Techno-economic review of rooftop photovoltaic systems: Case studies of industrial, residential and off-grid rooftops in Bangalore, Karnataka

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Abstract

The objective of this study is to assess the financial feasibility of setting up Rooftop Photovoltaic (RTPV) systems in Bengaluru which is in the state of Karnataka, India. The Renewable Energy Policy of the state mandates the installation of 250 MW of RTPV systems by 2014, while research shows that the domestic RTPV potential in Bengaluru alone is around 560 MW. To achieve this potential, the Karnataka Renewable Energy Development Limited (KREDL) and the Karnataka Electricity Regulatory Commission (KERC) formulated policy incentives in the form of net metering at rates of Rs. 9.56/kWh (without the Ministry of New and Renewable Energy (MNRE) capital subsidy) and Rs. 7.2/kWh (with MNRE capital subsidy). Techno-economic assessment of RTPV systems show that these rates lead to viable business cases for the consumers. However, due to Bangalore Electricity Supply Company׳s (BESCOM) poor finances, a cap of 75% on the capacity of any installed RTPV system based on rated load has been set for all interested parties. Unless this cap is removed, the net metering scheme can never gain momentum in Karnataka because the power generated from the RTPV system will not exceed the monthly consumption. An additional amount of Rs. 81.6 crores per annum is required to reach the 250 MW target. BESCOM can tap the proposed State Clean Energy Fund (SCEF) to pay RTPV project developers. Other revenue models such as feed in tariffs (FiT) and the Renewable Energy Certificates (REC) schemes have been considered for analysis of larger RTPV systems on industrial and commercial rooftops.

Introduction

Although India has witnessed most of its growth in solar power in the utility scale power plant sector [1], most states are now focusing on policies which promote Rooftop Photovoltaic (RTPV) systems. RTPV systems have the following advantages in terms of distributed and decentralized electricity generation and consumption:

  • No ground level land required

  • Reduced gestation period

  • Reduced transmission and distribution (T&D) losses because of the decentralized nature of power generation and usage

  • Environmental benefits from displacing small-scale diesel generator (DG) sets

  • Reduction in system congestion due to higher self-consumption

  • Capacity building of local electricians

This article reviews the techno-economics involved in setting up a RTPV system in Bengaluru, Karnataka, taking the existing policy framework into account. Households, industries and commercial establishments with roofs made of concrete, machine-made tiles and corrugated galvanized iron/metal/asbestos sheets have been taken into consideration for this study. According to the recent census data [2], the total number of such households in urban Bengaluru is 1,999,994. Taking a conservative approach, it is assumed that an average urban household in Bengaluru (with a demand of 2.4 kW in 2012-13) has a demand for 3.5 kW in 2021-22 which rises to 4 kW in 2031-32 (this assumption is based on the historical trends of per capita consumption statistics provided by BESCOM and it also takes into account the inclusion of domestic air-conditioning loads in households with a rated load of more than 2.5 kW today [3], [4]. If 5% of such households set up RTPV systems with the designated rated load by 2021-22, the total installed capacity would be around 350 MW and if 8% set up RTPV systems by 2031-32, the total installed capacity would increase to 560 MW. Today, BESCOM reports a shortage of around 200 MW in the city with respect to the peak demand. The projected installed RTPV capacity in 2021-22 and 2031-32 will effectively contribute in reducing this shortage (which is likely to increase) by a great extent. Owing to lack of data regarding industrial and commercial rooftops in Bengaluru, projections of capacity of RTPV have not been made.

The Karnataka Renewable Energy Development Limited (KREDL) and the Karnataka Electricity Regulatory Commission (KERC) are aware of this tremendous potential and have recently come up with draft policy measures to encourage consumers to adopt RTPV systems. At a central level, the Ministry of New and Renewable Energy (MNRE) offers a capital subsidy of 30% on the initial investment required to set up a RTPV system. However, there are barriers in receiving this subsidy and recent reports suggest that it will be a while before capital subsidies for RTPV systems are disbursed through reliable channels in the country [5]. The next section of this article presents an overview of policies pertinent to RTPV systems in Karnataka.

Section snippets

RTPV policy regime in Karnataka

According to the Renewable Energy Policy of Karnataka [6], 250 MW of RTPV systems have been targeted to be set up by 2014. The recently released draft solar policy [7] targets a total of 2000 MW of solar PV installations (including RTPV and off-grid systems) by 2020. To reach these targets KREDL and KERC formulated certain policy incentives for prospective proponents of RTPV systems. These are described briefly in the following sub-sections.

Methodology

The objective of this research is to assess the techno-economic feasibility of installing RTPV systems in an urban context taking Bangalore to be a case study. Since RTPV is a decentralized distributed power generation system, specific case studies have been undertaken in the industrial, commercial and residential spaces to represent the entirety of the city. For the sake of confidentiality the names of the sites are not revealed. Five units have been identified for analysis in the Peenya

Calculations

This section will enable the reader to grasp the results of the research which are presented in the next section. The approach taken to arrive at the calculated techno-economics using the methodology mentioned above is described here. The specific case studies that have been considered for this analysis are:

  • 1.

    An urban villa with a rated load of 7 kW and a RTPV system of 5 kWp capacity with and without storage; revenue model of net metering

  • 2.

    A sub-urban villa (weekend or holiday home) with a rated

Results and discussion

Each of the case studies has been analyzed in terms of financial feasibility for the consumer as well as the financial implications for the utility or the state/central government institution which enables the consumer to invest in RTPV systems. The significant results pertinent to each case study are highlighted in Table 6. The Net Cumulative Cash Flow of each system throughout its lifetime is shown in Fig. 2, Fig. 3, Fig. 4.

Some important inferences can be made from the findings in Table 6:

  • A

Conclusions

This article explores the profitability of various kinds of RTPV systems in Bangalore taking the different policy incentives existing today into account. Compared to other countries both the net metering and FiT schemes fare well in terms of financial performance in semi-urban spaces in the city. The reason why semi-urban domestic households have better financial performance with RTPV systems when compared to urban households is because the consumption from the grid is lesser along with higher

Acknowledgments

This article is based upon work supported in part under the US-India partnership to Advance Clean Energy Research (PACE-R) for the Solar Energy Research Institute for India and the United States (SERIIUS), funded jointly by the U.S Department of Energy (Office of Science, Office of Basic Energy Sciences, and Energy Efficiency and Renewable Energy, Solar Energy Technology Program, under subcontract DE-AC36-08GO283O8 to the National Energy Laboratory, Golden, Colorado) and the Government of India

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      Citation Excerpt :

      Large size PV plants were found to give best profit margins in Italy whereas medium size PV plants were more beneficial in Germany. Techno-economic studies were also performed in Karnataka (India) by Saptak-Gosh et al. [15]. Their conclusion was that due to the cap of 75% on the capacity of any installed roof-top PV system (RTPV), the net metering scheme will never gain momentum in Karnataka.

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