The photovoltaic technology is based upon a physical phenomenon that allows to transform directly sun-light into electric energy. This phenomenon is the so called photovoltaic effect, that is about the typical properties of some semiconductors, the most common is silicon. This material, properly processed, may generate electrical power under direct sun exposure. The generated power is in DC, so it needs special equipment to be converted into AC.

The silica transformation process into solar cells is made of the following different steps, that creates the so called silicon chain.

Polysilicon

Polysilicon is high purity level silicon (impurities are in the range of one part per billion). It is the result of an advanced technological chemical process, whose starting point is silica (SiO2 ), first transformed in metallurgical grade silicon (MGS), whose purity is then further increased to the optimal value.

Solar Grade Silicon

Polysilicon is the raw material to boost the manufacturing process of the solar grade monocrystalline silicon. The most common method to produce solar grade silicon is the Czochralski process (CZ), which consist of special furnaces (pullers) for growing the cylindrical silicon ingots. Specific dopants are then added to the process to increase the physical and chemical parameters of the resulting material. The grown ingot is then processed by tool machines to create the typical solar cell shape. Another kind of technology is the one that allows the production of multicrystalline silicon blocks through a special casting process, to be then cut into bricks. The physical parameters of multicrystalline ingots are not as high as monocrystalline, but it is commonly used due to its lower cost.

Silicon solar grade wafers

Silicon solar grade wafers is the final outcome of the ingots cutting. Commonly this production process requires the utilization of wire saws machines. Wafers is the raw material for solar cells manufacturers and it can be both monocrystalline (typical pseudosquare shape) and multicrystalline (perfectly square), depending on the type of silicon ingot used.

Solar cells

Solar wafers are the raw material for the manufacturing process of the solar cells. Solar cells is the most important device that can convert directly the sun-light into electrical power, through the photovoltaic effect. There are different types of solar cells, depending on the wafers used. So we can find monocrystalline silicon cells (efficiency in the range of 15-16%) or multicrystalline silicon cells (whose efficiency is lower than the monocrystalline ones, but being cheaper). Actually there is a third type of solar cells, coming from amorphous silicon technology, whose efficiency is in the range of 7–9%. They are particular suitable in low sun exposure (for example in cloudy weather conditions).

PV modules

The PV module is the device made of many solar cells interconnected (typical 36 or 72 solar cells) so to produce an electrical power depending on the total number of pieces used and on their single power output. In other words, solar module power is the sum of the single solar cells output.

PV power plant

The PV power plant is made of solar modules electrically connected, in the number to get the requested output. Another important device is the inverter which allows the conversion of DC into AC. These two major items must be completed with wirings, building frames and optionally batteries.
PV power plants can be stand alone, where connection to energy network is not possible (in this case batteries are strictly required), and grid connected, directly to the electrical network.

Risparmiare con Energia solare

PV is an important energy source and this for many reasons.

The most important is that this technology permits to have environmental benefits obviously. In fact the production of electrical power, simply cause of sunrays action, is not pollutant since no hazardous waste is released in the air.

PV systems don’t use any fuel, gas or liquid, but only sun light, that is so abundant and free, to secure a continuous electrical power production.
PV systems have no rotating devices, so they need very poor maintenance.
PV systems is long lasting (about 30 years).
PV plant is one of the most flexible power generator in terms of dimensions and size
PV plants allow the opportunity to have a real income, thanks to the government support, that finances the energy generated by the plant, added to the opportunity of reduction of usual electricity costs.

THE SUN: OUR PRESENT, OUR FUTURE!