Operation & Maintenance Testing Equipments

Globally, we now have a total of 305GW of solar power installed, up from around 50GW in 2010 and virtually nothing at the turn of the millennium. The experts have termed this growth “very significant” and have spoken briefly on the need to have solar power as an important measure for the world to meet its climate change commitments.

As the scope to generate more and more energy through solar power rises, the need to maintain the utility scale power generation plants become more and more important. A typical solar PV plant can sustain and perform for 20-25 years, and indeed while a PV plant does require almost no maintenance at all as compared to the other generation sources, one still need to address the operation and maintenance issues at certain stages. Just like any power plant, a solar plant in operation also requires maintenance. As the solar power plant starts aging, the need to implement Operations and Maintenance becomes more and more important to keep the performance of the plant intact. And as plant sizes increases with every new projects, the developers are expecting better performance levels and the Operation and Maintenance of the plant has become more critical, as it will impact the overall profitability of the plant and IRRs significantly.

There’s an increased requirement of higher performance guarantee and plant availability numbers. This coupled with reducing price expectations, is making the market highly competitive to operate in. Survival in the market can only be ensured through best in class service offerings, aligned with latest technologies and O&M testing equipment, that at competitive pricing.

Wondering what these latest technologies and O&M testing equipment are? We did so we found out. What tools and equipments are taken hold of when solar professionals conduct quality control, operations and maintenance activities on comm-ercial and utility-scale PV systems? In our previous editions we talked about Best Practices in O&M and Challenges, but this time we will talk through the test and measurement tools, power tools and hand tools? What drivers or torque wrenches are used? What are the most valuable equipments and tools? In other words: “What is in the equipment bag of O&M professionals.

Here we take into account Instruments & Testing Equipments that together make O&M an accomplished task even before starting the process. That said, these equipment and instruments includes clampon, digital, and multimeters; resistance testers; infrared scanners; portable test equipment such as high potential tester and many other types of equipment.

The prime function of instruments and test equipment is to help installation and maintenance personnel ensure dependability, efficiency, and profitability of electrical systems and equipment. They are the tools that allow measurements, rather than visual inspections, to determine the status of electrical components and systems. The equipment in this category can range from simple handheld items to precise laboratory instruments. All, however, require a degree of skill to be used properly and to accurately analyze the results.

Electrical Power Testers

Electrical Power Testers must be able to withstand both the expected steady-state voltage of the system you are measuring and any transient overvoltage (shortduration surges or spikes: for instance, those caused by a lightning strike or electrical motor starts and stops).

All meters produced since 1997 are identified with an overvoltage installation category (CAT) rating in accordance with the International Electrotechnical Commission (IEC) standard 61010-1, which details requirements related to the construction of low-voltage (<1,000 V) test and measurement equipment, as well as allowances related to their conditions of use.

Handheld Meters

The most widely used instruments are the handheld type, which normally includes clamp-on meters and multimeters. Clampon meters are widely used because of the ease of operation. Multimeters are also extremely popular because they are easy to carry and are capable of performing a wide variety and range of measurements. A large number of attachments for these units are available, so that they can be used for measuring light levels, temperature, and other variables to further expand their usefulness to electrical personnel. Most are available with either digital or analog readouts, the choice depending largely on the personal preference and accuracy requirements of the user.

Both clamp-one and multimeters can be average responding or true-rms types. The true-rms units respond to the effective heating value of an AC waveform. An averaging meter calculates the arithmetical mean of the waveform. When the signal to be measured approximates a pure sine wave, either an average responding or truerms meter can be used with reasonable accuracy. However, if the waveform is distorted, such as is common in circuitry powering phase-to-neutral and phase-tophase nonlinear loads, then the true-rms sensing device is preferred because the reading will be more accurate.

Insulation Resistance Testers

The single most popular meter is the Fluke 1587 Insulation Multimeter [$590–$700]. Its popularity attests to the fact that insulation resistance testing is not only a critical system commissioning activity, but also useful for tracking down faults.

The Fluke 1587 combines the ability to measure insulation resistance up to 50 GΩ, using 50 V, 100 V, 250 V, 500 V or 1,000 V test voltages, along with typical multimeter functionalities, including the ability to measure voltage up to 1,000 V ac or dc. Note that the Fluke 1507 Insulation Resistance Tester [$475–$525] is similar to the Fluke 1587, minus the multimeter capabilities.><1,000 V) test and measurement equipment, as well as allowances related to their conditions of use. Handheld Meters The most widely used instruments are the handheld type, which normally includes clamp-on meters and multimeters.

Clampon meters are widely used because of the ease of operation. Multimeters are also extremely popular because they are easy to carry and are capable of performing a wide variety and range of measurements. A large number of attachments for these units are available, so that they can be used for measuring light levels, temperature, and other variables to further expand their usefulness to electrical personnel.

Most are available with either digital or analog readouts, the choice depending largely on the personal preference and accuracy requirements of the user. Both clamp-one and multimeters can be average responding or true-rms types. The true-rms units respond to the effective heating value of an AC waveform.

An averaging meter calculates the arithmetical mean of the waveform. When the signal to be measured approximates a pure sine wave, either an average responding or truerms meter can be used with reasonable accuracy.

However, if the waveform is distorted, such as is common in circuitry powering phase-to-neutral and phase-tophase nonlinear loads, then the true-rms sensing device is preferred because the reading will be more accurate.

Insulation Resistance Testers

The single most popular meter is the Fluke 1587 Insulation Multimeter [$590–$700]. Its popularity attests to the fact that insulation resistance testing is not only a critical system commissioning activity, but also useful for tracking down faults. The Fluke 1587 combines the ability to measure insulation resistance up to 50 GΩ, using 50 V, 100 V, 250 V, 500 V or 1,000 V test voltages, along with typical multimeter functionalities, including the ability to measure voltage up to 1,000 V ac or dc. Note that the Fluke 1507 Insulation Resistance Tester [$475–$525] is similar to the Fluke 1587, minus the multimeter capabilities.

Digital Multimeters

While current clamps and insulation resistance testers can incorporate some of a multimeter’s functions, most survey respondents also carry a general-purpose multimeter. Compared to an all-in-one meter, a dedicated multimeter often offers additional measurement functions or improved resolution and accuracy. The most popular multimeters are the Fluke 179 [$300–$320] and the Fluke 87V [about $400]. While these models have similar features, the Fluke 87V offers improved accuracy and resolution. The basic dc accuracy of the Fluke 87V is 0.05%, versus 0.09% for the Fluke 179.

Disconnection Detector for DC Current Circuit (NSEI-100D)

This device can detect the disconnected & broken point of DC current lines between PV panels and power conditioners in PV systems, without cutting power off and without climbing the roof where PV modules are located. Furthermore, this model can find out the disconnecting point by applying the attached detector to the specific PV module.

PV Characterization Testers

Solar PV system commissioning and O&M also require some specialty electrical test equipment to characterize PV modules or source circuits. The most popular products in this equipment class are commissioning and safety testers, and portable I-V curve tracers.

Commissioning and Safety Testers

Seaward Group USA offers a suite of testing tools specifically for PV applications. For example, the PV150 Solarlink Test Kit [about $2,000] is designed to meet the IEC 62446 commissioning test requirements. The PV150 installation tester is an all-inone tester that verifies or measures ground continuity, insulation resistance (at 250 V, 500 V or 1,000 V), Voc, Isc, Imp and Pmp. The test kit includes the Solar Survey 200R, which is basically a souped-up irradiance meter (more on irradiance meters later).

The Solar Survey 200R measures real-time irradiance and temperature, and then wirelessly transmits these data back to the PV150, which can store up to 200 complete test records internally. Seaward provides USB connectivity for the data dump to PC and also offers proprietary software [about $250] for generating professional reports.

I-V curve Tracers

These tools are essential for gathering data for module power warranty claims. They are also commonly used to benchmark large-scale PV system performance, to quantify the impacts of soiling and to refine plant production models over time— often at the request of project financers. The most popular I-V curve tracers for field applications are the HT I-V 400, the Solmetric PVA-1000S and the TRITEC TRI-KA.

This CAT II-1,000 Vdc meter has a maximum current measurement range of 10 A. It has a 128-by-128-pixel LCD and is sold with an external reference cell and temperature probe, which you must physically connect to the meter to capture irradiance and module temperature. The meter’s internal memory capacity is 256 kilobytes, equivalent to roughly 200 I-V curves. The HT I-V 400 measures about 9.25 by 6.5 by 3 inches and weighs less than 3 pounds.

Solmetric’s PVA-1000S [about $5,500] is a portable I-V curve tracer with a maximum current measurement range of 20 A. This CAT III-1,000 V meter is sold with a wireless reference sensor that measures irradiance and module temperature at a range of up to 300 feet. The primary user interface is via a laptop or tablet (not included in the kit) that communicates with the PVA-1000S using a wireless USB adapter.

Solar Power and Thermal Testers

In addition to having electrical and PV characterization testers in their tool bags, most of the O&M professionals also carry an irradiance meter and an infrared (IR) camera or thermometer.

Irradiance Meters

If you want to estimate real-time system performance with confidence or field-check a pyranometer in a data acquisition system, you need a handheld solar irradiance meter or pyranometer.

In field applications, having laboratory-quality equipment is less crucial than having reasonably accurate, durable equipment that can stand up to local conditions. The most popular devices are Daystar’s DS-05 Solar Meter, Apogee Instruments’ MP-200 and Seaward’s Solar Survey 100.

IR Cameras

Thanks to dramatic price declines, IR cameras are more available than ever and are increasingly incorporated into standard O&M procedures for PV systems. They can identify high-resistance electrical connections and thermally stressed overcurrent protection devices. They are invaluable for locating module issues such as cracked cells, faulty internal connections and defective bypass diodes. While there are many IR cameras to choose from, the two most popular brands are FLIR Systems and Fluke.

IR Thermometers

If you do not want to carry IR camera around a dusty jobsite all day but you still want to take basic IR temperature measurements, a humble infrared thermometer is just the ticket. A basic IR thermometer is often nothing more than a 1- or 2-pixel, trigger-actuated thermal imaging device. These rugged and inexpensive devices are available from many manufacturers, in some cases for under $100.

Thermal measuring instruments also are quite popular as a means of detecting overheating in electrical system equipment. These instruments range from simple units that provide a direct readout on a meter of scale, to highly complex instruments that provide thermograms (infrared-created photos) that show precisely where hot spots are located.

Infrared sensing devices are excellent for finding loose connections, corroded fuse clips, deteriorated splices, and other potential trouble spots that generate heat.

Testo offers a perfectly matching professional thermal imager. With list of 31 products like Testo 865 Thermal Imager, Testo 868 with App, Testo 875-1i with Digital Camera, Testo 882 with IR Camera and more, Testo is known to supply thermal imager for all for high-quality thermographic measurement in solar PV O&M process.

Portable Test Equipment

Megohmmeters, including specialized versions to determine the resistance of grounding systems, are also widely applied. They can be hand-cranked or batteryoperated and are available in various degrees of sophistication.

Recording-type instruments have proven to be extremely helpful for analyzing system parameters such as current, voltage, electrical noise, wave shape, and many others, over a long period of time. This type of equipment ranges from relatively simple dot-matrix printers to high-speed computerized units.

Larger portable test equipment includes high-current test sets used to check the operation of power circuit breakers, relay test sets for accurately adjusting the settings of protective relays, and high-potential test sets to evaluate the conduction of medium voltage cable. Specialized equipment is used for making power factor tests on large motors and transformers.

Portable Computing Devices

The most common field applications for computers include logging data, interfacing with data acquisition systems, troubleshooting inverters, running test and measurement device software, generating customer reports, and downloading equipment manuals or plan set details.

With the total addressable market for solar PV operations and maintenance (O&M) expected to reach 395 GW worldwide in the FY 2017-18, the solar installation is will more than double by 2022 to exceed 900 GW worldwide, driven predominantly by China, the U.S., India, and Japan. In young solar markets, O&M is often coupled with EPC and performed by the same vendors, but in just a few years O&M becomes a separate market with its own landscape, trends, and dynamics. In mature PV markets with a large installed base and a low volume in installations, O&M revenue can even exceed development and construction revenue.

And as the commercial solar PV market becomes increasingly competitive, the industry is looking for ways to increase revenue while simultaneously decreasing costs. O&M is one area that presents some opportunities. Many of the O&M considerations that impact cost and revenue, such as performance optimization, system uptime and operational efficiency relate directly to testing equipments and monitoring system selection.