Photovoltaics

Photovoltaic Phenomenon

The photovoltaic phenomenon concerns the conversion of solar radiation to electricity. The photovoltaic phenomenon was discovered in 1839 by Edmund Becquerel (Alexandre-Edmond Becquerel). In summary it is the absorption of light energy by the electrons of the atoms of the photovoltaic component and the escape of electrons from theire normal position thus creating power. The electric field which already exists in the photovoltaic element leads the current to the load.

Structure analysis of a photovoltaic system

The photovoltaic system consists of the following sections:

(a) The photovoltaic generator (photovoltaic panel) with the supporting bases and maybe a (tracker system), monitoring the solar orbit.

(b) Batteries - Photovoltaic battery (if it is a standalone system).

(c) charge controllers to control and protect the batteries (if a standalone system).

(d) DC voltage converter dc (12v/24v/48v) inverter for transforming to AC as to 220V AC.

Photovoltaic systems and theire applications

Today, the energy produced by photovoltaic systems serve people in the most remote locations on earth as well as in city centers. Whether you are a homeowner, farmer, architect, or just someone who pays bills to the utility grid, the odds tell us that this technology has touched you in some degree. Applications of PV can be divided into the following categories:

Plain or independent photovoltaic system

Photovoltaic system with battery storage

Photovoltaic system connected to Public Energy Organizations

Photovoltaic system at power plant status

Mixed / Hybrid Systems

The energy is being produced whenever and wherever needed and the photovoltaic system is simple at all its stages - from the part of the wiring, the storing up up to its control centers. Small systems (up to 500W) are lightweight and are easy to transport and to install. In most cases, the installation takes a number of hours. One example is the water pumps that require frequent maintenance, while the photovoltaic system that supplies the electric only require a periodic inspection of their condition and cleaning.

Photovoltaic systems with batteries

PV systems with batteries are a very reliable solution to power a space or a machine 24 hours a day, with rain or sunshine. They are used around the world to give us light, supplying electrical household appliances, switches, phones, and even heavy machinery. During the day the elements collect sunlight, convert it into electricity and store it in batteries. These in turn supply us with electricity when requested. A device mediates called a "charge controller" which ensures that the batteries are properly charged and it lengthens their lifespan by protecting them from overcharging or from their total discharge. The batteries are useful in most cases but require a periodic maintenance. They look like car batteries, but are designed to give us more of the stored power each day. Their fluids should be checked periodically and must be protected from freezing temperatures. The amount of electricity that we can demand from them after sunset or during cloudy weather is determined by the energy production of the modules and the type / amount of batteries. Adding extra batteries and components raises the cost of our investment, that is why a good study of the energy needs has to be made, before installing the system, to define the most efficient system size. If our energy needs change adding other components to the system is possible and simple.

Photovoltaic system connected to the PPC

In areas where there exists already an electricity network it is possible connectiong our Photovoltaic system to the PPC power grid, thus complementing our power needs and replacing the need for batteries. Many homeowners use both power sources, thereby reducing the electricity bill. Also they are satisfied by the fact that do not pollute the environment. A user of a photovoltaic system connected to the network can also sell electricity to the PPC provider. This is achieved by placing a counter between the system and the network. The current generated by the photovoltaic system is being supplied (or sold) to the network. To make this possible an approved inverter is required which converts the AC to DC of the network, balancing the voltage, the frequency and its quality accurately.In the case of a voltage dropping, automatic circuit breakers disconnect the Photovoltaic system from the network.

Hybrid Photovoltaic Systems

This systems combine the elctricity produced by diesel generators, wind turbines, small hydroelectric generators and photovoltaic systems, depending on the energy needs, exploiting the advantages of the geographic area. These systems are ideal for applications at remote locations such as telecommunication stations, transmitters, military stationsand vorder villages. Knowledge needed to install a hybrid system is the demand for electricity as well as geographical and topological advantages, so it is necessary to measure the solar energy, the wind and other potential sources in a specific area. The measurements will be the basis for the design of a hybrid power system that covers as much a possible the power needs of a facility or a community.

The most important environmental advantages of  organized photovoltaic generators interconnected network are the excellent features aesthetic assimilation from the environment.

The low installation height of photovoltaic generators, even if trackers are used (heliotropic tracking systems) the aesthetic surrounding and the wider environment is not degraded in which they are installed.

It is no coincidence that in Germany, Denmark, the Netherlands, Spain and Italy, all countries that are known for their increased environmental awareness, the installation of photovoltaic parks knows highest social acceptance. 

A feature of the global acceptance of photovoltaic systems is theire full support from international environmental organizations such as Green Peace (www.greenpeace.org) and the International Fund for Nature (www.wwf.org).

Advantages

The installation of photovoltaic parks can keep harmony with all forms of landscapes, while not being a limiting factor for parallel land uses such as agriculture, livestock and agro-tourism operation units. Because of the underground path of connected conductors, the only visible parts are photovoltaic generators and supporting bases (fixed or heliotropic) . The plant can grow rapidly without much disturbance during the construction .

Their low height but alos their coordinate placement in symmetrical arrays and and geometric patterns, offer a sense of order and organization in the area of development, which does not create a negative picture.

Finally absence or fast moving parts and the complete absence of noise or vibration related to their operation does not disturb the natural balance of activities and the region hosts. These findings were reinforced by the fact that the operation of such stations are not linked to labor intensity.