How Solar Energy Works

Solar energy (power from the sun) is clean, free and inexhaustible.This energy drives our weather and climate and is a viable alternative to the fossil fuels that are wrecking havoc on our world and threatening our future. Solar energy supports almost all life on earth and is the basis for almost every form of energy we use.

While you've probably seen solar calculators that use solar cells for energy, we've been hearing about the promise of free elctricity from the sun for more than 20 years now. Solar energy technologies to harness the sun's energy for practical ends is not new. According to Wikepedia, these technologies date from the time of the early Greeks, Native Americans and Chinese, who warmed their buildings by orienting them toward the sun. But modern solar technologies can provide heating, lighting, electricity and even flight.

On a bright sunny day, the sun shines approximately 1000 watts of energy per square meter of the earth's surface. If we could collect that vast energy source, we could power our homes and offices for free. Solar power is often used synonymously with solar energy or more specifically, to refer to the conversion of sunlight into electricity. This can be done either through the photovoltaic effect or by heating a transfer fluid to produce steam to run a generator.

Electricity Generation

Electricity can be generated from the sun in several ways. Photovoltaics (PV) has been mainly developed for small and medium-sized applications, from the calculator powered by a single solar cell to the PV power plant. For large-scale generation, concentrating solar thermal power plants have been more common but new multi-megawatt PV plants have been built recently. Other solar electrical generation technologies are still at the experimental stage.

Photovoltaics

A solar cell or photovoltaic cell is a device that converts light into electricity using the photoelectric effect. Photovoltaic cells and panels are the most used method for taking the power of the sun and turning it into electricity. The first working solar cells were constructed by Charles Fritts in 1883. These prototype cells were made of selenium and achieved efficiencies around one percent. Photovoltaics have come a long way since then.

The Bottom Line

With many states now giving tax and rebate incentives, PV installations can pay for themselves in five to ten years in many places. "Grid-connected" systems - those systems that use an inverter to connect to the utility grid instead of relying on batteries - now make up the largest part of the market. While the deployment of PV power depends largely upon local conditions and requirements, most countries are taking an interest in developing PV as one of their options for renewable energy supply.