Hioki FT4310 – Bypass Diode Tester

Hioki FT4310 – Bypass Diode Tester

• Save time – simultaneously measure all electrical parameters
• Automatically transfer data wirelessly (Available for Android and iOS devices
• Inspect Solar Panel Bypass Diodes for Opens and Shorts in Broad Daylight Without Covering Panels
• Test for open or short-circuit bypass diodes even during the day
• Easily test using the strings in the junction boxes

Traditionally, bypass diodes can only be inspected for good working condition at night or when power is not being generated by the solar panels in order to verify that any applied current is guided past the solar cells. With the FT4310 Bypass Diode Tester, you can detect for open faults even when the sun is out without covering the panels. Also test for short-circuit faults and cell string losses.

Inspect solar panel bypass diodes for opens and shorts in broad daylight without covering panels​

Traditionally, bypass diodes can only be inspected for good working condition at night or when power is not being generated by the solar panels in order to verify that any applied current is guided past the solar cells. With the FT4310, you can detect for open faults even when the sun is out without covering the panels. Testing can also be performed at night.

[Reference] Issues caused by faulty bypass diodes

Normal reading:
When a solar panel is obscured by a partial shadow (or when it fails), the current bypasses the panel in order prevent any drop-off in generating efficiency.

Short-circuit fault:
When a short-circuit fault occurs, the generated current flows in a loop, making it impossible to capture the generated power, resulting in lowered efficiency.

Open fault:
When an open fault occurs, current is forced to flow to the defective cell when it’s covered by a
shadow, causing the panel to heat up and posing the risk of fire.

Save time – simultaneously measure all electrical parameters​

Simply set the rotary knob to “BPD TEST” and press the “Measure”button to measure and display all parameters necessary for fault identification (open-circuit voltage, short-circuit current, and bypass route resistance). Measurement takes 2 sec. or less per string!

Automatically transfer data with Bluetooth (R) wireless technology​

Measured values held on the display are sent immediately to a smartphone or tablet via Bluetooth (R) wireless technology. Save date in CSV or PDF format. Eliminate the need to take notes – particularly useful at sites with a large number of test points.

Be alerted to faults with an audible warning and by the instrument’s backlight​

Red backlight and audible warning alert the user to possible faults.

Ex) Open fault (Using BPD TEST mode)
RBPR：The instrument indicates the open state (“opn”)

High-precision voltmeter ideal for detecting short-circuit faults​

When a bypass diode experiences a short-circuit fault, the output voltage decreases (by about 10 V) because the corresponding solar panels are not contributing to the array’s generated power.
By detecting this difference, it is possible to detect bypass diode short-circuit faults and cell string losses.

The FT4310 incorporates a high-precision DC voltmeter so that it can detect a voltage difference of 10 V in a 1000 V system. When used in Voc mode, which is specifically designed to measure open-circuit voltage, the instrument displays the voltage difference in less than 1 sec. and tests for a short-circuit fault.

Convenient accessories​

• Bundled case with neck strap Leave both hands free so you can precisely position test probes without worrying about dropping the instrument.
• Integrated “hold” button right on test leads A button right at your fingertip on the test leads lets you hold measured values easily, eliminating the need to operate a control on the instrument itself. They also incorporate a handy light.

[Reference] The FT4310’s impact on strings

The impact of measurement on strings has been investigated thoroughly since even if bypass diode open faults can be detected while solar panels are exposed to sunlight, the endeavor would be pointless if the panels were damaged in the process. When the FT4310’s measurement button is pressed, the instrument first measures ISC (the short-circuit current) and then applies a voltage such that a current that is 1 A greater than ISC flows. Because bypass diodes are required by the JIS to function without issue even if a current equal to 1.25 times the module’s rated short-circuit current flows for a period of one hour, because the FT4310 performs constant-current control, and because the time of application is 5 ms or less, the FT4310’s impact on strings does not differ from that of I-V curve measurement or insulation resistance measurement. The FT4310 can be used with confidence that it will not damage solar panels.

Test for bypass diode open faults and other malfunctions using the strings in junction boxes​

Easily test using the strings in the junction boxes, eliminating the need to climb onto the roof and dramatically improving work efficiency.