∴ The number of lamps for normal operation of street lamps is: n = p =/kloc-0 /×107W200W = 5×104 lamps.

②t=2000h，

∴ The annual power output of the generator is: W=P Total t =10000kW× 2000h = 2×107kW? h.

(3) Photoelectric power generation, low-carbon mode.

Therefore, the answer is: 5×104; 2× 107; Photoelectric power generation is a model of low carbon.