Abstract:
Sewage treatment plants are the major consumers of energy throughout the world and most of the studies
consider completely self-sufficient treatment plants or off-grid solar PV. This study presents the findings of
the techno-economic feasibility study of using on-grid fixed tilt polycrystalline solar photovoltaic (PV)
modules to generate power for operating small capacity sewage treatment plants (STP) ranging from 1 to
10 MLD. Recent ongoing 4 STP projects in Rajasthan, India is considered for the study. With fixed-tilt solar
PV system, the maximum PV array capacity need to be installed is found to be 99kWp, 131kWp, 172kWp
and 403kWp for 1.5, 2, 3, 8 MLD STP’s respectively. Life Cycle Cost Analysis of a base case scenario with
30 years of service life and 10% discount rate indicates that the Net Present Value (NPV) of the system
comes around 3.7 Million INR, 5 Million INR, 6.5 Million INR and 15.3 Million INR for 1.5, 2, 3, 8 MLD
respectively. The Internal rate of return (IRR) is found to be 18.5%, the normal payback period to be 5.4
years and Discounted Payback period to be 8 years for all 4 STP’s. Life Cycle Assessment results of the
Solar PV modules indicates that the energy payback period is coming around only 1.6 years with carbon
payback period of 142 days in comparison with conventional coal-based power plants. It is found that
application of Solar PV in operating STP’s is highly favourable technically, economically as well as
environmentally in a tropical Country like India.
