Diffusion Coefficient at Double Resonances in Frequency and Temperature, Applied to (n+/p/p+) Silicon Solar Cell Base Thickness Optimization under Long Wavelength Illumination

The diffusion coefficient of the minority charge carriers in the base of a silicon solar cell under temperature and subjected to a magnetic field, passes in reso-nance at temperature (Topt). For this same magnetic field, the diffusion coeffi-cient of the photogenerated carriers by a monochromatic light in frequency modulation enters into resonance, at the frequency (ωc). Under this double resonance in temperature and frequency, the diffusion coefficient is used in the expression of the recombination velocity of the minority charge carriers on the back side of the base of the solar cell (n+/p/p+), to obtain, by a graphical method, the optimum thickness. A modeling of the results obtained shows a material saving (Si), in the development of the solar cell.

Back Surface Recombination Velocity Dependent of Absorption Coefficient as Applied to Determine Base Optimum Thickness of an n+/p/p+ Silicon Solar Cell

The monochromatic absorption coefficient of silicon, inducing the light penetration depth into the base of the solar cell, is used to determine the optimum thickness necessary for the production of a large photocurrent. The absorption-generation-diffusion and recombination (bulk and surface) phenomena are taken into account in the excess minority carrier continuity equation. The solution of this equation gives the photocurrent according to absorption and electronic parameters. Then from the obtained short circuit photocurrent expression, excess minority carrier back surface recombination velocity is determined, function of the monochromatic absorption coefficient at a given wavelength. This latter plotted versus base thickness yields the optimum thickness of an n+-p-p+ solar cell, for each wavelength, which is in the range close to the energy band gap of the silicon material. This study provides a tool for improvement solar cell manufacture processes, through the mathematical relationship obtained from the thickness limit according to the absorption coefficient that allows base width optimization.

AC Back Surface Recombination Velocity as Applied to Optimize the Base Thickness under Temperature of an (n+-p-p+) Bifacial Silicon Solar Cell, Back Illuminated by a Light with Long Wavelength

The bifacial silicon solar cell, placed at temperature (T) and illuminated from the back side by monochromatic light in frequency modulation (ω), is studied from the frequency dynamic diffusion equation, relative to the density of excess minority carriers in the base. The expressions of the dynamic recombination velocities of the minority carriers on the rear side of the base Sb1(D(ω, T);H) and Sb2(α, D(ω, T);H), are analyzed as a function of the dynamic diffusion coefficient (D(ω, T)), the absorption coefficient (α(λ)) and the thickness of the base (H). Thus their graphic representation makes it possible to go up, to the base optimum thickness (Hopt(ω, T)), for different temperature values and frequency ranges of modulation of monochromatic light, of strong penetration. The base optimum thickness (Hopt(ω, T)) decreases with temperature, regardless of the frequency range and allows the realization of the solar cell with few material (Si).

Surface Recombination Concept as Applied to Determinate Silicon Solar Cell Base Optimum Thickness with Doping Level Effect

New expressions of back surface recombination of excess minority carriers in the base of silicon solar are expressed dependent on both, the thickness and the diffusion coefficient which is in relationship with the doping rate. The optimum thickness thus obtained from the base of the solar cell allows the saving of the amount of material needed in its manufacture without reducing its efficiency.

Influence of Both Magnetic Field and Temperature on Silicon Solar Cell Base Optimum Thickness Determination

The minority carrier’s recombination velocity at the junction and at the back surface is used for the modeling and determination of the optimum thickness of the base of a silicon solar cell in the static regime, under magnetic field and temperature influence. This study takes into account the Umklapp process and the Lorentz effect on the minority carriers photogenerated in the base.

温度和光强对聚光硅太阳电池特性的影响研究

利用恒压频闪式I-V曲线测试仪研究分析温度和光强对聚光硅电池特性参数的影响。研究发现,聚光硅电池开路电压V_(oc) 的温度系数随聚光比升高不断降低,从1倍聚光比的-1.97 m V/K降低到30倍聚光比的-1.71 m V/K,和其理论计算值吻合较好;和普通单晶硅电池开路电压V_(oc) 温度系数相比,该电池的要小,上述说明聚光硅电池在聚光下工作有利于其在较高温度下操作。聚光硅电池填充因子和效率均随温度升高而降低;由于串联电阻影响,该电池效率随聚光比的增大先增后减,适合在小于20倍聚光比下的系统中工作。可进一步优化该电池金属栅线覆盖率和阻值引起的功率损失以提高其适合应用的聚光比。

采用CaO-SiO_2-CaF_2渣系去除硅中杂质硼(英文)

采用CaO-SiO2-10%CaF2渣系,对工业硅进行造渣除硼研究。研究不同工艺条件下,渣系碱性、反应温度T、渣金比和通气搅拌对硼在渣相和硅液中分配系数LB的影响。结果表明,在1873K下,当CaO/SiO2质量比为2时硼的分配系数可达最大值4.61。在1773～1973K下,lgLB与1/T成线性关系。随着渣金比的增大,硼的分配系数也相应增大,但当渣金比大于3时,硼的分配系数并无明显增加。通气可显著提高硼的去除效果,硼的分配系数随气体中H2O含量的增加而增大。

连续激光对太阳能电池辐照效应的波段性研究

为了研究太阳能电池在连续激光辐照下的波段性效应,使用位于波段内外的3种波长连续激光对单晶硅太阳能电池的辐照效应和损伤效应进行了实验研究,采用观察电池对激光的响应,对比电池的损伤形貌和太阳能电池组成材料的吸收曲线差异的方法,得到了太阳能电池对本征吸收长波限附近波长激光的吸收机制,分析了10.6μm激光和1064nm激光对太阳能电池的损伤效果差异的原因。结果表明,玻璃盖片和硅对不同波长激光的吸收系数的很大差距是造成它们对太阳能电池的损伤效果差异的原因。

硅太阳电池用UV/IR截止滤光膜系设计

根据光学薄膜原理,编制出计算机程序。在太阳电池封装玻璃的上、下表面分别设计出红外(IR)截止的带通滤光膜系A|[1.05(LMHML)](LMHML)6[1.15(LMHML)]1.15L| G和紫外(UV)截止的带通滤光膜系G|H/2LH/2|7s。透射曲线表明:这两种带通滤光膜系对于不同波长的光有着很好的选择性透射,IR截止滤光膜系能够使波长大于1120nm的大部分光在到达电池表面前就被反射,UV截止滤光膜系能够使得波长小于350nm的光在到达电池表面前几乎全部被反射掉。同时,350nm<λ<1120nm的光的入射几乎不受影响,加权平均透射率为97.49%。

机械刻槽深埋电极太阳电池中二氧化硅层的制备

结合实验室制备机械刻槽深埋电极太阳电池的工艺过程及实验结果 ,给出二氧化硅层参数的最佳设计及制备方法 .实验结果表明 ,10 0 0℃氧化温度下采用干 -湿 -干氧化法 ,经过 70分钟可生长 35 0 nm～45 0 nm厚的二氧化硅层 .这不仅大大缩短了高温氧化时间 ,降低了生产成本 。

槽式聚光系统聚光硅电池阵列特性实验研究

利用所设计的槽式聚光热电联供系统,对栅线平行分布和反方形分布的两种聚光硅太阳电池阵列进行了性能测试研究。结果表明,在能流聚光比为20倍的槽式聚光器下,两种电池阵列的光电效率分别为11.42%和13.89%,最大输出功率分别比聚光前放大16.06倍和19.33倍。两种电池阵列Pm、FF和η的温度系数分别为:-0.047 W/K、-0.45%/K、-0.035%/K;-0.029 W/K、-0.176%/K、-0.105%/K.研究结果为中低倍聚光系统聚光电池的选择和槽式聚光热电联供系统性能的优化提供参考。

印刷烧结工艺对单晶硅太阳电池栅线形貌及电学性能的影响

正面金属化是制备单晶硅太阳电池中的重要工艺步骤,栅线质量对电池的电学性能起着关键的作用。通过探究不同栅线处理工艺对栅线宽度的影响,发现烧结过程中栅线会向两侧崩塌,从而增加电极的遮光率,结合表征手段对这一过程进行了分析和机理阐释。在对浆料类型、网版开口宽度、网版图案以及烧结峰值温度的研究中,发现浆料中的有机物含量会影响栅线在烧结过程中的稳定性,而合适的网版开口及图案设计能降低遮光面积和栅线高度起伏,从而显著提升电池的电学性能,制得了最高转换效率为22.54%的单晶硅PERC电池。可以预见,通过优选浆料和网版,可以进一步改善单晶PERC电池的电学性能,获得更高的光电转换效率。

多晶硅太阳电池的电性能测试

对多晶硅太阳电池进行了电性能测试,研究了光谱响应及温度系数对多晶硅太阳电池电性能测试结果的影响。结果表明:多晶硅太阳电池与常规电池光谱响应不一致,光谱失配修正后测得的短路电流会有明显提高,相应地峰值功率也有所提高;温度对多晶硅太阳电池开路电压的影响较大,对短路电流的影响较小;经过修正,电池的峰值功率与之前相比提高了1.236%。

晶体硅/氧化钨背异质结太阳电池的制备及性能研究

采用热蒸发法制备了n型晶体硅/氧化钨(WO_(x))异质结,并将其应用于背结太阳电池,研究了不同背电极对电池性能的影响及电池的变温性能。结果表明:相对于背铝电极,背银电极能够有效地提升电池的光电转换性能,最高光电转换效率达到了15.1%。结合Sun-Voc测试,证实通过降低电池串联电阻可使其光电转换效率提升至17.2%。电池的变温性能测试结果表明,其光电转换效率的温度系数为-0.35%/K,相比传统的铝背场晶体硅电池的温度系数降低22%。

标准测试条件下晶硅电池输出参数的不确定度

以标准测试条件下晶硅电池输出参数为参考,研究了实际测试条件下,载片台与测试电池片之间热接触性质不同时,晶硅电池内部温度分布和输出参数的变化情况.研究表明,当测试的晶硅电池片与载片台之间形成良好的热接触时,相对标准测试条件,电池内部产生的温度漂移很小,测试电池输出参数VOC, JSC, FF和η的不确定度分别为0.0037%, 0.000196%, 0.000845%和0.0044%;当测试的晶硅电池片与载片台之间未形成良好的热接触时,相对标准测试条件,电池内部产生的温度漂移最大可达9.5℃,测试电池输出参数VOC, JSC, FF和η的不确定度分别为0.1644%, 0.0038%, 0.0533%和0.2134%.