Solar panels, formed from several types of photovoltaic cells, can be manufactured from a variety of different materials – most of which being crystalline silicon. Over a hundred different manufacturers produce photovoltaic cells all over the world.
Solar panels, formed from several types of photovoltaic cells, can be manufactured from a variety of different materials – most of which being crystalline silicon. Over a hundred different manufacturers produce photovoltaic cells all over the world.
As it stands, there are four main types of commercially available solar modules:
Monocrystalline Silicon PV – These are the most commonly used panel types alongside polycrystalline PV, accounting for around 93 percent of all modules sold globally. They are broadly used and can be applied to both domestic and commercial installations, ideal for both large and smaller scale systems.
These types of cells are produced by first growing a crystal of silicon from highly pure molten silicon. The crystal is then cut into thin slices with from the basis of a solar photovoltaic cell. These slices often measure between 0.2 and 0.3mm thick, cut into a hexagonal shape to optimise the module’s space.
Monosrystaline cells are the most efficient type of photovoltaic cell, with an efficiency level of 13-17%. This renders them ideal for smaller surface areas in order to optimize roof space. However, they are more expensive than other types of cell, as they take more energy and time to produce energy.
Polycrystalline Silicon PV – Polycrystalline silicon is a commonly used type of panel. They are produced from highly pure molten silicon, but instead of being grown as a crystal they are produced using an elaborate casting proves. The silicon is heated to a very high temperature, before being cooled under controlled conditions into a mould. It then sets as an irregular multi-crystal, or ‘polycrystalline’ form.
This crystal is then cut into 0.3mm slices to be used inside the panel. The blue appearance of many solar panels is down to the anti-reflective layer which is applied to the cells, which increases their efficiency. Polycrystalline cells formed through this process have an efficiency level of between 11 and 15 percent. While this is lower than monocrystalline panels, it is usually reflected in the costs. Due to their slightly lower levels of efficiency, polycrystalline PV cells are most appropriate when larger surface areas are available to lessen the cost of the installation. They are suitable for both commercial and domestic solar panel systems.
Amorphous Silicon PV – 4.2 percent of global market sales are composed of amorphous silicon, a non-crystalline method made in an entirely different way to mono and polycrystalline PV. The semi-conductor materials are thinner, measuring at just 0.5 – 2um thick (with 1um equating to 0.001mm). A considerably less amount of raw materials is needed for the production of amorphous silicon compared with the manufacturing of crystalline silicon. The thin film of amorphous silicon is deposited as a gas to further chemical purposes, before having a conducting grid and electrical contacts fixed.
These types of cells have an efficiency level of between 6 and 8 percent, which is lower than their crystalline counterparts. As a result of their low generation-density, amorphous silicon cells are not suitable for residential installations at present. Though their relatively low levels of efficiency call for a larger surface area, the output is less prone to become affected by high temperatures and/or shading.
Hybrid PV – Hybrid photovoltaic cells are classified as using two different types of photovoltaic technology. The most common type consists of a monocrystalline silicon cell coated in an ultra-thin amorphous silicon layer.
Hybrid cells combine the advantages of crystalline and amorphous PV technology, performing well at higher temperatures whilst maintaining considerably higher efficiency than conventional silicon cells, as well as bearing an increased sensitivity to lower and indirect light levels. Efficiency levels can exceed 18 percent and while the panels are deemed cost-effective for this level of efficiency, they are more expensive.
Which type of panel should you choose?
If you are considering installing solar panels, it is important to consider your requirements and specific circumstances. Will the panel array be used for a domestic or business installation? Do your concerns lie with cost or efficiency? Always try to ensure that the installer is reputable and accredited by the Renewable Energy Association and the Microgeneration Certification Scheme. They will be equipped to discuss your options and help find the best panel for your requirements.
Dane Cross is a green aficionado, passionate about getting the word out on renewable sources of energy and all things green. He currently works on behalf of Ardenham Energy, a UK-based provider of solar panels and wind turbines.
