This paper presents an in-depth analysis of state-of-the-art p-type monocrystalline Czochralski-grown silicon passivated emitter and rear cells (PERCs) fabricated in a near-industrial manner. PERC solar cells feature a homogeneous emitter on the front side, and an Al2O3 passivation layer and local contacts on the rear side.
Even though it is now more than five years since potential-induced degradation (PID) began to proliferate, and despite the fact that solutions are under development, it is currently still the most discussed mode of degradation associated with cracking in PV modules.
Conventional ribbons used for interconnecting solar cells in PV modules act like mirrors, causing a large proportion of incident light to be lost. Experimental results indicate that only around 5% of the perpendicular
incident light on the connections can be reused; as a result, this area contributes very little, if at all, to the current generation.
A highly promising concept for future solar cells is the heterojunction (HJT) architecture; according to the ITRPV roadmap 2016, the market share for HJT solar cells will increase to 10% by 2026. Over this timescale,
stabilized cell efficiency will increase to 24%, which is the second-highest predicted efficiency after backcontact cells with n-type mono-Si. Moreover, metallization of HJT cells offers the advantage of using low-temperature steps, which reduces energy consumption and hence production costs.
This paper presents the fabrication of front-junction n-type silicon solar cells with Cu-plated electrodes, using laser contact opening and forward-bias plating. The cells feature a back-surface field formed by a phosphorus implant, and a diffused boron emitter with aluminium oxide passivation. Laser ablation of the front-side dielectric layers is followed by a metallization based on Ni/Cu forward-bias plating, while sintered metal paste is used for the rear electrode. The results show improved line conductivity and contact resistivity for the plated electrode, leading to higher solar cell efficiency than for cells made with conventional Ag/Al paste. On 6" n-type Czochralski wafers, cell efficiencies of up to 21.3% have been demonstrated, with an open-circuit voltage of 654mV, a short-circuit current of 40.8mA/cm2 and a fill factor of 79.8%.
Perovskite microcrystals have properties that make them uniquely suitable as a basis of thin, light, semitransparent solar modules. However, there are some remaining challenges, including lifelong stability, that need to be tackled before this technology can become commercially available.
Project finance - Minimising risk to lenders is vital in ensuring the solar industry continues to have access to adequate sources of finance. Simon Turner and Paola Piazzolla outline the key ingredients for the technical due diligence needed to give peace of mind to investors.
Market overview - A number of false dawns have so far prevented solar from living up to its full potential in the Middle East and North Africa. But as Danielle Ola reports, with all the right ingredients in place, and an increasingly competitive business environment, the prospects in the region look better than ever before.
The first substantial barriers to rooftop solar in the Middle East are being eroded but a host of other challenges remain. Many are familiar, some are unique to the region.
Building integrated PV: Despite plenty of hype, BIPV has remained a niche segment in the solar business, held back by a combination of high costs and low efficiencies. But as Ben Willis hears, the high-profile entry of Tesla on to the BIPV scene could herald the start of a new era for the sector.
Module defects: The properties of module encapsulant materials are coming under closer scrutiny as their role in a number of common field failures becomes better understood. Juliane Berghold and Tsuyoshi Shioda report on new testing methods being developed to analyse the composition of encapsulants and improve the quality control of this crucial material.
Tom Kenning profiles some of the emerging solar markets around the world that look set to gain momentum in 2017.
Keeping on top of the impacts of dust and sand on power output is crucial to making solar a viable option in desert regions such as the Middle East. A fierce debate is currently raging over which methods are the most effective. Ben Willis listens to some of the arguments.
Chile has long been a strong contender for PV deployment with a growing economy, great solar resources and plenty of land. But as Tom Kenning learns, the market has several challenges ahead on its path to two-cents solar.
As the solar industry continues to squeeze out cost reductions, 1,500V architecture is tipped to make its mark in 2017. John Parnell looks at the potential pitfalls and likely winners as utility-scale plants dial up the voltage.