Although the engineering design is very good, but there is no perfect system.In this case, you can debug, establish performance benchmark for customer acceptance and follow-up.Debugging not only is important for the performance of photovoltaic (PV) system, but also for the service life of the equipment, security, investment returns and warranty is also very important.
Step 1: photovoltaic system design and production
To obtain the expected output of your site, please make sure your solar resource and consider any shade on panels.Solar energy resources with peak sunshine hours (i.e., radiation device receives 1000 watts per square meter every day the number of hours) measurement.In California, for example, many parts of the solar energy resources are very abundant, radiation can receive 6000 watts per square meter a day, or six peak sunshine hours.use雷竞技appSolar irradiance Fluke IRR - 1 meterThe scene of the determination of the actual solar irradiation (watts/m2) and shading conditions to generate the benchmark.
Suppose you have a 10 kW pv arrays.You can through the following ways expected: produce array x 6 to 10 kW peak sunshine hours 365 days/year x 0.85 x (due to the wiring and inverter power loss in the derating 15%).The array should be for us to produce 18615 kWh of electricity every year, or every day 51 kWh of electricity.
Step 2: photovoltaic performance measurement
After installation, by measuring the electrical characteristics and the actual power output of photovoltaic array, make sure the system run according to the design expectations.
The performance of the photovoltaic array based on its i-v curve (IV).Can not only converts dc to ac inverter, you can capture the current and voltage to try to improve the power output (because power x = voltage current), in this case, the maximum module generated by power.Short circuit current (Isc) is the maximum current from the battery, because there is no voltage difference (the positive and negative wires contact), so as not to produce power.Open circuit voltage (Voc) is the maximum voltage from the battery, because the circuit is open, will not produce power.Photovoltaic modules generate maximum power point known as the maximum power point (MPP).
To understand whether the array according to the design work, you need to understand the module data sheet lists the Voc and Isc.Please measure the Voc and Isc before and after installation.
Through the use of雷竞技appFluke 393 FC CAT clamp table IIIMeasurement of Voc, can determine the voltage between the positive and negative terminals.393 FC belongs to the CAT III 1500 V / 600 V safe level IV, CAT CAT III environments, such as in solar installation safety is measured in a reliable way.use雷竞技appFluke 64 MAX infrared thermometerDetermination of the temperature of the module, in order to consider the influence of temperature on the Voc (the lower the temperature, the higher the voltage, and vice versa).In the detection of Voc, 393 FC will pass audio polarity warnings.If it meet the junction box or other circuits may accident series, which can lead to voltage exceed the maximum input voltage of inverter.
To test the Isc, please disconnect all parallel circuit and short circuit safely.Through the multimeter to measure the current between the positive and negative terminals.To set the dial to is greater than the expected value of the current value.Thr雷竞技appough the Fluke Connect ™ application record and save the Isc and Voc, for trend analysis and generate reports
Check the insulation resistance of the wire, and the connection between module and frame between modules, and your resistance to ground.use雷竞技appFluke 1630-2 FC grounding clamp tableMeasuring grounding resistance, in order to ensure the resistance is less than 25 ohms.
Step 3: in the diagnosis of abnormal situation
Even if installed correctly, pv systems can also be short of the expected output.Electrical characteristics of pv modules with prescribed is very important, because the inverter has the minimum and maximum input current, below and above the current, there will be no power output.
Scene 1: the open circuit voltage and short circuit current higher or lower than the value of the data sheet
In this case, the circuit has the property of one or more modules do not conform to the requirements of the specification.Open circuit voltage inverter beyond range means that you may not power output.Beyond the scope of short-circuit current said modules do not match, this will seriously degrade the performance of the array, because the current of the circuit of limited has the lowest current module.To identify and replace the module.
Scenario 2: low power output
If you see the power output is lower than the expected value, then there may be a problem.Although there are some fluctuations in the output is normal, but remains below the predicted output may be said circuit failure, grounding failure or shading problem.
One of the reasons may be existed in hot spots, and heat accumulation in the short circuit current of battery, resulting in battery performance decline, and may be a fire.Thermal imager (e.g.,雷竞技appFluke Ti480 PRO infrared thermal imagerorTiS75 + thermal imagerCan quickly identify hot spot.
Ground faultIs another kind of fault, but they are harder to diagnosis, need to detect each wire and equipment grounding conductor (EGC) of voltage and current, the equipment grounding conductor is used for the transmission of stray current to the earth.EGC used to indicate the voltage and current on the grounding fault.Ground fault是由于导线绝缘损坏、安装不当、导线被夹住和进水造成的，这些情况可能会在导线和 EGC 之间形成电气连接。找出问题的根源，更换损坏的导线或改善状况。
Low power output for other reasons might be the location of the shading problems, you as well as the inclination and the compass direction (azimuth).Using solar tracking device to find any new source of shade, and where possible, eliminated.Although that may not by changing the inclination of the pv array and the compass direction, to make photovoltaic panels more directly toward the sun, but you should know the inclination and azimuth, so as to establish a benchmark for future reference.
In large photovoltaic system, solar power system of power transformer to rise after the inverter voltage, and then enter the switchgear and medium voltage cables, in this case, reduce insulation resistance is a common problem.For the high voltage cable, please use雷竞技appFluke 1555 FC 10 kV insulation tester, the tester can test up to 10000 V voltage.
For system is equipped with a battery, please use雷竞技appFluke 500 series battery analyzerThe expected battery voltage and charged state compared with actual value.
