The sun as a source of energy

Energy created through the solar electric system produces no pollutants and costs.

The ratio of the electric power produced by a PV device to the power of the sunlight shining

    on the device.

Light weight and simple structure is easy installation and extensively perform.

In opposition of traditional nonrenewable energy that renewable energy price is more expensive,

    but considering nonrenewable energy capitalized cost is fast rising, in the future will change the situation.

Solar cell types

PV cells usually fall into two silicon structures - crystal (crystalline silicon) and non-crystal (amorphous silicon). Amorphous cells are, however, less efficient than crystalline based cells, but they are easier and therefore cheaper to produce, ideal for many applications such as torches, calculators, shingles, glass curtain walls and so on.

Solar cells are classified into two groups-silicon and amorphous. The lower efficiency of polycrystalline is balanced out by a price advantage in manufacturing costs. Modules made from amorphous silicon have thus far been predominantly used in leisure applications (small applications, camping, boating).

Crystalline silicon solar cells convert sunlight into usable electricity is double efficiencies compared with noncrystalline solar cell. The high-grade silicon can now be further processed in different ways, such as to produce monocrystalline or polycrystalline cells.

PV modules made of silicon crystals are distinguished into monocrystalline (single crystalline) and multicrystalline (polycrystalline) cells. The chief advantage of monocrystalline cells are their high efficiencies with the laboratory tested efficiency of up to 24%, and commercial modules are around 15~16%. On the other hand, lab multicrystalline cells have lower efficiencies of about 18% and commercial PV modules enable efficiencies of close to 14%. In contrast, the same scale of PV module, monocrystalline cells absorb more sun energy than multicrystalline cells and therefore generate greater amount of electricity.

Crystalline cells are interconnected with one another when manufacturing PV modules. Standard modules are modules manufactured with the aim of achieving maximum energy.

Functional principle of a solar cell

A P-N semiconductor (solar cell) is exposed to light, photons are absorbed by the electrons. The electrons that are set free pulled through the electric field and into the N-area. The holes produced move in the other direction, into the P-area. This whole process is called the photovoltaic effect.

Solar cells are interconnected with one another and manufacturing different power output PV modules.

Crystalline silicon cells efficiency

Crystalline silicon cells efficiency depending purity and production technique. With respect to solar cells, the percentage of light energy that is converted to electricity by the cell, and ranges from as low as 5% to as high as 30%.

Owing to the different efficiency, the lower efficiency will have a larger cell surface area is required.

Standard test conditions

In order to be able to compare different cells or indeed PV modules with one another, uniform conditions are specified for determining the electrical data under which the solar cell characteristic curve is then identified.

  Irradiance G of 1000W/ m²

  Cell temperature T of 25ºC

  Defined light spectrum with an air mass AM=1.5

Abbreviated STC, a set of reference PV device measurement conditions consisting of irradiance of 1 kW/m², AM 1.5, and 25ºC cell temperature.

   There are certain points to consider in relation to the amount of electricity brought out by PV modules:

Facing south (northern hemisphere installation) to receive the maximum sun light: Due south is the best orientation for PV arrays set in the northern hemisphere, and conversely, north is the correct orientation for PV arrays positioned in the southern hemisphere.

Tilting PV arrays: The greater the latitude is, the further the sun is, and therefore PV arrays must be tilted in order to receive the maximum sun light. For grid-connected systems, the degree of latitude can be adopted as the ideal tilt angle; however, stand-alone systems require 10~15 degrees in addition to the degree of latitude as the optimal tilt angle of PV arrays in the winter. For example, the latitude of Taiwan is 23 degrees, so the tilt angle of stand-alone PV systems placed in Taiwan should be 33~38 degrees.

Avoiding shadows: The effect of shade affects the output of PV modules.

Wiring concern: Properly connected and sized wiring is essential for the optimum conductivity of power lines. Please refer to PV panel manuals.