A play of sun and shadows: As height of buildings increases across Pune, will rooftop solar plants be affected?

Rohit Gadhiani, a mechanical engineer who is leading the sub-committee on the solar project in the housing complex, says there is just enough space on the rooftop to accommodate more than 125 solar panels that are required to generate the 70 kWP of solar energy that the society needs to escape the Rs 1.25 lakh monthly electricity bill.

“We had investigated if Photovoltaic (PV) solar panels could be installed on the roof of our gym, but the area available on the rooftop of the three residential buildings is sufficient and we don’t want to go for generating more electricity than we consume. So, we dropped that option. Plus, it is not feasible as a building’s shadow falls over the gym. If we want to increase the plant capacity in the future, we cannot make use of the gym as a potential location for solar PV plant installation as it fails during the shadow analysis,” Gadhiani adds.

Even on the rooftop, he points out how certain areas fall under the shadows of other constructions, making the process of installing solar panels appear like a game with sunshine and shadows. In his flat, the chairman of the society, Ravindra Bhide, points at an adjacent empty plot of land and wonders “what would happen if a 20-storey building comes up here, which is twice the height of our building? It will put our solar panels in the shade, but we can’t stop them”.

A tall problem

Across Pune, several solar experts and building committee leaders are grappling with the challenges of setting up solar panels or converting existing building systems to green energy. The city is expanding upwards and sideways, thanks to the construction boom across Pune, and resulting in increasingly taller buildings.

Samir Gandhi, expert and consultant for Solar and Green energy systems, says that in cities, buildings are constructed very close to each other and the shadow of one building might fall on another. “In such cases, we have to find the shadow-free area because that is the basic requirement for the solar panel. Sometimes, we have to raise the structure. We call this an elevated structure. In such cases, the Pune Municipal Corporation (PMC) rules are not clear. The PMC has to take steps to make it clear so everybody can enjoy the benefits of the PM Surya Gaurav Yojana,” says Gandhi.

This issue came to the forefront in January when the PMC demolished a solar panel structure on the terrace of a housing complex in Sahakarnagar. According to the civic officials, the height of solar panel installations on roofs should be restricted to 1.8 m above the roof level – and the Sahakarnagar structure violated that. Residents, however, pointed out that the Prime Minister’s Surya Ghar: Muft Bijli Yojana allowed for solar structures to be constructed at an elevation of 2-3 metres.

Then, there are builders who develop amenities on rooftops, such as recreation areas, thus shrinking the space for installing solar panels. Vinay Hasabnis, a Pune-based solar consultant, says this is a problem that is going to keep happening in all cities. “You will find buildings with limited space available on the roof, so that only a small number of solar panels can be installed. It does not make any substantial contribution to the energy requirements of the buildings,” says Hasabnis.

Possible solutions

Hasabnis says that one of the solutions would be to have a solar park on the ground at the edge of the city. “Instead of distributed small systems at a single location, we could start putting up one or two megawatt systems on barren land outside the city and inject the power into the grid. Suppose you have a terrace which can house 5 kW of system and requires 500 sq ft of area. Instead of putting 5 kW systems on 200 buildings, which amounts to 1,000 kW, why not set up a plant at a single location of 1,000 kW,” he says.

“The efficiency of generation will improve because of the proper configuration of the installations, the angles and the orientation. Discoms can pass on the benefit to the above-mentioned 200 flat owners,” says Hasabnis.

Another option, he says, is to explore the potential of water bodies. “One can think of installing floating solar plants on nearby water bodies. This would not only keep the land available for other purposes but also help in reducing the loss of water due to evaporation,” he says.