Solar modules efficiency

The flexible solar module based on monocrystalline silicon cells with higher efficiency than thin film solar cells was developed in the VIESH. For example, the folding solar module 36/1-6-P depicted at FigurelO supplies 10W, output voltage 16V, and short circuit current, 0.7A under standard conditions of measurements. His dimensions are 395 x 370 x 4 mm and in the folded condition practically 6 times less by surface (135 x 185 x 12 mm). This folding solar module can be used for applications which small consuming equipment. 

The power output of solar modules is expressed in terms of their "peak" power output (Wp). This is the amount of electric power that a module generates when it receives 1.0 kW/m2 of vertical solar irradiation at 25°C module temperature (also called one sun). Therefore, a 10% efficient module receiving one sun, will produce 100 Wp/m2. If this solar irradiation exists for 8 hours per day, this module will generate 0.8 kWh/m2/day. Naturally both the number of sunny hours of the day and the intensity of insolation vary (see Figures 1.29 and 1.30 and www.bpsolar.com). In addition the angle of irradiation and/or cell temperature can also be less than optimum. 

Modules In 1993 already, the Siemens group was the first group to deposit successfully amorphous silicon (a-Si H) solar modules on ZnO layers grown by the CVD method. They reported [77] modules of 1 x 1 ft2 with an initial efficiency of 10.7% and a stabilized efficiency of 8.4%. 

The comparison demonstrates the potential of the a-Si H/pc-Si H tandem cell technology on textured ZnO coated glass substrates for highly efficient large area thin film solar modules. However, the transfer of the technology... 

Fig. 8.6. Aperture area efficiency of different silicon thin film solar modules (aperture area 8 x 8 cm2) as function of light exposure time. The a-Si 11/pc-Si H tandem and i< -Si H single junction solar modules on texture etched ZnO Al were prepared at the FZJ, the a-Si H/a-Si H tandem solar module was cut from an industrially produced (0.6 m2) module...

A necessary prerequisite for high module efficiencies is the uniform distribution of material and cell properties on the substrate to avoid power losses due to averaging effects. The total area of solar modules is divided into cell strips, which are interconnected by a sequence of deposition and cutting steps. Figure 8.11 illustrates the structure for series-connection in thin film silicon... 

Fig. 8.12. Calculated active area (gray) and aperture area efficiencies (black) of a-Si 11/jLif- Si 11 tandem solar modules as function of cell width for different TCO sheet resistance values Rtco 5 0 (dashed), 10O (solid), and 20 0 (dotted)...

The best stabilized cell efficiencies on ZnO Al obtained at the FZJ in a PECVD reactor for 30 x 30 cm2 substrates were 8.0, 8.9, and 11.2% for a-Si H p-i-n, )LLc-Si H p-i-n, and a-Si H/)j,c-Si H tandem cells, respectively [152], The best initial efficiency for pc-Si H single junction solar cells was achieved by Mai et al., who reached 10.3% for an absorber layer thickness of 1.6 J,m, which was deposited at a high deposition rate of 11 As-1 [153], Initial aperture area module efficiencies of 10.8 and 10.6% were achieved for a-Si H/pc-Si H tandem modules with an aperture area of 8 x 8 and 26 x 26 cm2, respectively [154,155]. The efficiency of the small area module stabilized at an efficiency of 10.1% after lOOOh of light soaking as confirmed by the National Renewable Energy Laboratory (NREL, see Fig. 8.29). 

In spite of its promise, the thin-film technology has been unable to reduce the cost of solar modules, owing to low deposition rates that have led to low capital utilization of expensive machines. The yields and throughputs have been low. These plants need better inline controls. In recent times, owing to manufacturing problems, some corporations have shut down their thin-film manufacturing facilities. Clearly, easier and faster deposition techniques leading to reproducible results are needed. Also, deposition techniques that would not result in a substantial drop in efficiency from laboratory scale to module scale are required. 

For photovoltaics the lion s share of GHG emissions is the result of electricity use during manufacturing. There is a wide variation in the results due to different factors, such as the quantity and grade of silicon, module efficiency and lifetime, as well as irradiation conditions. Recently calculated values of GHG emissions of different photovoltaic systems (mono-crystalline, polycrystalline, amorphous, and so on) lie between 20 and 140 g COj-eq/kWh (Pehnt, 2006 Fthenakis and Kim, 2007 Pacca et ah, 2007 Uchiyama, 2007 Weisser, 2007 Evans et ah, 2009). Solar thermal technologies such as parabolic trough emit around 15 g C02-eq/ kWhg (Pehnt, 2006). 

Research in the field of OPV based on small molecules or polymer/PCBM systems has developed tremendously within the past decade. Champion laboratory cells reaching efficiencies of 10% have been reported recently [132]. However, average solar cell efficiencies of optimized laboratory cells ranging in between 5 and 6% and PCE values of solar cell modules already commercially available on the market are usually lowered by a factor of about 2. 

MiaSole Achieves 15.7% Efficiency with Commercial-Scale GIGS Thin Film Solar Modules press release December 02, 2010 http //www.miasole.com/sites/ default/files/MiaSole release Dec 02 2010.pdf... 

First Solar Sets Another World Record for CdTe Solar PV Efficiency, 14.4 Percent Total Area Efficiency Module Confirmed by NREL (press release January 16, 2012) http //investor.firstsolar.com/ releasedetail.cfm ReleaseID=639463... 

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