?$解：?P=40×40\ \text {W}+20×30\ \text {W}=2200\ \text {W}?$?
?$? W_{ }=P_{ }t_{ }={ 2.2 }\ \text {kW}×{ 30×5 }\ \text {h}={ 330 }\ \text {kW}·\text {h}?$?
?$? P_{ 最大 }=U_{ }I_{ 最大 }={ 220 }\ \text{V}×{20 }\ \text{A}={ 4400 }\ \text{W}?$?
?$ 還可以安裝?\frac {4400\ \text {W}-2200\ \text {W}}{40\ \text {W}}=55?個$?
