Power generation is the cornerstone of a PV power plant, and power generation can vary a lot between power plants of the same capacity. So how does the power plant generation difference arise? What factors can have a big impact on system power generation?
Photovoltaic modules are the only source of power generation
"Many people see the amount of power generation as the task of the inverter, but in fact, the module is the only source of power generation.
Through the photovoltaic effect, the modules convert the energy radiated by sunlight into measurable DC energy, which leads to the subsequent conversion output and ultimately to the power generation and revenue. Without modules or insufficient module capacity, the best inverter can't help, because the inverter can't convert air into electricity. Therefore, choosing the right, high-quality component products is the best gift to the power station; it is also an effective guarantee of long-term stable income.
String design is critical, the same number of components using different string method, power station performance will be different. The rated working voltage of three-phase inverter is generally around 600V. If the string voltage is lower, the boost circuit will operate frequently, which will have certain impact on the efficiency. Take 56 pieces of 445Wp monocrystalline modules with 20KW inverter as an example, the power generation of string method ② is higher than string method ①.
The laying and installation of modules is crucial
The same module capacity at the same installation site, the orientation, layout, tilt angle, and whether there is shading, all have an important impact on the power. The general trend is to install the modules facing south. In actual construction, many users will make the modules face south by adjusting the brackets even if the original state of the roof is not facing south, in order to receive more light radiation during the year.
In principle, different latitudes require the installation inclination of the components to be close to or greater than the local latitude value, but also according to the actual situation, can not be mechanically implemented, to consider the roof load, wind resistance, rain and snow during the year and other climatic factors. For larger rooftop power stations, a smaller inclination angle is recommended, and the component arrays should not be kept at too large and appropriate a distance from the building roof, so that the end of the arrays are not too far from the roof and there are safety hazards. The azimuth angle has limited impact on the output of the module compared with the inclination angle, and generally Class III areas can be considered without much consideration, unless such areas as Xinjiang and Heilongjiang, which can be chosen to deviate to the west or east according to the actual light duration, because the light in these areas starts very early or the west light time lasts for a long time, and the deviated installation takes advantage of the situation, which can make the module receive light for a longer time and thus produce power continuously.
In addition, all kinds of possible shading is always a factor to be avoided in module installation, and it can even be said that shading is the biggest killer of power generation. If only half of the modules in a string are blocked by shading, there will be little to no current, so try to avoid obvious or potential shading during the installation phase.
Grid fluctuations should never be ignored
What is "grid fluctuation"? It is a situation where the voltage or frequency value of the grid changes too much, too often, causing unstable power supply to the load in the station. Generally a substation (station) to supply many areas of the power load, some end load even dozens of kilometers away, transmission line losses, so the station near side of the voltage will be adjusted high, in these areas of grid-connected photovoltaic system, may be too high because the output side of the voltage is raised and the standby situation; or the far end of the connected photovoltaic system due to low voltage and system failure to stop working situation . The power generation of PV system is a cumulative value, as long as the standby or shutdown, the power generation can not be accumulated, the result is the reduction of power generation. At the same time, in recent years, the PV market continues to boom, some of the original utility voltage is normal in the region, because the same station area into the PV system capacity accounted for too large a proportion of the station area voltage rise, and limited capacity to consume, these PV systems also face the problem of grid fluctuations. The most intuitive impact of grid fluctuations is the frequent fluctuations in the power generation curve, making the power generation time no output, so that compared to the power generation curve smooth and round power station, power generation is bound to be less.
Mean Time to Failure (MTBF) of a power plant
Originally this concept is for electrical products, but the PV system is not only one kind of inverter equipment, here can also borrow this concept, that is, the longer the time interval of a PV power plant failure, the longer the work of the power plant to maintain stable operation, can maintain stable work for a long time, naturally can bring stable power generation revenue.
PV power plant fault contains a wide range of content, not only refers to the inverter reported by the fault (warning or failed), the above-mentioned power grid fluctuations are actually a fault, in addition, for example, module snow and dust, PV reverse false connection, AC and DC cables aging loose, power company maintenance outages, AC distribution boxes in the false connection, tripping not restored, etc., are part of this scope.
