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
