French physicist Edmond Becquerel first described the photovoltaic effect in 1839, but it remained an unexplored avenue for the next three quarters of a century. At only 19, Becquerel found that certain materials would produce small amounts of electric current when exposed to light. Heinrich Hertz studied the effect in solids in the 1870s, producing PV cells that converted light to electricity at 1% to 2% efficiency. Selenium cells were used as light-measuring devices in photography.

The big step at commercializing PV was the development in the 1940s of the Czochralski process, generating highly pure crystalline silicon. In 1954 the Bell Laboratories used the Czochralski process to produce a 4% efficient crystalline silicon cell.

Photovoltaic cells, modules, panels and arrays

How Solar Power works

Solar Photovoltaic (photo - light and voltaic - voltage producing) or PV technology converts sunlight directly into electricity. The basic building block of Solar Module is the PV cells. A solar or PV cell consists of semiconducting material that absorbs the sunlight. The solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce dc electricity.

Photovoltaic cells are connected electrically in series and/or parallel circuits to produce higher voltages, currents and power levels. Photovoltaic modules consist of PV cell circuits sealed in an environmentally protective laminate, and are the fundamental building block of PV systems. Photovoltaic panels include one or more PV modules assembled as a pre-wired, field-installable unit. A photovoltaic array is the complete power-generating unit, consisting of any number of PV modules and panels. They are environment-friendly, noiseless, pollutant-free and produce no harmful residues.

Photovoltaic cell

Elements of a Solar Power System

Solar Systems begin with the solar module. Modules gather solar energy in the form of sunlight and convent it into direct current (DC) electricity. The more sunlight they receive, the more electricity they produce. Solar modules are the heart of the system. They are the power generators.

Components such as charge regulators, batteries and inverters regulate, store, condition and deliver the electricity. Other elements connect the different components of the system.

PV modules, because of their electrical properties, produce direct rather than alternating current (AC). Direct current (DC) is electric current that flows in a single direction - the type of current you get from a torch battery. Alternating current is electric current that reverses its direction at regular intervals, for example as supplied by utility companies through the national grid system. In the simplest PV systems, DC current is used directly. In applications where AC current is necessary, an inverter can be added to the system to convert the dc current to ac current.

Typical PV System Components

Types of Solar Power Systems

The size and type of the PV system that will meet your expectations depends on your individual needs, site location and climate.

Stand-Alone System

Without Battery Backup:

Since there is no battery to store electrical energy, energy is used immediately. Common applications are direct power to DC loads, water pumping and telecommunications. With an inverter it can also power AC loads. This system only works when it's sunny.

With Battery Backup:

A Stand-Alone System with Battery Backup can supply power 100% of the time including at night, on cloudy days and when the utility power is down. Excellent for remote applications where utility grid is inaccessible; cabins, boats, RVs and for emergency backup systems.

Grid-Connected System

This is the simplest and most cost effective way to connect PV modules to regular utility power. Grid-Connected systems can supply solar power to your home and use utility power as a backup. Grid- Connected Solar Power Systems work in parallel to the grid, providing the best possible combination of reliability, pricing and sustainability benefits. A properly designed and installed grid connected Solar Power System works seamlessly with exsisting building systems, resulting in zero impact to building operation, maintenance and performance. The grid inverter automatically synehronises with the grid network; no additional controls are required.

Generally in all countries, to install a grid connected system, the consumer needs to get the permission from the local Utility Company or Electricity Authority.