How Solar Works

Solar PV Cell Construction-How Are Silicon PV Cells Made?

By Cal Smith

October 11, 2021

How Solar Works

PV Cell Construction The majority of solar photovoltaic cells, or PV cell cosntruction are made using silicon crystalline wafers. The wafers can be one of two main types, monocrystalline (mono), or polycrystalline (poly) also known as multi-crystalline. The most efficient type is monocrystalline which is manufactured using the well-known Czochralski process. However, more recently heterojunction

By Cal Smith

October 11, 2021

What Is PV Cell Construction?

Silicon is first extracted from a specific type of sand known as silica sand, or silicon dioxide, which is usually made from crushed quartz rock. A number of different manufacturing processes are required to crystalline silicon solar cells starting from a raw material called Quartzite, which is a form of quartz sandstone rock.  First, Quartzite or silica sand is converted into metallurgical grade silicon by combining Carbon and Quartzite in an arc furnace. 

What Is PV Cell Construction?

Continued: This process occurs at very high temperatures and results in 99% pure silicon. Next, the metallurgical grade silicon is converted into Polysilicon using either a chemical purification process called the Siemens process, or upgraded metallurgical-grade silicon (UMG-Si) using a number of more economical metallurgical processes being developed.

What Is PV Cell Construction?

Continued: At this stage, we have a form of pure polycrystalline silicon which can be doped with trace amounts of either boron or phosphorous to become either P-type or N-type polysilicon. To make polycrystalline wafers, the doped silicon is melted and cast into large rectangular blocks before being thinly sliced using a diamond wire cutter to produce the polycrystalline or multi-crystalline wafers. The wafers can then be coated with a very thin layer of either P or N-type to form the PN-junction (photovoltaic cell).