PV Test Instrumentation Cuts Test Times on Major New California Solar Installation
A new concept in electrical test instrumentation has enabled the installation and commissioning of a large new solar PV installation in the California Central Valley to be completed in record time –and safely in compliance with all required standards.
Renewable energy design and integration company OCS Energy Inc., specified the use of the new Seaward Solar PV150 tester and Seaward Survey 200R irradiance meter for the installation of a new 20MW ‘behind the fence’ system in Fresno, California.
The system is comprised of 113,280 Sharp 240W and 235W panels arranged in a high voltage configuration of 24 panels in series mounted on single axis trackers, with Advanced Energy Solaron 500 1kV utility inverters with AC/DC switchgear and optional VRT.
With a tight construction schedule, OCS Energy calculated that the 4,720 circuits to be tested as part of the commissioning documentation would take approx. 3.5 minutes per test with manual irradiance and temperature measurements recorded every 15 minutes.
Another factor was safety, with NFPA 70E imposing strict procedures for protecting employees working on or around systems rated over 600 volts.
In this situation, OCS and the installation contractor devised a ‘commission during build’ schedule utilizing advanced solar PV instrumentation provided by Seaward. The strategy was to have OCS Energy “dove tail” the installation and construction crews to verify and document that the system was built to NEC code compliance and identify any problems or issues early on so that corrective action could take place during the build.
This meant that, once the substation was connected to the utility grid, final commissioning of the inverters, medium voltage switchgear and the substation followed in sequence.
The Seaward Solar PV150 is a dedicated multi-function PV electrical tester designed specifically for solar panel system installation. It performs open circuit voltage measurements (Voc), short circuit current measurements (Isc), earth continuity, insulation resistance, operating current (via AC/DC current clamp).
Results can be recorded and stored in the tester for subsequent USB downloading to a PC.
With the push of a single button the new combination tester carries out the required sequence of electrical tests in a safe and controlled manner, avoiding the risk of contact with exposed live DC conductors.
As a result it eliminated the need for multiple test instruments for PV panel electrical installation, commissioning and connection testing.
In the California Central Valley installation, the use of the PV150 tester was accompanied by the Seaward Survey 200R irradiance meter. This unit also incorporates a compass, tilt measurement meter and ambient temperature monitor, with time and date data logging features.
Uniquely, it also incorporates ‘solarlink’ wireless connectivity to the PV150 so that all data can be recorded in real time within the PV150 as the electrical tests are conducted.
With OCS Energy outfitted in the field with the means to run a laptop for the downloading of results into separate folders for each combiner box, the net result was that test crews were able to test three combiner boxes simultaneously – representing 36 circuits in approximately 3 minutes in total. This represents a considerable time saving in labor hours compared to other projects, where similar testing could take nearly 2 hours.
Richard O’Connell, CEO of OCS Energy Inc., said: “Typically most construction projects have ‘punch lists’ that occur at the end or near the end of a project to allow the owners and contractors to walk the job and identify issues to be addressed later.
“In the case of this project, the completion date did not leave any room for construction defects. Nevertheless, the testing schedule using the PV150 and 200R enabled us to meet our target project milestones and demonstrate compliance with all standards almost immediately.
“The commissioning of industrial photovoltaic systems requires attention to detail and an ironclad protocol to demonstrate to owners that they got what they paid for.
“In this circumstance, I cannot over stress how difficult it can be to obtain accurate and meaningful data collection on an industrial PV array while the temperature of the project is in the 90 degree or higher range. When technicians are in extreme heat the risk of poor data collection is almost a certainty, so minimizing these errors is not an easy task.
“However, using the new test technology ensured that we were able to overcome these challenges and meet all the requirements of the project safely, effectively and cost efficiently.”
With over thirty years experience in the electrical industry, OCS Energy understands the importance of accurate data collection for the owners and operators of these power plants – and recognizes the crucial contribution made by the new Seaward Solar PV150 and 200R instrumentation in the satisfactory commissioning of PV systems.