Solar Energy and Evolvement in Efficiency

I have been looking into solar power, and how much energy it is expected to produce by 2040. Bloomberg New Energy Finance estimates that by 2040 around 34% of electricity will come from intermittent renewables, of which solar power will account for a third. Solar power is expected to be developed more and more with and without the use of silicon, so the estimated number from Bloomberg does not really tell us much, since there most likely will be some unexpected percentage jump in efficiency these next few years.

Efficiency timeline:

Hoffman Electric achieves 14% in PV (photovoltaic) cells – 1960.

University of South Florida fabricates a 16% efficient thin-film cell – 1992.

Solar Frontier 18% efficiency – 2012

First Solar breaks 18% efficiency - June 2015

Panasonic announces 22.5% efficiency - October 2015

The National renewable Energy Laboratory (NREL) and Swiss Center for Electronics and Technology (CSEM) achieved 30% efficiency in 2016.

The primary material used in solar panels today is silicon, it can be formed in three different ways. Monocrystalline, Polycrystalline and thin-film panels. 

Monocrystalline efficiency is between 15-24% and has a lifetime of 25 to 30 years. Silicon is melted in bars and cutted into single crystal wafers Polycrystalline efficiency is between 12-18% and has a lifetime of 24 to 27 years. Manufactures melt many different fragments of silicon together to form the wafers.

The mixture of many kinds of crystals gives the electrons less room to move, so the Polycrystalline solar cells are not as efficient as monocrystalline cells. The benefit with Polycrystalline solar cells would be the price, since they are cheaper to produce.

The last and most non-efficient solar cell is Thin-Film, there efficiency is only 9 to 14% and has a lifespan of around 20 years, the cell can be applied to a flexible surface for example a boat or a an RV that is why it is so useful but not really efficient.

The Shockley Queisser limit refers to the calculation of the maximum theoretical efficiency of a solar cell. Shochley Queissers limit for silicon panels is around 30 percent.

The development of new and better solar panels are not just limited to using silicon. There has been new research around a material called Perovskite. Perovskite is a man-made material which shares the same crystalline structure.

How does a Solar panel work?

Sunlight activates the panels, The cells produce electrical current Within each solar cell is a thin semiconductor wafer made from two layers of silicon, One layer is positively charged, and the other negatively charged. (a solid substance that has a conductivity between that of an insulator and that of most metals, mostly silicon) forming an electric field. When light energy from the sun strikes a photovoltaic solar cell, it energizes the cell and causes electrons to “come loose” from atoms (adoms) within the semiconductor wafer. The loose electrons are set into motion by the electric field surrounding the wafer, and this motion creates an electric current.