The Human race has gone through many ages. The Stone Age …Iron Age … and now the Wind & Solar Age (Crystalline Silicone Age ) has begun. And in every age each action has had a reaction. The reason for worry, to put it simply – the stone age guy had lots of resources and very little impact on Earth by his action, while for the RE -age guy the opposite holds true.
Solar Panels, which is predicted as the next messiah along with its other RE counterparts needs a closer scrutiny from the perspective of what it is manufactured from. Simply because a wrong policy would kill the initiative before it truly matures from the nascent stage it is today. And nothing would give the detractors of RE more pleasure than seeing the premature death of the promising “One”.
Silicon : The chemical compound silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with the chemical formula SiO2. It has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms.
Uses: Silicon dioxide is used to produce elemental silicon. The process involves high temperature reduction with elemental carbon in an electric arc furnace.The most prevalent bulk material for solar cells is crystalline silicon (abbreviated as a group as c-Si), also known as “solar grade silicon”. Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon, or wafer.
- monocrystalline silicon (c-Si): often made using the Czochralski process. Single-crystal wafer cells tend to be expensive, and because they are cut from cylindrical ingots, do not completely cover a square solar cell module without a substantial waste of refined silicon. Hence most c-Si panels have uncovered gaps at the four corners of the cells.
- polycrystalline silicon, or multicrystalline silicon, (poly-Si or mc-Si): made from cast square ingots — large blocks of molten silicon carefully cooled and solidified. Poly-Si cells are less expensive to produce than single crystal silicon cells, but are less efficient. United States Department of Energy data show that there were a higher number of polycrystalline sales than monocrystalline silicon sales.
- ribbon silicon is a type of polycrystalline silicon: it is formed by drawing flat thin films from molten silicon and results in a polycrystalline structure. These cells have lower efficiencies than poly-Si, but save on production costs due to a great reduction in silicon waste, as this approach does not require sawing from ingots.
Health: Inhaling finely divided crystalline silica dust in very small quantities (OSHA allows 0.1 mg/m3) over time can lead to silicosis, bronchitis, or cancer, as the dust becomes lodged in the lungs and continuously irritates them, reducing lung capacities. However a study which followed subjects for 15 years found that higher levels of silica in water appeared to decrease the risk of dementia. The study found that with an increase of 10 milligram-per-day of the intake of silica in drinking water, the risk of dementia dropped by 11%.
That ends our brief introduction on the most common form of material being used to make Solar Photovoltaic Panels. Now we will understand what does CIGS stand for.
Copper indium gallium selenide (CuIn1-xGaxSe2 or CIGS) is a direct bandgap semiconductor useful for the manufacture of solar cells. Because the material strongly absorbs sunlight, a much thinner film is required than of other semiconductor materials. The CIGS absorber is deposited on a glass backing, along with electrodes to collect current. CIGS’s absorption coefficient is higher than any other semiconductor used for solar modules. Devices made with CIGS belong to the thin-film category of photovoltaics (PV). The market for thin-film PV grew at a 60% annual rate from 2002 to 2007 and is still growing rapidly. Therefore, a strong incentive exists to develop and improve deposition methods for these films that will allow lower cost and increased throughput.
Now having understood the process, what we must look at are the methods of obtaining these minerals. While we may be extolling the virtues of Solar Photo Voltaic, we must also keep an eye at the process of extraction, refinement and delivery of the basic raw materials that go into production of these wonderful RE tool. In effect we must map the complete manufacturing process and see to it that every time it is sustainable all the way. The question which then rises is, are we doing it ? Because as in other sectors and industry, the fact that the total supply chain must be green and sustainable is gaining traction and the RE industry, which is supposed to be the messiah should look into that aspect too.
The raw materials that go into making a solar photo voltaic panel starting with raking & tracking system, cabling, inverter and batteries and ending with the voltaic panels are a huge list. Most of them are mined, some like gallium are recovered from the by-products of zinc refining, Bauxite and the mineral sphalerite, as well as coal, often contain gallium as an impurity. No gallium is mined; it is obtained as a by-product of mining and processing other metals, notably aluminium, zinc and copper, and is produced in any nation that produces these metals.Therefore to get gallium we need all these mines and the problems associated with these will have a direct bearing on Solar PV.
Silica sand is the major raw material used by foundries for making moulds to pour molten metal to cast the intricate metal components for use in practically all industrial sectors. This too is the basic raw material for the most popular and efficient Mono & Poly crystalline Solar PV.
India is mineral-rich. Approximately 24 types of minerals, including iron, bauxite, copper, chromite, gold, lead, manganese, zinc and coal, are found in nearly 50 percent of its total landmass of 3.20 million sq km. But the main concentrations of this mineral wealth happens to fall in the ecologically rich, tribal-inhabited areas of south, central and north-eastern India that has suffered neglect say environmentalists and development activists. Then there are various emerging issues with mining that can be associated with cultural or industrial factors or trends, such as changes in commodity demand, workforce, or technology. Health and safety is also becoming a major issue in all countries.
It is therefore important that the sunrise industry look into sourcing most of its material from recycled materials. If it starts early, nearly 50% of its raw materials can be sourced from recycled material and this would in effect reduce the over all cost. In time as the industry matures, the older generation panels would itself feed into the raw-material chain.
To achieve this, industry captains need to pause and think in the direction of sustainable supply chain and the Climatologist could surely help with a nudge.
- Solar CIGS reach 18.7 percent efficiency (news.cnet.com)
- First Solar exploring new panels in Silicon Valley (news.cnet.com)
- NRG embraces CIGS solar tech [Earth2Tech] (gigaom.com)
- One leader, lots of consolidation as CIGS market emerges (renewableenergyworld.com)
- Solar Frontier to supply world’s largest CIGS solar plant (jcwinnie.biz)
- Charging the Earth (evoenergy.co.uk)
- It Doesn’t Matter How Many Times You Get It Wrong, You’ll Get It Right Eventually: (brothersjuddblog.com)