurement instrument....................................................................................................... 6
Included with the product..................................................................................................................................... 6
Intended use .......................................................................................................................................................... 6
Planning the installation and use of the DustIQ............................................................................................................. 7
Where to place DustIQ in the PV plant .................................................................................................................. 7
How to value dust measurements .................................................................................................................................. 8
Introduction........................................................................................................................................................... 8
Solar angle dependency........................................................................................................................................ 8
The influence of dew and rain............................................................................................................................... 9
Dealing with small offsets in transmission Loss or Soiling Ratio .......................................................................13
Dust measurements before local calibration .....................................................................................................14
Installation .................................................................................................................................................................... 15
Tools required...................................................................................................................................................... 15
Pre-installation .................................................................................................................................................... 15
Connecting the cables to the DustIQ................................................................................................................... 16
Connecting the cable to the USB converter and power supply ......................................................................... 17
Connecting the cable to the PMU485 interface box ...........................................................................................17
Changing the settings of the DustIQ....................................................................................................................18
Mounting the DustIQ outside .............................................................................................................................. 26
DustIQ physical installation ................................................................................................................................ 26
Use of the clamps for installation ....................................................................................................................... 27
Fitting the host connector and cable outside:....................................................................................................30
Fitting the daisy-chain cable ............................................................................................................................... 31
Installing the PV panel temperature sensor ....................................................................................................... 31
Connection to a RS-485 network......................................................................................................................... 32
Electrical details .................................................................................................................................................. 32
Operation and measurement ....................................................................................................................................... 33
Data collection..................................................................................................................................................... 33
Housing ................................................................................................................................................................ 33
Local Dust Calibration................................................................................................................................................... 34
The advantage of a local dust profile.................................................................................................................. 34
Post-processing of old DustIQ data after local dust calibration ........................................................................35
Making of a local dust profile .............................................................................................................................. 36
Maintenance and re-calibration ................................................................................................................................... 37

4
Yearly maintenance............................................................................................................................................. 37
Cleaning ............................................................................................................................................................... 37
Calibration ........................................................................................................................................................... 37
Specifications ................................................................................................................................................................ 38
Optical and electrical........................................................................................................................................... 38
Dimensions and weight ....................................................................................................................................... 38
Trouble shooting........................................................................................................................................................... 39
Output signal not present or incorrect ............................................................................................................... 39
Appendices .................................................................................................................................................................... 40
Modbus® commands ........................................................................................................................................... 40
DustIQ release 3.01 data model .......................................................................................................................... 40
DustIQ release 3.02 data model .......................................................................................................................... 43
Sample ModbusPoll data for data model 3.x......................................................................................................46
Tilt sensor output ................................................................................................................................................ 47
Reset using Modbus Write coil commands ......................................................................................................... 48
Open source licenses........................................................................................................................................... 50
Example Campbell programs.............................................................................................................................. 52
Frequently asked questions.......................................................................................................................................... 54

5
Introduction
Reading this entire manual is recommended for a full understanding of this product.
CAUTION
The triangle with exclamation mark is intended to alert the user to the presence of important installation,
operating and maintenance instructions in the literature accompanying the instrument.
WARNING Low voltage electrical equipment
This low voltage electrical equipment should only be installed and serviced by authorized personnel, meaning
people who have been trained and designated as “authorized” by their employers.
Useful information for the user
Safety precautions
Many hazards are associated with installing and maintaining instruments on towers or elevated structures. It is advised
to use qualified personnel for installation and maintenance. The client is responsible for following the local safety
regulations. The use of appropriate equipment and safety practices is mandatory. Check your company's safety
procedure and protective equipment prior to performing any work. If the DustIQ is mounted at a high position, special
care must be taken to secure both the person installing it and the instrument from falling during installation.
CAUTION Handling a breakable instrument
Since the DustIQ weighs 4kg, contains glass and is comparable to a regular PV module it is advised to use the
same safety precautions as the ones used for handling and fitting regular PV modules.
While every attempt is made to get the highest degree of safety in our products, the client assumes all risk from injuries
resulting from improper installation, use or maintenance of the DustIQ.
Waste disposal
The pictogram showing a waste bin with a cross means that the product is subject to European Union
regulations covering segregated waste disposal. This applies both to the productitself and to any accessories
marked with the same symbol. Disposal of any such item as unsorted domestic waste is not allowed.
Customer support
In case you need support, please contact:
OTT HydroMet B.V.
Delftechpark 36, 2628 XH Delft, or
P.O. Box 507, 2600 AM Delft,
The Netherlands
Tel. [phone]
[e-mail]
www.kippzonen.com
!

6
Product overview
This manual, together with the Smart Explorer manual and instruction sheet, provides information related to the
installation, maintenance, calibration, product specifications and applications of the DustIQ soiling monitor.
If any questions should remain, please contact your local OTT HydroMet representative or e-mail the Kipp & Zonen
customer and product support department at: [e-mail]
Please go to www.kippzonen.com for information about other Kipp & Zonen products, or to check for any updates to this
manual or software.
The DustIQ soiling measurement instrument
The DustIQ instrument is a unique, high quality instrument designed for measuring the light loss resulting from the soiling
of the panel. The measured light loss is an indication for the losses introduced by the soiling of the nearby PV panels too.
The DustIQ instrument features internal digital signal processing and interfaces optimised for industrial data acquisition
and control systems. Kipp & Zonen has developed a smart interface that features RS-485 Modbus® data communication
for connection to programmable logic controllers (PLC’s), inverters, digital control equipment and digital data loggers.
To achieve the required accuracy, the amount of reflected light is precisely measured and combined with the local dust
calibration that has to be performed, the right light loss is calculated.
The DustIQ panel soiling monitors are normally delivered with a 10m UV resistant cable with an 8 pin plug on the
instrument side and wire ends on the other side. Longer 25m and 50m cables are available as well.
Included with the product
Check the contents of the shipment for completeness (see below) and note whether any damage has occurred during
transport. If there is damage, a claim should be filed with the carrier immediately. In the case of damage and/or the
contents are incomplete, contact your local OTT HydroMet representative or e-mail the Kipp & Zonen customer and
product support department at: [e-mail]
Contents of part number 0386900 and 0386910: DustIQ panel, 4 mounting clamps with bolts, washers and nuts,
instruction sheet, 10 m cable to the host or SCADA system.
The 0386915 model comes without standard cable and the cable (10, 25, 50, 100m to host or 5,10m daisy-chain) or
just the ODU connector must be ordered separately.
Although all DustIQ instruments are weatherproof and suitable for use in harsh environmental conditions, they have some
delicate mechanical parts. Please keep the original packaging for safe transport of the instrument to the measurement
site, or for use when returning the instrument for possible repair or recalibration.
Intended use
The DustIQ instrument is an instrument meant to measure and report the transmission loss (TL) and soiling ratio (SR)
caused by light being blocked and reflected and subsequently not getting through the glass of the panel due to soiling of
the panel.
The DustIQ is meant to be mounted next to and in the same plane as the PV panels in the solar park. The instrument is
fully waterproof (IP65) and can be cleaned in the same way as the PV panels are cleaned, both wet and dry.
Communication is possible via Modbus® RTU using a RS485 2-wire connection and the power supply needed is 12 to 30 V
and max 300 mA.

7
Planning the installation and use of the DustIQ
This chapter describes the best locations to place the DustIQs and how to make the best of the acquired data.
Where to place DustIQ in the PV plant
Measuring dust and soiling ratio is a new field of science. There are many opinions about it, but there is no large history
of data and experience in measurements. Although the spot measurement of DustIQ is very precise, it is wise to do
interpretation and use common sense when extrapolating the measurement value to the whole PV plant, or a part of it,
for decision making. The measurement value thus is true, the only question is, whether this value is representative for the
PV park.
For giving a good representation of soiling across the PV plant, one should place multiple DustIQs across the plant. In fact,
the IEC61724-1:2017 Standard for PV system performance (Monitoring) prescribes that one should have as many dust-
sensors as irradiance sensors. This makes intuitive sense: it follows the same logic as irradiance that also is not constant
across a solar plant, and one has to have sufficient measurements to make a valid interpretation. For the number of
DustIQs, one can thus follow the own policy for the number of pyranometers. Of course, every additional DustIQ adds up
to a better overall measurement. For 1 MW plants, 1 DustIQ placed in the middle could do, whereas for larger plants – say
25 MW- one could imagine the one in the middle, and one near each corner could be a logical choice to understand the
soiling pattern across the plant.
Soiling is a different phenomenon than irradiation, and also very site specific. Where you normally expect the same
average irradiation value for all pyranometers at a solar plant, this is not necessarily true for DustIQs: if the wind always
blows from the east, one could expect moresoiling (and thus another cleaning interval policy) at the east side of that solar
plant. When wind direction changes over seasons, this pattern could shift during the year. Also, it is known that the very
ends of an array, and the bottom row of an array (closest to the ground), typically suffer more from soiling than the rest
of the PV modules. Therefore, better not place DustIQs here for cleaning policy, unless your purpose is to learn and study
soiling behaviour.
Again, soiling is a new scientific area, especially when applied to solar plants. Kipp & Zonen will build up the application
data base along with the users, in order to set standards for best practices. When installing the DustIQs, it makes sense to
follow up the instrument readings over a period of weeks, and do visual inspection as to reassure yourself on
representative values. DustIQ is designed in such a way, that you can easily dismount it, and put it at another location,
where you trust it to give the most representative information for your purpose. DustIQs can be placed at the side, and at
the top of PV modules, in the middle of an array or at the sides. Horizontal in not advised at soiling is uneven in the vertical
direction, influencing the PV module output. Kipp & Zonen has introduced DustIQ-array-fillers, in order to install the
DustIQ in the middle of a row and in the middle of an array, without making gaps in the array.

8
How to value dust measurements
Measuring dust is a new area with new challenges. Below are a few of them explained.
Introduction
DustIQ is not an indicator of dust, but a real accurate measurement device, in line with all Kipp & Zonen instruments. The
DustIQ measurement technology is unprecedented and new to the market. Therefore some extra words for the user of the
measurement information.
One should understand that measuring physical quantities needs careful interpretation. Measuring voltage or velocity
can be done very precise, and the answer is always very close to the truth. Influenced only by the accuracy of the used
instrument. Much more difficult it gets for instance with precipitation or solar radiation measurements; there is an
intrinsic limit as to how precise one can measure it and with which uncertainty.
Measuring dust / transmission loss /soiling ratio is a new field of science. There are many opinions about it, but there is
no large history of data and experience in measurements. Although the spot measurement of DustIQ is very precise, it is
wise to do interpretation and use common sense when extrapolating the measurement value to the whole PV plant, or a
part of it, for decision-making. The coming years, Kipp & Zonen will build up thisexpertise together with you and our other
customers and scientific users. Visual inspection seems the most logical validation for understanding and extrapolating
the dust measurement information. Before decision making and taking cost intensive cleaning actions, it is recommended
to do visual inspection: is the DustIQ device soiled in the same way as the average soiling on the PV modules? What helps
in data validity, is the fact that the DustIQ is designed to handle local irregularities of soiling, and that the DustIQ has two
measurement sensors, so one can compare the values.
For larger areas, it is wise to mount several DustIQs, just like you now mount several pyranometers across a PV plant.
Again: for DustIQs, one can trust the measurement value to be correct, the only judgement you have to make, is, whether
this value is representative for the whole PV park.
Solar angle dependency
The actual transmission loss and soiling ratio have a solar angle dependency. The DustIQ is not aware of the solar angle,
but based our test results and literature research we have two simple formulas to calculate the daily SR and TL averages.
SRDAILY_AVERAGE = 1.2 x SRDUSTIQ – 20 and TLDAILY_AVERAGE = 1.2 x TLDUSTIQ
Background: For the customer a very useful value is to know the weighted average value for the Soiling Ratio over a day.
Such a weighted average value is also prescribed by the IEC 61724-1 norm (page 30). We have chosen a weighting by PV
power output over the course of the day.
For this calculation, we have chosen multiple locations:
1) Close to the Dubai Mohammed bin Rashid Al Maktoum Solar Park in Dubai.
2) Close to planned new Solar Park in Baganuur near Ulaanbatur in Mongolia.
Dubai Mohammed bin Rashid Al Maktoum Solar Park Hypothetical PV AC output at the 8th of august 2017 in Dubai
We assumed the panels are mounted at 22° degrees in Dubai and soiling ratio (SR) over the day

9
Hypothetical PV AC output at the 6th of august 2017 in Mongolia
and SR over the day.
Combining the information from both graphs, we calculated the SRDAILY_AVERAGE weighted by the PV output for both locations
and concluded that there is very little difference between Dubai (latitude= 24.4) and Mongolia (latitude = 47.9)
The influence of dew and rain
The DustIQ measurement are sensitive to dew and rain and measurements done during these conditions must be ignored.
Morning
dew
followed by
dew
Rain

10
It’s the trend line over a longer period of time that gives the best overview of the transmission loss.
The spikes visible are due to morning and evening dew. The bigger, longer lasting changes are the result of rain cleaning
the panel.
The DustIQ performs a measurement every minute but since the accumulation of dust is a slow process one doesn’t need
to read and record a measurement every minute and by using data from a weather station it is possible to select enough
valuable measurements per day to show the soiling build up trend line.
The above sample data shows the data collected in Morocco with daily dew and occasional rain. Still the trendline in
soiling build-up is clearly visible.

11
Taking only few measurements per day improves the readability of the chart.
With all dew and rain events removed from the data.
Please also check: https://www.kippzonen.com/Download/1022/DustIQ-Application-Note-Data-Reduction
900
910
920
930
940
950
960
970
980
990
1000
0 10 20 30 40 50 60 70 80 90 100
Spiling ratio promille
12:00 o'clock measurements
Soiling ratio Morocco
!
cleaning action
cleaning action
rain

12
Filtering data based on the combined PV module temperature and calculated dewpoint based on local ambient
temperature plus relative humidity or the dewpoint as provided by a weather station plus a rain gauge has proven to be
useful.
Selection criteria:
•PV module temperature > 2 degrees Celsius higher than the dew point.
•No rain 1 hr before and 4 hours after.
•No snow. (this results in very high reflection and DustIQ output changes)
•No change in transmission loss in the last 24 hours of >5% unless the DustIQ has been cleaned.
Resources for dewpoint calculations: https://en.wikipedia.org/wiki/Dew_point

13
Dealing with small offsets in transmission Loss or Soiling Ratio
When a DustIQ is completely clean the sensors are not measuring zero reflection of the pulsed blue LED light. There is
some reflection from the glass. With soiling added there will more reflection and the increase is translated into
transmission loss.
This means that there is a reflected light signal that represents zero transmission loss (0% TL) and there is an
uncertainty in determining this value during the factory calibration process.
The result could be a small zero offset that is a maximum of ±1%. In practice, it is unlikely to exceed ±0.4% and it
remains stable.
If you know the zero offset for each DustIQ sensor you can add (negative offset) or subtract (positive offset) those values
from the DustIQ transmission loss (TL) data before logging to improve the accuracy.
Make sure that the DustIQ is very well cleaned and dried.
Then look at the data to identify the zero offset for each of the two sensors. The TL and SR data to be logged can then be
corrected in the PV plant SCADA system or data logger as follows:
Example 1:
Step 1: Step 2: correct values
DustIQ output: to be logged:
Transmission Loss sensor 1 TL1FROM_DUSTIQ = 0.2% TLTO_BE_LOGGED = TL1 – 0.2%
Soiling Ratio sensor 1 SR1FROM_DUSTIQ = 99.8% SR1TO_BE_LOGGED = SR1 + 0.2%
Transmission Loss sensor 2 TL2FROM_DUSTIQ = 0.0% TL2TO_BE_LOGGED = TL2 no change
Soiling Ratio sensor 2 SR2FROM_DUSTIQ = 100.0% SR2TO_BE_LOGGED = SR2 no change
Example 2:
Step 1: Step 2: correct values
DustIQ output: to be logged:
Transmission Loss sensor 1 TL1FROM_DUSTIQ = - 0.1% TL1TO_BE_LOGGED = TL1 - - 0.1 = TL1 + 0.1%
Soiling Ratio sensor 1 SR1FROM_DUSTIQ = 100.1% SR1TO_BE_LOGGED = SR1 – 0.1%
Transmission Loss sensor 2 TL2FROM_DUSTIQ = 0.2% TL2TO_BE_LOGGED = TL – 0.2%
Soiling Ratio sensor 2 SR2FROM_DUSTIQ = 99.8% SR2TO_BE_LOGGED = SR2 + 0.2%
Right after a successful local dust calibration the values reported by the DustIQ are the real clean values and these must
be used for possible corrections after the calibration as indicated above.
!
!
‘clean’ signal
LED Photodiode
‘soiled’ signal
LED Photodiode

14
Dust measurements before local calibration
The DustIQ is factory calibrated using Arizona Test Dust which is produced in compliance with: ISO 12103-1:2016 A4
coarse test dust.
Arizona Test Dust is available with certificates on chemical composition and grain size and is commonly used by the
scientific community, but it has proved to poorly represent the soiling observed by DustIQ users e.g. in the
Mediterranean, North America and in Arabia.
The shared calibrations showed a range of 1.5 to 2.3 times more transmission loss, with the average close to 2.
Based on these shared calibrations we advise customers to multiply the transmission loss, as reported by an DustIQ
uncalibrated for local soiling, with a factor of two until local calibration has been performed.
TLNEW = TL x 2
SRNEW = 100% -TLNEW
This way recorded data without local calibration will be closer to the expected local value after calibration.
It shows the importance of doing a local calibration, so please do so, once the transmission loss has reached 5% for the
first time.

15
Installation
Please follow the instructions in this section carefully for the mechanical and electrical installation of the DustIQ.
Do not turn on power to the instrument,
Do not connect the instrument to a computer,
Do not turn on power to the operating computer until instructed to do so.
Tools required
The tools required to fit the DustIQ instrument to a PV panel are:
Allen key 6 mm
Spanner 13 mm
The tools required to change the default DustIQ settings are:
A type of USB-RS485 converter that supports half duplex 2-wire connections and preferably has
optical isolation for increased safety and reliability.
DustExplorer software will be available from http://www.kippzonen.com/download
Pre-installation
If changing the settings from the factory default is needed then it is advised to set the Modbus® address prior to visiting
the site, otherwise a computer and RS-485 / USB converter may be required during installation. The SmartExplorer
software needed for setting the Modbus address and communication parameters is available on the Kipp & Zonen website
in the download section. Please perform the following steps without mounting the DustIQ and leaving it on your desk
before moving the DustIQ outside.
The DustIQ comes with the following factory defaults:
•Modbus baud rate: 19200
•Parity: even
•Data bits: 8
•Stop bits: 1
•Address: 1
•Local dust profile: Arizona test dust
!

16
Connecting the cables to the DustIQ
Connect the supplied or locally made data cable to the socket labelled Host.
First released model Pn 0386900 that doesn’t support daisy-chaining or PV panel temperature sensor.
Full feature models Pn 0386910 and 0386915.
Locate the 8 pin ODU plug correctly in the DustIQ socket, it only fits one way. The red dot on the plug should be opposite
of the red dot on the chassis socket. Push it in to secure whilst holding the plug by the end or by the grooved ring.
To unplug, pull the grooved ring back and then pull out the plug.
Do not remove the backing of the double sided tape of the sensor yet, as ithe sensor will stick extremely well and is very
hard if not impossible to remove.
!

17
Connecting the cable to the USB converter and power supply
When using an industry standard USB-RS485 converter he following connections need to be made.
The minimum power supply voltage for the DustIQ instrument is 12 VDC. However, for reliable performance it is advised
to use 24 VDC, especially when longer cables are used or if DustIQs are daisy-chained.
It is advised to protect the output of the power supply with a fast blowing fuse of maximum 500 mA rating.
Typical power consumption of the DustIQ instrument
12 VDC 60 mA LEDs off – 130 mA LEDs on, std duty cycle 5%
24 VDC 40 mA LEDs off – 70 mA LEDs on, std duty cycle 5%
Connecting the cable to the PMU485 interface box
When using the Kipp & Zonen PMU485 Smart Setup Hub, the following connections must be made
Green screw terminal, can be unplugged
+12V White
Power Ground Black
Data Ground Blue
D- signal Grey
D+ signal Yellow
Please see https://www.kippzonen.com/Product/534/PMU485 for more details.
!
n.c.
n.c.
n.c.
RS-485 data +
RS-485 data -
RS-485 Ground
Power +12 to 30V
Power ground

18
Changing the settings of the DustIQ
For changing the DustIQ settings the Smart DustIQ Explorer software is needed as well as one connected DustIQ.
Finding the COM port
After starting the Dust Explorer software the user needs to select the right COM port on which your USB-RS-485 converter
has been installed by the Windows® 7, 8 or 10 operating system.
One way of checking the COM port number is by using the standard Windows Device Manager via Control Panel
→

19
First start up
After the first start of the Smart DustIQ Explorer V2.0.1.0 or above software the window below will appear:
Configuring the settings
In order to connect to the DustIQ: click on Setup Connection
Select Serial RTU protocol for the direct RS485 connection that you’re using.
Select the COM port you found in the Windows Device Manager.
Leave the other settings unchanged as these are the factory defaults for all Kipp & Zonen products.

20
If you have changed the settings and return to the Smart DustIQ Explorer you have to change the settings to the ones used
by your instrument.
Click Confirm to save and use the settings.
Main window - connections
Once the Dust Explorer software can communicate with the attached DustIQ, the following window appears:
•The program starts in Normal Network Use, meaning you can have several instruments attached to monitor
•Changing setting is best done with only one instrument attached
•Finding an instrument with unkown communication settings is only possible with one instrument attached
•Allow 5 to 10 minutes for the instrument to stabilise before reading the measurements
•When started the first time and with a DustIQ straight out of the box: 19.200, 8E1 are the coms settings used and
working.
On the initial 0386900 model, Power Volt is not reported correctly and always 3.2V. Later models (0386910 & 15) report the
actual supply voltage.