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How viable (and sustainable) are solar PV systems? A debate

Post the Paris climate agreement, the world looks to solar energy more than ever to reduce carbon emissions and counter climate change, with multi-billion dollar solar programmes announced by just about every major country. But just how efficient,  and environmentally sustainable is the celebrated solar photovoltaic technology? Here’s what some leading voices have to say.

But what’s the REAL energy return of photovoltaic energy?
Ugo Bardi, Cassandra’s Legacy
Most of the current discussions on photovoltaic energy seem to turn around one or another kind of legend. The most recent one seems to be that photovoltaics has a low energy return (EROI or EROEI), sometimes said to be even smaller than one. If it were true, it would mean that photovoltaic plants are not producing energy, they are just consuming it! But it is not true. It is just one more example of confirmation bias: cherry-picking the data that confirm one’s pre-conceived ideas. It is true that you can find a few studies (very few) that look serious (perhaps) and that maintain that PV has a low EROI. However, in a recent study, Bhandari et al. (1)⁠ surveyed 231 articles on photovoltaic technologies, finding that, under average Southern European irradiation, the mean EROI of the most common PV technology (polycrystalline Si) is about 11-12. Other technologies (e.g. CdTe) were found to have even better EROIs. Maybe these values are still lower than those of some fossil fuels, but surely not much lower (if they are lower) and a far cry from the legend of the “EROI smaller than one” that’s making the rounds on the Web.

The Real EROI Of Photovoltaic Systems: Professor Charles Hall Weighs In
Ugo Bardi, Cassandra’s Legacy
Charles Hall is known for his multiple and important contributions in the field of sustainability, and in particular for having introduced the concept of Energy Return on Energy Investment, EROI or EROEI. He is now emeritus and still active in research; among other things as chief editor of the new Springer journal: “Biophysical Economics and Resource Quality, BERQ. Here, he intervenes in the recent debate on the EROI of photovoltaic systems.

How Sustainable is PV solar power?
Kris De Decker, Low Tech Magazine
Why does the production of solar PV requires so much energy? Because the low power density — several orders of magnitude below fossil fuels — and the intermittency of solar power require a much larger energy infrastructure than fossil fuels do. It’s important to realize that the intermittency of solar power is not taken into account in our analysis. Solar power is not always available, which means that we need a backup-source of power or a storage system to jump in when the need is there. This component is usually not considered, even though it has a large influence on the sustainability of solar power.

The Energy Return of Solar PV
Euan Mearns, Energy Matters
A new study by Ferroni and Hopkirk [1] estimates the ERoEI of temperate latitude solar photovoltaic (PV) systems to be 0.83. If correct, that means more energy is used to make the PV panels than will ever be recovered from them during their 25 year lifetime. A PV panel will produce more CO2 than if coal were simply used directly to make electricity. Worse than that, all the CO2 from PV production is in the atmosphere today, while burning coal to make electricity, the emissions would be spread over the 25 year period.

What’s the EROI of Solar?
Ramez Naam
The most comprehensive review of solar EROI to date is Bhandari et al ‘Energy payback time (EPBT) and energy return on energy invested (EROI) of solar photovoltaic systems: A systematic review and meta-analysis’. Bhandari looked at 232 papers on solar EROI from 2000-2013. They found that for poly-silicon (the predominant solar technology today, found in the second column below), the mean estimate of EROI was 11.6. That EROI includes the Balance of System components (the inverter, the framing, etc..) For thin film solar systems (the right two columns), they found an EROI that was much higher.

Photo-Voltaics Is An Energy Source, Not Sink!
Luis De Souza, At The Edge of Time
Energy Policy recently published a study conducted on the EROEI of Photo-Voltaics (PV) technologies installed in Switzerland. The end result is a remarkably low figure of 0.8:1, well below any EROEI assessments ever conducted on this energy technology. Such a figure naturally made the delight of those campaigning against renewable energy, who take at face value any hints of negative performance. However, from this study a number immediately stands out: average lifetime energy yield of 106 kWh/m2/a. As it turns out, a closer look at this single figure is enough to disprove the hypothesis of PV being an energy sink in Switzerland.

How viable is renewable energy?
Sagar Dhara, Bulletin of Atomic Scientists
Both solar and wind energy depend on rare earth elements that will likely become scarce in 20 years or so. China accounted for 95 percent of the world’s rare-earth production, raising fears that it might exert monopolistic control. Meanwhile, renewable energy technologies that could function without rare earths, particularly photovoltaic technologies, aren’t close to deployment.

Krugman’s Illusion: We Becoming Richer, But Not Damaging The Environment
Saral Sarkar
Factories that produce photovoltaic panels or wind turbines or rotors use electricity. Even if they need some heat energy for particular steps in the production process, they generally use electricity to produce that heat. Since photovoltaic panels, wind turbines etc. produce electrical energy, i.e. the same form of energy that is used to produce these equipments, they only make sense if they produce in their lifespan of ca. 15 to 20 years more energy than what is needed to manufacture them – in other words, if their energy balance is positive. In our days, one also speaks of EROEI to indicate the ratio between energy return on energy invested.

Once More on the Viability of Renewable Energies
Saral Sarkar
In an article written by Ugo Bardi1, a member of the Club of Rome, also published in a popular Indian internet journal (Countercurrents.org), I read that more and more people, even experts, are expressing their skepticism about renewable energy. Ugo Bardi and other optimists of today are of course still expressing optimism. But they are no longer as euphorically optimistic about renewable energies as, for example, the late high priest of solar energy euphoria Hermann Scheer (former president of Eurosolar). They are now roughly saying, 100% renewables is possible, but it will not be easy, and we must in future change the way we are living today in industrial societies; we must be satisfied with less. That is some progress. But the illusions still remain.

TAILPIECE: Energy issues – photovoltaics: limits?
Sandy Irvine
The research discussed here could be the basis for a major assault on major planks of the green energy programme, namely solar photovoltaics. One can easily foresee the nuclear lobby, the frackers, the big dam builders seizing on it to argue that solar PV at high latitudes in countries like the UK is a total waste of time, energy and money. The truth of the matter will depend on a number of assumptions and the accuracy of associated calaculations. However the energy return on PV does seem lower than enthusiasts have been claiming and its impacts are at the start of its cycle, ie in the present, the time when we must make the biggest strides to cut carbon emissions and otherwise reduce our ecological footprint.

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One Response “How viable (and sustainable) are solar PV systems? A debate”

  1. 16th June 2016 at 10:19 am

    Hi There, the ERoEI of solar PV has caused quite a stir. As ever, I don’t know where the truth lies 😉 But if the ERoEI is < 1 for panels made in China deployed in northern Europe then deploying solar PV will increase and not decrease CO2 emissions. It will also drag us toward the net energy cliff edge.

    Lost in this debate from the pro-PV side is the fact that Ferroni and Hopkirk are specifically discussing high latitude PV deployment. Here is what PV looks like in the UK. There is a huge energy cost to cover the high amplitude annual cycle + the diurnal cycle.


    Deploying PV on N facing roofs here in Aberdeen is quite simply bonkers. And it is really up to the PV enthusiasts to put their intellectual credentials on the line and to agree with me on this.

    Those who can't distinguish between the merits of deploying hydroelectric power in Norway and in Denmark don't really deserve a seat at the energy debate.

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