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Mono Vs Poly Panels

A lot is written about this subject and it is one of the most confusing areas to get your head around.

The good news is, in Perth, there is not much difference in energy output whether you have a polycrystalline (poly) or a monocrystalline (mono) panel and a poly panel would normally be the better of the two panels for Perth's climate.

Polycrystalline is more resistant to the effects of heat than mono so we recommend it for Perth and further north and it would be more beneficial in Perth if global warming continues, remembering panels should last at least 25 years. The efficiency of your inverter is likely to have more impact on your power generation than whether you have mono or polycrystalline panels.

If you want to get into the technicalities read on...

Mono Panels

• Mono panels are made up of single-crystal wafer solar cells.
• Single crystal wafer cells are more expensive to make than polycrystalline cells. These wafers are cylindrical ingots so they don't fit a square solar cell module without a lot of wastage so you can normally recognise  a mono panel as it will have uncovered gaps at the four corners of the cells. 
• These cells are more efficient than poly solar cells and that is why mono panels generally have a higher solar cell efficiency than poly panels.
• Mono panels have much greater embedded energy than poly panels i.e. it takes more energy to make these panels and thus they are less environmentally friendly.

Poly Panels

• Poly panels are made up of polycrystalline solar cells. 
• Polycrystalline solar cells are made from cast square ingots of molten silicon carefully cooled, solidified and cut. These poly cells are less expensive to produce than single crystal silicon cells, but are less efficient. This is why poly panels have a lower solar cell efficiency than mono panels and a lower embedded energy.
• Poly panels tend to be better in higher temperatures than mono panels as illustrated by the open circuit voltage.

Mono vs Poly

To illustrate, comparing an Auxin 200 watt mono panel with their 200 watt poly panel (both with 54 cells, maximum power of 204.9W and panels tested at 25^o C):

200 Watt Panel	Solar Cell Efficiency %	Open Circuit Voltage (V/oC)
Mono	15.63%	-0.35%/C
Poly	15.37%	-0.34%/C

As you can see there is not much difference between the solar cell efficiency of the mono vs the poly with the mono having the edge. However poly performs better in hotter temperatures. The Clean Energy Council states that the temperature around a panel is around 25^o C greater than the ambient temperature. Perth's average temperature is 23^oC so the expected average cell efficiency of mono will be 0.0805% and poly 0.0782% less than under test conditions. Not a great deal of difference but in practice it is enough for poly to get the edge.