Rooftop Solar Photovoltaic System

In a rooftop system, the electricity-generating solar photovoltaic panels are mounted on the rooftop of a residential or commercial building or structure. The various components of the Rooftop PV System include photovoltaic modules, mounting systems, cables, solar inverters and other electrical accessories.

Rooftop mounted systems are small compared to ground-mounted photovoltaic power stations. Rooftop PV systems on residential buildings typically feature a capacity of about 5 to 20 kilowatts (kW), while those mounted on commercial buildings often reach 100 kilowatts or more.

Salient Features of Solar Rooftop Photovoltaic System:
  • For installation, the Rooftop insolation (i.e. the amount of solar radiation reaching it) is to be estimated.
  • The factors to be considered for estimation of rooftop insolation include the time of the year, latitude, weather conditions, roof slope, roof aspect, shading from adjacent buildings & vegetation, etc.
  • Solar Rooftop Photovoltaic Systems can either be grid connected or off-grid.
  • In a grid connected rooftop photovoltaic power station, the generated electricity can be sold to the grid at a price higher than what the grid charges for the consumers. This is called Feed-in Tariff (FIT) Mechanism.
  • FIT Mechanism thus can provide payback for the investment of the installer

Types of Solar Rooftop Photovoltaic System:
  • Utility Scale (Commercial Purpose)
  • Grid Connected: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. 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.
  • Off Grid:Non-grid interactive systems ideally require a full load capacity battery power back up system. The non-grid interactive system with minimum battery back are viable only at places where normal power is not available during daytime. However, with the introduction of advanced load management and power conditioning systems, and safety mechanisms, it is possible to segregate the day-time loads to be served directly by solar power without necessarily going through the battery back-up.

Benefits of Solar Rooftop Photovoltaic System:
  • Green electricity
  • Long term reliable power source
  • Less operation and maintenance cost
  • Reliable and cost effective as no utility cost
  • Gives economic value for unused roof space
  • Reduces dependency on grid power
  • Can be used to replace diesel generator
  • Increases the ability for localized production
  • Reduces requirement of land for addition of solar capacities
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