Housing societies should replace diesel generator (DG) sets with rooftop solar power systems, recommends CSE
A new analysis done by Centre for Science and Environment (CSE) suggests that residential societies – which use diesel generator sets for power back-up — can easily replace them with rooftop solar power systems and save substantially on costs. “In all the residential societies that CSE studied and analysed, the cost of power from solar rooftop with battery back-up was found to be about half the cost of power generated by DG sets. This alone should make residential societies move away from the extremely polluting diesel generator and adopt solar rooftop to meet their power back-up needs,” said Chandra Bhushan, deputy director general, CSE, while releasing the results of the analysis in a conference organised here today by CSE.
The study and its findings
The CSE study examined the feasibility of solar rooftops in residential societies across Delhi, Haryana, Uttar Pradesh and Rajasthan. CSE’s research was aimed at understanding the economic considerations including financing and generation cost; architectural and roof space preferences; building by-laws; and constraints experienced by various stakeholders including customers, government agencies and distribution companies (discoms).
The study finds that the cost of power generation from a DG set, including the capital cost, is Rs 27 to Rs 33 per unit — compared to rooftop solar tariff of less than Rs 10 per unit. The CSE study finds that as power outage from the grid reduces, the cost of power generation from DG sets increases and that from solar rooftops with battery storage becomes more financially attractive. Says Priyavrat Bhati, programme director, energy, CSE: “DG back-up has become increasingly redundant because of reducing power outages in cities. On an average, many cities now have less than an hour of power cut in a day. We must realise that ‘full back-up’ was considered a basic need by upscale societies when the outages often lasted several hours a day.”
The study concludes that for most societies, solar rooftop would be able to meet the basic load for individual flats (‘partial load’ in industry parlance which covers lighting, fans and some communication and entertainment appliances) along with essential area loads. “Moving away from the DG set to solar rooftop requires a change in mindset. If power outage is less than a hour a day then the very definition of “full back-up” needs to be changed. For tens of minutes of outage, even for the high end societies “partial load back-up” should be sufficient,” adds Bhushan.
CSE researchers have estimated that up to 3 giga-watt (GW) of solar rooftop can be installed on new residential societies over the next five-seven years. This segment can, therefore, be a key to reaching the government’s ambitious target of 40 GW solar rooftop to be achieved by 2022.
Recommendations of the study
The report offers a set of recommendations (visit www.cseindia.org for a detailed pdf version):
Make installation of solar rooftops mandatory for all upcoming residential societies.
Ban DG sets in new multi-storied residential buildings except for common area loads in polluted areas.
Support discoms to encourage them to push solar rooftop.
Provide subsidy for hybrid solar rooftop systems.
Increase awareness among RWAs – provide single window information and initiate campaigns.
Initiate monitoring by regulatory authorities.
The rooftop solar calculator
In order to further the promotion of solar rooftops and democratise solar power generation, CSE released a website-based rooftop solar calculator with the aim of providing all the necessary information required for a common domestic consumer to install a solar plant on her/his rooftop. The calculator is specifically designed for residential houses, which is a huge untapped market for solar power in the country. Bhushan says, “This calculator would allow residential consumers to install a rooftop solar plant based on their electricity needs and also provide information on viability of the plant for consumers based on their individual investment patterns and rooftop space available to them.”
The calculator covers the entire country and a consumer can get data by just putting in the pin code of the area. It would help consumers design the system based on their electricity requirement and provide them the economic and environmental benefits of such a system. The model provides information on rooftop solar plants based on the presence of grid power and battery – these systems can be grid-connected, off-grid and hybrid systems. The tool also provides estimates of benefits and limitations, so that the users can easily compare among the three systems and conclude which one suits their requirement. In addition, one can play around with the available choices to determine the ways in which they can reduce the cost of the solar plant. Says Bhati: “CSE welcomes feedback and opinions from users. Developing this kind of a calculator is a constant process. User feedback will help us deliver the perfect model. The future versions of the calculator will include upgrades like inclusion of solar plant installers in the nearby area, including industrial and commercial sectors.”
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