1, background
Time: August 30, 2017, Venue: Guanlan Town, Shenzhen City, a 10kW power station, customer response power generation is not high, this power station is the network of August 11 and until August 29, a total of 500 degrees of power generation, Taking into account that there are four days of heavy rain, the actual number of days of power generation is 15 days, an average of about 33.3 degrees per day, and the average annual data is similar, but in August is the peak period of photovoltaic power generation, the author found the equivalent installed capacity of power stations in Shenzhen, 10kW per day It was around 40-50 degrees. Upon receiving a telephone call from the customer, the author immediately arranged an on-site inspection.
2, on-site detection
There are many factors that affect power generation, such as the quality of components, inverters, cables, installations facing azimuths, inclination angles, dust, shadows, system solutions, circuit design, construction, grid voltage, and many other factors. The author arrived at the scene at 10:30 and checked various factors one by one.
The module uses Empress 265W polycrystalline, the number is 40, the inverter is the use of Shenzhen Growatt 10000TL3-S, using 20 series, 2 way to the grid, DC cable uses a dedicated 4mm dedicated cable, The AC cable adopts a copper cable of type BVR with a diameter of 4mm. The AC switch adopts 500V20A. The inverter has no information such as leakage current alarm and grid voltage alarm, indicating that the electrical system scheme and circuit design meet the requirements.
The components have the same color, no color difference, the assembly is newly installed, the typhoon is just past, the surface is clean and dust-free, the assembly is installed at an angle just south, the PV1 tilt angle of the panel is about 5 degrees, and the PV2 tilt angle of the panel is about 15 degrees. From 10:30 to 12:30 in two hours, the maximum peak power of panel 1 is about 4580W, and the maximum peak power of panel 2 is about 3880W. Disconnect the components and the inverter wiring. The panel PV1 open circuit voltage is 648V. The open circuit voltage of PV2 is 635V, and the voltage difference is very small, indicating that there are no problems with the components, inverters, installation angle, and construction.
After on-site investigation, the shadows of the most possible factors affecting the power generation are affected. The panel PV1 is east, west and north, the panel PV2 is south, and the metal guardrail is in the north, which is close to the module, about 0.02 meters, about 0.5 meters higher than the module. To confirm the effect of shadow on the system's power generation, the author erected a metal rod on the edge of the power station to observe the shadow.
At about 11:10 a.m., the sun goes east to west. The panel PV1 power is 3230W, the panel PV2 power is 3640W, and the maximum power of the module is 410W, which is about 12%. Because the guardrail on the east side of the panel PV1, some shadows fall on it. On the assembly, there is no guardrail on the east side of panel PV2.
At 12:30 in the afternoon, the sun was strongest on the day of testing. From the south to the north of the day, the PV1 peak power of the panel reached 4580W. The PV2 peak power of the panel was 3880W, and PV1 was 700W greater than that of PV2, which was approximately 18% because of the south fence. There are shadows. The components are installed vertically, where shadows obstruct the lower half of the five components and have a greater impact on the power generation of the system.
3, summary
The shaded components have a great influence on the power generation of the system. This 10 kW system preliminarily estimates that the surrounding guardrail will affect about 15% to 20% of the system power generation. Therefore, when designing, components should be raised as much as possible to avoid shadow obscuration. .
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