Photovoltaic Devices: Life Cycle Considerations

Gavin D. J. Harper

Photovoltaic Devices:Life Cycle Considerations

Welsh Energy Sector Training (WEST) Conference,Liberty Stadium, Swansea, Wales,

16th September 2014

[email protected]@gavindjharper

www.gavindjharper.comhttp://orcid.org/0000-0002-4691-6642

http://www.gavindjharper.com/

What is Life Cycle Assessment?

A life cycle assessment gathers every aspect of the products environmental impact from the gathering of the raw materials used to produce the product components, all the way through the manufacture and use of the product to the impact the disposal of the product has on the environment.

Human Activities

Materials Inputs

Waste Products

Products and

Services

Energy

Why is Life Cycle Assessment Important?• Lifecycle assessment helps us to make comparisons

between different products and services to understand their impact on the environment over the whole of their lifecycle.

• The results of the study provide the manufacturer and material suppliers with information to reduce life cycle impacts of the products.

• It also helps consumers to make informed decisions about the relative environmental benefits of a range of different products.

• It can inform operating, manufacturing and supply chain decisions to move towards more sustainable options.

Standards for Life Cycle Assessment

• ISO 14000 series of environmental management standards.

• ISO 14040:2006 Life Cycle Assessment• Environmental management -- Life cycle assessment --

Principles and frameworkStage 1Defining the goal

and scope of the LCAISO 14041

Stage 2Life cycle inventory analysis

ISO 14042

Stage 3Impact

AnalysisISO

14043

Stage 4Interpretation

ISO14044

Identification of materials,

processes and products to be

considered within the LCA. What are

the terms of reference.

Collect numbers on the sources of

energy and raw materials that are consumed by and

the wastes that are released from the

process.

Translate the numerical data on

the inputs and outputs of the

system into real world terms; how

does this affect the environment.

Use the data gained from the LCA in order to

draw conclusions, make

recommendations on how

environmental impact can be

reduced.

The Lifecycle of a Photovoltaic Installation

Lifecycle of Silicon Photovoltaics

• Quartzite rock is mined.• Fossil fuels are used in the

processes of mining.• The landscape is

irrevocably changed by mining operations

Sherwani, Usmani & Varun (2010) Life cycle assessment of solar PV based electricity generation systems: A review, Renewable and Sustainable Energy Reviews, Volume 14, Issue 1, January 2010, Pages 540–544

Lifecycle of Silicon Photovoltaics

• The silicon dioxide (SiO2) is reduced to silica (Si) with carbon (C) in a large arc furnace.

• Further silicon is purified in the furnace by repeatedly pouring it and blowing with oxygen/chlorine mixture and finally solidifying it.

• This metallurgical grade is further purified for use in semi-conductor form. Sherwani, Usmani & Varun (2010) Life cycle assessment of solar PV based electricity generation systems: A review, Renewable and Sustainable Energy Reviews, Volume 14, Issue 1, January 2010, Pages 540–544

Image © Edgar A. Guntherhttp://guntherportfolio.com/2007/01/solar-grade-silicon-roads-lead-to-ruse-part-2/

Lifecycle ofSilicon Photovoltaics• The silicon is transformed

into PV cells.• The process will be

different depending on whether the cells are mono c-Si or poly c-Si.

Deutsche Gesellschaft für Sonnenenergie – (2008) Planning and Installing Photovoltaic Systems, Earthscan, London

Module Assembly

• The photovoltaic cells are then assembled into modules.

• Image right, Sharp Wrexham

Balance of Plant

• There is also the lifecycle of all of the “balance of system” to be considered as well.

All components of the system have a lifecycle impact.

For conventional energy generation technologies, the majority of the environmental impact is in the operation use or generation phase.For photovoltaic cells, the bulk of the impact occurs in the production of the cells.

End of Life (Disposal / Recovery)

• Energy and materials are consumed in the disposal of photovoltaic devices.

• Increasingly waste is seen as a resource, rather than something to be disposed of, there is the potential to turn this waste stream into new products with reduced environmental impact.

• Newer PV technologies such as DSC have shorter lifecycles due to degradation mechanisms and a lack of product durability. Here, end of life becomes a greater consideration.

• ‘Design for disassembly’• Building lifecycles are usually much longer than the lifecycle of PV

devices, so buildings must be planned with the anticipation of PV replacement at some point in their lifecycle.

Cradle to Cradle

• Look at moving towards a “circular” photovoltaic economy, where panels at the end of life become the feedstock for new panel production.

• Moving from “Open System” to “Closed Loop” recycling.

• End of life regulations are a substantial move in this direction.

Planning for End-Of-Life

End of Life Considerations for PV

• In a separate presentation, we will explore the impact of the WEEE regulations on the End of Life considerations for solar.

• Different photovoltaic technologies have different life expectancies.

• Silicon photovoltaics are a durable option.• Some technologies such as DSSC & Organic PVs currently

have shorter lifespans.

• From a construction perspective, if we are going to integrate photovoltaic devices into buildings, we need to consider carefully our plans for the end of the photovoltaic cells useful life.

How long do PV’s last?

• Insufficient data to be truly certain.

• Photovoltaic Degradation Rates — An Analytical Review NREL is a good study.

Amor

phou

s sil

icon

(a-S

i)

Cadm

ium

tellu

ride

(CdT

e)

Copp

er in

dium

galliu

m selen

ide

(CIG

S)

Mon

ocry

stallin

e sil

icon

(mon

o-Si

)

Polycr

ysta

lline

silicon

(poly-

Si)

00.5

11.5

22.5

33.5

PV Output Loss % per Year (NREL)

Output loss in percent per year Pre 2000 Output loss in percent per year Post 2000

PV Warranties

• The adjacent graph, from http://energyinformative.org/lifespan-solar-panels/

shows the warranties offered by some PV manufacturers.

• A warranty considered standard by many in the industry is the performance of the PVs should be no less than 80% of rated power after 25 years

http://energyinformative.org/lifespan-solar-panels/



Anecdotal Reports of PV Life

• There are a number of anecdotal reports that give encouraging signs about silicon PV lifespans.

• An Arco Solar 16-2000 33W outperformed it’s factory spec 30 years after it was manufactured.

• The first “modern” solar panel still works after 60 years.• Kyocera reports a number of solar power installations

that continue to operate reliably and generate electricity. These installations are all nearly 30 years old.

Financial Lifespan vs. Actual

• We tend to consider “20 years” as the lifespan of a PV installation when calculating the financial returns.

• However, the actual in-service life, in many cases would seem to exceed the performance used for financial calculations.

That said…

• More regular replacement required of other components.

• For off-grid, or grid storage systems, batteries typically require replacement every five years or so.

• Inverters and power electronics wear out, and may also require replacement every 5-10 years.

Cultures of ConstructionUnited States – Shingle Roof

Replaced every 25 years

United Kingdom – Slate Roof

Replaced every 100+ years

Cultures of Construction

• Building Integrated Photovoltaic Devices may require changes of culture within the construction industry.

• “Bolt on” photovoltaics can be removed relatively easily.• Truly “Building Integrated” PV devices may require structured

planning for End-of-Life and replacement considerations.

• If we consider the lifecycle of photovoltaics is relatively short in comparison with the lifetime of the building; then we can anticipate that within a building lifecycle, there may need to be several replacements of photovoltaic devices.

RelevantAcademicStudiesOn Photovoltaic LCA Considerations

Lifecycle Analyses in the Literature

• Over the past thirty years a great deal of data has been gained on the Lifecycle impacts of PV systems.

• There are hundreds of different LCAs available in the academic literature on a range of different types of system and technology.

• There are wide variations in the outcomes of LCA evaluations of PV technologies.

Variations in the Literature

• Variation could be attributed to• differences in technologies evaluated

• differing system designs• commercial versus conceptual systems,• system operating assumptions,• technology improvements over time

• LCA methods and assumptions

• Meta analysis “aggregates” these different examples from the literature into a more coherent picture.

NREL (2012)NREL/FS-6A20-56487

Comparison of as-published life cycle greenhouse gas emission estimates for electricity generation technologies. The impacts of the land use change are excluded from this analysis.Credit: Sathaye, J., O. Lucon, A. Rahman, J. Christensen, F. Denton, J. Fujino, G. Heath, S. Kadner, M. Mirza, H. Rudnick, A. Schlaepfer, A. Shmakin, 2011: Renewable Energy in the Context of Sustainable Energy. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation [O. Edenhofer, R. Pichs-Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)], Cambridge University Press. Figure 9.8

http://www.nrel.gov/analysis/sustain_lca_results.html

From:

MacKay (2008)

LCA: PV’s in Use• Land use an important

consideration “in Use”• (Hence the need to

make good use of roof spaces with BIPV).

Why is Life Cycle Assessment relevant to the Welsh Solar Industry• Trade wars between EU / China• China can manufacture Photovoltaic devices more cheaply.

• BUT Heavily reliant on dirty forms of energy.• Poor environmental controls compared to EU Solar Industry.

• Need to question ourselves and our motives…• Why are we actually pushing for photovoltaics devices.

• Cleaner, more responsible energy future.

• Potential for Welsh Solar industry to regain competitive advantage if life cycle impacts of PV installations rise up the political agenda.

Life Cycle Assessment: EU vs. China

• Yue, You & Darling (2014) identify that most pre-existing literature on Solar PV LCA focused on the US / EU.

• This contrasts with most PV manufacturing which is outsourced to non-OECD countries.

• These countries have radically different conceptualisations of industrialisation and environmental protection.

Dajun Yue, Fengqi You, Seth B. Darling, (2014) “Domestic and overseas manufacturing scenarios of silicon-based photovoltaics: Life cycle energy and environmental comparative analysis” Solar Energy, Volume 105, July 2014, Pages 669–678


• Their lifecycle analysis focuses on Crystalline Silicon technologies: looking at mono c-Si, poly c-Si and ribbon c-Si.

• Thin film cells not considered in this analysis.• Challenges as there are gaps within the literature.• c-Si cell manufacture has become “commoditised” using

standard processes and equipment, by contrast thin film cell manufacture is more “proprietary”.

• Organic cells similarly in their infancy, so lack of data.Dajun Yue, Fengqi You, Seth B. Darling, (2014) “Domestic and overseas manufacturing scenarios of silicon-based photovoltaics: Life cycle energy and environmental comparative analysis” Solar Energy, Volume 105, July 2014, Pages 669–678


•The factors evaluated include:• Energy Payback• Energy Return on Investment• Greenhouse Gas Emissions




CN = China, RER = Europe

Cumulative Energy Demand(Lower is better)




Energy Payback Time(Lower is better)




Energy Return on Energy Invested

(Higher is better)




Carbon Footprints(Lower is better)

Yue, You & Darling (2014) Conclusions• Mainstream Chinese-made silicon solar panels have

more than twice the carbon footprint than panels made in Europe

• Mainstream Chinese-made silicon solar panels take up to 30 percent longer to offset the energy used to make them

• Their analysis doesn't include transportation costs to get them to Europe, which would magnify the discrepancy even more.

Yue, You & Darling (2014) Conclusions• Monocrystalline was found to have the longest energy

payback period despite the best energy output.• Analysis comparing mono-Si and multi-Si technologies

suggest that these do not significantly differ in life cycle GHG emissions

• “Ribbon" silicon, stringing out the material from a molten bath, created the least efficient material but did so more efficiently and with faster energy payback.


• Yue, You & Darling (2014) present a ‘break even carbon tariff’ on imported photovoltaic devices.

• This would equate to €105–€129/ton CO2

• This would offset environmental burden of imported PV.

• Could improve fortunes of domestic manufacturers?Dajun Yue, Fengqi You, Seth B. Darling, (2014) “Domestic and

overseas manufacturing scenarios of silicon-based photovoltaics: Life cycle energy and environmental comparative analysis” Solar Energy, Volume 105, July 2014, Pages 669–678

Wales: Could Welsh manufacturing compete on lower environmental impact?"The fact is, we cannot any longer ignore things like carbon footprinting -- especially in the energy space, where we should be the people most aware of the issue,"

"Today it's essentially being ignored."

Seth Darling, ScientistU.S. Department of Energy's Argonne National Laboratory

Wales: Competing with China?

Photo by Peter Byrne/WPA Pool/Getty Images

Sharp Closure• Whilst Sharp has closed, it is

interesting to consider it’s activities through the lens of Yue, You & Darling (2014).

Sharp Manufacturing,Llay, WrexhamSharp Closure

Crystalline Silicon Cells

Brought From

Taiwan To Llay

Finished modules shipped back to Japan.

Where is the impact in“Welsh Assembled” Modules

The bulk of the energy and carbon impact occurs in the manufacture of the silicon feedstock, crystals, wafers and cells.Module assembly represents a relatively small proportion of the overall environmental impact.

How to assign value to sustainable solar manufacturing• Suggestion for the future – not currently on the agenda.• Challenges in tariffs based on location of manufacture.

• How to allocate if cell manufacture and module manufacture carried out in different places.

• How to equitably allocate tariffs across the supply chain.

• Look at the food industry for possible pitfalls• Product labelling based on last point food was handled / processed /

packaged. (Horsemeat scandal arose from poor knowledge of product origin).

• Need for PV carbon “chain of custody”?

• Don’t want product labelling based on “last point of contact” as it distorts perception of (environmental) quality & impact.

Opportunities for the Welsh Solar Industry• Were the regulatory environment to shift to recognise

the environmental impacts of PV manufacturing, there could be more opportunities for the ‘Western’ PV manufacturers.

• At present STA has fought against “Anti-Dumping” tariffs, and import restrictions as the jobs in “installation” outweight the jobs in “manufacture”.

• The UK is currently most vibrant market for PV in the EU, and no appetite to starve that growth.

• BUT, could we do things cleaner, greener, better with appropriate incentives and what opportunities would that present for UK industry?

Gavin [email protected]

http://www.cser.org.uk/

https://www.westproject.org.uk/

@gavindjharper

@CSER_PV

@LCRI_WEST

If you found any of this interesting…Please stay in touch

mailto:[email protected]

http://www.cser.org.uk/

Engineering

Photovoltaic Devices: Life Cycle Considerations