Solar Panels Converting Sunlight Into Usable Electricity

In the afternoon of a sunny day, the sun shines approximately 1,000 watts of energy per square meter (approx. 3.28 square ft) of the earth's surface. What's this cool fact mean? Free electricity. If we can collect and convert that solar energy into usable electricity, we could easily power our homes and offices for free.

As a clean and renewable energy, solar energy seem to work forever as long as your homeland have enough sunlight. All you need to do is collecting then convert it into usable electricity using solar panels system. With the world becoming more aware of environmental concern associated with conventional electric power sources, solar panels technology seem have a bright future.

However, when we talk about "solar panels", the term may refer to two types of power devices that collect energy from the sun:

1. Solar photovoltaic modules, use solar cells to convert sun beam into electricity.
2. Solar thermal collectors, that collect and use sun's thermal energy to heat water, oil, antifreeze, or another kind of fluids.

This article is about the first type of solar panels: device that converting solar energy into electricity using solar photovoltaic modules, or simply known as "solar cells".

T­he solar cells that you see on calculators, or satellites wingspan's panels are photovoltaic modules. As the word implies (photo = light, voltaic = electricity), photovoltaic means convert sunlight directly into electricity.

The first solar cell was built by Charles Fritts in 1883, who coated the semiconductor Selenium with an extremely thin layer of gold to form the junctions. This first solar cell was only have around 1% energy conversion efficiency.

Modern photovoltaic (PV) cells are made of special materials - prominently silicon. In 1954, Bell scientists Gordon Pearson, Darryl Chapin, and Cal Fuller found that silicon doped with certain impurities was very sensitive to light. This resulted in the production of the first practical solar cells with a sunlight energy conversion efficiency of around 6 percent. This moment also stimulated funding from several governments into research for improved solar cells technology. Further work brought the cell's efficiency up to 15 percent. Solar cells were first applied in the rural and isolated city of Americus, Georgia, as a power source for a telephone relay system, where it was used successfully for many years.

How Solar Panels work?

How solar panels work on converting sunlight into usable electricity can be explained in three basic converting steps:

1. When photons in sunlight hit the solar panels, a certain portion of it is absorbed within the semiconductor material, such as silicon. The energy of the absorbed light is also transferred to the semiconductor.
2. Electrons (negatively charged) are knocked loose from their atoms by the energy, allowing them to flow freely through the material to produce electricity. This flow of electrons i­s a current. Due to the special composition of one or more electric fields on solar cells, the electrons are forced to move in a certain direction. The complementary positive charges that are also created (like bubbles) are called holes and flow in the direction opposite of the electrons in a silicon solar panel.
3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity. By placing metal contacts on the top and bottom of the solar cells, we can draw that current off to use externally.

Solar Panels Efficiency and Energy Payback

Energy payback - also called harvesting ratio - is recovery period of the energy spent for manufacturing of the respective technical energy systems. Modern solar panels are net energy producers, means they generate significantly more energy over their lifetime than the energy expended in producing them.

While sunlight is free, the electricity generated by solar panels system is not. However, the photovoltaic technology has progressed significantly, and the energy payback time of a modern photovoltaic module is typically shorter from 1 to 4 years (depending on the type and where it is used). Thin film technologies achieve significantly shorter energy payback times than conventional systems (often < 1 year) with a typical lifetime of 20 to 30 years.

First Solar Inc, a solar panels manufacturer, brought its manufacturing costs for solar panels down to $1 per watt. According to Popular Mechanics, right now the cost of making solar panels accounts for a little less than half the total cost of installation. It needs to get manufacturing costs down to $0.65 to $0.70 per watt, and other installation costs down to $1 a watt in order to reach grid parity—goals First Solar plans to reach by 2012.

Many effort on decreasing solar panels manufacturing costs, however, still can't place solar panels in position to scale up enough to become competitive with other forms of conventional energy producer. But we should have a long-term thinking. Demand and module efficiencies are constantly rising, prices are falling. And we all need to build more awareness on environmental issues. It's all about green, renewable energy for brighter earth future.