How to Choose the Right Solar Panel For your Home?

One of the most significant problems that Indians face throughout the country is power cuts.

Using generators or home inverters is one way of ensuring that your office or home receives continuous power.

Generators can be cumbersome to use and are noisy appliances, as well. It also consumes a lot of fuel.

Home inverters have their limitations, especially when it comes to managing loads.

Installing a Solar energy plant is an ideal solution under such circumstances.

Fortunately, India is blessed with abundant sunshine, with most of the places getting more than 300 days of bright sunshine.

Secondly, solar energy is available for free. Therefore, harnessing this natural source of renewable energy should be the ideal solution to the power shortage problems that India faces today.

Advantages of Installing a Solar PV system

  • Installing a Solar Photovoltaic (Solar PV) system can address the issue of power cuts efficiently.
  • Here are the benefits of installing solar PV systems for generating electricity for your domestic and commercial needs.
  • Installing a solar PV system is a one-time investment.
  • The system requires minimal maintenance while providing a continuous supply of electricity to the household or commercial establishment.
  • The principal raw material, i.e., sunlight, is available for free. Your solar PV system harnesses this free natural resource for producing electricity.
  • Apart from generating electricity, this system also helps to reduce your consumption, thereby helping you to manage your electricity bills.
  • The modern-day solar PV system can also supply electricity to the primary grid, whereby you become a generator of electricity rather than being a consumer. It helps the respective states to meet their power supply shortfall.
  • The Government of India has introduced subsidies, thereby encouraging people to use solar energy for their electricity consumption.
  • The household gets a continuous supply of electricity. There are provisions to store the electricity generated in a battery that is connected to a home inverter. Therefore, your dependence on the primary grid for your electricity supply reduces drastically.

A Solar PV system comprises the following elements.

Photovoltaic Array

This array is made up of solar PV panels that produce DC voltage whenever it receives sunlight. One can connect these panels or modules in series to produce electric supply. We shall discuss the solar PV panels in detail in this article.

Battery Bank

The battery bank is similar to your inverter battery. This appliance can store the excess energy that can be used at a later stage as a back-up source of electricity when the energy from the sun is not available.

Power Conditioning Unit

This unit protects against electrical faults like short circuits and line-to-ground faults. It also converts the DC supply provided by the solar PV panels into AC supply for your home or commercial establishment. It also serves the purpose of controlling the input energy from the PV panels and the output energy from the battery bank.

DC and AC Disconnect

This component protects the technical personnel from electric shocks during system maintenance.

The central panel (AC)

The entire load of the building is connected to the main panel. Protection is available in the form of circuit breakers.

Electric Meter

This meter enables the user to know the quantum of power generation and its usage. If you generate excess energy, you can supply electricity to the primary grid. Under such circumstances, your electric meter should have ‘Net Metering’ capabilities.

In this article, we shall discuss solar PV panels and understand the factors that one should look for when purchasing them. This buying guide will help in understanding the concept of solar PV panels.

Why do you install solar panels?

Generally, people install solar PV systems for the following three reasons in India.

Compensate for the power cuts and reduce the overall electricity consumption from the primary grid

Store excess power generated in batteries for use when solar energy is not available
Inspired by neighbourhoods

The concept of supplying power to the primary network is not yet available on a large scale in India.

States like Tamilnadu, Andhra Pradesh, and Karnataka have started implementing the concept of net metering. However, it is yet to gain popularity.

Classification of Potential Solar Panel Buyers in India

Before we discuss the concept of the buying guide for solar panels, let us see the buying pattern and classify the buyers based on the methodology.

There are three kinds of solar panel buyers in India.

The Layman Buyer

This category comprises nearly 60% to 65% of the solar panel buyers in India. This class of buyers does not know much about the working of solar panels. The buying guide will prove handy for this category of buyers.

The Brand Conscious Buyer

Such buyers go for specific brands. This category accounts for around 15% of the total consumers.

The Technically Equipped Buyer

It comprises the qualified class who know the functioning of solar panels and its usage. They comprise 20% to 25% of the total consumers in India.

How does a layman purchase solar panels?

The layman buyer depends on search engines like Google to understand the concept of solar panels. Usually, they search using queries like ‘1KW solar PV system price in India, 1KW solar panels for a 3-bedroom house,’ and so on.

This buying guide will prove incredibly useful for this category of buyers, as we will explore the concept in detail.

The Brand Conscious buyer is different

The Brand-conscious buyer will directly access the website of the specific brand of solar panels. Such buyers do not have much knowledge of the working of the system.

They are the ones influenced by advertisements and society. Usually, they look for specific brands but end up purchasing the brand they have heard the most.

The technically equipped person makes a measured choice

The technically equipped person are solar experts, dealers, manufacturers, installers, and so on. This category of buyer knows about the best brands and the top manufacturers of solar panels.

They can guide other users, as well to purchase the ideal equipment for their homes. Usually, such people give bulk orders.

Buying Guide for Solar Panels

We have already seen the different components of a solar PV system. We have also touched upon, in brief, the functionalities of each part.

From the discussion, you can gather that the solar panels are the most significant components of a solar PV system.

Costs wise, the solar panels comprise nearly 50% of the overall cost of installing the system.

The battery bank and inverter make up almost 25% of the price. The other components, along with the mounting structures, wires, cabling, and junction boxes, and so on, comprise the remaining cost.

Solar panels – The components

Solar panels are made of solar cells. However, the solar panels alone do not constitute a solar PV system.

It requires different processes such as cutting, taping, stringing, connecting, laminating, fixing junction boxes, and testing, and so on. The solar PV system comprises the following components.

Frame: The outer protection layer

Glass: It protects the solar cells from damage

Encapsulant: It is a significant component that provides adhesion between the solar cells, the top and bottom surfaces of the PV module. It should be optically transparent while having low thermal resistance. The encapsulant should be stable at high UV exposure and temperature.

Solar Cells: The absorption of sunlight and the conversion of solar energy into electricity happens at this location.

Encapsulant: There is an encapsulant layer beneath the solar cells, as it serves to connect it to the back sheet.

The Back sheet: It provides support to the entire module.

The Junction box: This box comprises the wires that transport the energy from the individual solar cells to the power conditioning unit.

Solar Panels – How do they work?

The solar panels absorb sunlight falling on it throughout the day. The higher the sun’s intensity, the greater is the excitation of electrons to contribute to the flow of current.

The solar panels work on the principle of converting solar energy into electrical energy. It is possible to store this energy in battery banks for use at a later stage.

Solar PV Systems – Different types

Generally, there are two types of solar systems in India.

Off-grid Solar System

Here, the solar system does not connect to the primary grid. The solar system comprises solar panels, mounting structures, inverter, power back-up, and the central AC panel.

This system works independently of the network. It enables the storing of energy in the battery banks that can be used to supply current to the household using the domestic inverter.

Such solar systems are in place where the main electric power supply is unreliable. These systems have great use in areas witnessing acute power cuts.

On-grid solar system

The on-grid solar system works along with the primary grid. This system does not need to store electricity in battery banks.

It is generally handy when your overall electricity consumption is high.

Using the solar system for your electricity needs during the day reduces the total consumption from the primary grid. Thus, you end up saving on your utility bills.

Hybrid Solar System

There is a third type of solar system known as the Hybrid solar system. It is a combination of the off-grid and the on-grid solar systems.

This system uses battery banks and inverters like the off-grid systems. The beauty of the hybrid solar system is that it connects to the grid, as well.

Thus, it ensures an uninterrupted supply of power even during power cuts at night. The energy stored in the batteries come handy under such circumstances.

This system is such that you might not need the electricity from the primary grid during the day, as solar energy can take care of your needs.

At night, the energy that is stored in the batteries can take over. Therefore, you might even end up having surplus power that you can supply to the primary grid.

However, you should have a net metering system if you wish to provide power to the network. This system enables you to save the maximum amount of power and money, as well.

Types of Photo Voltaic panels

Generally, there are three types of photovoltaic panels, of which the first two named ones are the most commonly in use in India.

Mono-Crystalline Panel

Mono-crystalline solar cells are made of single-crystal polysilicon. In the manufacturing of the cells for mono-crystalline panels, silicon is formed into bars and cut into wafers.

This type of panel has the highest efficiency. At the same time, they are the most expensive, as well.

Poly Crystalline or Multi Crystalline Panels

This type of solar PV panels are made from multiple, small silicon crystals. The method of manufacturing the poly-crystalline panels require the melting of fragments of silicon to form wafers.

Thin Film

This category of panels comprise Amorphous crystalline, CdTe (Cadmium Telluride), or CIGS (Copper Indium Gallium Selenide) solar cells. They are the least efficient of all the solar photovoltaic panels.

This table will help you to understand the significance of these photovoltaic cells.

The thin panels are not much in use in India. Usually, the household PV systems use the mono-crystalline or the poly-crystalline photovoltaic cells.

Factors that affect the performance of solar photovoltaic cells

Direction

If the solar panels have a sun-tracking mechanism, the direction of the solar panels is not significant. However, in the case of PV panels that have a fixed position, the panels should face the southern direction for better output throughout the year.

Tilt or the Angle of Inclination

It depends on the latitude of the place. If you place the panels at the ground level, the angle of inclination is different from what you need at a higher altitude.

Shading

Ensure that your solar panels are placed in such a way that no shadow falls on them at any point in the day. A shaded solar cell will have a lower efficiency than the one with full exposure to sunlight. One should also make sure that there is no dust on the panels to get the maximum output.

Temperature

Surprisingly, the higher the temperature, the lower will be the output of the panel. The ideal temperature should be around 25 degrees Centigrade.

Factors to Consider when purchasing solar panels

Investing in a domestic solar PV system is a once-in-a-lifetime decision. It involves a lot of money.

Therefore, it becomes necessary to consider the following factors when shopping for solar panels.

We shall touch upon metrics like efficiency, tolerance levels, temperature coefficient, durability, and warranty that will decide the number of solar panels required for your home solar PV system.

It will also help you choose the right vendor. We endeavor to help the layman buyer become technically knowledgeable so that he/she chooses the right brand.

Efficiency

A lot depends on the efficiency of the solar panels. The higher the efficiency, the lesser is the number of panels you need for your solar PV system.

The effectiveness of a solar panel depends on how much sunlight it can convert into electricity.

Let us now go through the mathematical calculation of the efficiency of a solar module.

The area of a solar panel is roughly 2 square metres. If we exclude the space occupied by the frame, it comes to around 1.95 square metres.

Let us now consider the efficiency of a 350W Loom solar panel (one of the best brands of solar panels in India). Other panels have different efficiency levels.

Efficiency (%) = {Output power per square metre / Input power per square metre} X 100

= { (350/1.95) / (1000/1)} X 100

= {350 / 1950} X 100

= {0.1795} X 100

= 17.95% (approximately)

The Chinese brand Trina Solar boasts of an efficiency of around 17.80% whereas SunPower has advertised its efficiency as equal to around 24.1%.

The efficiency of Luminous Solar Panels is around 17.11%. This calculation will give you a fair idea of the efficiency of the solar panel.

An example

Assume that a solar PV panel has an efficiency of 17%. It occupies an area of around 1.5 square metres.

The amount of solar radiation falling on the panel is usually 1000 Watts / square metre.

Therefore, the panel can produce

1000 X 17% X 1.5 = 255 watts output per hour.

If this energy sustains for about five hours in a day, the panel will produce 255 X 5 = 1.275 KW/hour power in a day.

The efficiency of a solar panel becomes critical when you have limited space at your disposal. If the area is limited, it is better to opt for solar panels that have high-efficiency levels.

The efficiency of the solar panels depends on the following factors.

  • The amount of sunlight that falls on the panel
  • The intensity and temperature of sunlight falling on the panel
  • The tilt or the inclination angle
  • The presence of shadows or dust on the panel

Some of the factors, such as the amount of sunlight or its intensity, are beyond our control.

One should ensure that there are no shadows on the panel. Secondly, it is advisable to clean the panels and not allow dust to settle down.

The inclination of the panels is also a significant factor. Nowadays, you have automatic systems where the panels adjust the tilt depending on the intensity and direction of the sun.

Tolerance Levels

Under ideal conditions, a 100W solar panel should deliver an output of 100 Watts. However, there is a concept of tolerance level.

The manufacturer advertises a tolerance level of +/- 5%. Therefore, the output of the panel will be in the range of 95W to 105W.

A positive tolerance level is acceptable, whereas a negative figure is not.

Note that you should always go for a solar panel that mentions a positive tolerance level.

Temperature Coefficient

Solar panels require sunlight for its operation. However, one should note that solar cells can get extremely hot.

High temperatures can lead to degradation of the cells. The temperature coefficient is a crucial factor that decides the efficiency of a solar panel.

The lower the temperature coefficient, the better it is.

We shall take the example of a Loom Solar 350W solar panel to discuss the temperature coefficient.

Laboratory tests confirm that the ideal temperature for the optimum functioning of a solar panel is 25 degrees Centigrade.

Let us consider two different scenarios.

  1. If the temperature is greater than 25 degrees (temperature of solar panels is 45 degrees)
  2. If the temperature is less than 25 degrees (Assume temperature to be at 15 degrees)

Inference

If the temperature is greater than 25 degrees Centigrade

  • The power output will drop
  • The voltage will also drop
  • The current will increase

If the temperature is less than 25 degrees Centigrade,

  • The power output will increase
  • The voltage will increase
  • The current will drop

These are technical aspects, but it is better if you have an idea before purchasing the right panels for your solar PV system.

If the temperature is high during the day, you can change the tilting angle so that the intensity of light that falls on the panel reduces.

Therefore, it is better if you invest in a panel system that exhibits automatic tilting depending on the severity of the sunlight.

The durability of the Solar Panel

The solar panels are outdoor appliances. Hence, they have to bear the brunt of nature, such as heavy rains, wind, pressure, temperature, hailstorms, and so on.

Usually, the panels go through strenuous tests depending on the different types of environmental conditions before being certified for use in a specific country.

For example, a solar panel approved for installation in India will be different from the one in the UK. As a consumer, you should opt for panels that are certified as fit for use in your respective country.

Rating agencies compare these panels and assign individual ratings. In India, we shall look at some of the top solar panels.

Luminous – These panels are waterproof and have corrosion and torsion-resistant design. Hence, they offer excellent protection against high winds and snowfall.

Loom Solar and Microtek solar panels can sustain heavy winds and snowfall (2400 Pa and 5400 Pa, respectively). Besides, these panels can handle issues like mist, ammonia, hailstorms, excessive pressure, stone-throwing, and blowing sand.

It is advisable to opt for the solar panels that exhibit the maximum durability.

Warranty provided by the manufacturer

Based on the durability of the panels, the manufacturers offer attractive warranties. Solar panel manufacturers face tremendous challenges in their business, such as declining prices of the products and the effect of Government regulations.

The smaller players can find it challenging to sustain their growth. Hence, they offer lesser warranties. The brand-conscious buyer goes for the ideal brand that offers the highest efficiency, durability, and the maximum warranty.

Loom Solar and Luminous are brands that offer a 10-year product warranty along with a performance warranty of 25 years. Microtek offers 25 years on the performance and a one-year warranty against manufacturing defects.

Approvals and Certifications – The most crucial factor

Solar PV panels should have unique certifications as mandated by The Ministry of New and Renewable Energy. It is essential to understand these certifications.

Crystalline Silicon Terrestrial PV Modules – IEC 61215 / IS 14286

Thin-Film Terrestrial PV Modules – IEC 61646

Solar panels must conform to IEC 61730 Part 1 requirements for the construction and Part 2 requirements for safety qualification and testing.

In the case of coastal regions, the atmosphere can be highly corrosive. The solar panels must qualify for Salt Mist Corrosion Testing as per IEC 61701 or IS 61701

Solar panels are expensive. Hence, you should demand these test certificates and check its validity, as well. It is better to take these precautions before buying the panels instead of regretting the purchase later on.

We have seen the technical aspects of solar panels and discussed the factors that should influence your decision.

Now, we come to the most significant part of the discussion.

Power Requirement – It can change from one individual to the other

Before you invest in a solar PV system, you should estimate your power requirements. By power requirements, we refer to the electrical appliances like fans, tube lights, computer, TV, refrigerator, and so on that you will connect to it.

  • Calculate the total of the load in Watts.
  • Multiply this figure by 1.67 to get the UPS VA rating.
  • Choose your UPS based on the high VA rating.
  • Select the ideal battery that is compatible with your UPS AH.
  • Divide the energy consumption (Watt-hours) by 3 to arrive at the approximate panel size.
  • Ensure that the voltage and current of the solar array are compatible with your UPS.
  • Now, your UPS and solar sizing is complete.

Example

We shall consider the ideal Indian family of three to four persons.

UPS Sizing

Total Load = 490 watts

UPS Sizing = 490 X 1.67 = 816.7 VA

You should opt for an 850 VA UPS.

The 850 VA solar UPS will support a battery voltage of 12 Volts and 30 Ampere rating.

Battery Sizing

The selected UPS will support one 12V battery.

Battery AH = (Total Daily Watt-hours X 1.9) divided by (12 X number of batteries)

= (940 X 1.9) divided by (12 X 1)

= 155 AH

Therefore, you should opt for a minimum of 150 AH Solar battery

Panel Sizing

Panel Size = Daily Energy Consumption divided by 3

= 980/3 = 326.7 Watts

Our UPS supports the 12V system. Hence, we need 12V panels such as 100 Wp or 150 Wp
Therefore, you can opt for 3 X 100 Wp panels or 2 X 150 Wp panels in parallel.

Cost of a Solar PV System

In India, an off-grid 1KW solar PV system should be available in the range of Rs 1 lakh to Rs 1.25 lakhs.

If you opt for a grid-connected solar system, the costs should be in the range of Rs 60,000 to Rs 1 lakh

A 1KW system should require around two batteries and three solar panels. An inverter battery should cost you around Rs 20,000.

Essential Points to Know about Solar PV systems

As far as the area is concerned, a 1KW solar system will occupy 80 to 100 square feet for installation.

The advantage of a solar PV system is that you can use your existing home inverter and batteries. All you need are solar panels and a charge controller.

The State Government and Central Government encourage people to use renewable energy resources such as solar power and wind. Subsidies are also available from the respective governments.

Some of the best solar panel brands available in India are Loom Solar, Havells, Luminous, Microtek, Waaree, and Exide.

We have discussed all the aspects of a solar power system in this buying guide. If you hav e any queries regarding the solar panel selection, post them in the comments section below and we will try to answer them.

Sources

Wikipedia: Solar Panel

1 thought on “How to Choose the Right Solar Panel For your Home?”

Leave a Comment