THE SUN

Unlike conventional energy sources, such as oil, gas and coal, the sun is the source of electricity par excellence because it is inexhaustible, non polluting and does not release carbon dioxide (CO2) into the atmosphere.
Through electricity-producing photovoltaic systems, the sun ensures reliable profit and a safe, long-term investment. In fact, the overall energy that is generated during photovoltaic system operations is far higher than the amount invested in constructing them.

PHOTOVOLTAIC CELLS AND PANELS

A photovoltaic cell, the basic unit that will later be connected to others to form the panel, exploits the photoelectric effect to produce electricity from energy contained in solar radiation. The set of cells that are interconnected either in series or in parallel on a single supportive structure is called photovoltaic panel.

Photovoltaic cells directly transform solar radiation into electricity by exploiting the so-called "photovoltaic effect" that is based on the properties of certain appropriately processed semiconductor materials (such as silicon, an element that is extensively present in nature) to directly generate electricity when solar radiation strikes them.

PHOTOVOLTAIC SYSTEMS

A photovoltaic system is based on the photovoltaic module which is made of several cells. It converts the energy contained in solar radiation into electricity.

Photovoltaic systems are first divided into categories according to users and electric networks. In fact, they are known as stand alone systems and grid connected systems.

• Stand alone systems: these systems are only connected to users and present no connections with the national grid; therefore they must produce the energy required for the user at all times of the day.

Since sunlight really cannot be adjusted to conform to user requirements because it is strongly influenced by weather, such systems are usually fitted with an accumulation unit that compensates for any unbalances between production and demand during the various phases of the day.

System sizes are determined with a certain margin to guarantee that the energy accumulated in conditions of over production is always adequate to meet the demand during hours of low or zero production.

It is also evident that these plants are scarcely used for domestic purposes as they are unable to fully meet the flexibility demanded by these users.

This type of plant DOES NOT HAVE any incentive from the state.

• Grid connected systems: these systems are connected to the traditional electric network, whose normal operating mode envisages direct use of system energy when it is concurrently produced and demanded. It compensates for any low production levels compared to the demand by drawing energy from the grid. It also channels any excess production levels into the grid network when user demands are lower than the energy produced by the system.

The decision concerning the size of such systems takes into account the right combination of expected production, system costs and investment return times.

This type of system is underpinned by the Feed-in Tariff incentive.

FIXED AND TRACKING PHOTOVOLTAIC SYSTEMS

Besides distinguishing stand alone systems and grid connected systems, the type of system can also be classified by its capacity to track the course of the sun or not. These are known as fixed inclination systems (ground-based, integrated and partly integrated), and tracking systems that can, in turn, be classified as simple tracking (single axis) and total tracking (dual axis).

The fixed inclination type is the simplest in terms of supporting structures, since it only requires an anchoring system and brackets to fix the panels to the ground, and to integrate them either partly or totally to the roof or to any bearing surface.

Tracking systems require motorised structures that can constantly change the position of the panels with subsequent additional costs (and bearing surfaces, which must equal panel surfaces to take into account shadows between rows of panels during tracking) that can hardly by justified for domestic users.

THE FEED-IN TARIFF

Photovoltaic energy is an important resource that awakens the interest of many normal citizens and entrepreneurs. Some incentives have been offered to encourage the gradual introduction of this technology into the national energy framework. The goal is to enhance widespread use of the system and to motivate industries to seek increasingly efficient and economic solutions.

The Feed-in Tariff (“FiT”, “Solar Premium” - in Italy established by Legisl. Decree 19.02.2007) is an incentive plan issued by the Electrical Service Manager for photovoltaic systems exceeding 1 kWp that are connected to an electric network.

The system can be directly installed once the connection is requested from the local grid manager, and after the system is connected to the grid, the Electrical Service Manager can be requested to acknowledge the special rate for 20 years for the type of plant constructed.

The special rate depends on:

System size:

• 1 - 3 kWp
• 3 - 20 kWp
• over 20 kWp (no wattage limits are envisaged)

System type:

• non building-integrated system
• partly building-integrated system
• building-integrated system

All the energy produced will receive incentives for 20 years, from the moment the system starts operating. It is not a non refundable grant that covers the costs of building the system, but rather an incentive-based method that pays for the electricity generated by the systems.unerano l'elettricità prodotta dagli impianti.