How Reliable is Solar?

Photo from Flickr

According to the US Environmental Protection Agency (EPA), mankind started using the magnifying glass to concentrate sun’s rays and create fire since the 7th century BC. For the modern photovoltaic technology, one may trace its origins to 1954 when Bell Labs based in the US developed the silicon photovoltaic (PV) cell that was capable of converting sufficient solar energy to run everyday electrical equipment 

While solar technology has since progressed much, challenges remain in terms of efficiency, cost and variability. 

An article by Shaheen et al (2011) cited that PV cell production has been dominated by crystalline silicon modules representing 94% of the market. Limited by thermodynamic considerations, PV cells can likely achieve maximum efficiency of 31%. To this end, Zhou et al (2010) proposed that hybrid solar–wind energy systems could help improve system efficiency and power reliability

In the area of cost, the potential of organic PV cells has been actively researched. Organic molecules and polymer materials are typically inexpensive to manufacture and could offer substantive cost reductions that would make it economically viable for large-scale power generation. The chart below illustrates the cost gap that would need to be covered in order to meet the US Department of Energy's cost goal of $0.33/W for the PV cell. 

Historical and projected costs for wafer c-Si and film c-Si photovoltaic modules
Chart from Shaheen et al (2011)

There is also an added aspect of environment justice (EJ) proposed by Mulvaney (2013).The paper contends that PV technologies use materials and processes that rely on toxic materials and generate waste flows similar to those in the electronics and semiconductor industries which may impact on workers and communities. Enormous land resources to harvest solar energy would also be required that may result in conflicts with other ecological and cultural resources.

It would thus appear that solar energy from a life cycle perspective may not be as environmentally friendly as one would expect. Nonetheless, with on-going research into organic PV cells, hopefully we can one day witness a major breakthrough in PV technology in the areas of cost, efficiency and reliability.