聚光型太陽電池發展趨勢 (OE_10290)

Transcription

1 聚光型太陽電池發展趨勢 (OE_10290) 陳怡嘉 國立東華大學光電工程學系 (Friday) 14:10-17:00 (Contents are solely for educational purpose)

2 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

3 "Best Research-Cell Efficiencies" by National Renewable Energy Laboratory (NREL) - National Renewable Energy Laboratory (NREL), Golden, CO United States Department of Energywebsiteimageexplanatory notes. Licensed under Public Domain via Wikimedia Commons -

4 Concentrated photovoltaics (CPV) Concentrated photovoltaics (CPV) is a photovoltaic technology that generates electricity from sunlight. Contrary to conventional photovoltaic systems, it uses lenses and curved mirrors to focus sunlight onto small, but highly efficient, multi-junction (MJ) solar cells. In addition, CPV systems often use solar trackers and sometimes a cooling system to further increase their efficiency. Especially High concentrating photovoltaic (HCPV) systems, have the potential to become competitive in the near future. Commercial HCPV systems reached efficiencies of up to 42% with concentration levels above 400,[Photovoltaics Report] and the International Energy Agency sees potential to increase the efficiency of this technology to 50% by the mid- 2020s.[Technology Roadmap: Solar Photovoltaic Energy] "Photovoltaics Report". Fraunhofer ISE. 28 July Archived from the original on 31 August Retrieved 31 August "Technology Roadmap: Solar Photovoltaic Energy" (PDF). IEA. Archived from the original on 7 October

5 Major Components in CPVs 1. Concentrators 2. Multi-junction (MJ) solar cells 3. Solar trackers 4. Cooling system

6 The Amonix 7700 Solar Power Generator (53 kw AC, PVUSA conditions) This Amonix system consists of thousands of small lenses, each focusing sunlight to ~500X higher intensity onto a tiny, high-efficiency multi-junction photovoltaic cell. A Tesla Roadster is parked beneath for scale.

7 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

8 電網等價 (Grid Parity) Grid parity (or socket parity) occurs when an alternative energy source can generate power at a levelized cost of electricity (LCoE) that is less than or equal to the price of purchasing power from the electricity grid. The term is most commonly used when discussing renewable energy sources, notably solar power and wind power. US$1 per watt for manufacturing cost of PV cell modules.

9 一度電 (1kWh) 知道電器的容量以後, 再乘上您使用它的時數, 便可算出度數 總容量 1kW 的燈具使用 1 個小時 (hour 簡稱 h), 就被定名為使用 1 度電 (1kW h=1kwh) 若 1kW 的器具使用 5 個小時, 就是用了 5 度電, 即 1kW 5h=5kWh 實際上, 1kW 和 1kWh 兩者僅差一個時間 (h), 但意思便完全不同 故言, 1kW 是指電力設備或器具的容量, 而 1kWh 是指電力設備或器具, 在使用 1 小時或若干小時後的電力使用量 這個電力使用量的單位, 就稱為 1 度電 (1kWh) 發 1 度的電會製造多少污染? 台灣整體的數字為,1 度電產生 公斤二氧化碳 ; 台電數字為 公斤 ( 燃煤廠 公斤 燃氣廠 公斤 燃油廠 公斤 ) 2009 年 07 月能源報導 - 封面故事三 : 一度電的話題撰文 : 張明生

10 Reaching Grid Parity in Taiwan A one-kilowatt PV system will produce 1500 kilowatt-hour (kwh) of electricity a year in Hualien (see peak sun hours data provided by central weather bureau). Over a 25 year lifetime, the system will produce about 37,500 kwh (not accounting for the small effects of system degradation, about 0.25% a year). If this system costs $3,000 to install ($3 per watt), the LCoE (levelized cost of electricity) = 3,000/37,500 ~= 8 cents per kwh. (NT$ 2.4 per kwh ( 每度電新台幣 2.4 元 ))

11 Monthly and Annual Peak Sun Hours in Taiwan

12 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

13 Types of Concentration Photovoltaics (CPVs) Low concentration PV (LCPV) PV are systems with a solar concentration of suns. For economic reasons, conventional or modified silicon solar cells are typically used. The heat flux is low enough that the cells do not need to be actively cooled. May not require active solar tracking. The laws of optics dictate that a solar collector with a low concentration ratio can have a high acceptance angle. Medium concentration PV From concentrations of 100 to 300 suns. The CPV systems require two-axes solar tracking and cooling (whether passive or active). High concentration photovoltaics (HCPV) HCPV systems employ concentrating optics consisting of dish reflectors or Fresnel lenses that concentrate sunlight to intensities of 1000 suns or more. The solar cells require high-capacity heat sinks to prevent thermal destruction and to manage temperature related electrical performance and life expectancy losses. Multi-junction solar cells are currently favored over single junction cells, as they are more efficient and have a lower temperature coefficient (less loss in efficiency with an increase in temperature). The efficiency of both cell types rises with increased concentration.

14 CPV v.s. CSP CPV directly competes with concentrated solar power (CSP) as both technologies are suited best for areas with high direct normal irradiance. Currently, CSP is far more common than CPV. CPV uses the photovoltaic effect to directly generate electricity from sunlight. CSP often called concentrated solar thermal uses the heat from the sun's radiation in order to make steam to drive a turbine, that then produces electricity using a generator.

15 Concentrated Solar Power (CSP) Plant

16 Concentrated Solar Power (CSP) Plant

17 Related Technologies Luminescent solar concentrators They are composed of luminescent plates either totally impregnated by luminescent species or fluorescent thin films on transparent plates. They absorb solar light which is converted to fluorescence guided to plate edges where it emerges in a concentrated form. No dish reflectors or Fresnel lenses are required. The concentration factor is directly proportional to the plate surface and inversely proportional to the plate edges. The fluorescent concentrator is able to concentrate both direct and diffuse light which is especially important on cloudy days. They also don't need expensive Solar trackers. Concentrated photovoltaics and thermal (CPVT) Also sometimes called combined heat and power solar (CHAPS), is a cogeneration or micro cogeneration technology used in concentrated photovoltaics that produces both electricity and heat in the same module. CPVT at suns utilizes similar components as CPV, including dual-axis tracking and multi-junction photovoltaic cells. A fluid actively transports the collected heat and simultaneously cools the integrated thermal+photovoltaic receivers. An array of receivers and a heat exchanger operate within a closed thermal loop.

18 Luminescent Solar Concentrators

19 CPV Heat Sink Design Thermal Animation This 240 x 80 mm 1,000 suns CPV heat sink design thermal animation, was created using high resolution CFD analysis, and shows temperature contoured heat sink surface and flow trajectories as predicted. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.

20 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

21 Concentration Photovoltaics (CPV) System 白益豪教授

22 CPV Optics

23 Idea of CPV Concentrator photovoltaic (PV) systems use less solar cell material than other PV systems. PV cells are the most expensive components of a PV system, on a per-area basis. A concentrator makes use of relatively inexpensive materials such as plastic lenses and metal housings to capture the solar energy shining on a fairly large area and focus that energy onto a smaller area the solar cell. One measure of the effectiveness of this approach is the concentration ratio in other words, how much concentration the cell is receiving.

24 CPV System Assembly Concentrating lens Heat dissipation Receiver Module

25 Receiver Module

26 Receiver Module Secondary optics Solar cell chip Solder Electrical Connector Copper heat spreader and electrical contacts Solar cell module housing Conductive adhesive Heat sink

27 Advantage and Disadvantage Remedies Concentrator PV systems have several advantages over flat-plate systems. First, concentrator systems reduce the size or number of cells needed and allows certain designs to use more expensive semiconductor materials which would otherwise be cost prohibitive. Second, a solar cell's efficiency increases under concentrated light. How much that efficiency increases depends largely on the design of the solar cell and the material used to make it. Third, a concentrator can be made of small individual cells. This is an advantage because it is harder to produce large-area, high-efficiency solar cells than it is to produce small-area cells. However, challenges exist for concentrators. First, the required concentrating optics are significantly more expensive than the simple covers needed for flat-plate solar systems, and second, most concentrators must track the sun throughout the day and year to be effective. Thus, achieving higher concentration ratios means using not only expensive tracking mechanisms but also more precise controls. Both reflectors and lenses have been used to concentrate light for PV systems. Third, high concentration ratios also introduce a heat problem. When solar radiation is concentrated, so is the amount of heat produced. Cell efficiencies decrease as temperatures increase, and higher temperatures also threaten the long-term stability of solar cells. Therefore, the solar cells must be kept cool in a concentrator system, requiring sophisticated heat sync cooling designs.

28 Special Design of Prismatic Covers One of the most important design goals of concentrator systems is to minimize electrical resistance where the electrical contacts on the cell carry off the current generated by the cell. A pattern using wide grid lines, known as fingers, in the contacting grid on top of the cell are ideal for low resistance, but they block too much light from reaching the cell because of their shadow. One solution to the problems of resistance and shadowing is prismatic covers. These special covers act like a prism and direct incoming light to parts of the cell's surface that are between the metal fingers of the electrical contact grid. Another solution is a back-contact cell, which differs from conventional cells in that both the positive and negative electrical contacts are on the back. Placing all the electrical contacts on the back of the cell eliminates power losses from shadowing, but it also requires exceptionally good-quality silicon material

29 Fingers on top of the cell World Record Solar Cell with 44.7% Efficiency Press Release 22/13, September 23,

30 Busbar and Fingers

31 Module Assembly and Cell Assembly A typical concentrator unit consists of a lens to focus the light, a cell assembly, a housing element, a secondary concentrator to reflect off-center light rays onto the cell, a mechanism to dissipate excess heat produced by concentrated sunlight, and various contacts and adhesives.

32 Module Assembly and Cell Assembly Rather than using millimetre-wide busbars on the front surface of the solar cell, SmartWire forms electrical connections by use of a polymer laminate sheet prepatterned with a multitude of thin copper wires. These narrow copper wires, which are in the order of tens of micrometres wide, effectively conduct electricity generated by the cell whilst also reducing the shading caused by the metal on the front surface. And less shading means more electricity generation.

33 Prismatic Cover Aligned with Fingers

34 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

35 Commercial Receiver Module Example This 10mm*10mm HCPV Cell produced in and Fotrousi Electronics claimed that generate Watt in 1100 sun.

36 Receiver Module without Bypass Diode

37 Receiver Module with Bypass Diode protective bypass diodes CTJ RECEIVER 10mm x 10mm CTJ RECEIVER 5.5mm x 5.5mm

38 Protective Bypass Diodes The basic function of bypass diodes in solar cells is to protect against hot spot damage when the photovoltaic panel is partially shaded by snow, fallen leaves, or other obstructions.

39 Mounting of Secondary Optics

40 Mounting of Secondary Optics

41 Mounting on Heat Sink (Passive) Triple junction high efficiency solar cell SOE/ HCPV cell / heat-sink

42 CPV Module Viewing of receiver module through primary concentrating lens in the CPV module

43 CPV Module Viewing of receiver module through primary concentrating lens in the CPV module

44 A Complete Set of CPV Module

45 Backside Heat Sink

46

47 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

48 Types of Concentrating Optics Reflexives Refractive Lenses used in the CPV industry can be either reflexives (mirrors) or refractive (Fresnel lenses) and these elements are usually referred to as primary lens.

49 From: Recent trends in concentrated photovoltaics concentrators architecture Figure Legend: Fresnel lenses and parabolic reflectors are the classical concentrators in concentrated photovoltaics. Date of download: 3/25/2015 Copyright 2015 SPIE. All rights reserved.

50 Reflection Mirror Single Reflection Double Reflection SolFocus Gen1 Mini-dish

51 Single Reflection Example Wednesday, April 24, 2013 IBM Concentrated PV Thermal Solar system achieves 80% energy efficiency

52 Beam Path Description for Double Reflection 1) The primary mirror reflects sunlight to toward the secondary mirror. 2) The secondary mirror reflects sunlight toward the optical rod. 3) The optical rod concentrates the sunlight. 4) The solar cell receives the concentrated sunlight and turns it into electricity.

53 Beam Lines for Double Reflection

54 Converging Lens Conventional Fresnel

55 Schematics of Fresnel Lens

56 Design of Fresnel Lens

57 Fresnel Lens Example Insulation of module

58 Specialties of Fresnel Lens 1. Low cost 2. Low weight and availability in large sizes 3. Being generally equivalent to PCX (Plano-Convex) lenses Spherical aberration can be reduced by design 1. they can be used for collimating beams of light 2. intercepting and focusing light from a distant source onto an optical detector.

59 4. 聚光型太陽能電池 1. 組成系統 2. 電網等價 3. 聚光型太陽能電池分類 4. 電池模組結構說明 5. 電池模組結構分項說明 1. 太陽能電池晶片模組 2. 聚光鏡 ( 首次光件 ) 3. 均光鏡 ( 二次光件 )

60 Second Optical Element (SOE) Concentrated Photovoltaics principle by use of a refractive lens. Different SOE designs mounted on multi-junction cells. The system usually also has a second optical element (secondary lens or SOE) which is attached onto the cell. Its mission, amongst others, being to (1) increase the numerical aperture of the set whilst at the same time (2) ensuring a uniform distribution of the energy from the cell, which prevents the generating of hot spots on it.

61 Numerical Aperture a b c N. A. a c a b Numerical Aperture (NA) = n(sin )

62 Homogeneizers Serves the Purpose of SOE A CPV system using a mirror (primary optic) for sunlight concentration showing a homogenizer (secondary optic) as well as the solar cell (left). Illustration of two possible models of homogenizers (right) (Source: Schott) A homogenizer made out of N-BK7 for CPV

63 SOE required When Tracking the Sun

64 Köhler Integrator