Solar energy is widely accepted as being an excellent source of renewable energy. Photovoltaic (PV) cells which can convert sunlight into electricity have been studied for the past ˜70 years. The adoption and wide spread use of PV cells has been slow because they have exhibited poor conversion efficiency and have been expensive to manufacture. Therefore, the economics ($/Watt) of using PV cells to generate electricity have not been competitive with traditional sources such as coal, oil, natural gas, etc. The $/Watt metric represents the total system cost to generate a Watt of energy. Lower PV solar cell efficiencies and higher PV solar cell system costs increase this metric and lowers the competitiveness of the PV solar cell system relative to traditional energy generation systems.
Recent advances in the design and manufacture have improved the efficiency of the PV solar cells and lowered the manufacturing cost such that PV based solar energy systems have improved economics. It is a goal that PV based solar energy systems will be able to generate electricity at costs that are competitive with traditional electricity generation methods in the near future. For this goal to be realized, advances must be made to continue to improve the conversion efficiency of the PV solar cells and to lower the manufacturing costs.
In the manufacture of PV solar cells or TF modules, substrates are often processed in equipment configured in an “in-line” structure. That is, the substrates move through the equipment in a continuous manner or in small steps. The input portion of the equipment is positioned at one end of the system and the output portion is positioned at the opposite end. This type of equipment is to be distinguished from “batch” systems wherein the substrates are generally processed in large batches and the input and output portions of the equipment are generally found at the same end of the system. In the in-line equipment, an automation system is used to translate the substrates from the input end to the output end. The automation system may comprise a conveyor, a belt, discrete pallets, rollers, a “walking beam” system, chains, strings, or cables, among others.
Current in-line equipment for the manufacture of PV based solar cells or TF modules suffer from a number of problems. Examples of these problems may be high equipment cost, low throughput, large footprint, poor performance, contamination of the substrate by the automation system, shadowing of the backside of the substrate by the automation system, movement of the substrate during processing, and others. These problems may act individually or in combination to lower the efficiency of the PV solar cells or TF modules or increase the cost of manufacturing the PV solar cells or TF modules. This will increase the $/Watt economic metric used to evaluate energy system performance and slow the adoption of PV solar energy systems. Therefore, there is a need for automation systems to be used in in-line equipment used to manufacture PV solar cells or TF modules that address these problems.