SOLAR ELECTRICITY – GETTING BETTER ALL THE TIME Dr. Kylie Catchpole Australian National University

By 2070 under business as usual 10-20% drier 3-4 degrees hotter on average For context: The world is currently 5 degrees hotter on average than in the last ice age Climatechangeinaustralia.gov.au

Stabilizing the climate 500ppm Required to prevent the most damaging climate change By 2050 we need to install emission-free power equal to around the current level of world power use ie. about ~16 TW business as usual

Power Units: The Terawatt Challenge Power W 1 kW 1 MW 1 GW 1 TW Energy 1 J = 1 W for 1 s

The International Energy Agency Reports

Halving global CO 2 emissions by 2050 International Energy Agency Report Investment required in next decade ~ 3 times current investment (IPCC special report)

The small black dots show the area of solar panels needed to generate ALL of the worlds energy using 8% efficient photovoltaics. The Solar Resource Average solar irradiance, W/m 2.

Sunlight in Australia Supply all of Australia’s and the world’s electricity

Direct solar energy Solar electricity Solar hot water Passive solar (north windows) Indirect solar energy Wind energy Food Drying clothes

Worldwide production of PV solar cells 2011 production: 37 GW (Photon Int., March 2012) Over the last 10 years PV production has multiplied by a factor of 70 - a yearly growth rate of over 50%.

Growth of Australian Market MW of PV was installed in Australia in 2010, a 450% increase over 2009 Small grid systems averaged $6.50/Wp, down from $9/W last year.

Prices of solar modules Decrease in price of 20% with every doubling of cumulative production. $1/W means 20c/kWh in sunny location

Solar module Solar cell Silicon (also used in computer chips) Metal contacts

Cross-section of solar cell

Energy electron hole p-type silicon n-type silicon Diodes, light emitting diodes and solar cells

Operation of a solar cell usable (qV) Energy light electron hole p-type region n-type region

PV Production share by technology in 2009 Single Crystal Si Multi- Crystalline Si a-Si

Photovoltaic module fabrication Typical production rate: 1 cell per second Typical capacity of new factories: 1GW – about 600,000 modules per year

Residential systems ~1.3kW system ~5.5kW system Produce about kWh/year Can offset all electricity use for an efficient house

Commercial scale systems Crowne Plaza Hotel, Alice Springs, 305kW Produces 530,000kWh per year, reduces emissions by 420 tonnes/year

Utility scale PV Downloaded from Arizona system, 10MW Provides for 2500 households 25 million kWh per year

PV Plants in Spain In Spain there are 330 PV plants bigger than 1MW. The largest is 60MW. City Solar : 20 MW PV park in Alicante, 50 hectares, annual electricity yield 30 GWh – based on 1,500 kWh per kW of installed power. Tracking arrays produce approx. 30% more energy than fixed arrays

ANU Centre for Sustainable Energy Systems 80 people working in photovoltaics, from physics to systems Concentrating systems for combined electricity and hot water Sliver TM module, being commercialized by Transform Solar Basic science: Nanophotonics Recombination at interfaces Defects in silicon

25% fabrication costs 35% module costs 40% material costs Si module cost break-up 50% of Si is lost as saw-dust Reducing the cost of photovoltaics Need less material use for cheaper solar cells

Australian Solar Institute Project – ANU and Trina Solar ANU and Trina Solar partnering to increasing the efficiency of solar cells Aim to reach efficiencies of 20% with n-type solar cells with production ready process.

SLIVER ANU invention being commercialized by Transform Solar Ultra-thin Sliver cells TM can greatly reduce use of expensive silicon.

Concentrator systems Parabolic troughs concentrate light onto solar cells and heat water at the same time

Thin film cells and light trapping AM 1.5 solar spectrum and solar radiation absorbed in 2 μm c-Si wafer, assuming single pass light needs to be concentrated or “folded” into a thin semiconductor layer thereby significantly enhancing the absorption t optical thickness >> physical thickness ‘t’ glass Si (few µm) Thin film solar cells are an alternative for low cost PV

Plasmons in stained glass reflected light transmitted light Lycurgus cup, 4 th century AD

Tunable resonance Resonance tunable with size, shape, aspect ratio wavelength (nm) scattered intensity dark field microscope image

Increased Absorption of light in thin films solar cells Particles on solar cells resonance on nanoparticle trapped (guided) mode Acts like an antenna to direct light into solar cell

Making silver nanoparticles

Silver particles and Snow Globe Coating

Snow Globe Coating pH: 6-7 (closer to isoelectric point) Particle size: 1µm, no binder

Snow Globe Coating combined with Plasmonic Nanoparticles Plain4.0mA/cm 2 Snow Globe 8.0mA/cm 2 coated with plamonic particles 100% increase in Jsc A. Basch et al., Appl. Phys. Lett. (2012)

Localized plasmons Extraction of light from light emitting diodes can also be enhanced resonance on nanoparticle semiconductor

Photo of light-emitting diode Broken metal fingers Bare device Part of the device with silver islands Electro-luminescence from a LED partially deposited with islands 1mm 2 device Pillai et al. Appl. Phys. Lett. (2006)

What is doing science like? “In research the front line is almost always in a fog.” Francis Crick, co-discoverer of DNA “Research is the process of going up alleys to see if they are blind.” Marston Bates, American zoologist Being confused is normal!

Science is like orienteering I think I am here I am actually here

“Failure is simply the opportunity to begin again, this time more intelligently.” Henry Ford “Success is the ability to go from one failure to another with no loss of enthusiasm.” Winston Churchill Probably 90% of experiments fail. Constant optimism is necessary!

Scientists are like bees Find interesting research directionDiscover something interesting Tell everyone else about itOther scientists go there too and find more interesting things

Implications for science teaching Possibilities Include some open-ended experiments, without a pre-defined procedure. Have students define their own procedure. Then modify it when it doesn’t work. Give students some projects where they haven’t learned the theory yet and have to figure out possible approaches. Make good speaking and writing an integral part of science at school.

Summary A ‘global energy technology revolution is needed’ – International Energy Agency Solar is the fastest growing new renewable energy technology, and the price is now similar to retail. Nanotechnology can be used to improve solar cells. Doing science involves trying lots of things while you don’t know what’s going on. Doing science also involves plenty of telling people what you are doing.

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Western Wind and Solar Integration Study (US) Impact of up to 30% wind and 5% solar in Western US. Modeled 960GW wind, 15GW photovoltaics and 200GW concentrating solar thermal with 6 hours storage. Modeled different locations and sensitivities to eg. Fuel costs, operating reserves, grid balancing area size. Report sis.html sis.html Grid integration

Conclusions of WWSIS 35% renewables can be integrated without dedicated storage. Balancing over larger regions and more transmission is necessary. Incorporate forecasting. Increase flexibility of dispatchable generation (ie. more gas, hydro). Improve demand management (eg. pay large consumers to reduce load for a few hours a year). Increase operating reserves.

Cost components of Si-based PV electricity PV modules represent 60% of the system cost

Grid parity – Canberra 2kW system Assumptions: Conservative 30% industry growth. Historical price reduction for PV. Current Federal policy settings including MRET and carbon tax starting in 2012 Retail electricity price rise 3% above inflation. Predicted electricity prices from photovoltaics and retail 2011 dollars

Current cost of photovoltaics Production cost: $2/W on average Retail Price of PV modules is US$3/W in USA and Euro 2.50/W in Europe System price is about 2 x module price (cost of inverter, installation) This PV system cost results in an electricity cost of approx. ~US16c/kWh (5% discount rate) for industrial and 30c/kWh for residential ( Historically price has decreased by 20% with every doubling of cumulative production.