What is Rooftop Solar – Components, Types, Benefits, Size & Costs

Components of a Rooftop Solar System

A rooftop solar system comprises of:

a) Solar Panels/ Modules – The most important component of a rooftop system are solar panels. They are the nucleus of the system and everything revolves around them. Solar modules comprise almost 50% of the total cost of the system. Different types of solar modules will give different results, for example thin film modules though very suitable for the Indian climate, require more installation area when compared to a crystalline module.

b) Inverters – Are the powerhouses of the entire system that store the excess energy generated by the panels and can be used later when there is no sun. Approximately 25% of the total rooftop system cost comprises of inverters.

c) Balance of Systems – These include accessories like wires, cabling, mounting structures, junction boxes etc.

d) Installation cost – This cost depends upon the type of panel, its efficiency and varies from panel to panel. Generally fewer panels are required to generate the same amount of electricity in case of a panel with higher efficiency and hence the cost of installation will be lower, when compared to another panel.

Types of a Solar Rooftop Installation

A solar rooftop system can be divided into three types on the basis of its grid interactions/ connections.

• Customer owned – This is the oldest type of rooftop installation, wherein the customer is the owner and installs the system with his own equity or debt. The power generated is used for self-consumption and excess can be fed to the grid. The customer may use the entire power generated (captive/ off grid), feed all energy generated to the grid (Gross feed) or use a part of power generated and supply the extra power to the grid (Net metering).
• 3^rd Party owned – In this type of rooftop installation, third parties install these systems on the rooftops of its customers, either through solar leasing or power purchase agreement. The customer foregoes high capital investment for lease payments to these installers, who are the owners of this system installation.
• Integrated with utility – In the third type, utilities will install solar system on the rooftop of the customers and the power generated is fed to the grid.

Though the first two are more prevalent types around the world, the utilities have started entering the rooftop space in some parts. This shows how mainstream solar power is getting that utilities are also shifting towards solar. In India only the first tyoe is commonly seen, wherein the customer introduces funds either through equity or debt or a combination of both.

Size of a Rooftop Installation

Some important equations to determine the size of your rooftop installation:

• 1 watt of solar panel gives 4 watt hour of power per day.
• A typical 5 kW solar power plant which can comfortably power most of the needs of an urban 3 bedroom house, takes up only about 450-500 sq ft of area.
• 1 standard solar panel area requires an area of 0.56 square meters.

Important considerations before installing a Solar Rooftop system

It is very important to first know your energy requirement, the type of appliances that can run through a rooftop solar system and hence the size of the system. The dimensions and weight of the panels and mounting structure, panels with different efficiency levels – all affect the calculations. Care should be taken to choose the mounting structure wisely as it is going to hold the panels. The amount of sunlight your roof gets is another very important factor that can determine the efficient working of a rooftop system. It is important to do your math before installing a rooftop PV system.

Also read 5 Important Factors to consider before buying a Solar Panel.

Prudence must also be exercised in choosing your vendor and checking his bankability, since servicing, maintenance of panels will also be required from time to time.

Read Best Solar Panels to buy for rooftops in India.

Capital subsidies and incentives like accelerated depreciation, tax holidays, excise duty exemptions in India are other important considerations before installing a rooftop system. USA’s investment tax credit has been played a vital role in boosting solar installations across USA.

 You can read about subsidies on Solar Rooftop here.

Benefits of using a Rooftop Solar System

1) Long Delays in Permitting, Environment Clearance, Land Siting – Large Solar Farms have to go through a myriad of regulations and clearances. There have also been instances of lawsuits against solar thermal and solar PV plants in California by wildlife and environmental groups as well as local Indian tribes. This problem is non-existent in case of a rooftop installation. Free area of your home’s rooftop can be easily utilised for installing a rooftop.

2) Electricity Transmission Costs – Grid Connection leads to additional costs for solar farms, while rooftop solar can use existing transmission infrastructure.

3) More Grid Stability – A large part of distributed solar is consumed locally, while farms supply 100% to the grid. That makes managing the grid difficult when solar penetration increases. A rooftop installation leads to a more balanced grid.

Cost of a Rooftop System in India

A typical 1kW rooftop system should cost anything in between INR100,000- 125,000 (cost includes that of panels, inverters, batteries, cabling and installation). In addition to this, one is also entitled to various subsidies and incentives as discussed above. Approximately 50% of the cost can be saved through capital subsidies and AD.