How much roof area do I require for installing solar panels?
Solar panels should preferably be mounted in a shadow-free area for maximum energy generation. As a rule of thumb, approximately 100 sqft. or 10 sqm. area is required to place one kW of solar panels. Given that each kW of solar panels on an average generates about 4 to 5 units per day in most locations in India, approximately 25 sqft. or 2.5sqm. shadow-free roof area would be required to generate an average of 1 unit (kWh) of electricity per day. So, if your energy consumption is 10 units/day then you would require around 250 sqft. of shadow-free roof area to generate the required energy from your solar panels.
In case there are shadows from either obstacles on the roof or from taller structures outside the roof (more here) limiting the shadow-free are available at the roof level, the panels can be mounted on raised structures that will avoid shadows from falling on them.
In terms of direction, solar panels should preferably be mounted in a south-facing direction at an inclination equal to the latitude of the location to maximize energy generation. In case of sloped roofs it is best to install solar panels parallel to the roof as that minimizes the wind load on the structures while not leading to a significant drop in generation. In case panels are mounted in east facing direction the drop in generation might be around 3% – 5%, and this will be slightly higher in case of a west facing direction. In case of north facing roofs as long as the incline of the roof is not beyond 10 degrees, it won’t lead to a significant drop in energy generation. Any drop in energy generation can always be made up by installing additional solar panels and the trade-off should be evaluated against additional structural costs that will be incurred in mounting panels in a perfect south direction.
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