Energy srorage technologies for grid connected PV power generation: sizing, tariff suggestions and tool development for cost benefit analysis
Student name: Ms Aparna Sankar
Guide: Prof R L Sawhney
Year of completion: 2013
Host Organisation: Water & Renewable Energy IC, L&T Construction, Chennai
Supervisor (Host Organisation): Mr Milan Kumar
Abstract: This project executed in association with L&T is centered on finding the most cost-competitive
technology for energy storage at grid connected solar photovoltaic power plants. The addition of storage
can have multiple functions as saving energy loss due to grid unavailability, power quality control,
benefiting by feeding solar power to grid at high load time etc... A few technology developers were
contacted to get the data for a market that is currently very nascent in India. A tool based on MS Excel
was designed to analyse the impact of adding a storage unit to a power plant and with different energy
tariffs, technology costs and financial parameters. The data so obtained was used to assess the feasibility
of energy storage integrated projects at grid level. Initially addition of storage is evaluated on the basis of
storage of energy otherwise lost during grid outage and the possibility of using the storage unit for other
functions is considered briefly. Financial viability of a solar PV power project is very volatile when the
storage unit is incorporated since the cost of storage could be as high as INR 40 to 112 million per mega
watt hour. Unless the storage efficiency and life improve, and the costs fall down, the viability of such
projects are dependent on the optimal matching of the storage size with the requirement. Any over-sizing
would mean redundant investment and under-sizing would mean loss of energy.
The findings here are not absolute since the field of energy storage development for grid connection is
fairly nascent and newer technologies are developed and tested at a very quick pace. The results of the
project will be useful for solar PV project developers in India to choose the technology currently more
competent in the market and to keep watch on the emerging promising technologies.
Key words: Energy storage, Round-trip efficiency, Grid outage, Energy tariff, NPV, IRR
