Monocrystalline Solar Panels

Mono vs poly cells

Both monocrystalline (mono) and polycrystalline (poly) solar panels serve the same function in the overall solar PV system: they capture sunlight and convert it into electricity. The cells of both are made from silicon, which is a semiconducting material. The difference between the two technologies stem primarily from the production process of the silicon wafers. 

Visual differentiators: 
Polycrystalline panels have a blue hue while monocrystalline solar panels have a black appearance (although some bluish reflections can be observed depending on the light). Another visual difference noticeable as a result of the production process is that mono cells are not always rectangles because they are missing corners which is because they were cut from a round rod. However, also mono cells can sometimes be shaped perfectly rectangular. The panels on the picture are also different because the poly panels is full cell while the mono panel is a half-cell panel. 

Polycrystalline process: 
Poly wafers are made by melting raw silicon and pouring it in a square mold, casting a polysilicon ingot. This casting process doesn’t align the silicon structure perfectly, which results in the formation of many individual silicon crystals within the ingot. The nature of the many silicon crystals also produces the speckled, glimmering look and blue colour that polycrystalline solar panels are known for.

Mono half-cell panel and  full cell poly PV panel

Mono PERC wafer production

Monocrystalline process:
Mono ingots are formed from a pure refined silicon in a pulling process. This process involves a crystal rod that is dipped into molten silicon and rotated as it is raised back out. Each time this is performed the ingot grows into a larger single crystal as the layers of silicon are aligned by this process. The name “mono-crystalline” indicates that the wafer is made from single-crystal silicon. In mono wafers the electrons that generate a current have more room to move, making monocrystalline solar panels more efficient.

Mono solar panels are communicated nearly everywhere as mono PERC panels. PERC stands for “passivated emitter and rear contact” or “rear cell”. Solar panels built with these cells have an additional layer on the back of the cell. This additional layer allows more sunlight to be captured by reflecting unabsorbed light back into the cell for more efficiency.

From ingot to wafer to cell:
Both mono and poly cells go through these general steps. The silicon ingot is sliced into thin wafers. The wafer's bottom side is screen printed with aluminium paste and the top side is printed with silver fingers (fine lines) that conduct the electric charge. The detailed production process is more complex and some aspects are not covered in this brief explanation.

Half-cell PV panel close up

Our mono PERC PV panel line up

A few years ago, polycrystalline panels were the mainstream solution and made up the vast majority of all PV panels installed and sold. We used to sell both poly and mono panels. Over time the constantly improving price to performance ratio of mono PV panels has largely caused poly technology to be replaced. Our current PV portfolio only consists of mono half-cell panels, offering optimal performance and value for our customers. 

three PV panels