Laser grooved buried contact (LGBC) solar cell technology is an attractive method for the product... more Laser grooved buried contact (LGBC) solar cell technology is an attractive method for the production of solar cells designed to operate at one sun, and at low to medium concentration. This is mainly due to the low shading of the solar cell front by the grid contact and the front selective emitter under it, which ensures better collection for the short wavelength light. However, compared to standard screen printed solar cells, LGBC cells have a higher efficiency but require a more complex manufacturing process. As part of the EU funded project, "Lab2Line" we are marrying the screen printed and LGBC solar cell processing techniques in order to produce high efficiency 1 sun solar cells on large area (125x125 mm) wafers at the lowest cost. A fine line, screen printing technology has been used previously [1, 2, 3] along with LGBC processes to produce solar cells on multicrystaline Si. Using improved processing steps, this project aims to produce industrially scalable production of high efficiency, fully Screen Printed, Laser Grooved, Buried Contact Solar Cells (SPBCSCs) on large area monocrystalline wafers.
Laser Grooved Buried Contact (LGBC) solar cell technology is an attractive way for the production... more Laser Grooved Buried Contact (LGBC) solar cell technology is an attractive way for the production of solar cells designed to operate at one sun. Although LGBC cells can have higher efficiency when compared to standard screen-printed solar cells, a more complex manufacturing process is required, increasing their relative costs. In the FP6 EU funded project “Lab2Line,” screen print and LGBC solar cell processing techniques are hybridized in order to produce lower cost high efficiency solar cells processed on large area mono-crystalline wafers, using techniques scalable to industry. Two hybrid approaches have been considered: in the first, screen-print (SP) is applied for both rear and front contacts; in the second process SP is applied only to the rear and then electroless plating is used to form the front contacts. Both Lab2Line hybrid approaches offer high average efficiencies with a small performance distribution, while simultaneously presenting a more compact, cost effective optio...
Silicon solar cells for concentrator applications tend to be small in size due to the use of ligh... more Silicon solar cells for concentrator applications tend to be small in size due to the use of light focusing optics and minimization of material usage. As cells become smaller, isolation of cells at their edges therefore becomes relatively more important in terms of both accuracy and cell performance. A novel isolation technique designed to address these issues is presented, and demonstrated with LGBC cells (Laser Grooved Buried Contacts) manufactured in the Narec pilot production line. As concentration is increased, cells with our Front Dicing Technique (FDT) increasingly outperform cells having our standard isolation thanks to gains in VOC and FF. Internal Quantum Efficiency (IQE) remains high at short wavelengths and is improved in the long wavelength region. There is no net increase in the number of processing steps and no additional resource consumption, therefore providing an easily implemented route to reducing cost per Watt.
The use of photovoltaic modules in architectural applications is now firmly established and large... more The use of photovoltaic modules in architectural applications is now firmly established and large modules of glass-glass construction produced specifically for the BIPV market are available. However, the range of solar cell colours and shapes currently offered by suppliers is still very limited and this is a barrier to the widespread use of PV modules as constructional components. Initial investigations of the colour and efficiency of Laser Grooved Buried Contact (LGBC) solar cells as a function of the thickness of the LPCVD silicon nitride antireflection coating were reported in the late 1990s, but the subsequent commercialisation of coloured cell products has been limited in part by the difficulty in controlling the uniformity and reproducibility of colour in large scale cell production. The aim of the present work is to understand and control the processes that affect the thickness and hence colour of the silicon nitride ARC. Process conditions were optimised to enable the formation of antireflection coatings with thicknesses in the range 90 nm to 400 nm. LGBC solar cells were fabricated in 5 colours on both non-textured Cz and partially textured multicrystalline wafers. Good uniformity of colour was achieved both across individual cells and throughout whole process runs. Laser scribing was used to produce cells in a range of shapes which, in conjunction with the choice of colours, demonstrates the potential for novel BIPV applications.
The laser grooved, buried grid solar cell made in a production facility with silicon CZ wafers ha... more The laser grooved, buried grid solar cell made in a production facility with silicon CZ wafers had previously demonstrated efficiencies of over 18% at 19× concentration. Recent work has succeeded in reducing the cell series resistance and efficiencies of 20.1% (38 cm2) at 10 Suns and 19.8% at 20 Suns have been achieved. Efficiency in the best solar cell has been maintained to over 18% at 40×
... mm) and sup-w U Thermocouple and disc I Slip ring support assembly Platinum crucible I -w IR ... more ... mm) and sup-w U Thermocouple and disc I Slip ring support assembly Platinum crucible I -w IR Platinum disc Heating by rf Liquid (BSO) 205 Fixed thermocouples I---Top (Ct ) I---Middle (Cm) ~--- Bottom (Cb) Centre (Ca) Fig. 1. Basic apparatus and notation. 206 PAC Wbiffin et ...
Single crystals of Bi4Ti3O12 are required for a number of devices. To obtain crystal plates of 1 ... more Single crystals of Bi4Ti3O12 are required for a number of devices. To obtain crystal plates of 1 mm or greater, a seeded solution technique was tried. A novel method of saturating and seeding the solution at constant temperature was evolved and a change in morphology at low temperatures was discovered. Other fluxes have been investigated of which bismuth borate was the best and a study of the phase diagram has been made.
... [5] 0.F. Hill and JC Brice, J. Mater. Sci. 9 (1974) 1252. [6] EM Levin and RS Roth, J. Res. N... more ... [5] 0.F. Hill and JC Brice, J. Mater. Sci. 9 (1974) 1252. [6] EM Levin and RS Roth, J. Res. Nat!. Bur. Std. US 68A(1964) 197. 20 [7] GM Safronov, VN Batog, TV Stepanyuk and PM Fedorov,Russ. J. Inoig. Chem. 16 (1971) 460. [8] EM Levin and CL McDaniel, J. Am. Ceram. Soc. ...
This study compares the energy output of two types of crystalline silicon modules on continuous o... more This study compares the energy output of two types of crystalline silicon modules on continuous outdoor testing with the projected performance from RRC calculations based on a detailed characterisation of the test modules. Both module types, made using screen printed grid and laser grooved buried grid cells, gave high specific annual DC energy output exceeding 1000 kWh/kWp at the test
Laser grooved buried contact (LGBC) solar cell technology is an attractive method for the product... more Laser grooved buried contact (LGBC) solar cell technology is an attractive method for the production of solar cells designed to operate at one sun, and at low to medium concentration. This is mainly due to the low shading of the solar cell front by the grid contact and the front selective emitter under it, which ensures better collection for the short wavelength light. However, compared to standard screen printed solar cells, LGBC cells have a higher efficiency but require a more complex manufacturing process. As part of the EU funded project, "Lab2Line" we are marrying the screen printed and LGBC solar cell processing techniques in order to produce high efficiency 1 sun solar cells on large area (125x125 mm) wafers at the lowest cost. A fine line, screen printing technology has been used previously [1, 2, 3] along with LGBC processes to produce solar cells on multicrystaline Si. Using improved processing steps, this project aims to produce industrially scalable production of high efficiency, fully Screen Printed, Laser Grooved, Buried Contact Solar Cells (SPBCSCs) on large area monocrystalline wafers.
Laser Grooved Buried Contact (LGBC) solar cell technology is an attractive way for the production... more Laser Grooved Buried Contact (LGBC) solar cell technology is an attractive way for the production of solar cells designed to operate at one sun. Although LGBC cells can have higher efficiency when compared to standard screen-printed solar cells, a more complex manufacturing process is required, increasing their relative costs. In the FP6 EU funded project “Lab2Line,” screen print and LGBC solar cell processing techniques are hybridized in order to produce lower cost high efficiency solar cells processed on large area mono-crystalline wafers, using techniques scalable to industry. Two hybrid approaches have been considered: in the first, screen-print (SP) is applied for both rear and front contacts; in the second process SP is applied only to the rear and then electroless plating is used to form the front contacts. Both Lab2Line hybrid approaches offer high average efficiencies with a small performance distribution, while simultaneously presenting a more compact, cost effective optio...
Silicon solar cells for concentrator applications tend to be small in size due to the use of ligh... more Silicon solar cells for concentrator applications tend to be small in size due to the use of light focusing optics and minimization of material usage. As cells become smaller, isolation of cells at their edges therefore becomes relatively more important in terms of both accuracy and cell performance. A novel isolation technique designed to address these issues is presented, and demonstrated with LGBC cells (Laser Grooved Buried Contacts) manufactured in the Narec pilot production line. As concentration is increased, cells with our Front Dicing Technique (FDT) increasingly outperform cells having our standard isolation thanks to gains in VOC and FF. Internal Quantum Efficiency (IQE) remains high at short wavelengths and is improved in the long wavelength region. There is no net increase in the number of processing steps and no additional resource consumption, therefore providing an easily implemented route to reducing cost per Watt.
The use of photovoltaic modules in architectural applications is now firmly established and large... more The use of photovoltaic modules in architectural applications is now firmly established and large modules of glass-glass construction produced specifically for the BIPV market are available. However, the range of solar cell colours and shapes currently offered by suppliers is still very limited and this is a barrier to the widespread use of PV modules as constructional components. Initial investigations of the colour and efficiency of Laser Grooved Buried Contact (LGBC) solar cells as a function of the thickness of the LPCVD silicon nitride antireflection coating were reported in the late 1990s, but the subsequent commercialisation of coloured cell products has been limited in part by the difficulty in controlling the uniformity and reproducibility of colour in large scale cell production. The aim of the present work is to understand and control the processes that affect the thickness and hence colour of the silicon nitride ARC. Process conditions were optimised to enable the formation of antireflection coatings with thicknesses in the range 90 nm to 400 nm. LGBC solar cells were fabricated in 5 colours on both non-textured Cz and partially textured multicrystalline wafers. Good uniformity of colour was achieved both across individual cells and throughout whole process runs. Laser scribing was used to produce cells in a range of shapes which, in conjunction with the choice of colours, demonstrates the potential for novel BIPV applications.
The laser grooved, buried grid solar cell made in a production facility with silicon CZ wafers ha... more The laser grooved, buried grid solar cell made in a production facility with silicon CZ wafers had previously demonstrated efficiencies of over 18% at 19× concentration. Recent work has succeeded in reducing the cell series resistance and efficiencies of 20.1% (38 cm2) at 10 Suns and 19.8% at 20 Suns have been achieved. Efficiency in the best solar cell has been maintained to over 18% at 40×
... mm) and sup-w U Thermocouple and disc I Slip ring support assembly Platinum crucible I -w IR ... more ... mm) and sup-w U Thermocouple and disc I Slip ring support assembly Platinum crucible I -w IR Platinum disc Heating by rf Liquid (BSO) 205 Fixed thermocouples I---Top (Ct ) I---Middle (Cm) ~--- Bottom (Cb) Centre (Ca) Fig. 1. Basic apparatus and notation. 206 PAC Wbiffin et ...
Single crystals of Bi4Ti3O12 are required for a number of devices. To obtain crystal plates of 1 ... more Single crystals of Bi4Ti3O12 are required for a number of devices. To obtain crystal plates of 1 mm or greater, a seeded solution technique was tried. A novel method of saturating and seeding the solution at constant temperature was evolved and a change in morphology at low temperatures was discovered. Other fluxes have been investigated of which bismuth borate was the best and a study of the phase diagram has been made.
... [5] 0.F. Hill and JC Brice, J. Mater. Sci. 9 (1974) 1252. [6] EM Levin and RS Roth, J. Res. N... more ... [5] 0.F. Hill and JC Brice, J. Mater. Sci. 9 (1974) 1252. [6] EM Levin and RS Roth, J. Res. Nat!. Bur. Std. US 68A(1964) 197. 20 [7] GM Safronov, VN Batog, TV Stepanyuk and PM Fedorov,Russ. J. Inoig. Chem. 16 (1971) 460. [8] EM Levin and CL McDaniel, J. Am. Ceram. Soc. ...
This study compares the energy output of two types of crystalline silicon modules on continuous o... more This study compares the energy output of two types of crystalline silicon modules on continuous outdoor testing with the projected performance from RRC calculations based on a detailed characterisation of the test modules. Both module types, made using screen printed grid and laser grooved buried grid cells, gave high specific annual DC energy output exceeding 1000 kWh/kWp at the test
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