How are Solar Panels Made

Find out how solar panels are manufactured

Solar panels installed on the roof of a home

Photovoltaic Solar Panels (1) are the main source of domestic renewable electricity in Europe. Costing more per watt of electricity generated than wind power (2), solar panels have no moving parts and a lifetime of 30-40 years making them ideal for professional installation with virtually no maintenance required by the homeowner.

Crystalline and Amorphous Solar Panels

Their are two main types of solar panel: crystalline and amorphous. In both cases the key ingredient is silicon. Amorphous panels are typically cheaper to manufacture (and purchase), less susceptible to breakage, and use less silicon, however their power output is typically lower than crystalline panels meaning that an amorphous solar installation would take up more space than a similarly power-rated crystalline installation. Amorphous solar panels deteriorate faster than crystalline solar panels and so their power output will fall more quickly during the years of use.

What is Silicon

Silicon (Si) is an abundant non-metallic chemical element which makes up almost 30% of the earth's crust and is the 7th most common element in the Universe. Silicon has two forms - amorphous (brown), and crystalline (dark).

Crystalline Solar Panel Manufacture

To make the solar cells which make up a crystalline solar panel, crystalline silicon is sliced into thin disks (aka wafers) a few millimeters thick or thinner. These are then cut to shape, polished, and any holes in the filled to make the finished wafer uniform.

In order to generate electricity, dopants (contaminants) have to be added to the pure silicon wafer. Typically a layer of phosphorous is coated onto the wafer and the surface is heated. Phosphorous atoms then diffuse throughout the silicon wafer contaminating it as required.

The doped silicon wafers are then aligned together to make up a solar cell, and the solar cells are arranged on a backing panel to make a solar panel (or module). Conductive metal strips are fixed to the sunward face of each solar cell (pictured below).

Crystalline solar panel showing metal conductive strips

Finally a layer of glass is glued over the top of the collection of solar cells to provide protection from the elements while still permitting sunlight to pass through to the completed crystalline solar module.

Amorphous Solar Panel Manufacture

Unlike crystalline solar panels, amorphous panels are not made up of a collection of interconnected solar cells manufactured from expensive crystalline silicon . Instead a very thin homogenous layer of silicon atoms and dopants is simply sprayed onto a backing material - typically glass or metal, but also on plastic surfaces to make flexible solar panels, or on roofing tiles to make solar roof tiles (3). The silicon layer produced can be 100 times thinner than the silion wafers in a typical crystalline solar cell greatly reducing material costs.

Thin film amorphous flexible solar panel

An entire solar module is made in one go, so manufacturing costs are reduced by a) not having the expense of making silicon wafers, and b) the simplicity of assembly.

Amorphous solar panel manufacture only really kicked off in the 1970's and many experts see future developments in amorphous panels as key to bringing down the costs of solar power .

Multi-junction solar cells (4) for example are a recent development in amorphous solar technology using multiple thin layers of doped silicon to capture energy across the whole light spectrum. Multi-junction cells are the most efficient solar cells being manufactured today.

Web Link References

(1) http://www.reuk.co.uk/How-Do-PV-Solar-Panels-Work.htm
(2) http://www.reuk.co.uk/wind.htm
(3) http://www.reuk.co.uk/Solar-Roof-Tiles.htm
(4) http://www.reuk.co.uk/Multi-Junction-Solar-Cells.htm