What makes a roof good for solar?
Solar Roof: Solar panels help the environment by generating electricity from a clean source and reducing or potentially eliminating your consumption of electricity produced from fossil fuels. By installing a solar photovoltaic system at home you can also save your electric bill and increase the market value of your home.
Cooling Effect on Building: Solar panels are typically installed on a rack that stands off against the roof. The resulting gap between the panels and the underlying shingles allows air to circulate around the array. This setup is good for the solar panels, which perform best in cooler temperatures. It’s also good for the roof, the ceiling and the residents inside. It turns out that the gap and the panels create a thermal barrier that helps keep the inside of the building cool.
Light Colors: A light colored roof reflects more of the sun's rays, which could help to reduce global warming. By reflecting more sunlight, a white or at least a lighter-colored roof can reduce the amount of energy needed to cool the home or building during warm weather. So in addition to offsetting the warming effect itself, a light-colored roof helps reduce the consumption of energy and the emission of greenhouse gases that are causing global warming, assuming the energy to cool the home is coming from non-renewable sources.
Another option, in the interest of doing everything possible to help the environment and reduce global warming, would be to use the best combination of measures based on practical and budgetary considerations. Installing as many solar panels as economically feasible, planting a roof garden in available spaces on a flat roof, and covering the rest with white or light-colored materials could be a good solution.
Rent a Roof: Homeowners with nothing on their roof can now make money from solar PV roof rental schemes where we will install solar PV panels on their roof to receive free electricity for 25 years.
India has 98.05 MW of rooftop solar capacity coming up. Jharkhand tops the list of States with rooftop solar capacity with 16 MW under its belt. Rajasthan follows it with 12 MW and Andhra Pradesh has 10.5 MW.
Before going for a detailed site survey, if a client wants to perform a quick feasibility check, he or she should consider the following parameters:
1. Shadow test:To collect maximum sunlight during the day, the solar PV panel should face as much south as possible. The rooftop must be checked for the shadows of trees or adjoining builds etc., particularly from south direction. A clear rooftop without any shadow from all around is an ideal case for solar PV installations. In case there is shadow on rooftop, a detailed analysis of time and direction of sunlight needs to be performed by an expert to estimate the energy received by rooftop.
2. Rooftop type: The load carrying capacity of the roof should be checked.The solar panels with structure typically weigh 15Kg per Sq. meter. This weight varies with technology and type of structure.
3. Sizing of solar system: Size of solar system depends on the rooftop area available for panels. This can be calculated by dividing the available area by each panel area and multiplying it by panel’s rated output. For estimate purpose, 70% of rooftop area can be used for panel’s installation. Certain solar panels in market can use as high as 90% of rooftop area, but have much higher cost.
4. System output (annual units generated): The output per panel and hence system output depends on panel efficiency and the solar radiation at the site. These two factors define CUF (Capacity Utility Factor) for solar system for a particular location. For India typically 19% CUF is taken for estimation.
