Well, LEDs have a few attributes that make them superior over common High-Pressure Sodium Lamps (HPSL).
LEDs consume much less energy than any other commercially available lighting technology. Typical source efficiency
circles around 80 – 130 lumens/watt.
Also, they emit light directionally, i.e. over 180º, contrarily to common lamps which emit it at 360º.
LEDs kick out the need to redirect or reflect light, leading to far fewer losses than with conventional lamps.
LEDs’ lifespan is also much larger than other lighting technology, which is one of the big myths about LED lighting.
You can easily bet on an LED lasting up to 60,000 hours. Some of them even go up to 100,000 hours or more.
They also offer very high light quality with very low maintenance costs and hassle.
The fact that LEDs are more efficient than traditional lamps, implies smaller solar panels size.