Here comes the sun

Solar PV on the cusp of becoming widespread

By Catherine Bischofberger

Solar photovoltaic (PV) electricity is rapidly increasing its share of global power generation. Technology and production breakthroughs are making it cheaper to manufacture. The IEC is leading the way with the appropriate International Standards.

manufacturing solar cells Manufacturing of solar cells is becoming more efficient (Photo: Bosch Solar Energy AG)

Rise and shine

The use of solar energy is rising across the world and its share of the global energy pie is at last becoming significant. According to the 2017 Global Status Report by REN21, an international non-profit association, based at the United Nations Environment Programme (UNEP) in Paris, solar PV is increasingly cost-competitive with traditional power sources. The report states that “large-scale solar PV projects out-compete even new fossil fuel projects in some markets, especially in regions with low-cost financing.”

Figures released in the same report indicate that global production of crystalline silicon cells and modules rose sharply in 2016 compared with 2015, by 29% for cells and by 33% for modules, year over year. China dominated shipments in 2016 for the eighth year running, with Asia accounting for 90% of global module production (and China contributing 65% to that figure). Europe’s share is at around 5% and the US 2%.

Lower prices due to increased production capacity as well as new technology and efficiency breakthroughs are two of the main reasons for the increasing adoption of solar PV around the world. Government subsidies are another but then they also exist to encourage other forms of renewable energy - even traditional sources in some countries. Off-grid projects including solar PV are increasingly viewed as a way of implementing electricity access in developing countries, leapfrogging installations in the developed world.

The IEC has been facilitating the adoption of solar PV for a number of years. IEC Technical Committee (TC) 82: Solar photovoltaic energy systems, produces International Standards enabling systems to convert solar into electrical energy. These include the IEC 60904 series of Standards. The TC looks constantly at new technology, including the latest thin film developments.

IEC TC 21: Secondary cells and batteries has been publishing Standards in the area of renewable energy storage, both on-grid and off-grid. To better deal with rechargeable renewable energy storage systems, it formed a joint working group (JWG) with TC 82, JWG 82: Secondary cells and batteries for renewable energy storage.

More efficient production boosts PV

Manufacturers have been working to reduce barren spaces on modules to enhance light trapping, thereby lowering the number of modules required for a given solar capacity. Passive emitter rear cell (PERC) technology is being increasingly used in production lines. The technique reflects solar rays back to the rear of the solar cell increasing the overall energy efficiency of the product and improving its performance in low-light environments. Pre-assembly techniques and customized design testing are equally improving the efficiency of production.

Looking towards the future, perovskite, a form of crystal structured compounds, is being envisaged for solar cell production because it is simpler to manufacture and reflects light more efficiently than other materials such as crystal silicon. A number of research projects are focusing on the new crystal as it displays many exciting properties including superconductivity, which reduces the potential for energy loss.

Recycling is also part of the global effort towards improving the solar PV share of the market. A number of companies have established recycling procedures for solar cells. Two Japanese firms, for instance, formed a joint-venture in 2016 with the aim of recycling 80% of panel materials and reusing the rest.

Research lets the sunshine in

Research and development have focused on different areas of solar PV technology. A wide number of universities and institutes around the world are looking at techniques which will ultimately make solar PV cheaper and more efficient to manufacture.

In the US, the University of California, Berkeley, has filed an important number of patents and is the only US-based research hub to compete on that level with Chinese universities. Berkeley has been working, among other things, on improving the efficiency of perovskite, by merging two different perovskite solar cell materials, making one cell that absorbs nearly all the spectrum of visible light.

Given China’s dominant role in PV,  it is not surprising that the country’s research hubs have been at the forefront of research into solar cell technology. The Chinese Academy of Science has been focusing on thin-film copper indium gallium selenide (CIGS) semiconductor solar cells. The Laboratory of Photovoltaic Materials and Devices (LMPD) at Shangaï Institute of Ceramics is looking at a new concept of nanostructured PV materials and devices. It is also working on the preparation of high-quality graphene and its incorporation into PV devices.

In Europe, Germany’s Frauenhofer Institute has been looking at how to make solar cells more efficient for a number of years. It is also focusing on other areas related to PV power generation, including battery storage as well as power plants. One of its current R&D projects, entitled PV Power Plant of the Future is focusing on PV inverter regulators and is due for completion at the end of this year. The idea is to increase the energy portion provided by PV power in microgrids, thereby greatly saving on diesel, diminishing costs and reducing COemissions. The project has been contracted by the German Federal Ministry of Economic Affairs and Energy and is conducted in association with a number of partners ranging from German universities to companies involved in the field of solar PV.

The IEC has been publishing Standards in some of these promising new research areas. IEC TC 113: Nanotechnology for electrotechnical products and systems, for instance, prepares Standards relevant to products in the field of nanotechnology. IEC TC 21: Secondary cells and batteries issues Standards for energy storage (renewable, on-grid and off-grid). IECRE, the IEC System for Certification of Standards Relating to Equipment Used in Renewable Energy Applications, has been defining the certification schemes for the solar sector.

sun on solar panel The share of solar PV in energy generation is rising (Photo: Vera Kratochvil)
manufacturing solar cells Manufacturing of solar cells is becoming more efficient (Photo: Bosch Solar Energy AG)
perovskite Research into perovskite is opening up new perspectives for PV (Photo: Andrew Silver)