How Solar Cells Work - How It Works

Sun light is actually a mixture of light and heat, and the light itself is a mixture of different frequencies of electromagnetic radiation, including invisible ultraviolet (the sunlight that gives you sunburn) and infrared (the invisible light you feel as radiated heat if you stand near something like a camp fire or barbecue). The great thing about solar energy is that it's plentiful and free. In theory, every horizontal square meter of Earth receives about 1kW of power from the Sun (assuming overhead Sun at midday and a cloudless sky): that's 1000 joules of energy every single second, which adds up to a huge amount over the course of a (sunny) day. 

Energy from the Sun is the most abundant and absolutely freely available energy on planet earth. In order to utilize this energy we need help from the second most abundant element on earth, sand. The sand has to be converted to 99.999% pure silicon crystals to use in solar cells. To achieve this, the sand has to go through a complex purification process as shown. The raw silicon gets converted into a gaseous silicon compound form. This is then mixed with hydrogen to get highly purified polycrystalline silicon. These silicon ingots are reshaped, and converted into very thin slices called silicon wafers. The silicon wafer is the heart of a photovoltaic cell.

What are solar cells?

A solar cell is an electronic device that catches sunlight and turns it directly into electricity. It's about the size of an adult's palm, octagonal in shape, and colored bluish black. Solar cells are often bundled together to make larger units called solar modules, themselves coupled into even bigger units known as solar panels (the black- or blue-tinted slabs you see on people's homes, typically with several hundred individual solar cells per roof) or chopped into chips (to provide power for small gadgets like pocket calculators and digital watches).

What is solar cells made up of?

A solar cell is made of two types of semiconductors, called p-type and n-type silicon. The p-type silicon is produced by adding atoms such as boron or gallium that have one less electron in their outer energy level than does silicon.  Because boron has one less electron than is required to form the bonds with the surrounding silicon atoms, an electron vacancy or “hole” is created.

The n-type silicon is made by including atoms that have one more electron in their outer level than does silicon, such as phosphorus. Phosphorus has five electrons in its outer energy level, not four. It bonds with its silicon neighbor atoms, but one electron is not involved in bonding. Instead, it is free to move inside the silicon structure.

A solar cell consists of a layer of p-type silicon placed next to a layer of n-type silicon. In the n-type layer, there is an excess of electrons, and in the p-type layer, there is an excess of positively charged holes (which are vacancies due to the lack of valence electrons). Near the junction of the two layers, the electrons on one side of the junction (n-type layer) move into the holes on the other side of the junction (p-type layer). This creates an area around the junction, called the depletion zone, in which the electrons fill the holes.

How Solar Cells Work?

It generates electricity by using sunlight to make electrons hop across the junction between the different flavors of silicon:

1. When sunlight shines on the cell, photons (light particles) bombard the upper surface.
2. The photons carry their energy down through the cell.
3. The photons give up their energy to electrons in the lower, p-type layer.
4. The electrons use this energy to jump across the barrier into the upper, n-type layer and escape out into the circuit.
5. Flowing around the circuit, the electrons make the bulb light up.

Solar Energy Pros and Cons

Solar energy has pros and cons. It’s important to find an energy that works for you, and determining if solar energy will fit into your daily lifestyle is a priority. Here are some factors to consider when deciding which energy choice is right for you.

Advantages of Solar Energy

• Lowers your Electricity Bills
• Environmentally Friendly
• Moves us Closer Towards Energy Independence
• Sustainable
• Low Maintenance
• Benefits the Electricity Grid

Disadvantages of Solar Energy

• Expensive Initial Investment
• It Won’t Work at Night
• Limited Energy Storage
• Space Constraints
• Isn’t 100% Pollution-Free
• Depends on Location

Types of Solar Power Systems:

Solar energy is the use of solar energy in various technologies by taking in the heat radiated from the sun. A photovoltaic system is a system that uses the energy of the sun to generate electricity. Typical solar systems are solar panels (absorbing sunlight), inverters (converting DC power to AC power), batteries (to store  extra power generated), grid boxes, and system balancing (wires). , Nut, etc.). ). Solar systems come in a variety of sizes, including 1kW, 3kW, 5kW, and 10kW. 

 In general, solar  systems can be divided into three types.

On-Grid Solar System: 

This type of Solar Power System is the most common. A grid-tied or grid-connected photovoltaic system, as the name implies, is a photovoltaic system  connected to a home and a traditional power grid. This type of PV system does not include a storage battery.  The solar power generated by the 

solar module is  consumed instantly by all devices. If your PV system produces more power than you use at home, you can sell the surplus power back to your power company with a scheme called net metering. If the PV system does not produce enough power, the equilibrium current required by the consumer will be drawn from the public power grid. 

This type of system requires several electrical cabinets, junction boxes and circuit breakers, and an inverter. You will also need to sign a grid connection agreement with your local utility company.

Off-grid Solar Power System:

An off-grid solar power system, is a completely independent solar power system with energy storage that is not connected to the main utility grid. The solar panels are the only source of energy in an off-grid solar power system. This energy is either provided to the appliances, or, stored in the battery for future use.

Off-grid solar power systems are ideal for remote rural areas or applications where other power sources are either unavailable or impractical or load shedding. Off-grid solar power systems can either be AC-based systems, in which case they include an inverter that converts the energy stored in batteries to AC power & feeds it to AC appliances, or, DC-based systems, that are cheaper as they don’t need an inverter but the power can only be fed to DC appliances.

This type of system is more expensive because it is bigger as it’s not connected to the electric grid. This requires more solar panels and batteries.

Hybrid Solar Power System

A hybrid solar power system is a solar power system with energy storage that is similar to a grid-tied solar power system but comes with an energy storage system usually in the form of battery backup. In the last couple of years, this type of solar power system is becoming very popular, even though it’s more expensive. When solar energy production exceeds demand, the excess solar power is utilized to charge batteries & stored for later use. When production is lesser than demand, the stored energy from the batteries is used to make up the shortfall.

A well designed hybrid solar power system provides you dual benefits of reducing your electricity bills while also providing you the comfort of having back-up power during a power outage. The hybrid system consists of a PV array, a charge controller, a battery bank and inverter and in some occasions a tertiary power source like a wind turbine or a gas generator.

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Frequently Asked Questions: Solar Cells

Question No. 1: Can solar panels power a house?

Answer: Yes, solar panels can power a house. It depends on the power usage of your house, so you should install solar panels depending on that. Next thing that matters is amount of sunlight your panels are getting, more the better. 

Question No. 2: Why solar energy is good?

Answer: Energy from the Sun is the most abundant and absolutely freely available energy on planet earth and unlike fossil fuels, it won't run out anytime soon. As a renewable energy source, the only limitation of solar power is our ability to turn it into electricity in an efficient and cost-effective way.

Question No. 3: Will solar panels save me money?

Answer: Yes, they will save you money as you will be using free electricity generated by solar panels, and the excessive energy is sold to government. Units sold are deducted from the bill. Solar panels save you much more in the long-run. Your solar panel system can pay for itself in three years  

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