Solar 101 for the Duke Energy Academy

Transcription

1 Solar 101 for the Duke Energy Academy June 23, 2014 Peter Bermel School of Electrical and Computer Engineering

2 Outline The solar resource Approaches to harvesting solar power Solar photovoltaics technologies Recent and future growth in solar

3 The solar resource & potential Over 1000 times extra! Source: OECD Observer No. 258/59 December 2006 In principle, solar energy can scale to supply a large portion of global energy demand.

4 The solar spectrum Source: Robert Rohde, Global Warming Art

5 Insolation Incoming solar radiation Take into account movement of the sun throughout the day and throughout different seasons Also weather patterns Energy per unit area per unit time (kwh/m 2 /day)

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7 Solar land area to supply all US power Source: Nate Lewis (Caltech)

8 Electrical power generation Photo: Brightsource Energy, Photo: Stirling Energy Systems, Source: TGW, Photo: Ausra, Inc.,

9 Photovoltaic cell operation Light absorption / charge generation (photovoltaic effect) Carrier thermalization Charge separation Photon reemission Charge collection Nonradiative recombination I Excess energy above E g Conduction band E g = max. V OC heat dark light I SC V OC V Valence band

10 Solar photovoltaics: electrical engineering Circuit model I R S I L R P dark V OC V light V OC, open circuit voltage I SC, short circuit current FF, fill factor = max. power rectangle I SC Maximum power rectangle Power conversion efficiency η = V OC x I SC x FF V OC. I SC P inc

11 Photovoltaic technologies Major categories: Silicon CIGS Single crystal Polycrystalline Amorphous silicon Microcrystalline Cadmium telluride Multijunction Source: Impact Lab,

12 Monocrystallinesilicon PV One of the first, and still dominant, cell technologies Advantages: Process is mature Relatively high efficiencies Disadvantages High materials usage High costs Batch processing Czochralski process for creating monocrystalline silicon ingots Ingots are then sawed into individual wafers Source: DOE Solar Energy Technologies Program,

13 Polycrystalline silicon PV Manufacturing improvement; decreases: Costs Kerf loss Disadvantages: Lower electronic quality Increased fragility More difficult to texture Evergreen s string ribbon process Source:

14 CIGS (Copper Indium Gallium Diselenide) Engineered for direct bandgapat target wavelength Promising efficiencies: up to 20.4% Sticking point manufacturing processes: Vacuum deposition Inkjet-style printing CIGS cell diagram Source: AIST (Japan), / _cigs01.jpg CIGS manufacturing Source: Ibid.

15 CdTe (Cadmium Telluride) Advantages: Direct bandgapwith efficiencies up to 19.6% Inexpensive fabrication process, proven at GW scale Disadvantages: Susceptible to degradation Cd toxicity concerns Te feedstock issues CdTe cell diagram Source:

16 MultijunctionPV Combines two or more materials into a stack Allows for more efficient use of each photon in solar spectrum record efficiencies Challenges with lattice and current matching can greatly increase costs Schematic of triple-junction cell

17 Best Solar PV Efficiencies

18 Solar research is growing Solar research has seen increased investment from many players: US government Venture capital Manufacturers $2,500 $2,000 $1,500 $1,000 PV OEMs VC&PE Government R&D Drivers: Rising energy costs Environmental concerns Energy security Solar R&D Investments (in millions) $500 $ Source: Solar Energy Industries Association (2013)

19 Purdue Has Unique Expertise in PV + TPV Energy Systems Thin-film PV from new materials TPV portable power generator* G. Lush & M. Lundstrom, Solar Cells 30, 337 (1991); Q.. Guo et al., J. Am. Chem. Soc. 132, (2010); M. A. Alam et al., J. Mat. Res. 28, 541, (2013); L. Varghese et al., Adv. Opt. Mater. (2013). Lafayette Magazine, Sun Power, August 17 (2011). *R. Pilawa-Podgurski et al., APEC 25, 961 (2010); P. Bermel et al., Opt. Express 18, A314 (2010) Solar PV electricity for homes pbermel@purdue ECE Grad Open House, 19

20 Solar installations growing rapidly Solar is transitioning from niche to mainstream Improved efficiencies, lower costs enable rapid growth 32,000 MW installed in Europe APAC Americas China MEA ROW Over half of new energy capacity solar in Q1 2014! New Duke solar installation at Indy airport Installed solar capacity (MW) Source: Solar Energy Industries Association (2013)

21 Solar costs approaching grid parity Source: Emanuel Sachs (MIT) Potential for huge drop in installed costs of solar system through variety of sources Solar power on track to match grid prices in a variety of locations: grid parity

22 Conclusions Solar resource is large enough to meet future energy needs Two mechanisms to convert photons into power solar thermal and solar PV Technological landscape is diverse in terms of applications, maturity, and costs Thin-films expected to be major players in the near-term Solar market has been and will continue growing rapidly Grid parity already happening in certain places