PHOTOVOLTAIC

SYSTEMS

PV, or photovoltaic in short, is the application of a physical principle to convert sunlight into electric current. This principle was first discovered in 1839, although it took until 1954 to go from theory to practical applications.

The sun produces a huge amount of energy every day (173 millions of billions Watts). The amount we receive generates wind (converted into electricity through windmills), heat, photosynthesis of plants and trees and 1.37kw of energy per square metre. This energy can be harnessed by PV cells and converted into electricity. In fact, less than 1% of our planet’s desert areas would generate all the electricity we need if it was covered with PV panels.

Generating electricity this way is quite simple: light hits a cell made of a thin layer of silicium over a metal support which generates electrons. The motion of these electrons generates current. PV cells are assembled in panels, generating up to 100w/h of DC power (14v approximately). These panels are connected to a regulator, which controls the electricity production, sends some to appliances, some to battery storage and dumps any excess. PV panels generate electricity when subjected to sunlight. This means they do not produce at night. This is why most systems store electricity in batteries.

HOUSING APPLICATIONS

A modern house does not require a lot of electricity and it does not seem very efficient to burn diminishing fossil resources in huge plants located far away and then transport this electricity over hundreds of kilometers to houses. By having a few PV panels on the roof, any ordinary house can generate its electrical needs; this power can be supplied in DC (for halogen lighting for example) and AC (220V) through an inverter to power standard appliances.

A house connected to the grid can then sell electricity by day and buy some back at night.

An independent house generates all its needs by storing electricity in battery banks. In windy areas, a windmill can be a very good complement to PV systems.

PV systems do not require fuel, have no moving parts that can wear, require virtually no maintenance and last for a very long time (some PV systems have a 30 years warranty).

INDUSTRIAL APPLICATIONS

They constitute the bulk of the applications today, for remote lighting, transmitters, satellites in space, etc. Industrial buildings could also produce part of their needs through PV.

COST MATTERS

Is PV technology expensive? Prices are now going down and make it ever more competitive. PV systems last a very long time and over say 50 years, they should become extremely competitive.

The cost of fossil fuels is expected to increase over the next 20 years. Furthermore, fossil fuel generators require heavy maintenance. Another aspect to take in account is the pollution they generate: this has a heavy cost in terms of global warming, poor air quality, health problems and logistic costs (transport of fossil fuels, electricity on high power lines and their waste), not to mention collateral damage such as oil slicks, Chernobyl type accidents, respiratory diseases, chemical runoffs and other nasty results.

We believe the next ten years will see a dramatic increase in the use of PV, wind and other renewable energies. We simply cannot afford to use today’s solutions in the future .

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