Friday, 5 March 2021

PV Cell Formats and Size Guide


Here's a handy diagram I created to help show the difference between all the new solar PV cell formats in the market right now.

Monocrystalline cells are made by slicing across a cylindrical ingot of silicon.  The least silicon waste is created by having perfectly round cells, but these don't pack very neatly into a solar panel (or module), leaving gaps between the cells which reduce the power output of the panel compared to one that fills the area more effectively.  This trade off between panel power and cell economics has typically resulted in a compromise where mono-crystalline cells have rounded corners.

As silicon prices have fallen, the economics has moved decisively in favour of cutting to make a cell with a more perfect square shape, driving up the panel power by having all of the available area as working photovoltaic material.

After a long period of standardisation on the M2 cell format of 156.75mm, manufacturers cannot agree on a standard size going forward, with each proposing a slightly different format, and of course this means that the finished solar PV modules that the cells are assembled into also differ in size.

In what may come to be seen as a collective failure , and at least for the next few years, the industry has thrown away all the downstream benefits that come from having standard module sizes, a topic I will come back to in a future blog.