Rooftop PV and Net metering

As I chose to write on this topic, I realized that 3 out of my last 5 blogs were on the subject of Rooftop PV. The first one was about Karnataka rooftop PV programme, the second on the SECI’s bidding process for rooftops under the JNNSM and the third one about the advantages and disadvantages of East-West facing module mounting structures vs the traditional south facing structures.
As the title says, this blog is about a study on net-metering for rooftop PV done by Prayas Energy Group. Prayas is a non-profit think tank based in Pune and has been done some excellent work in the energy sector. It was co-founded by Girish Sant,  who passed away a year back at the age of 46. After completing his studies from IIT Bombay, he dedicated himself to social causes. I had the chance to listen to one of his presentations in December 2010 about the solar sector in India and I was thoroughly impressed by his knowledge of the subject and the passion for achieving energy access for all . It is unfortunate that he is no more with us(Tributes to Girish Sant can be found here).
In the study titled “Solar Rooftop PV in India – Need to prioritize in-situ generation for self consumption with a net-metering approach“, released in November 2012, the authors of the study examine several issues related to rooftop PV and come up with some recommendations. The report is quite detailed, but let me share some of the highlights below.
In the introduction of the study, net metering is defined and the advantages of rooftop PV are identified. Some of them are
– Savings in Transmission and Distribution(T&D) losses
– Lower gestation period for installation and commissioning of Rooftop PV projects
– No need for additional land
– Improvement of the tail-end voltages and reduction in system congestion with higher self consumption of electricity. In other words, better grid stability if properly done.
– employment generation.
While the advantages are fairly obvious to everyone, there are several challenges which restrict the proliferation of the rooftop PV systems. The study specifically highlights some of the challenges in a Feed-in-Tariff approach and some of them are
– High Monitoring, Verification(V&M) and governance challenges: Do the discoms(distribution companies) have the resources to monitor and verify the FiT administration. The study mentions that in the city of Pune, almost 11% of the meters are faulty and this leads to lack of confidence in the data from these meters. It cites this challenge as one of the reasons why the Delhi Government scrapped its rooftop programme.
– Higher burden on utility – due to the smaller sizes of rooftop PV(RTPV), the unit cost of electricity from these systems tend to be higher, making power purchase from  RTPV uncompetitive in comparison to power purchase from utility scale projects.
– Difficulty in estimating FiT – With the rapid fall in PV system prices, arriving at a FiT has been a challenge not only for utility scale projects, but also for RTPV.
The study argues that due to these challenges in the FiT based approach, a net-metering based approach, as adapted by the Tamil Nadu Solar policy(Generation Based Incentives for Rooftop PV), should be promoted. In order to promote net-metering, the study recommends the following steps.
– Progressively increase the tariff for high-end consumption in residential and commercial sectors, thereby bringing RTPV power generation cost close to the price of grid-electricity.
– Provide interconnection to the grid and banking facility for rooftop PV systems.
– Instead of providing payouts for the net electricity exported to the grid, the credit can be rolled over to the next billing cycle and upto a year. This way, the excess generation in summer will balance out with the less generation in winters.
The study clearly mentions that it is against extending REC benefits for rooftop PV systems. The authors support their suggestions with several examples and analysis. The full report can be read here.
I am sure that some of the suggestions by Prayas will be incorporated in the rooftop PV policy very soon.
(Prayas Energy Group also has a literature review on the topic of distributed power generation, which can be accessed here. )
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