ECONOMYNEXT – An international expert who prophetically warned about power system instability from a large rooftop solar power share, barely two weeks before a cascading power failure, expressed amazement about how Sri Lanka system operators are coping.
The CEB’s system control was unable to stop an outage from a suspected wildlife intrusion into a major cascading failure due to lack of ‘intertia’ in the system to withstand disturbance due to large share of solar on February 09.
Inertia comes from large rotating generators which are shut in Sri Lanka as solar power peaks in daytime, and the problem is bad on weekends when factories and offices are closed.
“They don’t have flexibility to control because they have limited inertia,” Jaimes Kolantharaj, Principal Energy Specialist, Asian Development Bank told a forum in Colombo on January 30, less than two weeks before a cascading failure.
“It is amazing to see how system control operates. The system is totally in darkness during the daytime.”
Related Sri Lanka cascading power failure fanned by big rooftop solar share: CEBEU
Sri Lanka’s power utility has been cash-strapped for years, due to a failure in price regulation due to various reasons. as the rupee collapsed from flexible inflation targeting and coal plants were blocked by activists.
The utility owed hundreds of billions of rupees to fuel and power suppliers when the International Monetary Fund stepped in with a stabilization program after a sovereign default in 2022, forcing the regulator to hike prices.
Sri Lanka had an estimated 1,400 MegaWatts of distributed solar units which was about half the daytime demand and very much more on weekends on which the system control had no data.
“The solar PV is not at all visible to the system operator, but this peak capacity may be much higher because the installed capacity is reaching almost 1.4 gigawatt and it may grow in the future in 2025,” Kolantharaj said.
“So over 50 percent of daytime demand will be met through distributed RE. And there is no visibility for system control, limited predictability. There is no forecasting tool available in system control, limited control.”
The Asian Development Bank recently approved a loan, which will give an initial control desk for system control to monitor renewable.
Widespread smart metering is needed to monitor the rooftops and other renewables which the CEB can neither see nor switch on or off at the moment.
The only option is to shut entire feeders.
Sri Lanka’s system control “needs immediate recovery”, Kolantharaj said.
After Sri Lanka’s debt was declared unsustainable by the International Monetary Fund five years ago in 2020 following rate and tax cuts by macroeconomists, multilateral lenders were forced to stop new lending.
After the IMF program started they focused initially on budget support, not project loans.
The Asian Development Bank recently approved a project loan of 200 million dollars to upgrade the grid and do the first battery storage unit.
The loan has allocation for a renewable energy center and a well as grid-scale BESS and urgent action was needed to implement the loan and bidding for equipment,
READ ADB approves $200mn Sri Lanka loan for battery storage, grid upgrade
In addition to the first battery storage unit which will only be 100MW/100MWh, the ADB and Sri Lanka authorities were working on a roadmap for Advanced Metering Infrastructure. New batteries can also respond to voltage changes in milliseconds.
At the moment the CEB’s low tension network is tripping due to over-voltage from solar rooftops. The CEB was reluctant to approve a new rooftop as a result and tripping in any case reduced the generation of solar power.
Discussions were ongoing on the statutory voltage response settings, and statutory voltage, he said. (Colombo/Feb10/2025)
