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Transparent and opaque hydrogenated amorphous silicon solar cells (a-Si:H) with various transparent electrodes are fabricated for indoor photovoltaics to supply power to Internet of Things devices. The performances of fabricated cells are investigated to evaluate the transparent electrode structures. The highest efficiency (6.05%) and highest average transmittance (24%) in the visible range are obtained with a transparent a-Si:H solar cell having single front and rear GZO electrodes, while the best efficiency is 9.29% with an opaque a-Si:H solar cell. Under LED indoor light, the best efficiencies are 5.12% with the opaque solar cell and 5.75% with the transparent solar cells.

We fabricated a-Si:H transparent solar cells with thin absorbers. The light induced degradation of 17 % to 22 % was obtained when 130, 150 and 200 nm thick absorbers were used in the fabrication of a-Si:H transparent solar cells. However, the cells with 108 and 120 nm thick absorber showed improved light induced degradation. In particular, the cell with 108 nm thick absorber showed highly improved degradation of 7.3 %. In this case, the p-layer thickness is crucial to determine the degradation rate.

Crystalline silicon (c-Si) surface should be passivated effectively to reduce the surface recombination losses for silicon heteroj unction solar cells. To prevent the epitaxial growth of a-Si:H films near c-Si surfaces and improve the effective carrier lifetime, dual passivation layers were obtained using inductively coupled plasma chemical vapor deposition process with an intermediate hydrogen dilution for smooth interface layer and high hydrogen dilution for dense cover layer. The effective lifetime and implied open circuit voltage are 148.1 μ s and 663 mV for a dual intrinsic a-Si:H passivated sample which is higher than 137.8 μs and 650 mV of single intrinsic a-Si:H film. Thus, the introduction of dual intrinsic a-Si:H layers is a viable method for the c-Si surface passivation.

This paper deals with a hybrid linearization method of a power system with FACTS (flexible AC transmission system) devices. The linearized power system model provides useful information, which is necessary for the small signal stability study and the control design. Although the algebraic linearization method provides an accurate and parameterized linear system, it may incur computation burdens for the large power system with multiple FACTS devices. The numerical identification of linearized system by utilizing input-output numerical data is highly versatile. However, quite an amount of valuable information may not be fully utilized. In this paper, a hybrid method in which the algebraic and the numerical linearization technique are combined is presented. While both the power system and the FACTS devices are separately linearized by using algebraic method, the interaction terms between the power system and FACTS devices are numerically identified by adopting the quadratic optimization technique. The proposed hybrid linearization technique is tested on the WSCC system in which one TCSC (thyristor-controlled series capacitor) is installed. Both eigenvalue analysis and time-domain simulation results verify that the proposed method can effectively identify the linearized model of the power system with FACTS devices.