Based on the analysis above, one can plot the curves of the effi-
ciencies and power outputs of the PV module, TEG, and hybrid system
varying with the current of the PV module, as shown in Fig. 3,
where G ¼ 1000 W m2; TC ¼ 300 K; ZTC ¼ 1:0; c ¼ 5 m; RL2=R ¼
1; U1A1 ¼ 140 W K1
; and U2A2 ¼ 20 W K1 [13,32]. The dash-dot
line in Fig. 3 corresponds to the case of the single PV module at
TP ¼ 345 K. This temperature is the minimum temperature of a single
PV module under the same operating conditions, as shown in
Fig. 4. In Fig. 4, the energy balance equation of the single PV operation
mode, i.e., GAPV I
2
RL1 ¼ UncAPV ðTP TCÞ, has been used, where
Unc is the natural convection heat transfer coefficient. It can be seen
from Fig. 3(a) that the optimal current of the hybrid system at the
local maximum power output point (MPP) is almost the same as that