There are three major types of solar panels: monocrystalline, polycrystalline (also known as mulit-crystalline), and thin-film. Nearly all solar panels are made of crystalline silicon and have a life expectancy of approximately 25 years.
Monocrystalline panels are made from top-grade silicon and have the highest efficiency rate (15-20%), perform well in low-light conditions, are space-efficient and are the most durable. While monocrystalline panels are more expensive than other options. They usually come with a 25-year warranty.
Polycrystalline panels (also known as multi-crystalline) are manufactured using a simpler, more cost-effective process. Made with less pure silicon, they have a lower efficiency rating than monocrystalline panels (13-16%) and require a larger installation with more surface coverage for equivalent performance.
Thin-film solar panels are made cheaper than crystalline-based solar panels. However, their lower efficiency rating (13-14%) means you will need significantly more coverage space to achieve similar energy production. Thin-film panels also tend to degrade faster than their counterparts and have shorter warranties as a result.