SOLAR SOLUTIONS

Sun Tracking:

Sun Tracker is the most widely used solution for tracing sun around the world in solar energy and meteorological applications. It has Baseline Surface Radiation Network (BSRN) levels of performance and reliability.

With the optional top mounting plate and shading assembly sun tracker can be configured as a complete solar monitoring station with up to three ventilated radiometers. A large range of mounting kits is available for direct solar radiation instruments.

An advance over conventional sun trackers is the integrated GPS receiver to automatically configure location and time data upon installation.

The rugged and distinctive cast aluminium housing has an integrated tripod stand with levelling feet, azimuth adjustment and provision for tie-down bolts. A side plate with zenith adjustment and mountings for a pyrheliometer is included.

Soiling Monitoring Solutions (SMS):

Our soiling monitoring solutions analyze effective irradiance loss in module soiling that causes project energy production loss. This solution optimizes measurement accuracy and uses data filtering to ensure the highest quality soiling data in solar resource assessment applications.

The Soiling Monitoring Solution (SMS) calculates soiling loss by comparing the effective irradiance from a test PV module—left to soil at a natural rate—to that of a clean reference PV module. Effective irradiance of each module is calculated in accordance with IEC 60904 by using the measured short-circuit current and back-of-module temperature to calculate effective irradiance. The effective irradiance is then used to determine the real-time soiling ratio. Daily values for the soiling-loss index are also calculated and reported, along with a quality factor for quality control purposes. In comparison, calculating soiling loss using maximum power, another IEC 61724 soiling measurement method, requires a strong dependence on cell temperature. This can result in back-of-module temperature uncertainty manifesting a higher uncertainty for soiling measurements, making it less reliable than the short-circuit method.

Several factors should be considered when selecting the two PV reference devices used to monitor soiling loss. The dynamics of dust adhesion on a PV module surface is a complex phenomenon that is affected by the local climate, the properties of the glass surface, and any coating it may have. Hence, the best soiling measurement is obtained when the PV modules used are the same make and model as those used on the PV power plant. Campbell Scientific strongly suggests using PV modules matching those deployed for power production at the site, but a customized solution can be provided if this is not possible. Additionally, the PV modules used to monitor soiling loss should ideally be mounted on the same racking as the rest of the string while not being tied into the string leading to the inverter.

The Soiling Monitoring Solution (SMS) Solar-Module Soiling Sensor supports Modbus TCP and can optionally support additional communication protocols such as DNP3, PakBus, PakBus encryption, and several internet protocols.

The Soiling Monitoring Solution (SMS) is delivered field ready and requires no programming to make deployment and configuration a simple process. This sensor will work with almost any user-supplied solar module. Two highly accurate and rugged back-of-module temperature sensors are also included.

Raw values of all measured quantities are stored locally on the Soiling Monitoring Solution (SMS) in a data file that can be retrieved and used for further analysis or debugging. Data used in calculating the daily soiling-loss index are filtered to avoid any influences that could cause irregularities in the data sets, such as angle-of-incidence effects from incoming irradiance at low sun angles.

Some projects provide soiling-loss monitoring on production racking, and they use test and reference PV modules of the same make and model as the production panels. In these situations, Campbell Scientific integrates back-of-module temperature sensors and a pre-programed data logger into an environmental enclosure to connect and measure user-supplied PV modules. For projects that cannot provide their own panels, Campbell Scientific will provide the same hardware, along with two 20-W solar panels on a single assembly as the two PV devices for soiling monitoring. Mounting of the panel assembly will need to be determined on a case-by-case basis.

The operation of the soiling station is straightforward and requires a manual cleaning of the reference module at a regular interval, usually cleaned at the same time as the on-site pyranometer(s).

ISN VOC Measuremnet:

With its small form factor, the Isc & Voc device is meant for use on solar PV panels already installed in the solar PV plant. The device can measure the Isc and Voc values from up to two solar PV panels simultaneously and when supplied as part of a complete measurement kit

Applications

Isc & Voc monitoring of solar PV panels. The Isc output can be used for irradiance calculations whereas the Voc output can be used for cell temperature calculations. The combination of both Isc and Voc outputs can be used to estimate the solar power output.

Solar Energy Measurement Solutions:

Solar energy is certainly one of the most important renewable energies available, and we use it under two forms: thermal and photovoltaic. The Solar Energy Measurement System (SEMS) designed by Ingenious is a technical solution for the measurement of all the components of Solar Radiation:

Direct Normal Irradiance (DNI)

Global Horizontal Irradiance (GHI)

Diffuse Horizontal Irradiance (DHI)

Global Normal Irradiance (GNI)

For solar energy resource assessment purposes and solar power plant monitoring, generally it is required to measure all the three components of the Solar Irradiance: DNI, GHI, DHI plus optionally GNI.

Solar Resource Monitoring:

Solar Resource Monitoring (SRM) refers to the effort by solar project operators to continually observe and optimize the energy output from a solar power plant. A variety of meteorological and other parameters are continuously monitored at each power-producing facility and are used as the basis upon which to evaluate the system’s electricity generation. We refer to this measurement of a solar plant’s fuel as ‘Solar Resource Monitoring’ – an important subset of plant-level monitoring and the denominator in the critical Performance Ratio (PR) metric (energy produced / energy available).

Inefficiencies at the module, string, and system-wide levels can be detected by tracking electrical output side-by-side with accurate measurements of the site’s solar irradiance, temperature, and wind conditions. This information can be used to trigger real-time maintenance and to build optimal long-term preventative maintenance and cleaning programs specific to each site.

We have leveraged years of expertise in the design of complete meteorological systems for the wind and solar energy industries to create our turnkey SRM and WRM System. 

Solar Resource Assessment:

Solar Resource Assessment (SRA) refers to the analysis of a prospective solar energy production site with the end goal being an accurate estimate of that facility’s annual energy production (AEP). As the designer, and provider of equipment used to conduct measurement campaigns in support of that goal, we at Ingenious often use the term “SRA” in reference to site-specific measurement. That is, the systematic collection of “ground truth” meteorological data for the purpose of lowering the uncertainty of the AEP estimate.

For Solar Resource Assessment and Solar Power Plants Monitoring, it is necessary to measure the three components of Solar Irradiance: The Direct Normal (DNI), the Global Horizontal (GHI), the Diffuse Horizontal (DHI), as well as the Global Normal (GNI) or the Global Tilted Irradiance (GTI).

Solar Energy Measurement for PV, CPV & CSP Power Plants:

Technical solutions in the Solar Energy sector

The SEMS System constitutes the most advanced technical solution to measure all components of Solar Radiation:

  • Direct Normal Irradiance (DNI)
  • Global Horizontal Irradiance (GHI)
  • Diffuse Horizontal Irradiance (DHI)
  • Global Normal Irradiance (GNI)
  • Global Tilted Irradiance (GTI)

Apart from the classic solar sensors as the Pyranometers and Pyrheliometers, the SEMS System admits the connection of additional sensors for the measurement of other meteorological parameters or of another nature such as:

  • Air temperature
  • Relative humidity
  • Wind speed and direction
  • Atmospheric pressure
  • Precipitation
  • Albedo
  • Dirt Index of the solar panels (soiling), etc.

The values of all these parameters are stored in the Datalogger of the SEMS System and are transmitted to a Data Reception Centre or SCADA via GPRS / 3G / 4G links, Radio, Fiber optics, etc. or through satellite data transmission networks, with global coverage.

Albedo:

Albedometers are instruments that measure global and reflected solar radiation, and the solar albedo. An albedometer is composed of two pyranometers with thermopile sensors; the upfacing one measuring global solar radiation, the downfacing one measuring reflected solar radiation. 

Albedo, also called solar reflectance, is defined as the ratio of the reflected to the global radiation. Ingenous offers a full range of albedometers, from second class to secondary standard.

Details

To support the growing adoption of bifacial PV modules, Ingenious offers the Albedo Measurement Kit for measuring the solar energy potential available to the backside of those modules. While bifacial PV modules appear to hold a compelling value proposition, the industry is still in the early stages of understanding the best way to deploy and operate this technology. For that reason, and also because of the wide variability and hyper-local nature of ground-reflected radiation, we strongly encourage anyone considering bifacial PV installations to conduct site-specific measurements.

The Albedo Measurement Kit features a 1.5 to 2m tall tripod stand with a horizontal mounting boom and sensor mounting fixture to enable unobstructed albedo measurements with the sensors of your choice (please note: sensors and cables are not included).

The Albedo Measurement Kit can be configured to meet your project’s unique needs and includes a pile-mounted option that features a pile-compatible horizontal mounting boom and sensor mounting fixture to enable unobstructed albedo measurement with the sensors of your choice (please note: piles, sensors, and cables are not included).

A tower-mounted option is also available. This configuration features a 6-foot [1.8m] boom and sensor mounting fixture to enable continuous, unobstructed albedo measurement with the sensors of your choice. Use this option to add RHI measurements through your tower mounted Albedo Measurement Kit.   

Benefits

  • Tripod folds up for easy transportation and installation and is painted flat black to prevent unwanted noise in measurement data
  • Mounting fixture compatible with industry-leading solar radiation sensor models
  • Compact design for easy installation and maintenance
  • Flexible, cost-effective solution to accommodate unique project requirements

How to measure albedo for bifacial PV

Hukseflux is the market leader in albedometers for bifacial PV system performance monitoring

The measurement of the albedo, or ground surface reflectance, of surfaces is gaining popularity. Bifacial PV modules generate power using both the global solar radiation and the reflected solar radiation. Downfacing pyranometers are suitable to make reflected radiation measurement, but you must carefully consider what the performance model requires as an input; the ground surface property or reflected irradiance? This note comments on instrument specifications, measurement location, and orientation.

Read the full article here: How to measure albedo for bifacial PV – note (PDF)

The Software Package manages all communications, data transmission and remote programming, also creating a database that collects all the information for later analysis and exploitation. This information can also be published on web and Internet Platform, with universal accessibility of the data for authorized users.

Why measure?

Contrary to a few short years ago, the routine collection of site-specific solar resource data has quickly become standard practice in the utility-scale solar PV industry, just as it is in wind. When properly installed and maintained, site-specific SRA campaigns provide an accurate context from which long-term satellite-derived irradiance data can be corrected. Together this combination of short-term “ground truth” and long-term satellite-derived data provide the lowest possible uncertainty for your prospective project, making it the preferred methodology by leading financial institutions. This uncertainty reduction translates to improved financial terms and faster return on investment.

How to measure

Over a period of one to several years, project developers use pyranometers to measure the solar resource, typically mounted on a short mast. Data from a variety of other met sensors are also collected to help characterize the resource, inform plant design decisions and estimate PV panel efficiency. Once installed, regular maintenance of the system is critical to produce meaningful resource assessment results. Most importantly, this entails cleaning pyranometers routinely (e.g., as frequently as every week depending on the site).

Our Solution

Our SRA product portfolio offers a complete toolkit for the utility-scale photovoltaic project developer. From the sensors to the data logger to the tower they are mounted on, our products are designed to integrate seamlessly for easy installation, precise data collection, and straightforward standardization. To learn how we can help with everything from equipment procurement to installation, ongoing maintenance, and data analysis.

Introduction

Figure 1 In PV system performance monitoring users typically employ Plane of Array (POA) on the right, Global Horizontal Irradiance (GHI), on the left, and increasingly also Reflected Irradiance (RI), in the middle.

An albedometer is an instrument that measures both global and reflected solar radiation and, by calculation, the solar albedo, or solar reflectance for a particular ground surface. An albedometer is composed of two pyranometers, both installed horizontally; the downfacing one measuring reflected solar radiation.

In the open field, the solar albedo depends on the directional distribution of incoming radiation and on surface properties at ground level. It is usually expressed as a single number, determined by taking an average over a day. Changes of albedo are typically slow and seasonal, except when it snows. Albedo’s of typical surfaces range from about 4 % for fresh asphalt and 15 % for green grass to 90 % for fresh snow.

The classic application of albedometers is in meteorological energy balance studies, studying albedo variations of large areas over multiple years. With the rise in popularity of bifacial PV modules, there is an increased demand to measure the albedo at PV power plants. This is possible with pyranometers, but there are a few things to keep in mind.

Recommendations in summary

A summary of Hukseflux’ recommendations for albedo measurement for bifacials:

  • keep the albedo definition simple: most models assume it is a ground surface property with a seasonal (monthly) variability; let the model take care of corrections for shading patterns, and conversion to Plane of Array
  • employ at least one instrument located away from the array, so that you have one unobstructed reference albedo measurement. This is under the assumption that the ground surface properties at the station are representative for those between the array
  • keep logistics simple; use the same instruments for POA, GHI and RI measurements. These are typically spectrally flat Class A (secondary standard) pyranometers. You can then also use the same calibration services
  • use either 2 x single pyranometers or modular instruments consisting of 2 x pyranometer, this is easier for servicing and recalibration
  • consider performing surveys for site characterisation in different seasons (also relative to the unobstructed reference station) to determine ground surface properties. This is a requirement for uncertainty evaluation
  • as an alternative for surveys, consider using multiple instruments between the arrays to verify model calculations of reflected irradiance and get an idea of its spatial variability; when using multiple instruments between rows, you may also employ lower accuracy (spectrally flat class B or C) instruments. Typically, these instruments are installed horizontally facing down, in some cases users choose to install in Plane of Array
  • do not install pyranometers for RHI measurement below 1 m height; 1.5 m is a good and practical compromise
  • for personnel safety, electrically insulate instrument body from PV array mounting frames
  • after snowfall, do not use the values measured by an unobstructed reference albedo measurement station. An unobstructed station will not have snow patterns representative of those between arrays

Performance model, ratio and index

The new IEC 61724 “Photovoltaic system performance” series of standards is the best available source that defines parameters such as “performance ratio” and “performance index”. IEC uses the following definitions:

  • performance modelgives a mathematical description of the electrical output of the PV system as a function of meteorological conditions, the system components, and the system design. This model is typically agreed upon in advance by the stakeholders of the test
  • predicted outputis the output for a given period as calculated using the performance model based on historical weather data
  • expected outputis the output calculated using the performance model when entering measured weather data
  • ratingperformance as specified by the manufacturer, usually confirmed via the name-plate on the panel, or as agreed upon by a supplier, typically under reference conditions such as Standard Test Conditions (STC)
  • performance ratio (PR)is the ratio of measured output to expected output for a given reporting period based on the system name-plate rating
  • performance indexis the ratio of measured output to expected output for a given reporting period based on a more detailed model of system performance than the performance ratio

Site survey on a sunny day

To investigate the characteristics of the site, users may perform a site survey. During the survey you may walk around with an albedometer and measure at different locations. Under stable solar conditions you may also use a single pyranometer and invert it.

The purpose of such survey is to investigate:

  • spatial variability of the (ground surface) albedo
  • seasonal variability of the albedo
  • correlation between a field station and the conditions at the arrays

At the location of all POA measurements, IEC 61724-3, clause 5 requires measurement of the local albedo to verify that it is representative of the albedo of the total power plant, fits the assumptions made in modelling, and to use the measurements in the uncertainty evaluation of the performance test.

Recommendations and boundary conditions for the survey are:

  • choose a sunny day, with limited cloud cover and solar elevations above 60 degrees
    you are interested to measure the ground surface properties: measure above unshaded locations with a representative ground surface / vegetation
  • measurements in shaded locations typically provide a signal level that is too low to make a good albedo estimate
  • in case there is seasonal vegetation, measure at 2 to 4 moments in the year
  • you may use an albedometer or under stable solar conditions you may use a single pyranometer and invert it.

 

Figure 2 The Tube mounts of SR30, SR15 and SR05 can very well be used to measure global, reflected, and Plane Of Array irradiance. For downfacing instruments we typically do not use the sun screen. See also Figure 1.

Silicon Irradiance Sensors (PV Reference Cells:

The world’s no. 1 in reference cells

Measure the irradiance intensity on your photovoltaics system precisely at an affordable price with robust silicon solar irradiance sensors (Si sensors).

The sensor element’s design is similar to that of a PV module; this means that their spectral response (SR) and incident angle modifier (IAM) are highly comparable. Consequently, these sensors are eminently suitable as a reference for PV system monitoring.

Benefits & Features

  • Reference solar cell for PV monitoring
  • Calibration measurement uncertainty: 1.2 % (class A as per IEC 61724-1)
  • Suitability for outdoor use verified by tests as per IEC 61215
  • Extremely few mismatch errors due to optical properties as those of PV modules
  • Calibration in relation to spectrum as per IEC 60904-3, AM1.5
  • Exceptional linearity significantly above IEC 60904-10 requirements
  • Pt1000 as per IEC 60751 Class A to measure cell temperature
  • Developed and manufactured in Germany

Precise tracking of the module temperature on PV systems:

Measure the temperature of your PV module with utmost precision and minimal drift to assess your system’s productivity.

Our module temperature sensors are equipped with a sturdy aluminium housing and robust, weatherproof cabling. Thanks to the use of premium components, the sensors achieve high accuracy and are ideal for use in industrial environments and on-site usage (e.g. PV module temperature).

The sensor element’s compact design also makes it perfect for measuring temperature of bifacial modules.

Benefits & Features

  • Sensors comply with all IEC 61724-1 requirements, including for bifacial modules
  • Very small sensor element; covers less than 2 % in full size M6 or half-cut M12 cells
  • Adhesive’s thermal conductivity > 500/m²/K
  • Pt1000 precision sensor element as per IEC 60751 Class A1
  • Sensor element, including extremely adhesive tape for long-term usage
  • Highly sturdy aluminium housing1
  • High-precision measuring electronics including calibration certificate for all active models
  • Developed and manufactured in Germany1

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Ingenious is a team of passionate experts delivering cutting-edge solutions in Environmental, Renewable Energy, Geotech, and Monitoring Technologies.

 

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