Top tips for solar installation troubleshooting using the Fluke 393 FC CAT III 1500 V Clamp Meter

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Eindhoven, Netherlands. 13 December 2021: Fluke is experiencing increasing demand for high-precision handheld devices which can measure photovoltaic (PV) systems in the United Kingdom.

The number of solar installations in the United Kingdom has doubled within the last year and is set to double again before 2030. Solar Energy UK, an established trade organisation, is working with 230 businesses across the solar and energy storage value chain to increase the UK’s solar storage capacity to 40 GW.  

This dynamic growth is creating an ever-increasing demand for technicians who know how to troubleshoot PV systems efficiently and effectively. Clamp meters are often used in the installation and commissioning phase as well as when completing maintenance and troubleshooting.

The new-to-market Fluke 393 FC Clamp Meter is the world’s only CAT III 1500 V rated true-RMS clamp meter which enables technicians to take measurements in DC environments, such as industrial solar farms. The tool was tailormade to test and measure solar PV applications with key functions including:  

• an IP54 rating which is ideal for working outdoors on solar arrays and wind power systems
• DC power measurement with readings displayed in kVA
• an audio polarity indicator to prevent accidental miswiring
• Visual continuity turns provide a bright green light in the display to aid technicians working in dark and noisy environments
• Logging and reporting of test results via Fluke Connect software

Hans-Dieter Schuessele, Application & Technology Expert EMEA of Fluke says: “The transition to using renewable energy is accelerating and it’s critical that installers and maintenance staff have access to the right instruments to not only get solar farms online fast but can keep them working at peak performance. As the world’s first solar clamp meter to offer a CAT III rating at 1500 V, the Fluke 393 FC allows technicians to work safely while ensuring the use of solar energy has a bright future.”

As solar distribution systems and loads become larger and more complex, the implications for the safety of a technician become more important. It is critical for technicians to understand the level of protection built into a tool and how to use it when completing maintenance and troubleshooting. According to Fluke, troubleshooting a PV system typically focuses on four parts of the system: the PV panels, load, inverter and combiner boxes.

1. Troubleshooting PV panels

A technician should first check the output of the entire system at the metering system or inverter. Before commencing troubleshooting, also check and record the inverter’s input voltage and current level from the array.

The combiner box can be a great place to troubleshoot the system because the individual wires from the modules are brought back to it. Each module may have a fuse that should be checked with the Fluke 393 FC.

Wiring problems and loose connections may cause a module to produce a voltage that is too low. These can be traced out using the Fluke 393 FC to check wiring connections at the junction boxes.

The Fluke 393 FC provides an audio polarity warning when testing Voc. If the polarity is reversed, it may mean that other circuits in the combiner box are unintentionally connected in series, resulting in voltages over the maximum inverter input voltage.  

2. Troubleshooting PV loads

Start by checking the load switches, fuses, and breakers with the Fluke 393 FC to see if the correct voltage is present at the load’s connection. Next, check the fuses and circuit breakers. Find and replace blown fuses or tripped breakers. If the load is a motor, an internal thermal breaker might be tripped or there might be an open winding in the motor. For testing purposes, plug in another load and see if it operates properly.

As with any electrical system, check for broken wires and any loose connections. Clean all dirty connections and replace all bad wiring. With the power off, check for and repair any ground faults. If any fuses blow or breakers trip again, there will be a short that will need to be located and repaired.

If the load still does not operate properly, use the Fluke 393 FC to check the system’s voltage at the load’s connection. The wire size may be too small and need to be increased. This will show up as a low voltage at the load and to resolve either reduce the load on the circuit or run a larger wire.

3. Troubleshooting PV inverters

The inverter converts DC from the PV system into AC power for building use. For troubleshooting the AC side, use the Fluke 393 FC to check the inverter’s output voltage and current levels. Many of these systems have a display that indicates current inverter and system performance. As the Fluke 393 FC produces a true-RMS reading, you can use the voltage and current to measure and record the power output in kilowatt (kW). If possible, use the inverter display to show the current total energy in kilowatt-hours (kWh) and compare it to the one recorded during the last inspection. When troubleshooting the DC side, use the Fluke 393 FC to check the DC power and save the reading to the Fluke Connect™ app on your phone.

If the inverter does not produce the right amount of power, there may be a blown fuse, tripped breaker or broken wires — all of which can easily be checked with the Fluke 393 FC.

4. Troubleshooting Combiner Boxes

When troubleshooting combiner boxes, amperage measurements and calculations are crucial to establishing whether the PV arrays are operating correctly. Measuring current on individual arrays or combining current measurements will help determine if a module has malfunctioned.

The thinner jaw design of the Fluke 393 FC clamp meter ensures several conductors are used in the jaw for combined current measurements, even in tight or crowded spaces like inverter or combiner boxes.