What is photovoltaic energy?

The foundation of solar energy using photovoltaic is photovoltaic or photoelectric effect, which involves converting light into electricity. This process is achieved with some materials that have the ability to absorb photons and emit electrons. When these free electrons are captured, the result is the electric current can be used as electricity.

In 1905, the French physicist Edmund Bequerel was the first to observe the photoelectric effect. Later, in 1873 Smith Willbughby Lenard in 1900 and verified their existence under different conditions. In 1921 Albert Einstein wins the Nobel Prize in physics due to his work which describes the nature of light and the photoelectric effect and in which photovoltaic technology is based. In 1920 the American physicist Millikan fully corroborated the theory of Einstein. However, it was in 1954 when he built the first photovoltaic module at Bell Labs and is treated as a scientific experiment and its cost was too high for widespread use.

Since then, a success of new industrial processes, along with expansion of the consumer market, has led to a drastic reduction in production costs of modules. Photovoltaic cells are made from silicon semiconductor material is also widely used in electronics.

For photovoltaic cells, a semiconductor wafer receives a special chemical treatment to form an electric field, positive on one side and negative on the other. When sunlight strikes the cell, electrons are displaced from the semiconductor material.
If electrical conducts on both the positive and negative sides, forming an electrical circuit, electrons can be captured as electricity.

This electricity can be used to power a load, for example to light a bulb. The combination of several cells electrically connected to each other and mounted on a support structure or frame is called a photovoltaic module.
Multiple modules can be connected to each other to form a solar field. The modules produce DC electricity, which can be connected in series or in parallel to achieve the voltage required.

Isofotón, a pioneer in the manufacture of photovoltaic modules, is dedicated to develop solar power technology since 1981, currently is the leading in Spanish and European ranks and as the seventh worldwide.

The electricity produced by the modules is used in different ways according to requirements. The main uses of E.S.F. are the electrification of isolated parts of the grid (housing, remote control systems, telecommunications, illuminated signs, street lights, boats, and alarms), direct solar pumping and networking.

There are basically two types of applications by solar photovoltaics, off-grid installations and electrical generation plants connected to the network.

Isolated systems of photovoltaic solar energy: depending on this technology we can provide electricity in remote areas without the electricity distribution network. Thus, we can supply electricity to cottages, mountain shelters, water pumping, livestock facilities, lighting or marking, communications, etc.

Isolated systems are mainly composed of solar energy using photovoltaic solar panels and storage of electrical energy generated by the panels in batteries.

Electrification of isolated systems

In the case of electrification of isolated parts without the electricity distribution network, energy produced by the modules goes through a charge controller and stored in batteries, also called accumulators. The drive, if necessary, is responsible for transforming the direct current from the batteries into alternating current to power consumption. The power module is measured in watt-peak (Wp). The energy storage capacity of batteries is called Ampere-hour (Ah) and the ability to load regulation in amperes (A).
Energy consumption is determined by watt-hours (Wh) and the required power in watts (W). The energy consumption determines the elements whether can make up an installation or not.
Autonomy of the system is called the number of days that be catered for consumption without received charge of batteries, which means the modules can´t receive sunlight.

Direct solar pumping
On the premises of Direct Solar Pumping energy produced by the modules is converted by means of a variable speed to provide
electricity to the pump.
The number of modules required for pumping is determined by the height of elevation and volume needed. It should also take into account whether the water will rise to the wellhead, if it is used directly to drip or be stored in a tank.

Grid-connected photovoltaic systems: this application is to generate electricity using photovoltaic solar panels and inject it directly into the electrical grid. Nowadays, some countries like Spain, Germany or Japan, the electricity distribution companies are obliged by law to purchase the energy injected into the network by these photovoltaic.

The selling price of energy is also fixed by law so that it can encourage the production of solar electricity to these facilities be amortized over a period of time can vary between 7 and 10 years.

This type of photovoltaic installations ranges from 1 to 5 kWp on the terrace or roof, up to 100 kWp installations on roofs of warehouses or in soil, and even plants with several megawatts.

The model developed in Spain known as the solar farm, which would consolidate several different facilities in rural land owners. Each facility has a capacity up to 100kw which is established by law for the maximum selling price of electricity. These facilities can be fixed or tracked, so the photovoltaic panels are mounted on structures that move along the path of the sun to maximize power generation.

The demand for such facilities has been saturated power lines in many rural areas in recent years, while it has increased the price of rural parcels and triggered the point of connection requests.

Currently, we are closed to a turned point in this market due to the huge consumption market.

Networking
On the previous network connection to electrical power distribution, which produced by the modules is converted to AC with the same voltage and frequency, as the electrical grid to be injected to it. In this case the company must pay all the energy produced by the photovoltaic system.
In Spain and other countries the allowed connections to network energy price is 0.12 c € / kWh, and in a few years this type of energy will be competitive with other energies (grid connected).