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PLANAR MULTIJUNCTION HIGH VOLTAGE SOLAR CELLS ( NASA-TN-81389 ) PLANAR ULTIJUCTIOi HIGH NBO-16914 VOLTAGE SOLAr CELLS ( NASA ) 10 p , HC A 02 / MF A 01 CSCL 20
| Content Provider | Semantic Scholar |
|---|---|
| Author | Unclas |
| Copyright Year | 2010 |
| Abstract | further reduces high temperature effects in these cells. This paper presents technical considerations, preliminary results, and fabrication details on a However, while these cell structures share new family of high-voltage Planar Multi-junction many good features, each'structure suffers from its (PMJ) solar cells. The new cells combine the atown drawbacks. None of these structures is a high tractive features of planar cells with conventional voltage cell on a single substrate with the advan or interdigitated back contacts and the Vertical tage of simple fabrication. The IBC and the TJC g Multijunction (VMJ) solar cell. The PMJ solar cell are not high-voltage solar cells, the VMJ is not a is internally divided into many voltage-generating planar device on a single substrate, the HMJ is regions, called unit cells, which are internally felt to involv6 a fairly complex fabrication pro connected in series. The key to obtaining reasoncess and the VCGMJ ends up having physically sepa able performance from this device was the separarate semiconductor unit cells held together on a tion of top surface field regions over each active glass plate. unit cell. Using existing solar cell fabricating methods, output voltages in excess of 20 volts per It is the purpose of this paper to present linear centimeter are possible. Analysis of the preliminary experimental results on a new cell, the new device is complex, and numerous geometries are Planar Multijunction (PMJ). This new device is not being studied which should provide substantial only a high voltage solar cell fabricated on a sin benefits in both normal sunlight usage as well as gle semiconductor substrate, but it is also ex with concentrators. pected to share the good features common to the previous structures, such as elimination of losses due to gridshadowing, reduction of the sheet re sistance component of series resistance, and reducINTRODUCTION tion of high temperature effects. Also, the rela tively simple geometry of the PMJ solar cell should In a number of existing and future applicaallow for a simple fabrication process using stan tions of photovoltaic systems, one can see the dedard integrated circuit techniques. sirability of having solar cells which can provide two orders of magnitude higher voltages, while still retaining the characteristics of present PRELIMINARY DESIGN CONSIDERATIONS wafer devices. Other desirable features include simplicity of fabrication, ease of interconnection Figure 1 shows the PMJ cell in schematic and panel assembly, ready bonding of cover glasses cross-section. The illuminated top surface area is for space usage, and reduced losses due to grid divided into several field regions corresponding to shadowing, series resistance and high temperature. the unit cells positioned beneath. These unit voltage-generating cells are electrically connected Various innovative designs such as the Interin series within the wafer. A number of alternate digitated Back Contact (IBC) solar cell (1), the concepts are being considered'including the inTandem Junction Cell (TJC) (2), the Vertical Multiverted structure of that shown in Figure 1, a cell junction (VIJ) solar cell (3), the Horizontal with unit cells both top and bottom, and a concenMultijunction (HMJ) solar cell (4), and the tric unit cell device with center and perimeter V-Groove Multijunction (VGMJ) solar cell (5), have output pads, which may be used with sunlight con been proposed to reduce or eliminate losses due to centrators, and a six unit cell device containing grid-shadowing and the sheet resistance component circuitry for alternating current output. of series resistance. Also, all cells except the IBC and the TJC operate as high-voltage, lowcurrent Because we have not developed the mathematical devices and further reduce series resistance as theory completely for this device, it is not pres well as temperature effects due to 1R heating. ently possible to optimize geometric and material Significant transparency to infrared photons design parameters. However, some preliminary de sign values of key parameters may be obtained from *NASA-ASEE Faculty Fellow, Cleveland State physical considerations and from theory developed University, Cleveland, Ohio 44115. from a somewhat similar structure, the TJC (2). In REPR'-ODUCBILTTY OF TH OIGINL PAGE IS POOR Figure 1, W is the width of the unit voltagegenerating cell, while the subscripts refer to the respective widths of the n and p+ doped regions and the gap separating them. The implanted or diffused metal interconnection bar is intended to be as narrow as possible, but its exact dimensions are not presently known, From simple physical considerations the longest path which a photo-generated electron needs to travel'in order to be collected is approximately: |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800008654.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
