30 January 2017

Kerf-less Wafers – Start-Ups Working On True Revolution For Crystalline Silicon Solar Wafer Manufacturing

Reducing silicon consumption has always been the focus of PV manufacturers – and it still makes a lot of sense. Though silicon is not expensive these days, this core material for most cells is still a significant contributor to module costs - with a share of over 20% for the cost leaders. One way to reduce silicon usage per cell is to decrease the thickness of the wafer. An even more interesting option is to reduce the so-called kerf. As much as close to 50% of the silicon is lost as waste (kerf) during the ingot sawing process to produce wafers. While reducing kerf losses is on the agenda of wafer makers, some companies, especially start-ups, are trying to eliminate kerf losses completely. Their kerf-less solutions not only dramatically save on silicon raw material, if it worked in large-scale manufacturing, it could revolutionize today’s value chain for crystalline silicon modules by eradicating the upstream production processes of ingot growing and wafering, but depending on the process, even polysilicon production. According to one company active in that field, NexWafe, their technology could save up to 60% of silicon lost during sawing, reduce energy consumption during manufacturing by up to 80%, and require 70% less investment cost for its scrap-free wafer production.

 

nextwafe

Photo Credit: NexWafe

04 January 2017

Trends in Solar Module Manufacturing

From the distance, today’s solar module might not look any different than 20 years ago, but researchers and module manufacturers have been pretty innovative on improving the solar module’s contribution to efficiency and yield, often independent from the cell.

The so-called cell-to-module losses (CTM) value is a clear indication of this progress. According to the 7th edition of the International Technology Roadmap for PV (ITRPV), published by the German Engineering Federation’s (VDMA) PV Chapter, the CTM losses for multicrystalline modules would be zero already by 2017, whereas monocrystalline modules would reach this level in 2019. This difference is mainly due to monocrystalline cells featuring already a superior surface texturing that leads to relatively lower reflection losses, but it also means that they benefit less from the ‘coupling gain’ after encapsulation.

19 December 2016

Perovskite Solar Cells – Impressive & Fast Efficiency Developments, Now It’s About Research On Stability

The development speed of perovskite solar cell efficiencies is breathtaking. When the technology was reported first in 2009, efficiencies were mere 3.8%. But in only 7 years, single-junction perovskite cell efficiencies skyrocketed beyond 20%, getting increasingly closer to the level of incumbent crystalline silicon technology.

Perovskite is a structured compound made of a hybrid organic-inorganic lead or tin halide-based material, which is used as the active PV layer. The fundamental advantages of this new material class are twofold - perovskites crystals can be manufactured at low temperatures of about 200 °C, and they can be produced at low cost. Perovskite solar cells are also several folds thinner than typical crystalline wafer-based cells. They enable simple application methods, such as spraying and printing, provide flexibility in choosing different substrates, such as glass or plastic, which in the end offers sheer endless product designs.

7 December 2016

Heterojunction Solar Cells – A High-Efficiency Technology With Huge Potential

For years, heterojunction-based silicon solar cells have scored high in efficiency rankings. The well-known HIT cell from Panasonic reached a world record 25.6% efficiency in early 2014, according to the solar cell efficiency tables edition of Progress in Photovoltaics, -  and has kept this record for over 2.5 years.

The reason for Panasonic’s dominance is simple – Sanyo (which was overtaken by Panasonic) developed the crystalline silicon heterojunction cell concept, has been mass-producing it, and protected the intellectual property. But Sanyo’s patents expired in 2010. Since then the race is on, with several PV module companies and equipment manufacturers working on product solutions for heterojunction cells.