The connection between cells are done using tabbing wire, the connections in parallel
handling most of the current and power are made using bus wire, which is similar
to the tabbing wire but is wider and thicker to handle more current. Be sure to calculate
the current panel generated and select the proper current handling bus wires.
Framing the Panel
Soldering all the cells to form the electrical panel is only part of the job, now
is necessary to frame and mechanically secure the panel to protect it from the outside
world and the weather.
They are many types of frames designs, a generic one will be presented here, remarking
the main points to be taken in account.
The layers shown in the above picture are typical components of a solar panel, also
known as photo voltaic panel or PV panel for short.
Tempered Glass Cover
Is the outside protection of the cells facing the sun it keep the dust and weather
elements outside the module, while letting the light entering the cells, tempered
glass must be used that withstand the handling during transportation, installation
and small object drops like small branches during storms or high speed winds. Recently
other resin based materials are being used in increasing quantities because of their
lower cost and lightness, however select with care one with minimum sun light opacity
and high durability again the destructive UV radiation.
EVA or Ethylene Vinyl Acetate
This is a transparent thermoplastic material used to encapsulate the solar cell
layer, normally this encapsulation process is made with a vacuum machine to seal
the cells from the exterior elements, and to expel all the humidity and air that
could degrade the cells with time.
This is the layer with all the cells and wires connections that make the reason for
the panel to exist.
This is a laminate material used to insulate and space critical areas below the solar
PV Back Sheet
This is a laminated material specially formulated to protect the PV from the elements
and UV rays, many variations suitable for different type of PV modules exit in the
market, be sure to select the proper one for your module.
The frame is the structure that holds all the parts together, it can be made of aluminum
or with a UV resistant plastic or resin, the frame can be glued or screwed. The frame
must be seal with a UV resistant glue or silicon compound to keep the weather elements
The junction box is a plastic box with connectors specially designed to connect the
bus wire from the cells to the power distribution cables, normally it contains also
the rectifier diode.