双面光伏组件在多类型光伏电站中的发电特性研究

针对双面光伏组件在水面、农光互补、平单轴、彩钢瓦等不同背景和不同支架类型光伏电站中的发电特性进行了分析与实证,结果表明:在水上光伏电站,双面光伏组件较单面光伏组件的年均发电量增益为5.39%;在农光互补光伏电站,双面光伏组件较单面光伏组件的年均发电量增益达11.96%;采用平单轴跟踪支架的双面光伏组件较采用固定支架的单面光伏组件的年均发电量增益达20.17%;以10°倾角铺设时,白色彩钢瓦上的双面光伏组件较蓝色彩钢瓦上的单面光伏组件的年均发电量增益可达9.11%。利用PVsyst软件对上述电站进行发电量模拟,结果显示:采用平单轴跟踪支架的双面光伏组件的模拟结果与实际数据基本一致;彩钢瓦屋顶电站的模拟值与实际值趋势一致,但实际值比模拟值偏低;水上光伏电站的模拟值和实际值在夏季的趋势相同,但在冬季时相差较大;农光互补光伏电站受地面植被的影响,其模拟值和实际值有较大差别。     

不同安装方式时双面光伏组件发电系统的理论建模分析

基于PVsyst仿真软件,以青海格尔木市为模拟地点,考虑了场景反射率、组件前后间距、安装方式与高度、逆变器匹配设计等因素,在固定倾角式、平单轴跟踪两种安装方式下,分析对比了双面光伏组件与常规光伏组件的辐射接收量、发电量、系统效率和度电成本,并研究了场景反射率对双面光伏组件发电量的影响和此类光伏发电系统逆变器的限光损失。仿真结果表明,在固定倾角安装或平单轴跟踪的安装方式下,采用双面光伏组件的发电系统比采用常规光伏组件的发电系统的发电量理论上平均可提升10%以上,且随着场景反射率的增加而增加;当场景反射率为60%时,度电成本可降低14%,具有较高的经济效益,在降本增效方面具有较大的技术价值。     

双面光伏组件背面无遮挡时的发电量研究

针对以常规方式安装双面光伏组件时组件背面存在一定遮挡会影响其发电量这一情况,通过对双面光伏组件分别安装于固定式光伏支架、平单轴跟踪光伏支架时组件背面有、无遮挡,以及背景反射率不同时双面光伏组件的发电量情况进行分析,结果发现,在双面光伏组件背面无遮挡的前提下,当采用平单轴跟踪光伏支架且地面背景为白色时,双面光伏组件的发电...     

双面光伏组件安装特点的模拟研究

针对影响双面光伏组件背面接收的太阳辐射量的因素进行了研究,应用PVsyst软件,以采用前后排光伏组件固定间距、固定式光伏支架安装的光伏发电系统为例,以草地作为代表地表特征,模拟分析了双面光伏组件在不同安装高度和不同安装倾角条件下其背面接收的太阳辐射量的变化情况。研究结果表明,当双面光伏组件的安装倾角一定时,其安装高度与其背面接收的有效太阳辐射量成正比;而当双面光伏组件的安装高度一定时,其安装倾角越小,双面光伏组件背面接收的有效太阳辐射量中地面反射辐射量的占比就越大。     

四川省某光伏发电项目的光伏支架选型设计

以2021年建设的四川省某光伏发电项目为例,针对其光伏支架选型设计,利用平准化度电成本(LCOE)对该项目分别采用固定倾角式、固定可调式、平单轴和带倾角的平单轴4种光伏支架进行定量分析,从而得到LCOE最低时的光伏支架方案。结果显示：本项目在地势平坦区域推荐安装采用2P方案(2块光伏组件竖排)的平单轴光伏支架,其他区域推荐安装固定倾角式光伏支架。     

采用双面光伏组件的光伏电站在系统集成设计中应考虑的因素分析

采用双面光伏组件是一种能够有效提升光伏电站发电量的手段。基于双面光伏组件的特点,通过列举行业内常用的双面光伏组件辐照度数学模型,对影响双面光伏组件发电量的地面反射率、前后排光伏阵列间距、光伏组件最佳安装倾角和光伏组件离地高度这几个主要因素进行了研究,并通过PVsyst软件对这几个主要因素进行了逐一仿真验证,从实际应用角度提出了采用双面光伏组件的光伏电站在系统集成设计中应考虑的几个因素。研究结果表明：1)双面光伏组件的最佳安装倾角比单面光伏组件的最佳安装倾角大,根据地区、地面反射率的不同,二者的差值大致在2°～10°之间;2)提高光伏组件离地高度可以增加双面光伏组件的发电量,而发电量增益大小会因光伏组件所在地纬度的不同有所不同,实际光伏电站的系统集成设计中,可选择最具经济性的光伏组件离地高度;3)在光伏组件最佳安装倾角过低的地区,光伏组件的自遮挡效应严重,需要根据实际情况选择是否采用双面光伏组件。     

双面光伏组件辐照度模型的研究

针对双面光伏组件正面和背面获均能吸收太阳光的特点,通过光线跟踪辐照度模型分析,构建区分阴影区和无阴影区的热传输理论视觉因子太阳辐照度模型。模拟结果表明:当双面光伏组件倾斜角比单面组件增加约4°,在地面反射率为30%和50%的情况下,年辐照度增益可提高17.41%和28.79%;且随着离地高度与行间距增加,年辐照度可进一步提高。双面光伏组件辐照度模型为双面光伏组件电站安装时的地面反射率、最佳倾斜角、离地高度及行间距的设置提供了理论支撑。     

基于双面组件的可调支架光伏发电系统仿真研究

以双面光伏组件和可调支架系统为基础,以青海格尔木为模拟地点,利用PVsyst光伏仿真软件,分析了不同调节次数的可调支架系统与固定支架系统在组件正面和背面辐射量、系统发电量、系统收益的差异。研究结果表明：通过调节支架改变光伏组件的角度后,组件最低点离地高度也在变化,直接影响组件正面和背面的辐射接收;光伏方阵前后间距影响土地利用率（GCR）,土地利用率降低后,背面的辐射量和系统发电量都有一定的增加;相对于固定支架双面发电系统,可调支架双面系统在不同调节次数下的组件背面全年辐射量均有一定降低,但整体的发电量得益于正面辐射的增益,最高可达4.8%左右;技术和经济比较结果显示,双面组件采用可调支架系统,每年2次的调节方式,25年生命周期内系统收益最高。文章还分析了单面发电组件和双面组件系统使用可调支架的经济性对比,在相同的调节次数下,双面组件系统的增益明显高于单面组件系统。本文的研究成果对可调支架双面组件发电系统的设计具指导作用。     

双面光伏组件与单轴跟踪相结合的光伏发电系统发电量研究

对比分析了采用"最佳固定倾角+双面光伏组件"与采用"斜单轴跟踪+双面光伏组件"2种方案的光伏发电系统的理论发电量与实测发电量情况,结果表明,实测与理论较为吻合,"斜单轴跟踪+双面光伏组件"的方案具有一定的应用参考价值。     

平单轴跟踪光伏发电系统容量配比研究

针对目前平单轴跟踪光伏发电系统组件与逆变器容量配比普遍采用1.2:1左右的现状,本文通过选取4个典型地区的年小时辐射量数据,计算组件与逆变器容量配比范围在1:1~1.8:1的最佳度电成本(LCOE),以获得最佳容量配比,并给出了日照资源对最佳容量配比的影响分析。此外,还分析了LCOE计算的各参数变化对LCOE和组件与逆变器最佳容量配比的影响,最终给出了平单轴跟踪光伏发电系统容量配比的研究结果。     

基于光伏组件的太阳能资源观测

鉴于太阳能资源的测量和评价是太阳能开发利用的重要基础,按照光伏电池两种主要安装方式(倾斜固定和太阳跟踪),利用单晶、多晶和非晶三种典型的光伏组件设计进行了太阳能光伏资源观测试验,获得了各季节典型晴天条件下各类型光伏组件辐照度的日变化特征和倾斜面光伏组件一年中月均每日可发电量的极大值、极小值及其月份。通过对比各类型光伏组件在太阳跟踪器上和纬度倾斜面上光伏辐照度变化,得出跟踪光伏组件日均光伏曝辐量与倾斜光伏组件日均光伏曝辐量的相比较优势。根据光伏组件的观测结果推算出各类型光伏组件的光伏反演辐照度,与气象辐射观测用总辐射表的总辐射辐照度趋势非常一致,在太阳能光伏主要利用时段相对误差基本在10%以内。     

单面和双面单晶硅光伏组件的发电性能实证

针对p型PERC单面单晶硅光伏组件和n型双面单晶硅光伏组件,利用光伏组件户外实证测试系统,分析了2016年12月15日~2018年7月20日期间,上海市嘉定区某屋顶的地面采用白板背景时双面和单面组件,以及水泥背景时双面组件的等效发电时长,并对白板背景和水泥背景时双面组件较单面组件的发电量增益情况进行了分析;计算了组件的PR值;分析了阴天和晴天时组件最大输出功率与组件背板温度、太阳辐照度和环境温度的关系;最后对比了单面和双面组件运行13个月后的衰减值。该实证结果为单面和双面组件的户外实证发电性能提供了数据支撑,并对双面组件较单面组件的发电量增益情况进行了有效证明。     

Impact of solar radiation variation on the optimal tilted angle for fixed grid-connected PV array—case study in Beijing

A key design parameter for fixed grid-connected photovoltaic (PV) arrays, the optimal tilt angle, does not only depend on the geographic location but is also directly affected by atmospheric conditions. In this paper, long-term variations of solar radiation (i.e. global solar irradiance, direct horizontal irradiance, diffuse irradiance, and ratios of direct and diffuse irradiance) in Beijing are considered to determine their effect on the optimal tilt angle for a fixed grid-connected PV array. We found that there is a declining trend in global solar irradiance over the past 55 years, mainly caused by the decreased direct horizontal irradiance. In contrast, the decline of diffuse irradiance is not obvious, leading to a considerable decrease in the direct irradiance ratio and consequent increase in the diffuse irradiation ratio. Likewise, the long-term optimal tilt angle shows a downward trend. Compared with the optimum in the 1960s, the optimal tilt angle has decreased by 2° in 2011–2015. These results suggest that the declining trend in the optimal tilt angle is mainly caused by the decrease in direct irradiance ratio, which is highly related to atmospheric conditions. Therefore, the design and construction of PV power stations must consider the variations of atmospheric conditions and solar irradiance to determine the optimal tilt angle.     

Determining optimum tilt angles and orientations of photovoltaic panels in Sanliurfa, Turkey

The performance of a photovoltaic (PV) panel is affected by its orientation and its tilt angle with the horizontal plane. This is because both of these parameters change the amount of solar energy received by the surface of the PV panel. A mathematical model was used to estimate the total solar radiation on the tilted PV surface, and to determine optimum tilt angles for a PV panel installed in Sanliurfa, Turkey. The optimum tilt angles were determined by searching for the values of angles for which the total radiation on the PV surface was maximum for the period studied. The study also investigated the effect of two-axis solar tracking on energy gain compared to a fixed PV panel. This study determined that the monthly optimum tilt angle for a PV panel changes throughout the year with its minimum value as 13° in June and maximum value as 61° in December. The results showed that the gains in the amount of solar radiation throughout the year received by the PV panel mounted at monthly optimum tilt angles with respect to seasonal optimum angles and tilt angel equal to latitude were 1.1% and 3.9%, respectively. Furthermore, daily average of 29.3% gain in total solar radiation results in an daily average of 34.6% gain in generated power with two-axis solar tracking compared to a south facing PV panel fixed at 14° tilt angle on a particular day in July in Sanliurfa, Turkey.     

不同地面背景对双面光伏组件发电性能的影响

以双面光伏组件为研究对象,通过理论计算和实验研究的方法,对双面组件在不同地面背景下的发电性能进行理论分析与实验验证。研究结果表明:双面组件的功率增益随地面背景的反射率增大而增大,随辐照度增加而降低,双面组件在反射率最大的铝箔地面与反射率最小的草坪地面的最大功率增益分别为25.30%和8.24%。     

Improved photovoltaic energy output for cloudy conditions with a solar tracking system

This work describes measurements of the solar irradiance made during cloudy periods in order to improve the amount of solar energy captured during such periods. It is well-known that 2-axis tracking, in which solar modules are pointed at the sun, improves the overall capture of solar energy by a given area of modules by 30-50% versus modules with a fixed tilt. On sunny days the direct sunshine accounts for up to 90% of the total solar energy, with the other 10% from diffuse (scattered) solar energy. However, during overcast conditions nearly all of the solar irradiance is diffuse radiation that is isotropically-distributed over the whole sky. An analysis of our data shows that during overcast conditions, tilting a solar module or sensor away from the zenith reduces the irradiance relative to a horizontal configuration, in which the sensor or module is pointed toward the zenith (horizontal module tilt), and thus receives the highest amount of this isotropically-distributed sky radiation. This observation led to an improved tracking algorithm in which a solar array would track the sun during cloud-free periods using 2-axis tracking, when the solar disk is visible, but go to a horizontal configuration when the sky becomes overcast. During cloudy periods we show that a horizontal module orientation increases the solar energy capture by nearly 50% compared to 2-axis solar tracking during the same period. Improving the harvesting of solar energy on cloudy days is important to using solar energy on a daily basis for fueling fuel-cell electric vehicles or charging extended-range electric vehicles because it improves the energy capture on the days with the lowest hydrogen generation, which in turn reduces the system size and cost.     

Performance modeling and investigation of fixed, single and dual-axis tracking photovoltaic panel in Monastir city, Tunisia

Presented in this paper was an overview on research works on solar radiation basics and photovoltaic generation. Also, a complete PV modeling and investigation on the effect of using multi-axes sun-tracking systems on the electrical generation was carried out to evaluate its performance using the case study of the Monastir city, Tunisia. The effects of azimuth and tilt angles on the output power of a photovoltaic module were investigated. The instantaneous increments of the output power generated by a photovoltaic module mounted on a single and dual-axis tracking system relative to a traditional fixed panel were estimated. The results show that the yearly optimal tilt angle of a fixed panel faced due to the south is close to 0.9 times Monastir latitude. The gain made by the module mounted on a single-axis tracking panel relative to a traditional fixed panel was analyzed. The monthly increments of the gain are more noticeable for two critical periods which correspond to those surrounding the summer and the winter solstice dates. It reaches the value of 10.34% and 15% in the summer and winter solstice periods, respectively. However, the yearly gain relative to a fixed panel installed with the yearly optimal tilt angle is 5.76%. In some applications, covering loads at early morning or late afternoon hours and in order to more optimize the solar systems exploitation suggest the adjustment of the PV panel orientation to azimuth angles different from the south direction by using a dual-axis tracking installation. The gain made by this recommendation relative to a traditional fixed panel is evaluated. This gain reaches 30% and 44% respectively in the winter and summer solstice days.