These solar powered lights would normally be connected to the mains power supply to allow for long overcast periods (the batter allows for about five nights of power). They have lower energy use, but increased capital and maintenance costs, as the batteries need to be replaced regularly. Also as they are not designed to put excess electricity generated during the day back into the grid.
It should be noted that the solar panel represents most of the cost of the solar street light. The same type of LED street lights (such as the 120 Watt double arm street light by Tri North Lighting) can be purchased without the solar panel, at a far lower capital cost. While such street lights come with a photocell to switch them off during the day, they could be made far more efficient with more intelligence and networking, which switches them to a dimmer setting in the absence of people and vehicles.
The 90 LED cool white solar street light with arm contains 90 each 1-watt high powered LED light bulbs. The has a color temperature of 6500K +/- 500K. This light input voltage can be between 100-240 volts. The light has a luminous flux of 4025 lumens and an average illumination of 14-lux/7-meters. This light is the equal to a 350 watt mercury pressure lamp but only consumes 90 watts of power. The dimensions of the light fixture are 74.8 inches long by 11.9 inches wide by 2.4 inches high. The solar panel dimensions are 63 inches by 63 inches. The panel has to be set on top of pole at a 16 degree to 40 degree angle. The solar panel comes with a maintenance free battery (100AH/24V) which will run 10 hours a day for up to 5 days on one full charge. The panel also has a light control, over charge protection, over discharge protection and auto switching to main power when the battery falls below the predetermined level. All of are LED street lights are UL and CE listed with an IP65 rating....
From: 90 LED cool white solar street light with arm by Tri North Lighting, 2011
The 120 LED cool white street light with arm double and photocell contains 120 each 1-watt high powered LED light bulbs. The has a color temperature of 6500K +/- 500K. This light input voltage can be between 100-240 volts. The light has a luminous flux of 5308 lumens and an average illumination of 14-lux/8-meters. This light is the equal to a 400 watt mercury pressure lamp but only consumes 143 watts of power. The dimensions of the light fixture are 153.2 inches long by 14.8 inches wide by 2.4 inches high. The auto switching photocell sensor is located between the pole coupler and the led lights. You still the light like you would a traditional street light. When the amount of sun light is lower then 13 lux the will automatically turn on and when above 13 lux the light will turn off. All of are LED street lights are UL and CE listed with an IP65 rating.
From: 120 Watt double arm street light by Tri North Lighting