Many owners of the benefits of photovoltaic power generation know little about it, do not know how to install distributed photovoltaic power generation in the end to bring their own income?
To answer this question, you need to understand the amount of photovoltaic power generation. Today, photovoltaic Jun to take you to see the impact of photovoltaic power generation several factors.
First of all we need to know, the calculation of photovoltaic power generation method:
Theoretical annual power generation = total annual solar radiation * total battery area * photoelectric conversion efficiency
But because of the impact of various factors, photovoltaic power generation is actually not so much:
Actual annual power generation = theoretical annual power generation * actual power generation efficiency
There are several factors that affect the amount of photovoltaic power generation have these:
Solar radiation
The solar cell module is a device that converts solar energy into electrical energy, and the intensity of light radiation directly affects the amount of electricity generated. Solar radiation data for each region can be obtained from the NASA Meteorological Information Web site, or by means of PV design software such as PV-SYS, RETScreen.
The tilt angle of the solar cell module
Information obtained from the weather station, usually the amount of solar radiation on the horizontal plane, converted into the PV array tilted surface of the radiation, in order to calculate the photovoltaic system power generation. The optimum inclination is related to the latitude of the project location. The general experience values are as follows:
A, latitude 0 ° ~ 25 °, tilt angle equal to latitude
B, latitude 26 ° ~ 40 °, angle is equal to latitude plus 5 ° ~ 10 °
C, latitude 41 ° ~ 55 °, inclination equal to latitude plus 10 ° ~ 15 °
Conversion efficiency of solar cell modules
PV modules are the most central factor in power generation. February 5, 2015 The National Energy Board Comprehensive Division promulgated the "on the role of the market to promote the progress of photovoltaic technology and industrial upgrading of the letter" provides that since 2015, enjoy the state subsidies for photovoltaic projects used in photovoltaic modules and Grid-connected inverter products should meet the "photovoltaic manufacturing industry standard conditions" related indicators. Among them, the polysilicon battery module conversion efficiency of not less than 15.5%, monocrystalline silicon cell module conversion efficiency of not less than 16%. At present, the market line of brand polysilicon components conversion efficiency is generally up to 16% or more, monocrystalline silicon conversion efficiency is generally more than 17%.
System loss
As with all products, photovoltaic power plants in the life cycle of 25 years, the efficiency of components, electrical components will gradually reduce the performance, power generation decreases year by year. In addition to these natural aging factors, there are components, inverter quality problems, line layout, dust, serial and parallel losses, cable loss and other factors.
General photovoltaic power plant in the financial model, the system power generation capacity decreased by about 5% in three years, 20 years after the power generation decreased to 80%.
(1) combined loss
All the series will be due to the current difference in components caused by current loss; parallel will be due to the voltage difference between the components caused by voltage loss; and combined losses can reach more than 8%, China Engineering Construction Standardization Association standards less than 10%.
Therefore, in order to reduce the combined loss, should pay attention to:
1) should be installed in the power plant before the strict selection of the same current components in series.
2) The attenuation characteristics of the components are as consistent as possible.
(2) dust shelter
In all the factors that affect the overall power generation capacity of photovoltaic power plants, dust is the biggest killer. Dust on the impact of photovoltaic power plants are:
1) by shielding the components to reach the light, thus affecting the power generation;
2) affect the heat, thus affecting the conversion efficiency;
3) with acid and alkali dust for a long time deposition on the surface of the component, erosion board caused by rough surface, is conducive to the further accumulation of dust, while increasing the diffuse sunlight.
So the components need to wipe clean from time to time. At this stage the main cleaning of photovoltaic power plants, sprinkler, artificial cleaning, robots in three ways.
(3) temperature characteristics
Temperature rise of 1 ℃, crystalline silicon solar cells: the maximum output power decreased by 0.04%, open circuit voltage decreased by 0.04% (-2mv / ℃), short circuit current increased by 0.04%. In order to reduce the effect of temperature on the amount of power generation, the components should be kept well ventilated.
(4) line, transformer loss
The system of DC, AC circuit line loss to be controlled within 5%. To this end, the design to use a good conductive performance of the wire, the wire needs to have enough diameter. System maintenance should pay special attention to the connector and the terminal is solid.
(5) inverter efficiency
Inverter due to inductors, transformers and IGBT, MOSFET and other power devices, in operation, will produce loss. General group of string inverter efficiency of 97-98%, centralized inverter efficiency of 98%, transformer efficiency of 99%.
(6) Shadow, snow cover
In the distributed power station, if there are tall buildings around, will cause shadows on the components, the design should try to avoid. According to the principle of the circuit, when the components are connected in series, the current is determined by the least one, so if there is a shadow, it will affect the power generation of this way. When the components on the snow, it will also affect the power generation, must be cleaned as soon as possible.