Photovoltaic technology

Photovoltaic technology is particularly suitable for small power requirements and remote area applications. The provinces of Sindh and Balochistan, and the Thar Desert are specially suited for the utilization of solar energy through photovoltaics. Balochistan, the largest province of Pakistan area-wise, has a population density of just 21 persons per square kilometer, with 77% of the population living in rural areas. About 90% of the villages are yet to be electrified. Large distances with absolutely no approach roads separate these villages. The houses are mostly 'kacha' hut type with walls and roofs made with a combination of mud and straw. Light is the main requirement for these houses. Most of the houses consist of only one room. The electric requirement for each house varies from 50 to 100 W maximum. Transmission lines are very expensive to build in these areas and there is only a remote possibility of grid connection in the near future. Also, the extension of grid lines for such small power requirements is very uneconomical. Local power generation is a possible solution to these problems. When considering diesel generators, transportation of fuel to such remote areas and maintenance are again a costly proposition, therefore, solar energy looks like the best (and only) option for these areas.

In Photovoltaic technology PCRET has photovoltaic device fabrication facilities. Six main labs have been established within PCRET. These Labs are:

 

 

The Crystal Growth Lab is equipped with two Czochralski Crystal Puller of Model CG 300 and CG 6000 from Hamco USA. Silicon Single Crystal ingots of diameter 4” to 6” can be grown in this Lab. Photograph of the systems is given at Fig(1). The grown ingots are sliced in wafering Lab which is equipped with ID Saw, Wire Saw, Squarer and Cutter machinery as shown in Fig (2) to (5)

 

The Silicon cut Wafers are then processed in the cell fabrication lab for making of Solar Cells. For this purpose etching, polishing, junction, formation, alloying, masking and contact making are performed in this Lab. Some of the systems/equipments of cell processing Lab are shown in Fig (6) to (9). In this Lab heat resistive and electron beam high vacuum systems are also available, which can be used to grow thin films for research study and making of thin films solar cells Fig (10)

 

The fabricated solar cells are interconnected in the lamination Lab for PN module making. Three (03) Laminations are available in the Lamination Lab to produce Photovoltaic Panels of various dimension and ratings, Fig (11) to (12). Solar cells can be cut to small pieces using Nd-YAG laser cutter for fabrication of small size solar panels for low power applications. The facility of Laser cutter exists within Photovoltaic Division Fig (13).

 

The cells and PV Panels are tested in Test and Measurement Lab as per International Standards. The Following facilities exist within this Lab (14) & (15).

 

§  Solar Cell Testing

§  Photovoltaic PV Panel Indoor Testing

§  Photovoltaic PV Array Outdoor / Field Testing

§  PV Panel Environmental Testing

§  PV Panel Insulation Testing

§  Solar Cell Contact Adhesion Testing

§  Inverter Testing

§  Battery Testing

§  Solar Flat Plate Collector Testing

§  Solar Water Heater Testing

 

Whereas in the Analysis Lab, the spectroscopic analysis of the semiconductor and other geological materials is done for detection of metallic and non metallic impurities up to the level of parts per million (PPM) and parts per billion (PPB) level. The Lab is equipped with Inductively Coupled Plasma (ICP) Spectrometer and Gas Chromatograph (GC). ICP detects impurities using options of Atomic Absorption, Atomic Emission and Flameless Techniques whereas gas chromatograph GC analyses gases using FID and TCD detectors. The photograph of such systems installed within PCRET analysis Lab are shown in Figs (16) & (17).