Several manufacturers offer testing equipment for PV system commissioning, including the following products:
Seaward PV150 Solar Installation Test Kit, which includes the meter, leads, and AC/DC current clamp ($1,495). This device can perform all the minimum IEC 62446 commissioning tests (except performance verification) with the push of a button. It is designed to connect directly to MC4 output and can safely perform the short-circuit current measurement using an internal switch. The PV150 performs the insulation resistance testing of a module or string by safely shorting the array output (+ and -) and applying the appropriate test voltage between the shorted outputs and ground. (Note: Some methods of testing that involve measuring megohms of insulation resistance between a positive and ground or the negative and ground may damage the module or diodes and/or void module warranties.)
The PV150 can also measure irradiance, and ambient and cell temperatures simultaneously during all the test measurements used in performance verification calculations with its optional 200R irradiance meter ($475). (Note: The 200R has radio frequency communications with PV150 and the ability to download the data to a computer.) By using the separate clamp-on meter, you can verify the inverter efficiency.
There are other advanced tools that provide additional analyses and troubleshooting ability. If the system you’re testing does not pass the IEC 61446 commissioning tests, these tools can help find the problem quickly. They are not required for standard IEC 62446- or NABCEP-recommended commissioning, but are briefly mentioned in both of those documents.
Hukseflux Solar I-V($5,625) combines the I-V400 curve tracer ($4,165) and parts of the Solar300 ($7,595). The Solar I-V can test each module or string’s IV curve, and the output performance of a single-phase AC circuit from the inverter with one DC input into the inverter during operation, up to a maximum of 1,000 VDC and 10 A. Voltage-current curve tracing of installed modules and strings is useful to ensure they are matched and offers a good baseline for future performance validation and troubleshooting. This level of testing is not really necessary for most residential systems, but is becoming necessary for bank-financed utility-scale projects that are expected to give a minimum return on the investment. These tests were done on the Cloudview installation (see the “Commissioning Cloudview” sidebar).
Flir E40 infrared thermal imaging camera ($3,995) is helpful for detecting module defects, since it can show “hot spots” on modules, revealing problems like internal module wiring issues or failed diodes, which can be responsible for reducing the module’s output. Thermal cameras are also useful for checking system connections, since loose or improperly torqued connections are hotter than other connections because of increased resistance. Like the IV curve tracer, these are not generally used in a typical residential installation except to troubleshoot problems that have been indicated by the other measurements.
Bill Hoffer has worked in the solar industry for more than 20 years. He is an alumnus of Solar Energy International, where he now teaches. Bill also consults with manufacturers in product development and testing, and specializes in the third-party commissioning, performance validation, and troubleshooting for commercial- and utility-scale systems.
Flir E-40 infrared thermal camera • Flir • flir.com
Hukseflux Solar IV curve tracer • Hukseflux USA • huksefluxusa.com
Seaward PV150 • Seaward Solar USA • seawardsolar.com