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Knowledge points of photovoltaic construction

Since the main factor affecting photovoltaic power generation is the amount of sunlight, the modules should be installed in the direction with the most sunlight. Different installation angles also affect the power generation efficiency of photovoltaic modules. The figure below shows the different efficiencies of photovoltaic modules in different orientations in a city in southern China. (Note: In different locations and under different climatic conditions, the power generation efficiency of photovoltaic cells in different orientations is different.)

The photovoltaic inverter generally chooses outdoor type, adopts natural cooling method, and has a high protection level of the shell (usually up to IP65), and requires little environmental modification for installation, and the cost is low; The impact of the noise generated by the operation of the inverter on the user will also be greatly reduced, but good equipment protection is required.

Generally, the inverter of the corresponding power segment is configured according to the requirements of the system. The power of the selected inverter should match the maximum power of the photovoltaic cell array. Generally, the rated output power of the photovoltaic inverter is selected to be close to the total input power, (usually exceeding The configuration is controlled within 1.3), which can save costs.

On the other hand, the selection of inverter capacity can be optimized according to the installation conditions. If the installation site is not clear at the early stage of the design, and the installation site is not fully considered, it is necessary to choose a low-power photovoltaic inverter as much as possible to realize multi-channel independent power tracking. If necessary, select a micro-inverter to achieve the maximum power of a smaller unit. Tracking, so as to protect the series-parallel mismatch and other problems caused by the venue not being large enough or not regular enough in the later stage.

As the core component of the photovoltaic system, the inverter directly affects the power generation of the system. The following points should be paid attention to:

(1) Since the connection between the inverter and the grid changes the impedance characteristics of the inverter, it is easy to cause the inverter itself to resonate, which usually occurs when multiple inverters are connected in parallel;

(2) After the inverter is installed, it must be re-inspected by a special person, and marked and recorded;

(3) The joint between the inverter ventilation duct and the external air duct should adopt a soft connection to prevent mechanical noise caused by mechanical vibration;

(4) When the noise of the inverter increases and there is a peculiar smell, attention should be drawn, check the internal faults of the inverter, find out the cause and deal with it as appropriate;

(5) Pay attention to the detection of inverter leakage, grounding, phase sequence, etc. during installation and commissioning;

(6) At least 2 people should be present at the same time when the inverter is being debugged, pay attention to the safety protection of the operators.