SUN Xiao－yu

（College of International Education of Shenyang Institute of Engineering，Shenyang 110136 China)

0 Introduction

Under the condition of the vertical radiation of sunlight，the output electricity of solar PV cells can achieve the maximum value.The fixed bracket is adopted in most of solar station and the inclination angle can’t be changed.Sunlight tracking can improve the power generation efficiency of the solar PV cells and cost of station can be reduced.We divide a year into multiple time periods and the optimum tilt angle of each period is calculated separately.The results of software calculation and experiment prove that the manual adjustment bracket system could increase the power of PV plants significantly and shows high e－conomy and practicality.

1 Calculation of increasing the generating capacity by adjusting the inclination

We enter the radiation data in Shenyang，the local latitude and other natural condition data into software designed in this study，and the calculated results are show in Tab 1.The annual peak sunshine time is 1 700.4kWh／m2under two inclinations a year，which increases5.1percent compared with that under fixed inclination.And the annual peak sunshine time is 1 795.6kWh／m2under three inclination a year，which increases 5.6percent compared with that under fixed inclination.

Tab1 The calculation results of radiation on tilt surface under fixed inclination and multiple inclinations

2 Economic analysis

We take 1 10MW PV power plant as an example to analysis how the method of regulating inclination can improve the economic benefits.There are 43 200 solar cells and power of each cell is 235Wp.There are 4 320brackets and every 10panels are installed on a bracket.Every group is composed by two persons and adjusting one bracket cost one group 3minutes.It takes one group 8hours to adjust 160brackets.10groups（20persons)can complete all bracket adjustment in three days.In accordance with 200 yuan each day for each person pay，it cost 12 000yuan to adjust all bracket one time.So two inclinations a year cost 24 000yuan and three inclinations a year cost 36 000yuan.

According to the annual peak sunshine time shown in Tab1，the generating capacity under fixed inclination is 12million kWh each year after considering reduction.The generating capacity under two inclination is 12.612million kWh each year and the generating capacity under three inclination is 12.672 million kWh each year.The benefit analysis is shown in Tab 2，the price of electricity is 1yuan／kWh.The increased cost of bracket material cost is 0.2yuan／walt.The increasing cost is 2million yuan for a 10 MW PV plant.In accordance with 25years service life，the annual increasing cost is 80 000yuan.The economic benefits calculation results are shown in Tab 2，as can be seen the income increases by 4.03%under two inclination a year and increase by 4.39%under three inclinations a year.

Tab 2 The comparison of economy benefit under fixed inclination and multiple inclinations

3 Conclusions

In this study，the method that dividing ayear into multiple time periods and calculating the optimum tilt angle and the maximum radiation of every period is proposed.The calculation results shows that compared with that under fixed inclination，the annual peak sunshine time increases by 5.1%under two inclinations a year and 5.6%under three inclination a year.And income increases by 4.26%and 4.51%respectively.

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