Council on Energy, Environment and Water Integrated | International | Independent

kWh from kW: Achieving Optimum Energy Generation from Rooftop Solar Systems

Insights from Field Visits in Delhi

Bhawna Tyagi, Sachin Zachariah, Neeraj Kuldeep, Deepak Singh Chouhan, Shailendra Singh Chouhan, Aayush Mahajan, and Atul Kumar Jain
November 2023 | Energy Transitions

Suggested citation: Tyagi, Bhawna, Sachin Zachariah, Neeraj Kuldeep, Deepak Singh Chouhan, Shailendra Singh Chouhan, Aayush Mahajan, and Atul Kumar Jain. 2023. kWh from kW: Achieving Optimum Energy Generation from Rooftop Solar Systems -Insights from field visits in Delhi. New Delhi: Council on Energy, Environment and Water.



The study examines the performance of the installed grid-connected rooftop solar systems in the BSES Yamuna Private Limited service area. CEEW partnered with BSES Yamuna Private Limited (BYPL) and PV Diagnostics to evaluate the performance of rooftop solar systems. The assessment was carried out using desktop analysis based on generation data, complemented by site visits. The study aimed to evaluate system performance and identify the root causes of underperformance.

Solarising rooftops provides an opportunity to reduce dependence on conventional energy sources. However, poorly maintained solar systems lead to low energy output, increase in the payback period, make the system economically unviable, reduce lifespan, and increase safety concerns. Unsatisfying experience impacts consumer sentiments and can adversely affect the organic growth of the sector in the long run.

Key Highlights

  • Rooftop solar installations are concentrated in domestic and commercial areas in the Southeast, Northeast and Central parts of Delhi.
  • The study performed a desktop analysis of 681 systems with a total capacity of 27 MW. For the survey, 61 systems were studied with a capacity of 9 MW. Projects considered for field assessment in Delhi are net-metered and at least a year old.
  • The study finds that high soiling and shadow effects are the most recurring maintenance issues observed in rooftop solar systems.
  • Air pollution and water quality impacts the system performance in Delhi, necessitating proper maintenance for better performance of the RTS systems.
  • Low awareness of how to maintain the system and a lack of proper documentation and transfer of knowledge to consumers lead to maintenance issues. More than 70 per cent of residential consumers maintain the RTS system themselves whereas commercial and industrial (C&I) consumers prefer third-party annual maintenance contracts (AMCs).
  • System performance improves by over 10 per cent with onsite cleaning. The performance of the RTS system can be increased by 4-6 per cent with regular maintenance (considering all issues that can be resolved with proper O&M). This will lead to 35-60 per cent more energy production from the existing system. Approximately 10 million units of electricity are lost annually due to underperformance of the RTS systems.
  • Overall, ~INR 2 crore (USD 250,000) savings could be realised by consumers collectively just by cleaning RTS systems. The benefits will be higher if we include other maintenance issues such as shadow effect, cable damage, etc.
  • Discoms can save an additional ~INR 5 million and ~2300 tons of CO2 emissions from the existing RTS capacity with proper O&M schedules.

Key Recommendations

  • Create a standard operating procedure for consumers for the post-AMC period. This could be part of the post-installation documents. This will facilitate a smooth transition from the developer to the consumer and ensure the optimum performance of the solar photovoltaic (PV) system.
  • Increase the accountability of developers by a rating mechanism for vendors, which is published on the discom’s website. The rating should be based on feedback from verified consumers. This will be critical in identifying vendors receiving complaints and in encouraging them to improve their performance.
  • Convert MNRE’s detailed guidelines on the dos and don’ts for consumers to maintain their system post-installation into a simpler language. Explainer videos or infographics showing steps to maintain the system can also be created.
  • Improve system performance by offering the annual maintenance services to consumers in their license area. It helps discoms in generating additional revenue, improving the system performance and retaining consumer confidence in the technology.


  • What is the subsidy on solar rooftops in Delhi?

    The central government subsidy for rooftop solar plant installed by a residential consumer in Delhi is INR 14,588 per kW for installations upto 3 kW.

  • How do you maintain a solar rooftop system?

    The maintenance of a solar rooftop system involves routine inspection and servicing and the periodical cleaning of modules. Maintenance also includes the real-time monitoring of equipment condition and plant operations. In addition, there are unscheduled maintenance requirements in the case of equipment failure.

  • Why is solar system maintenance important?

    The maintenance of rooftop solar systems is important to optimise the energy yield and maximise the system life. The lack of proper maintenance of solar systems leads to low energy output, increase in payback period, reduces the economic viability of the system, reduces its lifespan, and increases the safety concerns.

  • What is the maintenance cost of rooftop solar? Can maintenance allow for savings?

    The O&M costs are typically 1-2 per cent of the initial system cost annually. Yes, the study finds that ~INR 2 crore (USD 250,000) savings can be realised collectively by residential rooftop solar consumers just by cleaning their systems.

“Maximising the contribution of rooftop solar to overall clean energy mix necessitates proper maintenance of rooftop solar systems. There is a need to simplify the process for consumers by creating standard operating procedures and ensuring optimum solar PV system performance.”

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