Progress in Photovoltaics: Research and Applications

We produce a 43 µm-thick free-standing Si solar cell from the layer transfer process using porous silicon and achieve an independently confirmed record efficiency of 19.1%. This efficiency exceeds the prior state of the art by over 2% absolute and is therefore a milestone in the field of layer transferred cells.

A power conversion efficiency record of 10.1% is reported for kesterite absorbers, using a Cu₂ZnSn(Se,S)₄ thin-film solar cell made by a hydrazine-based solution process. Key device characteristics are also compiled, including light/dark J–V, quantum efficiency, temperature dependence of V_oc and series resistance, photoluminescence, and capacitance spectroscopy, providing important insight into how the devices compare with high-performance Cu(In,Ga)Se₂. Attainment of the 10% efficiency level for the kesterites points to significant technological promise for this class of materials.

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2011 are reviewed.

A detailed investigation of the impact of different models for the Auger recombination on the determination of the emitter saturation current density J_0e with injection-dependent lifetime spectroscopy in high and low injection regimes is performed. It has been found that a good agreement for the extraction of J_0e under high and low injection conditions can be obtained if the Auger parameterization of Kerr et al. is used.

The paper demonstrates how to solve the fully coupled semiconductor transport equations in two dimensions with diffused layers being treated as conductive boundaries that are characterized by their sheet resistances and diode saturation current densities. The model is implemented using COMSOL and is applied to emitter wrap through solar cells.

In this paper, the durability of PVP-Pt CE for DSSC has been extensively evaluated including electrochemical durability (1000 cycle CV scans), thermal stress durability (60 and 85°C for 1000h) and light soaking durability (1 sun irradiation for 1000h under 60°C).

We determine one-dimensional photogeneration profiles as a function of the distance to the front surface beneath various pyramidal textures via ray tracing. Certain compatabilities between surface morphology and cell design are quantified when the pyramidal texture drives photogeneration into regions of favourable collection efficiency. Finally, we assess a common one-dimensional model for photogeneration beneath textured surfaces, finding that its deficiencies compromise device simulation when collection efficiency varies strongly across the device.

17.9% cell efficiency on thin and large mc-Si REC wafers using ECN's metal-wrap-through (MWT) concept was obtained by optimizing several cell processing steps. With these cells 36-cell back-contacted modules were manufactured at 100% yield in ECN's industry scale module pilot line. The highest module efficiency obtained was 17%, which was the world record in early 2010.

This paper presents a study about the theoretical efficiency of multi-junction solar cells. The optimized band gap combinations, the temperature dependence, and efficiency gain between different cell concepts have been investigated. In the end, a new material concept with a-Si:H/µc-Si/µc-Ge will be introduced as an promising candidate for a high efficiency thin film solar cell.

The current work is motivated by the development of the hot the carrier solar cell, which relies on slowed carrier cooling after photoexcitation. A detailed time resolved photoluminescence study of InP and GaAs emphasize the influence of the hot phonon effect and Intervalley Scattering on the cooling rate of hot carriers. It has been demonstrated that carrier cooling is significantly reduced by the Hot Phonon Effect and, to a lower extent, by intervalley scattering

When they were first introduced, luminescent solar concentrators promised a cost reduction in the generation of solar energy. Here we show that if luminescent concentrators are to become a cost effective concentrator technology, then it must happen by a shift towards new second generation devices. These devices employ either molecular or optical methods to enhance the photon transport within the waveguide. The fundamental operating regimes that we identify provide a performance threshold that must be overcome by future devices if they are to significantly outperform the limits of the traditional technology.

This paper reports on the IES-UPM experience from 2006 to 2010 in the field of the characterization of PV arrays of commercial large PV plants installed in Spain within the framework of the profitable economic scenarios associated to feed-in tariff laws. This experience has extended to 200MW and has provided valuable lessons to minimize uncertainty, which plays a key role in quality assurance procedures. The paper deals not only with classic I–V measurements but also with watt-metering-based procedures.

B implanted emitters (5 keV, 1 × 10¹⁴–3 × 10¹⁵ at./cm², anneal at 1000°C for 10 min.) are investigated in the back junction cell configuration and their material properties are tested in double side implanted Si wafers. N-type 8 × 8 cm² mono-crystalline cells are fabricated. Both fill factor and efficiency increase for high B doses. However at 10¹⁵ at./cm² B dose the V_oc drops, which is in agreement with lifetime degradation in the wafer. Defect evolution simulations of B_n.

After rapid thermal annealing, transmission of GZO films prepared by sputtering at room temperature enhanced significantly and low film resistivity was preserved. Strong improvement in performance of Si thin film solar cells was demonstrated when using the annealed GZO film as substrate.

In this work, a fiber-based optical powering system capable of providing more than 1 W is developed. The prototype was used in order to power a shunt regulator for controlling the activation and deactivation of solar panels in satellites. The work involves the manufacture of a light receiver (a GaAs multiple photovoltaic converter), a power conditioning block, and a regulator and the implementation and characterization of the whole system.