1. The turn-on voltage drop test is to test the forward voltage drop of the entire solar junction box (n diodes in series) through the set current, as shown in the figure above: set the current 10A, (three diodes) test voltage drop at 1.3V- 1,5V qualified. Powered Pins General Fastening Tool Powered Pins General Fastening Tool ,Powered Pins General Fastening ,Power Actuated Fasteners,Powder Actuated Pins Yibin Heheng Technology Co.,Ltd , https://www.actuated.nl
Analysis of Functional Characteristics of a Solar Junction Box Tester
one. The instrument has functions such as measuring the conduction voltage drop (series) of the solar junction box, the on current (set value), and the breakdown voltage of n diodes in series.
two. The measurement menu is as follows: 
1. The turn-on voltage drop test is to test the forward voltage drop of the entire solar junction box (n diodes in series) through the set current, as shown in the figure above: set the current 10A, (three diodes) test voltage drop at 1.3V- 1,5V qualified.
2. Breakdown voltage: Test n diodes in series, set the current breakdown voltage, set the current 1mA as shown above, and the breakdown voltage is qualified at 130V-150V.
three. Now analyze the function and measurement principle of the solar junction box tester:
1. Normally, the bypass diode reverse breakdown voltage VRR of the solar junction box is about 50V-60V, the forward voltage drop VF is about 0.45-0.5V, and the leakage current is below 100uA at normal temperature. The leakage current is below 10 mA at °C. The diode has a large leakage current and a relatively small voltage drop.
2. When several diodes are connected in series, if one of the diodes has a large voltage drop, and a little diode voltage drop is small, the defect diode with large voltage drop cannot be judged by using this kind of instrument. This instrument simply measures the total voltage drop across the series diode, which is the sum of the series diode drop and the line voltage drop.
3. The instrument measures the breakdown voltage and also measures the total voltage of the series diode. Dipole breakdown voltages of different types and different batches are highly discrete. When one of the diodes has a large leakage current, the second causes the breakdown voltage to be about 10V less than the normal value. This method cannot be judged.
4. For example, a junction box consists of three diodes in series, and the VF (10A) of three diodes is 0.45V, 0.50V, and 0.42V, respectively. VRR (1 mA) is 55V, 58V, 40V, second, third, defective, second, large voltage drop, and third, general leakage current. The total forward voltage drop in series is completely normal. The test direction voltage is also unrecognizable.
four. Some other models of instruments will cascade the leakage current of a series diode. When several diodes are connected in series, the measurement method can only measure the current value of one of the series leakage diodes, and the leakage current of other diodes in the entire junction box cannot be correctly discriminated.
Fives. Solar junction box and solar module function introduction:
Solar junction box and module schematic: 
In the figure, BT1/BT2/BT3/ are three solar panels, and the entire solar power plant is composed of several modules connected in series and in parallel.
Solar junction box FAQ:
1. The large voltage drop of the series diode will affect the power generation efficiency of the module when the module is not generating power.
2. In several diodes connected in series, if one of the diodes has a large leakage current, the discharge current of the battery cell connected in parallel will be discharged, and the temperature of the diode will rise and the bleeder current will continue. The increase can eventually lead to damage to the battery.
3. The wire connection is not reliable, the wiring resistance is too large, or changes.
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Analysis of Functional Characteristics of a Solar Junction Box Tester