where η is the charge/discharge efficiency of the storage, also called
“round trip efficiency”. The storage efficiency is approximated as a
constant parameter, evaluated considering the average charging, discharging
and storing losses. The steady-state model does not accountfor the change in external conditions (e.g. temperature, humidity)
which, in the real case, would affect the storage efficiency. This simplified
model is particularly suited for a preliminary technoeconomic
feasibility study in Singapore’s climate characterized by
almost steady ambient conditions along the day and across the year