Generate your own electricity at your Solar Rooftop

by | Jul 30, 2021 | Solar Panels

Overview

The Indian economy has been facing great hardships on the energy front with the background of large import dependence thus exposing towards exogenous shocks from fossil fuel markets. India imports nearly 80% of its oil demand and has also become a large coal importer. Solar energy plays a major role in the energy mix for achieving sustainable energy security in the years ahead.

Accordingly, India has committed at United Nations Framework Convention on Climate Change (UNFCCC) to increase its share of non-fossil-fuel generation to 40 % by 2030 as a part of our Nationally Determined Contributions (NDCs). In the immediate term, the ambitious target of 175 GW of installed renewable power by 2022 will be a crucial contribution to this NDC goal. Of this, 40 GW of Solar power has to be achieved by 2022 from Rooftop Solar (RTS) power plant.

 

What is Rooftop Solar Plant?

 

Rooftop Solar (RTS) power plants are solar photovoltaic (PV) panels installed on top of roofs of commercial, institutional or residential buildings. They convert the light energy emitted by the sun into electrical energy. It produces a clean and eco-friendly form of energy, without producing any type of pollution or harmful gases. In an on-grid RTS plant, the power generated from PV panels during the daytime can be utilized for powering captive loads and for feeding surplus power to the grid. 

Types of Rooftop Solar Plant

 

Technically a Rooftop Solar (RTS) power plant is of the following types:

  1. On-grid RTS: A plant connected to the grid through the net or gross metering without any battery backup. Most of the state and central governments are encouraging this type of RTS.
  2. Off-grid RTS: As the name suggests, the off-grid plant is not connected to the grid. They are installed with a battery backup and are considered to be expensive. They are often installed in remote and unelectrified areas.
  3. Hybrid plant: A hybrid RTS is similar to grid-connected solar rooftop PV, but it is installed with a battery. In the event of power failure, the battery supplies power to the consumer, which a simple on-grid RTS cannot do.

 

Designing and key components of an on-grid RTS

 

  • Solar PV Modules – The Solar PV modules convert solar energy to direct current electrical energy. They are available in different types of PV cell technologies such as crystalline silicon, thin-film silicon, CIGS, CdTe, HIT etc. Of these, crystalline Silicon Solar PV panels are, by far, the most popular and commonly used in solar rooftop systems. Multiple panels are connected in series or parallel to form arrays as per the desired capacity.
  • Inverter – Inverter converts direct current (DC) output of Solar PV panels into a utility frequency alternating current (AC)variable. The inverter also synchronizes with the grid so that generated power from the PV modules can be injected into the grid.
  • Module mounting structure – The module mounting structure, is the support structure that holds the Solar PV panels at a particular angle and orientation for entire plant life and is exposed to all weather conditions and should withstand wind gust.
  • Bi-direction Meters – Meters are used to keep record the generation or consumption of electricity. Bi-direction (or Net-Meters) are used to keep track of the electricity that RTS injects into the utility grid and the electricity that is drawn from the utility grid.
  • Balance of System – These comprise of AC DC cables, junction boxes, earthing system, circuit breaker, fuses, lightning protection system, etc.  

 

Rooftop Area and Cost

 

On an average, 1 kWp RTS can be developed over shadow free rooftop area of about 10 sqm and at the benchmark cost of Rs. 47,000 in general category states and Rs. 52,000 for special category states. On a clear sunny day, 1 kWp solar power plant can generate 4 to 5.5 kWh in a day. 

Benefits of Rooftop Solar Plant

 

While the majority of the solar installations globally are on rooftops, RTS plants are yet to gain popularity in India. RTS projects offer several advantages and opportunities for a DISCOM and consumer as follows:

  • They do not require securing of land or separate transmission facilities, unlike ground-mounted solar projects
  • Saving on electricity bill by the consumers
  • They have minimal technical losses as power generation is near to the place of consumption
  • RTS project ensures that DISCOM is effectively able to meet its renewable purchase obligation (RPO)
  • Electricity from RTS systems can also help in managing daytime peak loads
  • Localized generation helps meet daytime peaking power requirements and avoids the need to buy expensive short-term power
  • RTS plant ensures utilization and economic value of idle rooftops
  • RTS plants help improve tail-end grid voltages and reduction in system congestion with higher self-consumption
  • Decentralized generation reduces pressure on the grid