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Photovoltaking the future

Photovoltaking the future.

You might have noticed that the world is currently undergoing an energy transition – from fossil fuels to renewables. Despite great resistance to this shift from the traditional purveyors of energy, the trend seems inexorable.

By 2013, around 20% of global final energy consumption was from renewable sources (although half of this was from traditional biomass) and according to Bloomberg, in 2014, investment in low carbon technologies rose by 16% to $310 billion after 3 years of stagnation.

While photovoltaics are but one of a suite of renewable technologies, they are perhaps the most prominent. And given the democratizing effect they have on energy production, they’re pretty popular too.

A 2014 review of a decade of renewable energy by REN21 (the Renewable Energy Policy Network for the 21st Century) noted that the “photovoltaic (PV) market has experienced double digit growth in the past decade and has now reached a global capacity of approximately 67Gw”.

PV’s surging popularity is obviously related to cost. Adjusted for inflation, the per watt price of PV cells fell from $US 77 in 1977 to 74 cents in 2013. In sunny Australia where PV uptake has exploded in recent years, solar panels currently produce energy for around 12 cents per kilowatt hour. By 2020 this is expected to decline to 8 cents.

The price reduction is driven by a number of factors such as the institutional support from government. But it is largely attributable to economies of scale from mass production. Naturally, supportive government policies foster PV uptake which feeds a virtuous cycle of increasing quantities and falling costs – the so-called “production learning curve”. Deutsche Bank even predicts that by 2017 PV will have reached grid parity in up to 80% of global markets.

An often overlooked element in the cost competitiveness of PV is efficiency. All other things being equal, the energy produced by a panel producing twice as much power costs half as much. Currently the efficiency of commercial panels is between 16% and 21% but a record was recently set in Germany of 46%.

Efficiency is obviously important – especially if our concerns extend beyond cost. Critics of early photovoltaics argued that these devices would never repay the energy invested in them. This skepticism was a legacy of the origins of PV. It was originally a NASA technology and for such specific applications, embedded energy was off no consequence. But with the current imperative of decarbonization and dematerialization environmental efficiency is paramount.

So enter life cycle analysis. Last week’s article noted that our industrial food systems consumed ten times as much fossil fuel energy as the food energy it produced. So what about PV?

The news here is pretty good. A recent study has suggested that by 2020 the energy payback period of PV will be around 6 months (for crystalline silicon modules installed in areas with in-plane irradiation of 1700 kWh/m2 year).This represents a pretty handsome 60:1 energy return on energy invested (EROEI).

This sort of energy return is especially appealing at a time when fossil fuels EROEI is trending the other way. A 2009 study into energy recovery in the oil and gas sector estimated “that EROI at the wellhead was roughly 26:1 in 1992, increased to 35:1 in 1999, and then decreased to 18:1 in 2006”. These figures reflect the increasing amounts of energy required to exploit more difficult to access reserves.

In light of the above – that photovoltaics are becoming increasingly environmentally and cost efficient – the future of solar power looks extremely bright.

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