After the installation of the photovoltaic system, the user is most concerned about the power generation, because it is directly related to the user's return on investment.
There are many factors affecting the power generation, such as the quality of components, inverters, cables, installation orientation azimuth, inclination angle, dust, shadow blocking, component and inverter ratio system scheme, circuit design, construction, grid voltage and so on.
For long-running photovoltaic power generation systems, the impact of panel dust cannot be underestimated. The dust on the surface of the panel has the functions of reflecting, scattering and absorbing solar radiation, which can reduce the transmittance of the sun, resulting in a decrease in the solar radiation received by the panel and a decrease in the output power, which is proportional to the accumulated thickness of the dust.
The full name of PID effect is potential-induced decay. The direct harm of PID is that a large amount of electric charge accumulates on the surface of the battery sheet, which makes the surface of the battery passivated.
The harm of the PID effect makes the power of the solar cell module attenuate sharply; the fill factor (FF), open circuit voltage, and short circuit current of the solar cell module are reduced; the output power of the solar power station is reduced, the power generation is reduced, and the power station income of the solar power station is reduced.
String monitoring technology is to install a current sensor and a voltage detection device at the input end of the inverter component to detect the voltage and current value of each string, and to judge whether the operation of each string is obviously normal by analyzing the voltage and current of each string.
If there is an abnormality, the alarm code will be displayed in time, the abnormal string can be accurately located, and the fault record can be uploaded to the monitoring system, so that the operation and maintenance personnel can find the fault in time.
Although the string monitoring technology adds a little cost, which is still insignificant for the entire photovoltaic system, it has a great effect:
(1) The early problems of solar photovoltaic modules are found in time, such as module dust, splinter, module scratches, hot spots, etc., which are not obvious in the early stage.
However, by detecting the difference in current and voltage between adjacent strings, it is possible to analyze whether the strings are faulty and deal with them in time to avoid greater losses.
(2) When the system fails, it does not require on-site inspection by professionals, and can quickly determine the type of failure, accurately locate which group string, and the operation and maintenance personnel can solve it in time to minimize losses.
Manual cleaning is the most primitive way of component cleaning, which is completely done by manpower. This cleaning method has low work efficiency, long cleaning cycle, high labor cost, and has hidden dangers to personal safety.
Manual dry cleaning components: Manual dry cleaning of solar photovoltaic modules is carried out with a long-handled velvet mop and a special cleaning agent, and oil-based electrostatic dust collectors are used.
It mainly uses the principle of electrostatic adsorption, which has the function of adsorbing dust and sand, which can enhance the ability of cleaning tools to absorb dust and decontaminate, and effectively avoid the flying of dust and sand during cleaning.
Due to the complete reliance on manpower, there are problems such as a lot of residue on the surface and uneven force on the components, which may cause deformation and cracking. Compressed air purging is to blow out compressed air through a special device to remove the dust on the surface of the components, which is used in areas where water resources are scarce.
Manual washing components: Manual washing is to spray water on the surface of the solar photovoltaic module with the nozzle connected to the waterwheel (or the water pipe), so as to achieve the purpose of cleaning.
The pressure generally does not exceed 0.4MPa. This cleaning method is better than manual dry cleaning, and the cleaning efficiency is higher, but the water consumption is larger.
However, excessive water pressure will cause cracks in the photovoltaic module cells, resulting in a large-scale short circuit, which will reduce the power generation efficiency. In addition, after the water-washed solar photovoltaic modules are naturally air-dried, water stains will form on the surface of the modules, forming micro-shading shadows and affecting the power generation efficiency.