Solar FAQ

1What is a Solar Rooftop System?
In a solar rooftop system, the solar panels are installed in the roof of any residential, commercial, institutional and industrial buildings. This can be of two types (i) Solar Rooftop System with storage facility using battery, and (ii) Grid Connected Solar Rooftop System.
2How does solar work?
While solar is comprised of a diverse suite of technologies, there are three main types: photovoltaics (PV), solar heating & cooling (SHC), and concentrating solar power (CSP). Homeowners and businesses interested in going solar are primarily interested in the first two technologies, while utilities and large-scale energy project developers primarily utilize the latter. PV panels directly produce electricity from sunlight, while SHC technologies use thermal (heat) energy to change the temperature of water and air. PV panels have no moving parts, and use an inverter to change the direct current (DC) power they produce to usable alternating current (AC) power. SHC technologies are often used to heat water for domestic or commercial use, but can also be used to heat or cool the air in buildings. Most concentrating solar power systems use concentrated sunlight to drive a traditional steam turbine, creating electricity on a large scale. There are also concentrating solar technologies that use photovoltaic technology to produce electricity without a thermal process. Visit SEIA's solar technology section to learn more about the various types and applications for solar energy systems. For an in-depth look at how solar panels work, check out this animated graphic from Save On Energy:
3What is a Solar Rooftop System with Storage facility?
Such rooftop system has battery as storage facility. The solar electricity is stored in the battery and can be utilized during night also when the sun is not available.
4What is a Grid Connected Solar Rooftop System?
In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using power conditioning unit and is fed to the grid either of 33 kV/11 kV three phase lines or of 440/220 Volt three/single phase line depending on the capacity of the system installed at institution/commercial establishment or residential complex and the regulatory framework specified for respective States. These systems generate power during the day time which is utilized fully by powering captive loads and feed excess power to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., the captive loads are served by drawing power from the grid.
5Where such Rooftop plants can be installed?
Such rooftop systems can be installed at the roofs of residential and commercial complex, housing societies, community centers, government organizations, private institutions etc.
6How much roof area is required to set up the grid connected rooftop solar system?
About 10sq.m area is required to set up 1 kWp grid connected rooftop solar system
7What are the advantages of Grid-Connected Rooftop Solar System?
  • Electricity generation at the consumption center and hence Savings in transmission and distribution losses
  • Low gestation time
  • No requirement of additional land
  • Improvement of tail-end grid voltages and reduction in system congestion with higher self-consumption of solar electricity
  • Local employment generation
8Net metering
The grid connected rooftop system can work on net metering basis wherein the beneficiary pays to the utility on net meter reading basis only. Alternatively two meters can also be installed to major the export and import of power separately. The mechanism based on gross metering at mutually agreed tariff can also be adopted.
In feed-in-tariff the Government offers a tariff for purchase of the solar power generated from such plants.
10What happens to solar panels when it’s cloudy or raining?
Photovoltaic panels can use direct or indirect sunlight to generate power, though they are most effective in direct sunlight. Solar panels will still work even when the light is reflected or partially blocked by clouds. Rain actually helps to keep your panels operating efficiently by washing away any dust or dirt. If you live in an area with a strong net metering policy, energy generated by your panels during sunny hours will offset energy that you use at night and other times when your system isn't operating at full capacity.