Rooftop Solar PV System: Basic Guide for Your House!
Janvi Desai is a Civil Engineer (BE). She graduated from Government Engineering College – Bharuch in 2017. She is an Engineer (Civil) at SDCPL – Gharpedia. She is passionate about research and study of latest developments. You can easily reach her via LinkedIn, Facebook, Twitter, Instagram, Pinterest. Besides being blogger, she also participates in quantity survey, site management, design & detailing.
The solar photovoltaic(PV) system for solar power generation is becoming more popular these days because the production of electricity through coal, petroleum, hydro, or nuclear i.e., convertor plant is becoming more and more expensive and these are not that environment friendly. Frequent power cuts have increased the dependency on Diesel Generator sets; thus, the environment is experiencing high alerts on ecosystem balance, and global warming is increasing almost every day.
People had started thinking of an alternate way to satisfy their energy needs long back. The demand and supply gap for electricity is increasing day by day. Keeping the need of alternative renewable energy in mind, Ministry of New and Renewable Energy (MNRE), the Government of India, has started promoting solar PV systems under the Jawaharlal Nehru National Solar Mission. Many people in the country are installing a solar PV system for their homes, apartments, offices, schools, etc.
Let us discuss in detail about the rooftop solar PV System including advantages, disadvantages, types of PV systems, etc.
What is Rooftop Solar PV System?
In a solar PV system (photovoltaic system), the solar panels are installed on the roof of any residential, institutional, social, government, industrial, commercial buildings, etc. Multiple solar panels are joined together to create a solar array. It is also known as a solar electric system.
The main purpose of the solar PV system is to generate electricity by using solar energy. This electricity is used for various purposes such as lighting, water pumping, traffic signals, heating etc.
How do Roof Top Solar Photovoltaic (PV) Panel Works?
Solar panels use layers of special materials called semiconductors (Solar cells) that convert sunlight into electricity when exposed to sufficient sunlight. PV systems contain inverters to change direct current (DC) into alternating current (AC). AC is the standard electrical power that we use in our homes.
PV cells are connected to solar panels that are mounted in an orientation to take the most advantage of the sunlight. This installation can be placed on rooftops, canopies, on the ground, or integrated into roofing shingles or other building materials.
What are the Benefits of Installing Solar PV System?
- The fuel source for a solar panel is sunlight, which is direct, free and endless.
- It is a clean green energy and it is 100% environment friendly and inherently short circuit protected.
- It can generate powers from milli-watts to several megawatts and can be used for almost every devices including a small electronic device to a large scale MW (Megawatt) power generation station.
Is Solar Panel Right for my Home?
Solar energy offers many benefits. The installation of rooftop solar power system is not the first step to saving energy, money, and the environment, it means many more advantages. If you have heavy energy requirement in your home, improving the energy-efficiency and introduction of an alternative energy source should be your priority to reduce your energy bill.
An energy-efficient home reduces the amount of power you use from any source. Therefore it is the best option for the environment if you can conserve energy from non-renewable resources. It is a definite help in our nation’s energy security, and it will also help you in saving money for other things.
What are the Disadvantages of Solar PV Systems?
- The initial cost of a solar rooftop PV system is high.
- The climatic condition, location, latitude, longitude, tilt angle, sunlight, etc. can affect the rooftop PV system’s output.
- A large area is required for the installation of a solar panel.
What are the Components of Solar PV Systems?
The solar PV system contains various components like solar panels, batteries, controller, inverter, electrical devices etc. based on the type of system.
What are Various Types of Roof Top Solar PV System?
A solar rooftop PV system is classified on the basis of the end-use application of the technology. There are two main types of solar PV systems: Grid-connected Solar PV Systems and Off-grid Solar PV systems.
01. Grid-Connected Solar PV System
In this solar electric system, the solar panels are connected to your local utility electrical grid to complement your regular power supply from the utility company. The grid-connected solar PV system consists of:
- The solar panel is the main component of the system that is mounted on the roof.
- An inverter is installed to convert the electricity produced by the system from DC (Direct Current) energy into AC (Alternating Current) energy.
- These systems also contain junction box that connects the solar panel wiring to the breaker panel on the home.
- A power meter that displays how much power is produced and how much energy has been used in the home.
- A disconnect switch prevents the system from sending power to the grid during power outage.
It is the simplest and the most cost-effective solar PV system to install. This system will pay for itself by offsetting utility bills in the next 5-8 years after installation. A grid-connected solar PV system is an excellent choice for reducing your electric bill and reducing the carbon footprint.
02. Off-Grid Solar PV System
The off-grid rooftop solar PV system is not connected to the utility grid or power Supply Companyand produces own electricity for use. This type of system is the most common in a remote area where connecting to the utility grid is more expensive than purchasing it. It is also known as the standalone photovoltaic system.
The off-grid rooftop solar PV system represents the main source of power for a home. These systems contain batteries to store unused solar energy for use at night. Generators and other backup fuel sources are sometimes used as a backup. These systems consist of:
- The main component of the system is a solar panel that is mounted on the roof.
- An inverter to convert DC (Direct Current) energy into AC (Alternating Current) energy produced by the system.
- A Charge controller is installed to prevent overcharging of the battery.
- A junction box connects the solar panel wiring to the breaker panel on the home and for backup power supply from the generator.
- A power meter displays the amount of power produced and stored in the battery bank.
- A disconnect switch prevents the system from sending power to the grid during power outage.
Things to be Considered Before Planning for Solar PV System
When purchasing a rooftop solar PV system, the perfect choice will depend on
- Sunlight received in your area
- Quantity of power that you want to offset with solar power
- Sufficient space for solar panels etc.
What are the Roof Requirements for Solar PV System?
Before purchasing a solar PV system, you need to consider the following things:
01. Space and Location of Solar Panel
According to National Renewable Energy Laboratory (It is a national laboratory of the US Department of Energy), For maximum performance of the solar panel, your system needs about 100 square feet area of roof, unshaded with south-facing location or yard space for every kilowatt of electricity to be produced.
If your roof does not face the south, you can still use a rooftop solar PV system, but performance will be about 5% less in comparison to the south-east or south-west facing system. East, West, and North facing roof locations are not recommended for the rooftop solar PV system installation.
02. Condition of Roof for Solar Panel
If your roof is more than 15 years old, you may need to replace it when you purchase your solar PV system. Most solar panel vendors recommend using quality roofing materials so that the system lasts for about 25 to 30 years.
Ensure that the roof can carry the weight of the system, which depends on the type of system and its installation methods.
03. The Shadows of Other Things on Solar Panels
The shadow from other things on the solar panel reduces its performance because it blocks the path of sunlight. The most common things that shade solar panels are nearby buildings, trees, chimney, electrical cables, cooling and heating systems at the house, etc.
You can hire a solar panel expert to assess possible shading problems. They use a software program that can estimate possible shading at the site. Some people will investigate a proposed location throughout the day or during the sunny month of the year to see how the shading changes are experienced in the target zone. For example, shade in an area changes during summer in contrast to winter because the sun’s path gets changed during summer and winter solstice, respectively.
What can you do if you do not have Sufficient Space and a South-Facing Location Roof to Install a Solar PV System?
You may consider a ground-mounted solar PV system if you don’t have a south-facing roof or enough space on the roof. Ground-mounted systems are great for homes in which solar panels are installed at large yards. It can be installed with the same orientation and tilt as a roof-mounted system.
How much Electricity will Solar PV System Generate?
Solar panels are assigned a rating in watts based on the maximum power they can produce under ideal sunlight and temperature condition. You can use this rated out-put to estimate the number of panels you will need to meet all your electricity needs.
The exact amount of energy produced by the rooftop solar PV system also depends on roof orientation and tilt, as well as other factors like shading, dust, etc. According to the US Department of Energy, an average 1-Kilowatt system with optimal orientation and tilt will produce between 1400 Kilowatt and 1700 Kilowatt hours per year.
Does Solar PV System Produce Electricity All the Time?
No, it is not. The production-capacity largely depends on the season and your location, the solar PV system typically generates power from 8 AM to 6 PM. It gives maximum output between 12 noon and 1 PM when the sun is at the peak.
When PV systems are not producing power, you may use electricity from your local power company to run devices and for other works.
Can Roof Top Solar PV Systems Produce Electricity on Rainy or Cloudy Days with No Sunlight?
Yes. PV Systems can generate electricity on cloudy days, but their output becomes highly compromised. On a rainy or cloudy day, a PV system might receive only 5 to 10 % of the usual amount of sunlight. Therefore the electricity output gets decreased.
What is the Approximate Cost of Solar PV Systems?
The cost of a roof-top solar PV system depends on the type of solar panel system you select. According to the Ministry of New And Renewable Energy, if you choose a grid-connected solar PV system, the approximate benchmark cost of grid-connected systems is between RS. 53,000 to RS.60,000 per KW (Kilowatt).
Are the Subsidies Available from the Government for Rooftop Solar PV System?
Yes. It is available but you have to apply through proper channel.
Residential, Institutional and Social Sector:
In India, the government provides a subsidy for solar PV System up to 30% of the benchmark cost for general category states and up to 70% of the benchmark cost for particular category states i.e., North – Eastern states including Himachal Pradesh, Jammu & Kashmir, Uttarakhand, Sikkim and Lakshadweep, Andaman & Nicobar Islands).
For the government sector, the government provides subsidy for solar PV System up to 25%, 15 % and 10% of the benchmark cost for general category states and up to 60%, 36% and 24% of the benchmark cost for particular category states i.e., North – Eastern states including Himachal Pradesh, Jammu & Kashmir, Uttarakhand, Sikkim and Lakshadweep, Andaman & Nicobar Islands).
Does your Roof Top Solar PV System Require Maintenance?
Most of the rooftop solar PV systems come with a 25-year warranty, but maintenance may be required to comply with the manufacturer’s warranty. The warranties of Inverter are usually 10 years, and you can replace the inverter during the system’s life.
Proper maintenance of your solar PV system will keep it running steadily. The vendors recommended a yearly maintenance usually, but you should carefully review the maintenance instructions given in the system manual with your system provider.
The systems with different electrical components require replacement after 10 years. Solar panels need to be cleaned in the climate with infrequent rainfall. Also, the surface of solar panels should be wiped clean with a wet rag to remove dust, fallen leaves, etc.
Solar PV System is one of the most mature and fast-evolving renewable energy technologies. It will play a significant role in future global electricity generation. Solar electricity can be a great source of power where your power requirement is the modest.
There are several reasons to consider installing a solar PV system:
- If there is no other reliable source of electrical power available, and where the cost of installing conventional electrical power is too high, solar power systems can act as a cost-effective contingency.
- Solar power provides clean green energy without damaging the environment.
- When there are other sources of electricity easily available but you can enjoy a good amount of sunshine, it is a wise choice to use solar power.
Grid-connected solar PV systems have environmental benefits in a sunny climate where typical electricity usage patterns are similar to the supply of sunlight.
The off-grid system for the average homeowner or handyman is not recommended. Their payback is long-awaited. One has to wait for investment recovery. However, those who can afford it, should install it. It would ultimately result in saving money, and it will help in decreasing carbon footprint &reducing harmful greenhouse gas emission.
Solar electricity is not the same as solar heating. Know more in detail about solar heating system: