The Fruits of Civilization (24-4-14) Photovoltaics

  Photovoltaics

It takes a lot of energy to extract and process solar-grade silicon. ~ American chemist Seth Darling

French physicist Edmond Becquerel discovered the photovoltaic effect in 1839. Becquerel’s discovery was a mere curiosity, as his selenium cells could only convert 1% of sunlight to electric power.

That changed in 1954, when Bell Labs physicists developed silicon-based solar cells that worked at 6%. Suddenly, photovoltaics fell within the realm of semiconductor technology development.

Solar cell electrical output is directly related to photonic input. Engineers sometimes incorporate mirrors to up the incident sunlight striking the cells.

Solar cells are put together into panels for deployment. An electrical inverter is employed to convert photovoltaic output into usable electricity.

In stark contrast to concentrators, the most atrocious fraud of clean energy is photovoltaics, the fawned-upon star of the solar show. Producing solar panels is an egregious exercise in pollution, and the environmental destruction does not come cheap. The silicon material used in solar cells is the same as for semiconductors, but far more is required for photovoltaics.

Producing silicon wafers is energy intensive and produces mostly waste. 80% of the initial high-grade silicon is lost in the process.

Sawing silicon wafers releases dangerous dust as well as dispensing sodium hydroxide and potassium hydroxide. 50% of the material is lost in the air and water used to rinse wafers. All told, 90% of the silicon used to make solar cells is wasted.

Silicon solar cell processing involves the use or release of numerous toxins, including arsenic, arsine, hexavalent chromium, lead, phosphine, phosphorous oxychloride, silicon tetrachloride, silicon trioxide, sodium hydroxide (lye), stannic chloride, trichloroethane, and trichloroethylene. Further, caustic and corrosive chemicals, including various acids, are used to remove impurities and clean materials. Perhaps the most dangerous chemical employed is silane, a highly explosive gas involved in accidents on a routine basis. The latest thin-film solar panels also employ numerous toxins, most notably cadmium, a potent carcinogen, and selenium.

Beyond the photovoltaic material, making solar panels produces pollutants such as lead, nitrogen oxide, and sulfur dioxide.

The manufacture of solar cells involves hexafluoroethane (C2F6), nitrogen trifluoride (NF3), and sulfur hexafluoride (SF6). These greenhouse gases make CO2 seem harmless.

C2F6, which is entirely man-made, is 12,000 times more potent than CO2 and survives in the atmosphere for 10,000 years. NF3 is 17,000 more virulent than CO2, while SF6, the most treacherous greenhouse gas, has 25,000 times the warming effect of CO2.

The photovoltaics industry is the leading emitter of these gases. Since photovoltaic production has ramped up in the 21st century, atmospheric concentrations of these gases have been rising at an alarming pace, except that no one seems alarmed.

Solar panel proponents tout photovoltaic efficiencies (~20%) that can only be achieved under ideal laboratory conditions. Those are the only numbers you will ever read. In the field, solar panels produce less than half that percentage on their best days.

The first common cut in efficiency comes with placement: panels not aligned with Sun greatly reduces performance. This is ubiquitous in rooftop placements.

Atmospheric humidity and haze disperse the Sun’s rays, and so cut photovoltaic productivity. Dust downs efficiencies even more; often by 20% or more.

Even modest blotches, such as from bird droppings or leaves, can cut solar cell outputs dramatically. Due to wiring characteristics, small obstructions disproportionately drop solar panel productivity. Small soiling losses can rob as much 80% from potential output.

Everyone in the solar industry knows that photovoltaic systems are expensive. That is why this solar technology had scant application before governments stepped in and granted heavy subsidies, misguided into considering this a clean energy technology.

Silicon represents only 20% of the cost of solar panel fabrication. Copper, aluminum, glass, and plastics comprise the bulk of the costs. None of the components are obtained without considerable pollution somehow.

Manufacture and installation are only the beginning of the expense for photovoltaics. Repair and maintenance costs of solar panel systems remain stubbornly high.

At the end of a solar panel’s life (25 years at best), the embedded chemicals can either leach into groundwater, if dumped, or released into the air if incinerated. As there is almost no recycling of solar panels, the rare and precious metals that go into them are wasted.

Companies are surviving on razor-thin margins. They’re not thinking 20, 30 years down the road, where scarcity might enter. ~ American environmental scientist Dustin Mulvaney