4.4. Formulations
If the hybrid energy systems are well designed, they provide a
reliable service for an extended period of time. The sizes of system
components are decision variables, and their costs are objective
function. Objective function here in is the cost of PV, wind turbine
rotor, battery and also the battery charger, installation, maintenance,
and engineering cost. A solar and wind hybrid energy system
with the sizes of as and aw, respectively, can be defined as
As ¼ g As ð1Þ
where g is the PV module efficiency, As is the PV array area and
aw ¼ Cp ðp r2Þ ð2Þ
where Cp is the power coefficient, and r is the rotor radius. Here, p.r2
represents Aw, rotor swept area. g value is taken as a variable value
depending on PV module type and module temperature. In the
study, mono-crystal silicon PV module type, rated output of 75W
at 1000 W/m2 is used. Here, g value changes between 7% and 17%
based on module surface temperatures which are between 10 C
and 70 C [27,28]. In the simulation model, for December, January
and February the temperature and the g values are assumed to be