Planning approvals for special buildings (ground plus four floors) and multi-storeyed buildings (above four floors) will be issued by the Chennai Metropolitan Development Authority and the Directorate of Town and Country Planning only if they are provided with a solar energy system. The Housing and Urban Development Department issued a Government Order to this effect recently.The G.O. paves way for certain amendments to be made in Development Regulations to the Second Master Plan.Further, the developer has to use a minimum of one-third of the terrace area for installing the solar photovoltaic cells.While the measure has been welcomed by people in the construction industry, there are concerns about the cost component, especially for smaller builders and also individuals engaged in joint development of property, as the industry average to set up a quality solar plant is Rs. 1.4 lakh per kilo watt (KW).S. Harish, chief executive officer, Future Renewable Energy Infrastructure, said the GO stressed on the solar power to be used for common space areas for lighting, lifts and pumps, off grid (having batteries), but solar plants come at a price.Experts said consumers can install solar plants with assistance from the Chief Minister’s Rooftop Capital Incentive Scheme and JNNSM of Ministry of New and Renewable Energy.Representatives in the building industry said it was a positive development, reflecting the seriousness of the State government to promote renewable energy.A builder said the cost of installing a solar plant may not be much for multi-storeyed apartments.