The majority of Photo Voltaic cells produced today use crystalline silicon (c-Si), a light absorbing semiconductor. Mono-crystalline technology uses thin wafers sliced from a single, pure crystal silicon ingot. Mono-crystalline solar panels have the highest efficiency rates since they are made out of the highest-grade silicon. The efficiency rates of mono-crystalline solar panels are typically 15-20%. Most solar panel manufacturers put a 25-year warranty on their monocrystalline solar panels. Mono-crystalline solar panels to perform better than similarly rated poly-crystalline solar panels at low-light conditions. The Mono-crystalline solar panels are most expensive when compared to the poly-crystalline solar panels