1. I am planing a project explaining how street light can be made more intelligent with smart batteries & other features.
2. I am thinking on what communication should I use.
3. Wired communication is not possible. As it include huge wiring
4. GSM is costly as per SMS cost is high.
5. How can I connect them wirelessly. Can I put them in network?
Edit: I am using MCU.

 

Why would you want batteries in street lighting, they would have to be charged, so mains cables would have to be installed,in winter the nights are longer than days, so solar is useless, street lights come on with a photo cell, that's intelligent.

 

As dodydave says forget the batteries but I can see that you could for example dim the lights until a car passes and then may be light up the next 200m or so of road by turning on the lights ahead. There are various wireless comms systems for things like this, have a look at xbee. You could probably use bluetooth depending on spacing or just plain old WiFi, you would have to consider security otherwise the kids would be messing with it.

 

In urban areas (which is where the vast majority of street lights are) it would be very distracting to have the lights going on and off or dimming frequently. For safety reasons (think vehicle accidents, personal attacks, crime generally) it would be best to have the lights on continuously during hours of darkness. I'm struggling to think of any 'smarter' system than the present one, using just photo-sensors to control the lights.

 

I have lived in villages where the lights went off at midnight and where I currently live it would be very rare indeed to see a person or a car after 1am however the street lights are on all night. It would save energy to only bring them on when needed and dim them when not.

 

I had searched for some cheap solution.
Solution I have got till now, get SIM module, use GPRS and send the data on network. Lowest cost
No SMS

 

Did you look ar XBee? Also try http://www.rfsolutions.co.uk/