Global ubiquity of Solar Photovoltaics (PV)

Whatís common between a solar cell and a natural plant?Itís the energy transfer of light, i.e. photons from the sun or another source, to electrons the carriers of electricity.Photovoltaics (PV) is the direct conversion of light into electricity by a material called a semiconductor.The first step of PV and photosynthesis is the same: transforming light into electrical energy.In PV, the electrical energy is immediately extracted into an external circuit for power, but in photosynthesis, the plant internally uses the electrical energy to trigger a chemical reaction to feed itself.A plant contains a biological complex for a cascading energy transfer from photons to electrons, while the solar cell does it more directly, simply, and efficiently in a semiconductor junction.

 

Once you appreciate the commonality between PV and photosynthesis, you will not be surprised to know that out of all the technologies and natural resources presently available to us, PV has by orders of magnitude the greatest energy capacity for the planet.Letís do a quick back-of-the-envelope calculation of the global PV potential. Assume (i) we can use 0.1% of the Earthís surface for PV power systems, note these systems can be installed on both land and water; (ii) a ground cover ratio for a total of 3.5 acres per MW PV array capacity; (iii) a relatively low solar irradiation on the PV arrays of 1000 kWh/m2/a, e.g. conditions in northern Europe; and (iv) a modest net power conversion efficiency of 13%, the product of the array efficiency and system losses; the global PV output comes to 30,300 TWh/a.

 

The total global electricity consumption, as of now, is around 20,000 TWh/a. Thatís easily covered by our below-par PV estimate.Electricity consumption per capita is grossly skewed worldwide between the haves and have nots - over 200x more in affluent economies like the US and Qatar than most of Africa. The requirement to bring the global population of 7.4 billion people to an even keel of 5,500 kWh per capita (e.g. that in Britain), is 40,700 TWh/a - well within the grasp of PV, extending installations to 0.14% of the Earthís area with currently available PV technology and its financial economics.††††

(one TWh is a billion kWh, /a is for per annum).††

 

 

 

 

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