India has almost 5000 trillion kWh per year of solar energy. We cannot use this energy directly, but with the help of solar panels we can get access to this solar radiation and convert it into usable clean electric energy with the help of photovoltaic principle.
The solar photovoltaic panel consists of one or more PV modules (typically a single solar panel is known as a solar module) and the solar module consists of a series of solar cells connected to produce the required output power. A solar cell produces power in a few watts (0.1 to 3 watts) which is not sufficient to provide power for any practical usage, hence they are connected to get the desired output.
Solar panel development :
Working of solar panel (Module) :
The solar panel consists of a solar cell, glass casing, metal frame, and wires which allows the flow of current from all the cells. Glass casing offers protection against the high temperature, it consists of a protective sheet at its back to protect against humidity and heat dissipation. To receive maximum solar radiation anti-reflective coating is provided on the solar panel.
Solar cells are formed up of semiconducting material such as silicon which can absorb solar rays. Solar radiation in the form of photons falls on solar cells (it consists of the positive and negative electron) that absorbs the light and causes the electrons to flow thus generating electricity. The generated electricity is transmitted through a solar inverter to the loads with the help of the wires. The energy produced depends on the number of solar cells connected and its voltage capacity.
Types of solar panels :
Solar cell depending on the formation is of mainly three types :
- Thin Film
1. Monocrystalline :
It is the purest solar panel with dark uniform color and round edges. These panels consist of a single uniform black color solar cell (formed using the Czochralski method). They are arranged in row / column fashion to form a rectangular structure coated with a glass sheet.
As these cells are made up of a single silicon crystal, electrons can freely move in the cell which improves the cell efficiency. To generate the same amount of power the number of monocrystalline solar modules required is less as compared to the polycrystalline solar modules. With the evolving technology, an advanced version of the monocrystalline cell is introduced known as Passivated Emitter and Rear Cell (PERC) that can seizure more energy with the help of additional layers on the rear side of the cell.
2. Polycrystalline solar panel :
Polycrystalline solar panels also known as multi crystalline or many crystal silicon are formed by using fragmented silicon solar cells, in which molten silicon is poured into the casing. Due to this construction, they have limitations to the flow of electrons hence less efficient compared to the monocrystalline solar modules. They have bluish grainy gemstone-type non-uniform cubical structure.
3. Thin-film solar panel :
A thin-film solar cell is very thin, of about 1 to 4 μm thick and they are made from different materials such as given below
- Cadmium telluride (CdTe) – Cadmium telluride layer is placed between the conducting layers to capture maximum possible radiation; it has a glass coating on the top to protect the layers.
- Amorphous silicon (a-Si) – Thin film solar cell is made up of non-crystalline amorphous silicon material deposited on the top of plastic, glass, or metal.
- Copper Indium Gallium Selenide (CIGS) – A thin layer of copper indium gallium selenide is placed on the top layer of glass, aluminum, plastic or steel and electrodes are placed on the front and the back of the material to capture electrical currents.
Thin film solar panels prove to be a good option for low power requirement and are flexible and lightweight. They are usually used where the space area is large.
Comparative analysis (Monocrystalline V/S Polycrystalline V/S Thin Film) :
|Type||Efficiency||Temperature Tolerance||Cost||Life Span||Space Requirement|
|Monocrystalline||17% – 22%||0 to +5% (Performs well at high temperature)||High||25-30 years||Requires less area|
|Polycrystalline||15% – 20%||-5% to +5% (Efficiency is reduced at high temperature)||Low||25 years||Requires comparatively greater area|
|Thin Film||4% -12%||-3% to +3%||Low||15 years||Requires comparatively larger space area|
Factors affecting the solar panel :
Solar panel efficiency can be affected by following factors such as:
- Irradiance (Watt/m2)
- Shadows (Shading effect)
- Orientation of Panel
- Time Zone
How are the solar cells connected ?
Generally solar cells are made up of silicon material. A single solar cell is not capable of generating sufficient power, hence the number of solar cells are connected in series or parallel depending on the prerequisites.
The most common solar panel available is 12 V or 24 V. For a 12V panel we need 36 solar cells and so on.
Which is a better option: Series or Parallel ?
As we know, solar modules can be connected in series or parallel. Parallel wiring seems to be a good option because in a parallel connection even if one panel gets damaged the entire system will not be affected. But, to achieve the voltage requirement, series connection of the panel is a good choice.
A hybrid connection can be the way to gain the advantage of both the types. It is difficult to choose between series and panel without knowing the design requirement, so one needs to know the exact system requirement to choose the connection.
Solar panel wiring connection depends on the power requirement.
- First, calculate the required power for your loads
- Individual solar cell generally comes with a power of 0.1 to 3V. Select the rating of the solar cell.
- Depending on the output power required, connect the solar cells in series or parallel.
- Voltage and current ratings are to be considered for system design and for choosing an inverter
Don’t worry, our design engineer will provide you with the best cost-effective solution.
Solar module(panel) for your home :
Solar panel installation in your residential area will not only save electricity bills but also will reduce grid dependency and will offset release of harmful carbon dioxide. For installing a solar system at your place, performance with low cost plays an important selecting factor.
Monocrystalline and polycrystalline are the two widely used options, thin film cells are not considered for residential buildings due to its space requirement and low efficiency.
Depending on the power requirement and the space availability, one can choose the panel. But in general, monocrystalline solar panels are used for installations above 1000 watts and polycrystalline solar panels are used for low power requirements.
When it comes to residential buildings, installing monocrystalline solar panels prove to be more beneficial even if the cost is high as the return these solar panels will give you is worth the cost. But if budget is the constraint, polycrystalline can be the option.
Point to be considered: Monocrystalline solar cells work best when solar radiation falls directly on the cell. If you are in the zone where you get abundant direct sunlight and very few shadows this solar panel will give you the best result for a long time. But if you are in the zone with non-uniform solar radiation, then using mono crystalline will be the same as poly crystalline.
Solar panel technology – Trends :
With the increasing solar adoption, researchers are trying to improve the solar efficiency with reduction in the cost. Some of the emerging technologies are:
1. Bifacial solar technology
This technology generates electricity from both sides of the solar cell. It can generate 15% to 20% more electricity when compared to traditional solar panels. It is a good choice for large scale installation with high power requirements.
2. Concentrated PV technology (CPV)
CPV solar panels are three times more efficient than traditional silicon solar panels, capable of reducing energy loss by concentrating solar radiation on a large surface area. They are usually suitable for space or military applications and can withstand a concentration ratio of a thousand or more. Currently, CPV is expensive due to the added components like solar trackers and cooling mechanisms.
3. Solar tile technology
Solar tile technology also known as solar slates or solar shingles are placed on solar roofs. This technology uses thin film or monocrystalline silicon material and proves to be slightly less efficient but is trendy when it comes to look as compared to the conventional solar cell.
4. Transparent solar panel (TPV)
Transparent solar panel is able to absorb the invisible infrared and ultraviolet radiation that falls on the cell. As it is transparent, one can use any design to improve the look. TPV with thin silicon film is able to absorb the longer wavelength of light thus improving cell efficiency to capture photons.
Recycling solar panels :
Although generating electricity from solar is clean, after the solar panel lifespan which is almost 20 years, the solar parts are waste. This solar photovoltaic module consists of some chemical elements such as lead and cadmium that can be hazardous if not disposed of properly.
Some elements in the solar panel like silicon, glass sheet, metal frames, and wire can be recycled. The Ministry of New and Renewable Energy (MNRE) has announced compulsory disposal of solar panel modules.
Government Scheme :
The government is constantly trying to reduce dependency on fossil fuel, and adopting more renewable sources of energy. Households can save up to 95% of the electricity bill by installing solar panels.
To motivate residential solar rooftop installation, Central financial assistance (CFA) of 40% is given for plant capacity upto 3KW and above 3KW upto 10KW CFA is limited to 20% according to the MNRE 2021 stated guidelines.
For group housing societies (GHS) and residential welfare associations (RWA) CFA is limited to 20% for rooftop solar plants. The capacity limitation for this sector is limited to 10KW per house with maximum capacity upto 500KWp (Kilowatt peak) including RTS per house in the GHS/RWA.
To make India ATMANIRBHAR, under the guidelines of the PM-KUSUM scheme and the rooftop solar subsidy program, to take advantage of the Central Financial Assistance (CFA), the project must use modules and its cells made in India.
To install solar panels, one must check all the government initiatives and guidelines to get maximum benefits out of the solar plant.