A solar cell is essentially a photosensitive semiconductor which, thanks to its properties, is capable of producing electrical energy when exposed to light. When light particles called photons hit the surface of a solar cell they have a chance of exciting an electron which then travels inside the cells structure. The movement of electrons, which are negatively charged particles, causes a potential difference which we know as voltage. The effect of creation of electrical potential under exposure to light is called a photovoltaic effect and it has been discovered by a Frenchmen called Edmond Becquerel in 1839.
The solar panels are made of solar cells connected in series and in parallel. There are two main families of photovoltaic panels:
- Solar panels that contain silicon
- Solar panels that do not contain silicon
Below photos of a monocrystalline solar panel (left) and a polycrystalline one (right) –
In the family of solar panels that contain silicon, we can distinguish three main types depending on the fabrication technology:
- Polycrystalline solar panels: these photovoltaic modules are a little less expensive than monocrystalline but have a lower surface yield (which means that a higher number of panels must be installed to produce the same energy), generally less than 16%. The main advantage of these solar panels is that they have rather low temperature coefficients which define how the solar production decreases when the temperature rises. This type of panels is therefore well suited for hot regions with strong sunshine.
- Monocrystalline solar panels: these photovoltaic modules are a little more expensive than polycrystalline ones but they have a higher surface yield, which can go beyond 20% (requiring lower number of panels to achieve the same performance). These solar panels have higher temperature coefficients than polycrystalline ones, and are therefore preferred in cooler regions with lower sunshine which require stronger performance from the cells.
- Amorphous solar panels: these panels are mainly dedicated to large surface installations due to a very low surface yield which does not exceed 10%. The prices of polycrystalline and monocrystalline solar panels have heavily declined since 2010, making them widely available to the larger public and because of that, the amorphous solar panels currently represent a tiny part of the market. The main advantage of these solar panels is that they perform better than crystalline panels under diffused sunshine, during cloudy days.
- In the family of solar panels that do not contain silicon, there are several different types of modules depending on the semiconducting material used instead of silicon:
- CdTe solar panels: which are made from Cadmium Telluride.
- CIGS solar panels: which are made from Copper, Indium, Gallium and Selenium.
- CIS solar panels: which are made from Copper, Indium and Selenium.
- Organic DSC: which stands for dye-sensitized solar cell.
- Those technologies, together with amorphous silicon panels belong to a category of thin film solar panels, and are made by various ways of deposition of a semiconducting material on a substrate (usually glass). There are several advantages of the thin film technology notably:
- the substrate can be flexible, resulting in flexible solar cells,
- they can be fabricated using commonly available materials, which can drive the manufacturing costs down.
- The major disadvantages include:
- Low surface yield, generally less than 12%, so the surface required for installation is larger than with crystalline modules.
- Only inverters with built-in transformers are compatible with these solar panels (more expensive inverters with lower efficiency).
Below is a table summarizing the advantages and disadvantages of each type of solar panel. This table is given for information only because currently almost the entire market has switched to mono and polycrystalline panels. There is no longer any real difference in price between crystalline panels and other types of panels).
|Price||Efficiency||Availability||Temperature coefficient||Performance : diffused light|
|Other thin Film||ooo||o||o||ooo||ooo|
IMEON hybrid inverters are transformerless inverters and are therefore compatible with monocrystalline and polycrystalline solar panels.