We took a different approach to measure the three irradiance components (DNI, GHI, DHI). A spectroradiometer with rotating Shadow Band (RSB) is an attractive alternative to a conventional 3 component sun tracker system. Just one spectroradiometer used for all measurements lowers the costs associated with the instrumentation required. Accurate DNI measurements can be obtained from a MS-711 Global spectroradiometer with RSB comparing with the MS-711 DNI spectroradiometer on a sun-tracker. The comparison between the outputs spectral DNI from the two configurations reveals a consistency in the method and the measuerements of all 3 irradiance components. EKO will provide the RSB solution for all spectroradiometer models.

Discover the new 2018 product guide including several new products. The pyranometer line up with MS-40 and MS-60 pyranometers with analog and digital interface. 

EKO’s new solar Monitoring System, the STR-21G-S0/ S1 and S2, are turnkey sensor systems for the most accurate solar radiation measurements of the direct solar radiation component. It can be easily integrated to any DAQ system, which has multiple analog or digital inputs.

Designed to withstand all weather conditions, the ASI-16 All Sky Imager features a digital camera and fish-eye optics with a 180° field of view assembled under a robust coated quartz dome, avoiding sensor degradation due to direct exposure to the sun and allowing the automated acquisition of high dynamic range (HDR) images of the hemispherical sky. 

The standard ASI-16 Sky Imager is capable of operating under harsh environments from temperatures as low as -40°C up to 50°C, with an integrated ventilation and heating system, which also prevent condensation on the dome surface and promote the fast removal of raindrops and snow. Furthermore, the imager is powered over ethernet (POE), with a durable and waterproof cable. The users can have full control of the imager to perform settings, data acquisition, visualization, and storage, with a web browser-based manager with live video stream and network storage.

The Sky imager is complemented with the Find Clouds software, in which the images acquired with can be processed to classify cloudiness. Using different algorithms to calculate cloudiness, the cloud analysis software, allows the calculation of the sun position in the image as well as to run algorithms such as the blue/red and blue/green channels ratio (BRBG), and the cloud detection and opacity classification (CDOC), to quantify cloudiness on the image set. 

Dowload here the full article

Download here the article published in PES S1 18

Recently, the National Renewable Energy Laboratory (NREL) published the latest version (second edition) of the Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications. In addition to describing the typical radiometers used to measure direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI), there is a section on instruments that derive these values using different methods. EKO Instruments created the MS-05, a sensor based on the MS-093 Sunshine Duration Sensor. The MS-05 and the MS-093 has a rotating mirror that directs the incident solar irradiance onto a pyroelectric detector. In the case of the MS-05, the output is an analog signal and its maximum value correlates rather well to a DNI measurement made by a pyrheliometer. The data is presented in the handbook on page 3-27 and 3-28. Starting in 2018, EKO modified the MS-05 to improve performance and has released the MS-90. The MS-90 has a higher quality glass tube and a precision ground mirror. These improvements over the original design (MS-093) will further reduce measurement uncertainty and allow users the ability to make DNI measurements without the need of a sun tracker and pyrheliometer.

View NREL Best Practices Handbook

EKO delivered the second unit of MS-713 near-infrared (NIR) spectroradiometer to Meteorological Research Institute (MRI).

The Meteorological Research Institute (MRI) is a Japan Meteorological Agency (JMA) facility that conducts research to clarify and support the prediction of meteorological, terrestrial, and hydrological phenomena and develop associated techniques, also contributes to the advancement of fundamental technology for meteorological services. 

MRI has been moving towards installing precise spectral irradiance observation instruments which can measure in the range from 300nm and 2550nm for researching the effects of aerosol and clouds on the earth radiation budget.

Recently, MRI installed EKO’s spectroradiometers MS-711, MS-712, MS-713.During the latter half of 2017, MRI installed a second unit of the EKO Instruments near-infrared (NIR) spectroradiometer, the MS-713 and STR-32G heavy-duty sun tracker. In this research, inspections of spectroradiometers properties and research of calibration method for spectroradiometers using Langley calibration method had been performed.

The MS-713 (3) is shown above on the EKO STR-32G heavy duty sun tracker (4). This image was taken from the NOAA Mauna Loa Observatory, located on the island of Hawaii. The MS-713 was calibrated using the Langley method. Other instruments that were calibrated at this time include the MS-711 (1) and MS-712 (2) spectroradiometers. Each instrument can be used with collimating tubes to measure the spectrum of direct normal irradiance. The MS-713 will help MRI research as it is a rare field deployable field instrument capable of measuring spectral irradiance from 900 nm to 2,550 nm. If combined with MS-711 and MS-712, spectral irradiance in the wide wavelength range can be measured with very high accuracy.

To the Meteorological Research Institute website

2018 looks to be another booming year for installed solar power sites around the world. In addition to traditional major markets in Europe, China, and the United States, emerging countries in the Americas and Middle East look to big movers as the install larger projects. As solar power plants have increased in size and numbers, new standards were needed to help a fast-changing industry. During 2017, the International Electrotechnical Commission (IEC) released a new standard, 61724-1, Photovoltaic system performance – Part 1: Monitoring. The standard provides guidance as to the measurements needed to attain a specific level or classification of accuracy. The standard provides all the details as to when and how to measure the critical environmental parameters. It also provides information on the differences in requirements based on installation size and power generating technologies and methods. Only considering the most common form of power generation, non-concentrating photovoltaic (PV) installations, the standard provides 3 classifications or levels of accuracy.

This new standard will provide crucial guidance to various stake holders as to what measurements are needed. Couple this information with EKO’s 90 years of intense development and you have the right combination to make certain any PV site is monitoring at the optimal level. For the highest level of performance, EKO recommends using the MS-80 series pyranometer with the MV-01 heated ventilator. The MS-80 surpasses the requirements of ISO 9060 and sets a new bar for pyranometer performance. While the IEC standard calls for recalibration annually, the MS-80 has a 5 year recommended recalibration interval. The MS-80 has been designed such that the user does not need to change the desiccant. As for performance, the MS-80 has fastest response time of any secondary standard on the market. It also is immune to thermal offsets, monitoring with the MS-80 provides greater confidence in measurement accuracy as well as the ability to detect fast changes in irradiance with passing clouds.

With a global presence and a persistent drive to improve solar radiation measurements, EKO stands ready to help the solar energy industry with any project, regardless of size or complexity. Please contact your local or regional EKO Instruments office.