SOLAR SYSTEM BASICS

Solar Panels – Free Power from the Sun!

Solar power is the most reliable source of electricity in the world today.  Photovoltaic (PV) modules (solar panels) generate electricity when they are exposed to sunlight and generally contain no moving parts, operate silently, have no fuel requirements and call for little to no maintenance. 

Residential PV systems are most cost effective in areas where there is not an existing utility power line and if the site has good solar exposure.  In Alaska, where solar availability in the winter months is negligible, solar power can not be expected to provide full power year round.  However, incorporating solar within a hybrid system eliminates the sunlight availability problems associated with using solar power in Alaska.

The actual creation of a usable electrical current in a photovoltaic cell takes place at the atomic level, through a process called the “Photovoltaic Effect”.  PV cells convert sunlight directly into electricity and are wired together to obtain a specific power output.  Cells have no protection from the elements; to be used outdoors, the cells are interconnected, sealed, and usually framed as modules.  A solar module (panel) is the smallest environmentally protected photovoltaic unit and multiple modules are called a “solar array”.

The most widely used photovoltaic cells are single-crystal silicon (mono-crystalline), multi-crystalline silicon and amorphous silicon (thin-film).  Single-crystalline cells are the most efficient at converting sunlight to electricity.  Multi-crystalline cells are slightly less efficient than single-crystalline while advanced amorphous silicon cells are about half as efficient as single-crystalline cells.  All cell technologies have operating lives well over twenty years.

Mono-crystalline Silicon Cells:

These cells are made from very pure mono-crystalline silicon.  The silicon has a single and continuous crystal lattice structure with almost no defects and impurities.  The principle advantage of mono-crystalline cells are there high efficiencies; typically around 15%.  This increased efficiency results in better low light level performances when compared to other manufactured cell types. The manufacturing process required to produce mono-crystalline silicon is complicated, resulting in slightly higher costs than other technologies.

Multi-crystalline Silicon Cells:

Multi-crystalline cells are produced using numerous grains of mono-crystalline silicon.  In the manufacturing process, molten polycrystalline silicon is cast into ingots; these ingots are then cut into very thin wafers and assembled into complete cells.  Multi-crystalline cells are cheaper to produce then mono-crystalline ones.  This is largely in part due to a simpler manufacturing process.  However, they tend to be slightly less efficient than mono-silicon cells with average efficiencies of around 12%.

Amorphous Silicon:

Amorphous silicon cells are composed of silicon atoms in a thin homogenous layer rather than a crystal structure.  Amorphous silicon absorbs light more effectively then crystalline silicon, so the cells can be thinner.  For this reason, amorphous silicon is also known as a “thin film” PV technology.  Amorphous silicon can be deposited on a wide range of substrates, both rigid and flexible.  This makes it ideal for curved surfaces and “fold-away” modules.  Amorphous cells are however less efficient than crystalline based cells, with typical efficiencies of around 6%.  One benefit is that they are easier to manufacture and therefore cheaper to produce.  Considering the low cost, they are ideally suited for many applications where high efficiency is not required and low cost is important.

Contact us by Phone (907)561-7941, Fax (907)561-7946, Email or U.S. Postal Mail 145 West Dimond, Anchorage, AK, 99515

Federal solar tax credits extended thru 2008!