FAQ - ECOPROGETTI - Specialist in photovoltaic production process

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Ecoprogetti answered your most common questions and gathered them in one place. If you can’t find the answer to your questions please send us an email, we’ll do our best to provide a proper answer to your query.

A standard solar panel consists of a layer of silicon cells, a metal frame (commonly aluminium), a glass casing, and various wiring to allow current to flow from the silicon cells.

Silicon is a nonmetal with conductive properties that allow it to absorb and convert sunlight into electricity. When light interacts with a silicon cell, it causes electrons to be set into motion, which initiates a flow of electric current.

This is known as the “photovoltaic effect”, and it describes the general functionality of solar panel technology.

The photovoltaic effect is a process that generates voltage or electric current in a photovoltaic cell when it is exposed to sunlight. It is this effect that makes solar panels useful, as it is how the cells within the panel convert sunlight to electrical energy. The photovoltaic effect was first discovered in 1839 by Edmond Becquerel.

When doing experiments involving wet cells, he noted that the voltage of the cell increased when its silver plates were exposed to the sunlight.
The general photovoltaic process, as described above, works through the following steps:

  1. The silicon photovoltaic solar cell absorbs solar radiation
  2. When the sun’s rays interact with the silicon cell, electrons begin to move
  3. Moving electrons creates a flow of electric current, captured by nodes and wiring in the panel
  4. Wires feed this direct current (DC) electricity to a solar inverter to be converted to alternating current (AC) electricity

The production of photovoltaic modules consists of a series of consecutive operations that can be performed by automatic machines dedicated to optimizing the single production phases that transform the various raw materials in a finished product.

The production phases are:

  1. Preparation of the raw material: In this first phase the various raw materials used for the assembly process are being checked and prepared. The glass has to be clean; the rolls of encapsulant and back sheet material must be cut to measure in quantities that correspond to the planned production; the solar cells can be checked with a dedicated sun simulator or with an EL tester to make sure they reflect the necessary quality standards.
  2. Tabbing and Stringing: The photovoltaic cells are placed in the tabber-stringer machine that interconnects the solar cells in series, by soldering a coated copper wire (ribbon) on the bus bars of the cells. This delicate operation creates the string that is the basic element which creates the electrical series of the photovoltaic module.
  3. Positioning of the strings on the glass: The strings of photovoltaic cells created by the stringer machine are automatically or manually positioned on the glass previously prepared with the first layer of encapsulant material. The machine that performs this operation in the PV module production line, called layup, can at the same time perform automatic quality controls on the solar cells.
  4. Bussing: In order to create an electrical circuit,  every piece of ribbon of the strings is soldered with the bus ribbon (thicker ribbon placed along the short side of the panel)  to create a connection between the strings. Also, this phase can be manual, atomatic (Automatic Bussing) or customized according to the desired final product. 
  5. Pre-lamination preparation: When the electrical circuit between all the strings of the cells is finished the second layer of encapsulation material is applied, followed by a foil of insulating material called back-sheet. The operator brings out the terminal ribbon that will be connected in a successive step with the junction box. At this point of the production process, since it is still possible to correct possible failures, it is important to perform some electrical tests and possibly also an electroluminescence test in order to verify that there are no short circuits or broken photovoltaic cells inside the module.
  6. Lamination: During the lamination process the multi-layer sandwich composed until now is transforming into one single unit thanks to the polymerization of the encapsulating material. Laminators developed for the photovoltaic industry are the machines performing this phase. These machines work at a high level of vacuum for a certain time at a certain temperature. The setting of the temperatures and the time is being defined by the encapsulating material used. The extraction of the air is a fundamental aspect to guarantee the quality and durability of the product. The photovoltaic modules that exit from the laminator are called laminates. Production lines with a high throughput often have cooling systems installed after the laminator to permit a quick cooling process without waiting times.
  7. Trimming: The trimming of the surplus material of encapsulant and back sheet that is left around the glass after the lamination process can be done manually with a safety knife and a turning table or automatically with a dedicated machine.
  8. Framing: The aluminium frames are filled with an even amount of silicone or the edges of the laminated panel can be taped to perform the framing process. Machines are available for each of these steps that can also be integrated into fully automatic solutions.
  9. Application of the J-Box: The last assembly phase consists of the application and the connection of the junction box. The process is done by attaching the j-box with a suitable silicone or glue on the back-sheet of the module and by making the electrical connection between the bus ribbon prepared before the lamination and the cables of the junction box. At the inside of the box, you can find by-pass diodes that protect the photovoltaic module when operating. After finishing this operation the module is cleaned.
  10. Final test: Once the assembly phases are finished, the PV module is controlled and tested. This phase is one of the most important steps because with these tests you measure the electrical output of the module and the product gains a commercial value. The measure is done by a sun simulator that can reproduce the spectrum of the sun and recreate any light conditions to measure the peak power of the module according to the norms.
    Normally after this test, the following operations follow:
    – Insulation and dielectric rigidity test called Hi-Pot;
    Electroluminescence test to verify the construction quality;
    Labelling of the module according to the chosen classification.

    At the end of this process, you obtain a photovoltaic module that is ready to be commercialized and installed on the field.

Ecoprogetti Srl offers equipment and accessories dedicated to each manufacturing step. Moreover, Ecoprogetti develops complete turnkey lines for the manufacturing of photovoltaic modules. Our packages consent to any company to start production of high-quality modules in a very short time. The package is composed according to the requirements of the customer and can be anything from a small semi-automatic solution to a high capacity fully automatic plant.

The environment for photovoltaic panel production doesn’t require to be dust proof like in medicinal production.

The temperature should be lower than 25° C (required by the encapsulants).

The humidity should be around 60% RH.

We recommend the usage of white lights (lights that don’t modify the appearance of what you watch). 

The ideal terrain should be plain and smooth, possibly covered with epoxy resin.

In order to be compliant with the auditors of the production line’s certification, the following Quality Testing Machines are a must:

  1. Sun Simulator (with calibration module)
    We advise the use of a very accurate LED Sun Simulator.
  2. Hi-pot tester (to check the electrical insulation of the PV panels).
  3. Gel content test kit (To guarantee that the many layers of the PV module remain sealed with time and that the lamination process was of good quality)
  4. Electroluminescence Tester (We highly advise to take advantage of the features of this machine to detect damages of the solar cells, such as micro-cracks which are invisible to the human eye)

The electrical heating makes temperature reach a very quick process, It can indeed be reached in about 20 minutes and the Electric laminator from Ecoprogetti is ready to work.

A soft start can be performed, doing so reduces the energy consumption of TIK. Compared to any oil laminator it consumes far less energy and it saves you the cost of an electrical cabinet

The laminators of Ecoprogetti enable fine control of the lamination areas through the thermocouples reading and PID calculation system (Proportional-Integral-Derivative).

The maintenance operations needed over the heating system are slim to none and the possibility to calibrate through a quick operation the readings of the thermocouples is all that is needed.

Great thermal elasticity of the laminator.
Possibility to work on thermal ramps with high gradients of temperature. This makes possible to use a wide range of recipes.

The Ecolam Series guarantees high durability and reliability of the heating elements (at least 10 years).

Ecoprogetti guarantees a temperature variation over the whole laminating area of less than 2 C°.

The system of the membrane manages to modulate, even with partial pressures, the level of vacuum.

Ecoprogetti electric laminator can laminate modules of a wide variety of typologies, from flexible panels to glass-glass panels.

Once you know how many MW a year you want to produce and how automated your production line should be, Ecoprogetti can prepare a detailed offer for you upon those requirements.

Excluding the building loads that are not directly linked to the production area, to produce a photovoltaic panel the energy consumption is required is around 7,5 kWh.

The storage area must be closed, with a maximum humidity level of 70% RH (The best humidity level is around 60% RH).

Plastic materials such as back-sheet, encapsulants and silicons should be stored in a controlled environment compliant with the values indicated on the datasheets of the products.

The photovoltaic cells require controlled humidity and given their high economic value they should be stored 

Some raw material producers display their products on ENF Solar‘s website where you can compare prices and look at the products’ datasheets.

However, Ecoprogetti provides consulting services for these inquiries upon request.

Ecoprogetti can support the customer with the entire certification process both by spotting the best suitable raw material as well as performing precertification quality tests on the material and on the finished product.

The certifications required to sell photovoltaic panels are IEC 61215 and IEC 61730.

All the other certifications are optional and have the purpose of demonstrating that a PV module is most suitable to a specific application and for marketing purposes.

The optional certifications are:

  • Salt and Mist Test
  • Ammonia test
  • PID resistance
  • Load charge 5400 Pa
  • Sand and Wind test (test for glass surfaces)
  • ISO 9001, ISO 14001
  • OHSAS 18001
  • Factory Inspection

The certifications can be issued by any accredited body.
The accreditation body is called ACCREDIA.