The multi factor comprehensive calculation technology of component inclination and array spacing alternating feedback has been applied in a 10MW photovoltaic power station in Golmud, Qinghai Province. The component inclination and array spacing designed by this method can effectively improve the power generation efficiency and increase the income of the power station. The component inclination and array spacing design of the project are analyzed in detail below.
(1) Preliminary calculation of inclination and spacing
According to the hourly radiation data of Golmud meteorological station from 2001 to 2010, the international general pvsyst software and other special software for solar power generation are used to check, and the average annual radiation on inclined planes with different angles is obtained.
Considering only the amount of solar radiation received by different inclined planes, the optimal inclination of Engineering fixed photovoltaic modules is 34 °. The annual acceptable solar radiation of flat panel solar cells placed at a fixed inclination of 34 ° is 2298.19kw · H / m ²。 Then, the inclination angle is further optimized after determining the installation spacing. When determining the front and rear spacing of photovoltaic modules, according to the local site conditions, each row is composed of 9 groups of photovoltaic cells in series side by side. A substation center is arranged between the two rows of photovoltaic arrays in the east-west direction. The substation center is 4m high and 3.5m wide. After considering the shadow, the East-West spacing of the two rows is set to 20m. The above serial size and the best installation inclination angle of photovoltaic modules are introduced into pvsyst and other solar professional calculation software for verification. The minimum distance between the front and rear rows of photovoltaic array between supports (the minimum distance between the front and rear rows) is 4.12m.
(2) Array spacing optimization
Generally, the optimization scheme will start from two aspects:
1) Increase the spacing between the front and rear rows of the array to increase the power generation.
2) Control the spacing between the front and rear rows of the array to save cable consumption.
When determining the final array spacing, we should comprehensively consider the two factors of power generation and cable cost, and balance the two, so as to achieve the optimal static investment per unit electric energy. Considering that the northwest is vast and sparsely populated, the land acquisition cost is relatively low, and the impact on the actual floor area is relatively small in the optimization scheme, the impact of the front and rear row spacing of photovoltaic modules on the floor area of photovoltaic power station and land acquisition cost is not considered for the time being. The unit megawatt capacity module of fixed photovoltaic array is selected as the research object, and the calculation is carried out by pvsyst and other solar professional calculation software.
The power generation of modules with unit MW capacity increases with the increase of the spacing between the front and rear rows of photovoltaic modules, but the increment decreases gradually. The maximum power generation shall not exceed the theoretical value of 1.698gw · h without shadow influence. At the same time, choosing different spacing also has a great impact on the construction cost and electrical efficiency of photovoltaic power stations. The increase of the front and rear spacing of components will lead to the increase of cable consumption and array floor area, which will increase the construction cost and line loss. Through the analysis of the relative distance between the front and rear rows of components and the cost of the line construction, we can determine the optimal distance between the front and rear rows of components. The increase of cable consumption, cost, power generation, line loss and component spacing are basically linear.
When the spacing between the front and rear rows of photovoltaic modules is small, with the increase of spacing, the static investment per unit electric energy decreases significantly due to the rapid increase of power generation. After the distance reaches a certain length, the increment of power generation gradually decreases to the limit, and the static investment per unit power increases slowly with the increase of cable consumption and line loss. Considering the convenience of engineering construction, the distance between the front and rear rows of photovoltaic array is finally determined to be 5m.
(3) Component inclination optimization
As mentioned above, the optimal inclination of the fixed PV module of the project is 34 ° when only the amount of solar radiation received by different inclined planes is considered. However, in the actual project, because the photovoltaic power station is composed of many sub arrays, shadows are inevitably generated between the front and rear rows. Under this inclination angle, calculate the condition that there is no shadow in the front and rear rows of photovoltaic modules from 9:00 to 15:00 in the winter solstice, and determine that the spacing between the front and rear rows of photovoltaic modules is 5m in combination with factors such as cable consumption, line loss and floor area of photovoltaic array. However, on the basis of determining that the distance between the front and rear rows is 5m, considering that the shadow shielding loss in a whole year decreases with the decrease of the inclination of the module, and the amount of solar radiation received by the photovoltaic module also decreases with the decrease of the inclination, it is very necessary to recheck the inclination of the module.
Introduce the front and rear row spacing of 5m and each installation inclination into pvsyst and other solar energy professional calculation software, and recalculate the radiation obtained on each installation Inclination after considering the shadow loss.
Comparing the solar radiation received when the inclination angle of the module is 30 ° and 34 °, it is found that when the shadow shading loss is not considered, the annual average solar radiation received by the 30 ° inclined plane is 2286.67kw · H / m ²， The annual average solar radiation received by the 34 ° inclined plane is 2298.19kw · H / m ²； When considering the shadow shielding loss, the annual average shadow loss of 30 ° as the installation angle is 2.3%, and the annual average solar radiation is reduced to 2234.08kw · H / m ²， When 34 ° is selected as the installation angle, the annual average shadow loss is 2.9%, and the annual average solar radiation is reduced to 2232.69kw · H / m ²。 Therefore, for the fixed photovoltaic array, when the current rear row spacing is 5m, considering the shadow shielding loss, the maximum solar radiation can be obtained when the fixed installation inclination is 30 °. Therefore, in this project, the installation inclination angle is not 34 ° as that of similar photovoltaic power stations in adjacent locations, but 30 ° is selected as the installation inclination angle of photovoltaic modules.
According to the comprehensive calculation technology, the shadow loss is reduced by about 0.6% and the power generation efficiency is improved by about 0.062% by adopting the 30 ° inclination optimization scheme; Compared with the conventional array spacing scheme, the 5m array spacing optimization scheme increases the investment per megawatt by about 17000 yuan, the line loss by about 0.33%, the annual power generation by about 1.02%, and the comprehensive power generation efficiency by about 0.75%. Based on the actual power generation data and considering the static investment of 1.15 yuan / kW · h per unit electric energy, the technology proposed in this book can directly create economic benefits of about 3 million yuan.
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