How can thin-film PV meet the demands of Terawatt scale generation?

Nicola Courtier,Lana Lee,

Silvia Mariotti,Michael StringerSunny Side Up

How much Energy do we need?

From http://www.nrel.gov/docs/fy14osti/60894.pdf

• Human population consumes approx. 16 TW/year

http://www.solar-uk.net/article/78797-UK-Universities-receive-solar-boost.php

How much Energy can we make?

Current state of PV – The success of Silicon

From http://www.nrel.gov/docs/fy14osti/60894.pdfhttp://reneweconomy.com.au/2014/iea-renewables-report-solar-pv-exceed-expectations-79110

Bloomberg, New energy and finance.

• PV generated approx. 140 GW in 2013

• International Energy Agency (IEA) projectedPV 405 GW by 2020, average growth 40GW/p year

• 13% of PV from thin-film 0.1% total power generation in 2013

Silicon dominates PV market BUT;

• Expensive purification techniques

• Thick films – 200μm

What are thin film PVs

Deposition of one or more PV material layers on a substrate.

Advantages over Crystalline Silicon (c-Si);

• Thickness: from few nanometers (nm) -> micrometer (µm)

• More flexibility

• Less weight

• Highly absorbing active layer

• Large scale thin film has the potential to be cheaper

• Multiple possible substrates such as glass, plastic or metal, potential for scalability

http://en.wikipedia.org/wiki/Thin_film_solar_cell

Photovoltaic thin films available on the market (2014)

http://www.nrel.gov/ncpv/images/efficiency_chart.jpg

http://en.wikipedia.org/wiki/Thin_film_solar_cell

High Performance Thin Films

Emerging photovoltaics:

• Organic solar cell

• Quantum dot solar cell

• Copper zinc tin sulfide solar cell (CZTS) and derivates CZTSe and CZTSSe

• Perovskite solar cell

Name c-Si CIGS a-Si CdTe GaAs CZTS CZTSS GaAs/InP

LabEfficiency (%)

25 13 10 19.6 28.8 8.5 12 38.8

Area for TW(km2)

4000 7700 10000 5100 3500 12000 8300 2600

Thin film PV Advantages over typical c-Si

a-Si Direct band gapGlass, steel, plastic substrateLow temp deposition

CdTe Good absorberLow cost manufacture Vapour Deposition

CIGS Good absorberTuneable band gap

CZTS Earth abundant, cheap materials

The Current Big Contenders Thin Film

• CIGS

The Current Big Contenders Thin Film

http://www.firstsolar.com/Home/Technologies-and-Capabilities/PV-Modules/First-Solar-Series-3-Black-Module

• CZTS

• CdTe

• Most widely used PV after Silicon

• Eg = 1.4 eV Extremely good matching for solar spectrum

• Competitive pricing against Silicon

• Module Efficiency10-13%

• CIGS

• CZTS

• CdTe

• CdTe First Solar, Large scale Vapour Transport Deposition.

• Currently deployed 8GW

• Scale up CdTe

Process for large-scale production of CdTe/CdS thin film solar cells Nicola Romeo, Alessio Bosio, Alessandro Romeo

The Current Big Contenders Thin Film

• CIGS

• CZTS

• CdTe

• Module efficiencies 12-16%

• CuInxGa1-xSe2

• Band-gap 1 – 1.7 eV (dependent on x)

• 2 main low cost methods

- Co-evaporation of sublimed elements

- Two stage deposition - Low temp deposition of Cu and In/Ga followed by annealing with e.g. H2Se

• Chemical Bath Deposition (CBD) of CdS layer follows

http://energy.gov/eere/sunshot/copper-indium-gallium-diselenide

The Current Big Contenders Thin Film

http://www.sivapower.com/#!technology/c23pn

• CIGS

• CZTS

• CdTe

• 2009 – 2014 20 CIGS companies failed.

• Due to ‘attempting to scale too quickly or overestimating their ability to reduce costs’

• Only 1 company succeeded to produce GW scales, American manufacturer, SIVA Power

The Current Big Contenders Thin Film

• CIGS

• CZTS(Se)

• CdTe • CuZnSnSxSe1-x

• Band gap 1-1.5 eV dependent on Se concentration

• Gained attention in the last decade, hasn’t yet been scaled but reaching efficiencies up to 10% in the lab (solution processing)

• No toxic materials

• Interface defects causing unwanted recombination

• Currently limited to lab scale production

http://energy.gov/eere/sunshot/earth-abundant-materials

The Current Big Contenders Thin Film

Why might some thin films not make it?

Log Abundance (ppm)

From Phil. Trans. R. Soc. A (2011) 369, 1840–1856

Log Cost per Tonne

Environmental Limitations

• Element Abundances

- CdTe - Only to 816 GWp by Te

- CIGS – Limited to 1.3 TWp by In

• Toxicity of product synthesis

• Toxic content

• Waste Processing

• Storage and Transport inefficiencies

Source: P. Sinha, M. de Wild-Scholten, A. Wade, and C. Breyer, Total Cost of Electricity Pricing of Photovoltaics, presented at EU PVSEC 2013.http://www.greentechmedia.com/articles/read/siva-power-thin-film-cost-target

Promising Solutions

• Mix and match thin film PV types, many other applications, can be used on many different surfaces.

• Storage of energy new electricity grids (that can store up to 5 GW)

• Additional Heat-energy collection from IR rays on solar cells

• More focus on the research of new organic/inorganics or hybrid PV technologies

http://en.wikipedia.org/wiki/electrical_grid

UK Policy

http://www.solar-uk.net/article/78797-UK-Universities-receive-solar-boost.php

The National Centre for Photovoltaics (NCPV), part of the American National Renewable Energy Lab (NREL)PHOTOVOLTAIC SUMMIT 2008: DR. PV, MR. PV AND THE TERAWATT DILEMMA Friday, June 20, 2008

• UK’s target of 15 % renewable energy by 2020

• 20GW (18TWh)being the max PV deployment by 2020

"The overall £350m sum invested bythe Government and the Engineeringand Physical Sciences ResearchCouncil is the UK’s largestinvestment in postgraduate trainingin engineering and physicalsciences.“

UK Solar PV Strategy Part 1: Roadmap to a Brighter Future Gov.UK

“Recently solar received the highestpublic approval rating of all renewableenergy technologies at 85 per cent”

What can we

do?

Keep researching new materials to aim for higher efficiencies

Expand into new markets for thin film in Asia and

around the world

Advertise scientific data to attract investment from governments and

companies

Raise awareness to manufacturers and

consumers

Develop solar cells with storage systems

for off-grid uses

Thank you for listening. We’re happy to (try to) answer any questions.

• Whilst it has been shown by companies such as First solar that thin filmlarge scale deployment can be achieved, limited abundances of theelements needed in CdTe and CIGS thin film devices will limit theremaximum deployment, in order to reach Terawatt scales, the future ofthin film may be spread across many technologies.

• The balance between efficiency and cost leads us to believe that due totheir component abundance CZTS or emerging organic thin film devicesmay offer a decent prospect at Terawatt scale deployment, but it has yetto be seen if they will successfully make the transition away from a labscale production.

Sunny Side Up Conclusions