Mono/PolyCrystaline and bifacial

Crystalline solar cells are connected together in series to create solar panels. Each cell produces a voltage of just over half a volt. 36 individual cells would be required to produce an unconnected voltage of approx 20 Volts which is enough to charge a 12 Volt battery.Monocrystalline cells have a slightly higher efficiency than polycrystalline cells but in real world applications there is little practical difference between them.

Mono-crystalline - solar panels use solar cells made from a very pure single large crystal, cut from ingots. They are usually blue-grey in color and have a fairly uniform consistency

A new type of Mono-crystaline solar panel has recently become available which has glass on both sides so that it can collect energy from both. By collecting light from both sides the bifacial panels have higher efficiency (up to 20%) for about the same cost.

Poly-crystalline solar panels use silicon cast from large blocks of silicon which may contain many small crystals. Manufacturers have varying approaches to creating poly-crystalline solar cells and they are the most common. Poly-crystalline cells are dark blue to almost black color and overall efficiency is about 11-13%.