Most photovoltaic cells are made from silicon, which is the second most abundant element in the crust of the earth. Silicon is commonly used for manufacture of computers. Silicon is extracted by heating silica to very temperatures before being cooled. The speed of cooling determines the size of the crystal with slower formed crystals being larger. So the question what is the difference between monocrystalline and polycrystalline PV panels can be easily answered.
Though made from the same material, single-crystal photovoltaic cells are those made from a single large silicon crystal while polycrystalline photovoltaic cells are those made from one piece of silicon consisting of millions of crystals.
Since multiple-crystal photovoltaic cells contain several crystals, they have a less perfect surface than their single-crystal counterparts. This causes them to absorb less solar energy and therefore produce less electricity than the single crystal cells. However, the process involved in the manufacture of multiple crystal cells is simpler making the cells cheaper per square meter.
The two types of panels look totally different, with the single crystal one having a perfectly uniform appearance while the multiple-crystal one having a grainy feel and look. However, they may not look any different when seen from a distance.
Although the cost is roughly the same per watt of power produced, the multiple-crystal cells are normally larger than single-crystal cells of the same price. Therefore if space is a major consideration, single-crystal cells are ideal. If space is not constrained, the buyer should worry about other factors apart from whether the panels are made of single or multiple-crystalline cells.
Temperature rise can cause a decrease in power production of the solar cells. Single-crystal has a lower percentage of decrease in production when compared to their multiple-crystal counterparts. Therefore a buyer should pose the question, what is the difference between monocrystalline and polycrystalline PV cells, to a seller before deciding on what panel to buy.