| As a kind of inexhaustible clean energy, solar energy will be the first choice of new energy development and utilization in future, it can thorough eliminate present energy structure which causes server air pollution at home and abroad, and is of broad prospects for development and utilization. The key to rational developing and utilizing solar energy is how to estimate and maximize the use of solar energy. In this paper, the sunshine hours, sunshine percentage, temperature, precipitation, relative humidity, cloudy days, total cloud of 80 weather stations in Gansu during the recent thirty years were used to study the temporal and spatial distribution of weather conditions and solar radiation here. Solar energy utilization of two photovoltaic power stations in Minqin and Dunhuang area, were researched by using data of two PV stations’ power generation, global solar radiation, direct radiation and horizontal plane scattered radiation, and other meteorological elements of Minqin and Dunhuang weather stations during 1963～1992 based on the relevant formulas, RETScreen software, PVsyst software. The main conclusions are as follows:(1) Gansu Province has few total amount of radiation observed stations. For the annual average of total amount of radiation, Dunhuang weather station is highest (6461.7 MJ·m-2), followed by Minqin weather station (6138.1 MJ·m-2) and the lowest are Lanzhou (5043.4 MJ·m-2) and Xifeng weather stations (5069.3 MJ·m-2). The radiation amount is higher in May, June and lowest in December. In Gansu Province, the sunshine hours and sunshine percentage is decreasing from northwest to southeast. However, the precipitation, average relative humidity, cloudy days and total cloud trend present inversely spatial trends. The distribution of temperature is spatially uneven and largely influenced by topography. It shows low in the central region and high in end regions, in which the western region is lower and eastern region is higher.(2) The total amount of radiation deviations calculated by three methods is relatively lower from April to August and relatively larger from September to next March. Compared to average, the radiation in September to December calculated by RETScreen software is smaller about 2-6% and the other months are in middle level; the radiation calculated by PVsyst software in November to next February is smaller about 1-8%; and by formula, it is larger about 2-9% in October to next January. The monthly radiation calculated by three methods were slightly different, however, the annual radiation was nearly closed. Compared to average, the annual radiation of station 1 and station 2 that is smaller about 1.68% and 0.62% which calculated by RETScreen software and is smaller about 0.04% and 0.5% by PVsyst software, meanwhile, it is larger about 1.72% and 1.12% calculated by formula.(3) On station 1, the power plant conversion rate of total amount of radiation of fixed package and adjustable package are basically same, which are 82.2% and 81.9%. The radiation which is calculated by three methods received by actual package adjustment scheme increased 3.09%. However, the actual conversion of radiation to electricity of adjusted is bigger than fixed about 2.67% that is slightly smaller than software calculated value. On station 2, the conversion rate of fixed package 65.3%, which is far below station 1. This study shows that solar theoretical calculation and actual conversion value are close to truth and the results are credible.(4) The 2-12 times angle adjustments experiments of two stations in a year showed that even the optimal scheme of different software at the sane angle are different, the trend are generally same. For three methods, when the total number of adjustment increased, the radiation increasing received by PV modules are same. Compared to fixed angel, the radiation increased 394-462 MJ·m-2 when there is twice adjustment and the increasing is 34～40 MJ·m-2 for four time adjustments. Considering the great personnel costs of adjustment, four times adjustment is recommended.In a word, this paper analyzes the difference between actual generation data and theoretical value of two power PV stations in Hexi region, and the optimal scheme of manual adjustment numbers of PV modules. Therefore, the generating capacity of PV station is increased by correcting the average month adjustment which is used by former engineering design, and increases the radiation received by PV modules. These results can provide a scientific basis for the full development and utilization of solar energy resources in Gansu Province. |
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