Are you thinking about going solar? Buying a solar plant for your home may seem like a complex task but it is as simple as buying a new phone. We do a lot of research before buying a phone or laptop. The same theory applies to buying a solar plant. There are many types of solar panels available in the market. Each has its pros and cons. But before digging deep into the types of solar panels, let us first understand what Solar panels are and how they work.
Understanding Solar Panels
All types of solar Panels are used to convert solar energy into electricity. Each panel consists of several individual solar cells. Most commonly used solar panels are of 72 cells & 60 cells, which have a size of 2m x 1m & 1.6m x 1m respectively.
The solar cells are made from layers of silicon (which acts as a semi-conductor), phosphorous (negative charge) and boron (positive charge). Likewise the sunlight is composed of various particles of energy called “photons”.
When these photons strike the surface of solar panels, they knock out electrons from silicon. This initiates an directional electric current which flows through busbars and fingers made of silver which are printed on the silicon cells. This is how energy is produced from solar panels and this process of light producing electricity is known as Photovoltaic Effect.
Types of Solar Panels
The solar panels can be divided into 4 major categories:
- • Monocrystalline solar panels
- • Polycrystalline solar panels
- • Passivated Emitter and Rear Contact cells (PERC) solar panels
- • Thin-film solar panels
The solar panels are determined by the type of solar cells present in it. Each cell has a unique characteristic and has a different appearance.
Monocrystalline Solar Panels
The monocrystalline solar panels are also known as the single crystal panels. They are made from pure silicon crystal which is sliced into several wafers forming cells. These wafers are cut to an octagonal shaped wafer because of which they get their unique look and uniform colour. They can be easily identified by their black or dark blue colour, as they are made from pure silicon.
Within monocrystalline solar panels, there is a technology known as Half Cut cells. Here the square shaped cells are cut in half, so there are twice the number of cells. The top half of the panel has all cells connected in one series and the bottom half in another series. This allows the panel to continue power generation in the top half even if there is a shadow on the bottom half of the panel. Thus, the overall power generation from half cut cells is higher in installations with partial shadow issues.
Feature of Monocrystalline Solar Panels
- • Monocrystalline solar panels have higher conversion efficiency which means that they produce more kW/hour of electricity. It is because they are composed of a single silicon crystal which allows more space for the electrons to move.
- • The monocrystalline panels display higher heat resistance as compared to other panels, which means that their electricity production capacity is less affected by heat and they produce electricity at a higher efficiency at high temperatures.
- • The monocrystalline panels are more expensive as compared to other panels since the manufacturing process of single-crystal silicon cells is complex.
Polycrystalline Solar Panels
The polycrystalline solar panels are composed of multiple silicon crystals. They are made from silicon fragments that are melted and poured into square molds. Once these crystals are cooled, they are sliced into thin wafers and assembled together to form a polycrystalline solar panel. They are also known as “multi-crystalline” panels.
Features of Polycrystalline Solar Panels
- • Polycrystalline solar panels have lower efficiency than monocrystalline solar panels as they are composed of multiple silicon crystals due to which there is limited room available for the electrons to move.
- • The polycrystalline panels can be identified by the square shape of the cells and shining blue hue with straight edges.
- • These panels are more affordable than monocrystalline solar panels as the manufacturing process is simpler and less silicon is wasted during the whole process.
Passivated Emitter and Rear Cell (PERC) Solar Panels
Also known as ‘rear cells’, PERC solar panels are manufactured using advanced technology. It is done by adding a layer on the back of solar cells. The traditional solar panels absorb sunlight only to some extent and some light passes straight through them. The additional layer in the PERC panels allows this unabsorbed sunlight to be absorbed again from the rear side of the panels, making it even more efficient.
Nowadays, PERC technology is typically combined with Monocrystalline cells to produce high efficiency Mono-PERC panels which have the highest power ratings among commercially available solar panels.
Features of Passivated Emitter and Rear Cell (PERC) solar panels
- • PERC solar panels are more efficient as compared to traditional solar panels as they absorb more sunlight.
- • There is an additional layer at the back of the panels which reflects the unabsorbed sunlight back to the solar cells for further absorption of the sunlight.
Thin-film Solar Panels
Unlike monocrystalline and polycrystalline solar panels, thin-film solar panels are manufactured using photovoltaic substances which include Amorphous silicon (a-Si), copper indium gallium selenide (CIGS) and cadmium telluride (CdTe). These substances are deposited onto a solid surface such as glass, metal or plastic making it lighter and easy to install.
Categories of Thin-film solar panels:
- • Cadmium telluride (CdTe) – CdTe solar panels have the lowest carbon footprint, however, the toxicity of cadmium is an environmental concern as it is not easily recycled
- • Amorphous silicon (a-Si) – Amorphous silicon panels generally are shapeless in nature and their silicon is unstructured on the molecular level.
- • Copper indium gallium selenide (CIGS) – CIGS is manufactured using a thin layer of copper, indium, gallium, and selenium on a glass or plastic sheet. This makes CIGS most efficient among other thin-film panels due to its higher absorption abilities.
Features of Thin-film solar panels
- • Thin-film solar cells are comparatively lightweight and more flexible than traditional silicon panels, thus making them easy to install.
- • They are less efficient compared to silicon crystalline panels. However, they have a lesser carbon footprints and are comparatively cheaper than the other panels.
- • These types of panels are most suitable for large rooftop areas or places having wide open space.
Comparison of Types of Solar Panels on Cost, Efficiency & Appearance
|Appearance||Black/ Darker colour with octagonal shape||Blue colour with square edges||Black and rounded edges||Depends on the variant|
Less space required
|Lowest installation cost|
High carbon footprint
|Low heat resistance|
Lower energy efficiency
|Most expensive||Shorter life span|
Power Capacity of Solar Panels
The power rating of solar panels is measured in Wp, i.e. Watt peak, which is the peak DC power generated by the panel under standard testing conditions. Different types of solar panels have different capacities in Wp due to their different efficiencies.
Mono-PERC panels, which combine monocrystalline silicon cells with PERC technology have the highest power rating among commercially available solar panels. This is because of the high efficiency of monocrystalline cells combined with PERC technology. Panels of up to 540 Wp DC power are available from most of the Tier 1 Chinese solar panel manufacturers.
Polycrystalline solar panels are typically available in the range from 320 to 370 Wp. Thin film solar panels are typically not used in commercial or residential applications. They are mainly used only in large utility scale power plants.
What Type of Solar Panel is Best & How Should I Choose?
While Mono-PERC solar panels with Half Cut cells are possibly the most advanced & efficient technology of solar panels available today, the choice of solar panels to use for your installations depends on a number of factors.
Monocrystalline or Mono-PERC panels have the highest efficiency, the highest power output and hence are most suitable to install a higher capacity of solar plant in a smaller area. For instance, if your electricity bill is very high, you would want to maximize the capacity of your solar plant. If you have a limited area available for installation, using monocrystalline panels instead of polycrystalline will help you install up to 50 to 60% higher capacity of solar plant within the same area. While the up-front cost of mono panels is higher, having a higher capacity of plant will be beneficial in the long run by reducing your electricity bills much more than polycrystalline panels can.
Polycrystalline panels can be chosen due to their lower cost, especially in case where sufficient rooftop area is available. Moreover, if you want to avail the benefit of government subsidy, polycrystalline panels are currently the only option. Subsidy is available for residential solar only for panels manufactured within India. Currently Indian manufacturers can only supply polycrystalline cells for projects to be installed under government subsidy, as monocrystalline cell manufacturing is not yet started in India.
Thin-film solar panels are typically not used for residential or domestic installations due to their lower life. They are normally used more commonly in larger utility-scale power plants.
Choosing the right and suitable type of solar panels for your home may seem challenging but once you have gathered all the information it is easier to make the decision. When selecting the right solar panel for your home you should always consider all the pros and cons of each option.