DC overloading gains increasing acceptance in India

19 April 2018 |

A solar power plant rarely produces nameplate capacity power as solar modules operate at their maximum efficiency only during limited peak hours. It has therefore become routine industry practice to over-size DC module capacity, a concept commonly known as DC overloading. It allows solar plants to increase generation during non-peak hours and optimizes overall performance. In 2017, 45% of the projects installed in India used DC overloading of over 20%.

However, DC overloading may create a situation where peak-hour generation crosses capacity constraints of the inverter forcing it to ‘clip off’ extra generation. Optimal DC overloading requires balancing the trade-off between clipping losses during peak hours and extra generation during off-peak hours through the year. This trade-off is complicated by the fact that solar modules degrade over time causing reduction in clipping losses in later years. 

Figure: Benefits and losses of higher DC overloading

Figure: DC overloading in India in 2017

Increasing DC capacity reduces effective cost of transmission lines, AC side equipment and soft costs. Choosing optimal DC:AC ratio depends on multiple parameters:  

  1. Irradiation: Higher irradiation results in higher clipping losses and hence, lower DC overloading is suggested for such projects.
  2. Site temperature: High site temperatures adversely affect power output from the modules. Most utility scale project sites in India have high temperatures (over 40 deg C) during peak-hours, resulting in underperformance of the system and lower clipping losses. Hence, higher overloading may be desirable for such sites.
  3. Land availability: Increasing DC overloading requires more land. Land availability constraints, in solar parks or other projects, may dictate the amount of overloading.

New project tenders in India in recent years have not prescribed any cap on DC overloading. The trend to use higher DC overloading has increased in India. A few projects have even used overloading of over 50%.  

For more details of Indian inverter market and various design and operation issues related to inverters, download our report, Inverter Design and Selection.

Back
"; ?>

Recent reports

India Solar Rooftop Market Analytics   

This report presents trends and observations from over 16,000 rooftop solar installations with an aggregate capacity of 2,265 MW in our database. It p...

Buy Report Download Executive Summary

Forecasting and Scheduling Regulations   

India’s central electricity regulator, the Central Electricity Regulatory Commission (CERC), issued an amendment to the Deviation Settlement Mechani...

Buy Report Download Executive Summary

India RE Map | September 2019

India added 9,327 MW of utility scale wind and solar capacity in the last 12 months. Total installed RE capacity is estimated at 66,650 MW as on 30 Se...

Download

India Solar Compass Q2 2019   

Q2 was again a slow quarter for the solar sector with new capacity addition coming in at only 1,104 MW, down 55% over previous quarter and 28% below o...

Buy Report Download Executive Summary

India Solar Map | June 2019

Indian utility scale solar capacity reached 26,154 MW as on 31 March 2019. Capacity addition fell to 4,810 MW in FY 2019, down a steep 47% over previo...

Download

India Solar Rooftop Map | June 2019

India is estimated to have added a record 1,836 MW of rooftop solar capacity in FY 2019. Rooftop solar continues to grow rapidly registering a growth ...

Download
Award winnig research
We use cookies to offer you an optimal user experience and collect information on website usage.