This article continues a series of stories about the production of components for the solar industry, which began in the article «The basic technology of silicon photovoltaic cells». Today we look at a typical manufacturing process of solar cells based on crystalline silicon photovoltaic cells (solar cells).
Solar modules (or as they are often called — solar panels) are an essential component for the construction of solar power plants. The technical parameters of solar modules depends, how much electricity will be able to get from a unit area, how long it will last and what will have to bear the costs. To date, the price of solar panels world-wide are gradually lower, which in no small measure contributes to the improvement of technological processes and the transition from manual operation to automatic operation. Achieving equality of prices for electricity generated from renewable sources, and electricity generated from traditional sources — the main goal of the whole industry.
Production of solar panels a includes number of technological operations: Soldering photovoltaic cells in accordance with a predetermined electrical switching circuit, sealing of FEP in laminate, mounting frame and junction box testing. Overall block diagram of an exemplary production process of solar modules is given below.
As with any production, manufacture of solar cells begins with the input control and the preparation of materials and components. Also in the production of photovoltaic cells used glass, copper bars, fluxes, protective and adhesive films, wires, connectors, switching boxes, protection diodes, aluminum profiles and other materials. Thereafter, in a special way to enter sorted solar cells assembly operation using tabbers/stringers, i. e. equipment on which occurs first soldering to top and front contact solar cells pre- tinned copper straps, and then — a serial connection of these solar cells into strings (strings) required length.
In the next step is carried out series-parallel connection previously prepared solar cell’s chains in a matrix (e. g., the size of 6×10 cells) and formed a «sandwich» consisting of glass, pre-cutted film sealing material (EVA), photovoltaic cells, a second layer of sealant and back protection module (Tedlar). In fact, at this stage the internal circuitry of the solar module and its value is determined by the operating voltage and operating current.
After assembly of all components of the resulting semi-finished solar module is tested for the absence of gaps and the circuit enters the seal at a high temperature and a pressure. This operation is called lamination, and semi-finished product, resulting in its result — laminate.
Prepared in the previous stages laminate is already capable of generating electrical energy, but still not a final product. To complete the production of the frame must be installed around the perimeter of the solar module and mount the connecting junction box. These operations can be carried out both manually and by means of special robotic systems:
Testing of the finished solar module includes definitions and measurement of electrical parameters of voltage breakdown. As testers can be used as a compact device like the one shown in the figure below, and specially equipped workshop premises in which the ultra-precise set simulators solar radiation with the required characteristics. After testing the finished solar modules are sorted by class products, packaged and fed smoothly or sent to the consumer.
Like any process, manufacturing solar panels is quite a lot of nuances and technological «know-how». It is very important how carefully comply with the requirements in the production technology, input and conducted interim controls which photovoltaic cells, and other materials and equipment used , and how likely the intervention of the «human factor». In the recent trend for consolidation of factories to produce solar cells. A typical semi-automatic production line has an annual capacity of about 30 MW. And the world’s largest manufacturers moved their assembly lines in Asia and increase performance up to hundreds of megawatts per year. Their products undergo the strictest quality control and certified to comply with international quality standards. All this creates a very unfavorable conditions for smaller manufacturers, but generally lower the cost of solar cells and reduce the cost of «solar» power .