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City Streetlights Become Smart: The New LED Street Lamps, Part 1

Cities are becoming smarter day-by-day: This is the modern trend of the smart grids of energy distribution. The main reason is clearly exposed in Keith Dawson’s blog, When Utilities Fight LED Street Lights: “For cities, the upside of replacing energy-guzzling street lights with efficient LEDs is evident. But there is a downside for utility cash flow”

This makes it easy to understand that the new strategy for street illumination is mainly focused on LED (light-emitting diode) lights. The main reason is the good lighting in terms of energy conversion efficiency and the easy control of the brightness of the light emitted by LED lights, which can be done in a smart modality by an automated protocol of a smart integrated system. The long-term cost savings of this solution are really promising.

It’s clear that an automated system cannot control the quality of the light emitted from the LED; this can be done by a good design of the LED lamp. An integrated solution to control the light emitted by LED lights has to take into consideration that, basically, the tone of the light emitted from the LED depends, not directly on the electrical power absorbed, but on the concentration of the emitted light. The light concentration is the ratio of the total light flux (measured in lumens) and the surface that is exposed to that light, hence the effect of the light emitted from an LED depends essentially on the lens used.

LED structure (Source: euroled)

LED structure
(Source: euroled)

Although the quality of the light emitted by the LED is not directly related to the electric power supplied to the LED lamp, the electric current supplied to the LED is the key parameter to control automatically the brightness of the LED light, and this control can be implemented automatically by a smart system.

This is the basic idea of the smart lighting solution: The brightness of the LED light can be dimmed by controlling the current flowing into the LED, so the controller is able to regulate the energy consumption, depending on the feedback signal coming from a control sensor. This feedback may be, for example, the output of a light intensity sensor (a photodiode for instance), hence this design strategy makes the overall system really effective by leading to an auto-regulating process.

In Part 2 of this series, I will describe some solutions for smart street illumination, adopted by some companies that are major players in the semiconductor market.

What do you think of smart LED lighting? Is this solution appealing to the accounting departments of the administrations of the big cities?

55 comments on “City Streetlights Become Smart: The New LED Street Lamps, Part 1

  1. Davidled
    June 3, 2014

    When I am looking at LED structure, there is no any protection component except diode, even though this picture shows a brief explanation. Protection circuit would be designed depending on the CRI and the brightness level as well as lumens-per-watt.

  2. fasmicro
    June 4, 2014

    >> What do you think of smart LED lighting?

    Lots of money to be made there. I see it and there is no going back. The exciting aspect of this industry is the realization that we can have a really durable product that delivers great performance without breaking the bank. I hope the move and transition to LED lighting will continue as the benefits are huge.

  3. goafrit2
    June 4, 2014

     Is this solution appealing to the accounting departments of the administrations of the big cities?

    That is one reason why we do not see a lot of innovation in our cities. The accountants must not be making these calls. This goes beyond money, you have to look at the ROCE, ROI and other important factors like environmental impacts, green emission etc. Engineers must be empowerred to make calls.

  4. goafrit2
    June 4, 2014

    When I am looking at LED structure, there is no any protection component except diode, even though this picture shows a brief explanation

    Do you expect STMicroelectronics to show the whole game? Not possible because that is the business.

  5. Davidled
    June 4, 2014

    I expect that analog circuit LED driver circuit with heat management in the board could be illustrated in a brief diagram except inorganic semiconductor material which is not easy to explain, because circuit design could be a variable depending on LED electric requirement.  

  6. Netcrawl
    June 5, 2014

    @Daej LED convert most of the elctrical energy they receive into heat rather than light, without adequate heat management, this heat can degrade the LED's lifespan and affect output. 

  7. Netcrawl
    June 5, 2014

    @goafrit2 I think innovation is all about ideas and information flow, how easily you can access information and opportunities, and intercation mechanism drive this innovation.  

  8. SunitaT
    June 5, 2014

    CFL street lights powered by solar energy are commonly used in remote locations where there is crunch in electric supply. Replacing LEDs with the CFL will be even more efficient solution.

  9. SunitaT
    June 5, 2014

    Ambient air temperature effect junction temperature playing one of the important role in LED thermal management. Ambient temperature varies as per the application and needs to be considered in LED design.

  10. SunitaT
    June 5, 2014

    LED drivers playes important role in LED thermal management. LED drivers incorporates thermal shutdown failsafe mechanism. If the drivers exceed a specified temperature  will turn off itself along with the LED.

    The driver can also be used to monitor LED's flux output(in terms of lumes) where natural light illumination changes over a day.

  11. etnapowers
    June 5, 2014

    You can find a good example of protection of the IC from the heat at this link

  12. etnapowers
    June 5, 2014

    True, and the thermal resistance junction – case is a really important parameter to be considered in the LED design.

  13. Hughston
    June 5, 2014

    Street lights cost thousands of dollars.  The cost of the smart features is insignificant compared to the pole and light assembly. I am amazed at the cost of such things compared to what I normally work on.  Future lights will be controlled and monitored with a wireless network.  I have to think the downside of the new lights is the cost of the labor in replacing old lights.

  14. Hughston
    June 5, 2014

    I was looking at LCD display backlighting last year and the LED backlighting had a 50,000 hour lifetime.  The CCFL backlight had a much shorter lifetime quoted.  Displays have now switched to LED backlighting because costs have come down and the lifetime is so much better.

  15. Davidled
    June 5, 2014

    For any project, Initial investment should be triggered. Investor will look at the ROI. I think that LED on street light will save power consumption compared to old lighting bulb. More analog circuit will be designed to support this project with wireless network requiring a more precise circuit design.  More labor creates more job. Even though there is some downside, there is more positive impacts compared with the downside.   

  16. etnapowers
    June 6, 2014

    @DaeJ, I agree with you, the LED streetlights project is very convenient on the long term, because of a lower power consumption, due to a better efficiency respect to incandescent bulbs.

  17. goafrit2
    June 7, 2014

    >> I expect that analog circuit LED driver circuit with heat management in the board could be illustrated in a brief diagram

    That is most likely basic. LED driver seems standard unless the process is new where you can use some special transistors to make really nice high voltage units. Yet, that could be a no go area for a company out in the competition. They rarely show the important stuffs.

  18. goafrit2
    June 7, 2014

    >>  LED convert most of the elctrical energy they receive into heat rather than light, without adequate heat managemen

    That is new to me. I was thinking the proportion to light is more than the wasted heat. It may be most likely related to the production quality of the LED.

  19. goafrit2
    June 7, 2014

    >>  I think innovation is all about ideas and information flow, how easily you can access information and opportunities, and intercation mechanism drive this innovation.

    That is what they teach us in schools. Unfortunately, the most innovative are not the most knowledgeable or educated. Look at the greatest innovators of the last 100 years, few have PhD or worked in an innovation policy office. Most times, too much info diminishes your thinking horizon.

  20. goafrit2
    June 7, 2014

    >> LED drivers playes important role in LED thermal management. LED drivers incorporates thermal shutdown failsafe mechanism.

    Most LED drivers are the same. I think this is really basic. Unless they are using new process where HV transistors are deployed with no charge pumps to bump up the voltage levels of traditional CMOS  transistor in the circuit, most driver circuits are basic.

  21. goafrit2
    June 7, 2014

    >>  The cost of the smart features is insignificant compared to the pole and light assembly. I am amazed at the cost of such things compared to what I normally work on.

    The main cost factor is the labor to change these bulbs when they go bad. That is why the durable LED light should be a good option. Unfortunately, politicians do not see things that way because the labor providers are unions that help to win elections and you cannot innovate them out.

  22. fasmicro
    June 7, 2014

    >> Displays have now switched to LED backlighting because costs have come down and the lifetime is so much better.

    Besides the cost, the quality is also better. I think LED provides a more dense light than most alternatives.

  23. fasmicro
    June 7, 2014

    Even though there is some downside, there is more positive impacts compared with the downside. 

    There are few downsides in this example since LED will emerge as the key technology in streethlighting. Yet, the contracts with utilities and special interests are things technology cannot displace. Cities have decisions to make and most times better technology is one of the factors to consider.

  24. Netcrawl
    June 9, 2014

    @Goafrit2 I agree with you, LED is really a good option, it key strength is its reduced power consumtion, when designed properly LED will approach 80% efficiency which means that almost 80% of the electrical energy it received is converted to light energy. Another is lifespan, LEDs have extremely long lives, they don't have this filament that could quickly burn out, and they're safe because they don't contain toxic like mercury.

    And in term of cost they're quite different, in incandescent bulb, the true cost is the cost of replacement bulbs, time and labor to replace them, while in LED, there's no need for replacement, LEDs would virtually eliminate the need for replacement. For large building and infrastructures maintenance costs to replace bulbs can be enormous and time-consuming, these issues can all be eliminated using LED option, its probably the best option here.       

  25. Netcrawl
    June 9, 2014

    Because of its efficiency and longer lifespan, LED lightings are advocated as a means for reducing carbon footprint, they're increasingly becoming a popular alternative to compact flourescent and incandescent bulbs in homes and building. It quite popular and useful, I'm using LED lightings as a emergency lights during power interruption. 

  26. Netcrawl
    June 9, 2014

    @fasmicro I agreew ith you  it will emerge as a key technology. I think the greatest barrier to widespread adoption of this technology is education, many people are still unaware of the many uses of solid-state lightings, and that the initial costs can lead to long-term savings.  

  27. eafpres
    June 9, 2014

    @Netcrawl–” when designed properly LED will approach 80% efficiency”

    The wall plug efficiency of most LED lights is much less than 80%.  Soraa claimed nearly 75% earlier this year although I don't think that figure will hold up in production.  Cree has some blue LEDs in the 50% to 60% range but in an acutal lamp it is less because the other colors to make white are lower WPE.

  28. eafpres
    June 9, 2014

    @goafrit2–this is a common misunderstanding about LEDs.  The issue has more to do with the physics of LEDs I think than the production quality per-se.  You will find that thermal design for LED luminaires is one of the most important topics in LED lighting.

  29. eafpres
    June 9, 2014

    @goafrit2–“Most LED drivers are the same”

    For some applications you are correct.  However, consider that for home use the lights need to be dimmable, which is done by modifying the AC power waveform, and the driver has to deal with that.  There are many other complexities as well such that driver design is a fairly active area in LED lighting.

  30. eafpres
    June 9, 2014

    @Hughston–Over on a sister site to this one (All LED Lighting, edited by Keith Dawson) this topic of the costs to install a new street lamp has come up many times.  Actually, on another (now closed) UBM site (The Connecting Edge) this came up a few times.  The figures run a few hundred dollars per pole to install a new fixture on an existing pole with wiring in place.  That can be a big barrier in some cases.

  31. eafpres
    June 9, 2014

    Hi Paolo–” hence the effect of the light emitted from an LED depends essentially on the lens used.”

    I wonder if for certain high-power applications, perhaps street lighting, could become “active” using DMD (digital micromirror device) to manage the shape/distribution of the emitted light and even change it dynamically, such as changing the distribution across the light cone to level the intensity across the illuminated field.

  32. fasmicro
    June 9, 2014

    >> And in term of cost they're quite different, in incandescent bulb, the true cost is the cost of replacement bulbs, time and labor to replace them, while in LED, there's no need for replacement, LEDs would virtually eliminate the need for replacement.

    You are correct, the cost of replacing street light is more than the cost of the bulbs which are being replaced. That will translate to the highest savings if LED is adopted since LED last longer and will not need replacements.

  33. fasmicro
    June 9, 2014

    >> I'm using LED lightings as a emergency lights during power interruption. 

    What is the difference if that is LED or not? When the power goes off, whether LED or not, everything is shutdown. Maybe you have a battery backing up the power.

  34. fasmicro
    June 9, 2014

    >. many people are still unaware of the many uses of solid-state lightings, and that the initial costs can lead to long-term savings.

    You are correct that education is one of the problems. But you need to know that when the middle class is denigrated, they begin to think in days and not months. So, if I go to the shop and see two light bulbs – one X and another 3X. I will likely buy the X despite the fact that I may end up buy 6 of it before the one of 3X could go bad, if it will ever.

  35. fasmicro
    June 9, 2014

    >>  Cree has some blue LEDs in the 50% to 60% range but in an acutal lamp it is less because the other colors to make white are lower WPE.

    Any number on the comparative incadescent bulb. I guess that one will be less than 30% as it keeps heating up the whole place that you can use it for your heating!

  36. fasmicro
    June 9, 2014

    >.  You will find that thermal design for LED luminaires is one of the most important topics in LED lighting.

    That is very interesting. I used to think that LED is a matured area but these conversations have educated me. There seems to be a lot of work in this area on improving efficiency.

  37. fasmicro
    June 9, 2014

    >> However, consider that for home use the lights need to be dimmable, which is done by modifying the AC power waveform, and the driver has to deal with that. 

    The mobile apps will take over that work very soon. There are many people doing that though I do not know the immediate impact as customers still need to have a WIFI network at home. Many people but that is not a given. It will be an easier way of controlling intensity of the light.

  38. fasmicro
    June 9, 2014

    >> The figures run a few hundred dollars per pole to install a new fixture on an existing pole with wiring in place.  That can be a big barrier in some cases.

    The cost is one factor but the elimination of jobs for unions may be the vital reason. Imagine what happens if there is no dead bulb for a year after LED migration. You think the major will still keep the guys. He may decide to outsource that away from unions. The frequency of changing dead bulbs keeps people at work.

  39. etnapowers
    June 10, 2014

    Hi Blaine, for sure there's the chance to put intelligence in the street lighting applications , DMD is one of the possible solutions and for sure it is feasible, provided that the digital micromirror device is robust to the ambient conditions of the environment where it has to operate, in a long term time basis.

  40. etnapowers
    June 10, 2014

    Agreed. A sensibilization campaign about the advantages on the middle term of a good choice of the LED lights solution, instead of the incadescent bulbs, might be very good.

  41. eafpres
    June 10, 2014

    @fasmicro–I'm not sure if you are part of the All LED Lighting community (another UBM community like this one) but if you are interested in LED lighting developments it is a great place to lean.   http://www.allledlighting.com

  42. eafpres
    June 10, 2014

    @fasmicro–“Any number on the comparative incadescent bulb”

    The figures I can find for incandescent bulbs range from less than 1% up to 5%.  Typical is probably 2-3%.  That is why even a very poorly designed LED source beats any incandescent on energy efficiency.

    Some LED replacement bulbs however can be poor performers when dimmed.  This article on All LED Lighting is intersting and discusses this.  One thing to keep in mind is that  LED lighting technology is changing very fast and improvements seem to come often.

  43. RedDerek
    June 26, 2014

    Your description of the LED operation is lacking one vital component for the street lamp application. The typical LED does generate light directly. However, to get a white or other non-direct, single wavelength color output, they use phosphors to generate the visible light.

     

    As for general protection, I was thinking about this a bit more and with the plethora of LEDs w/ heatsinks, one should be able to design a simple controller that uses temperature feedback for the current control. Basically, sense the heatsink temperature. As the temperature rises to a value, start cutting back on the current drive. This would extend LED life, based on temperature setting.

     

    I have played with some early high-current LEDs, and they do tend to get hot quickly.

  44. goafrit2
    July 3, 2014

    Hi Blaine, for sure there's the chance to put intelligence in the street lighting applications , 

    All streetlights in Europe do – they have intelligence to handle basic things at the “system level” without getting the control room worked up. Intelligence is as simple as a sensor that can pick data around its environment and use it to control the light.

  45. goafrit2
    July 3, 2014

    >> A sensibilization campaign about the advantages on the middle term of a good choice of the LED lights solution,

    Solar advocataes have done better job than LED in making their cases with regards to the impact on the environment. LED as you noted have to develop a strategy in this case. I think the key point may be that established U.S. firms are not the pioneers in this sector. So, we may not have the big budgets to fund real advocacy. Phillips may be doing great in its home turf but it may have less incentive to do so here.

  46. goafrit2
    July 3, 2014

    >> One thing to keep in mind is that  LED lighting technology is changing very fast and improvements seem to come often

    I see a lot of players at the level of making apps to control smart LEDs here in U.S. But getting to know semiconductor (startups) firms working at the process level seems scarce. Are they building these LEDs in U.S or China. My concern is that what happened in the solar panel industry should not happen here. Many U.S. solar firms collapse owing to fast technology innovation pace.

  47. fasmicro
    July 3, 2014

     http://www.allledlighting.com

    Great resource – Thank you.

  48. eafpres
    July 3, 2014

    @goafrit2–I think the LED market has moved very quickly to production in low-cost regions, but there is still such a pace of technology advancement that the value comes from new, innovative products, not ultra-low cost.  Having said that, if you read some of the articles on the sister site (www.allledlighting.com) you will see that there is already a race to the bottom in things like LED light bulbs.

  49. fasmicro
    July 6, 2014

    >> many people are still unaware of the many uses of solid-state lightings, and that the initial costs can lead to long-term savings.  

    Even in the basic SSD storage, it took a lot of explanation for people to appreciate that incessant crashing of disks did not stop by chance. It was done because most makers moved to SSD memory.

  50. fasmicro
    July 6, 2014

    >> -I think the LED market has moved very quickly to production in low-cost regions, but there is still such a pace of technology advancement that the value comes from new, innovative products, not ultra-low cost. 

    It is always a better paradigm when innovation drives advancement over mere low-cost. However, both are related. If innovation does not reduce cost, it will not be sustainable. You do not innovate merely to increase cost, you try to do so while reducing cost.

  51. goafrit2
    July 6, 2014

    You are correct, LED production has moved to low-productione region. It is usually the thing. The West creates these technologies and then outsources them thereby empowering the people that make them. In few years, they realize they cannot compete. I give you an example – solar panel development began in U.S., but today, it has shifted outside U.S. LED is doing that already.

  52. Netcrawl
    July 6, 2014

    @goafrit2 I think its China or other Asian countries, they have these low cost production things and massive labor force there, the high cost of producing LEDs has always been a major roadblock to widespread adoption. LEDs has huge potential, and it may soon become the standard for most today's lighting needs, the problem is on production side.  

  53. eafpres
    July 6, 2014

    It is true that a model has been repeated whereby the West creates technology, then in the drive to make it low cost, teaches regions like China, Singapore, now Vietnam, India how to build such things.  

    The reality though is that as some products become commodities, there isn't much margin in there for any body.  So it becomes hard to make money under any model.

    In the case of LEDs, the basic designs are still in flux; I see a lot of work on phospors–see my short note on ths in All LED Lighting.  There are many other things going on with substrates, and then of course the whole OLED direction.

    I think in this way it will be some time before those low cost producers can copy everything, and of course the protection of intellectual property may keep unfair copies out of Western countries, at last for some years.

  54. goafrit2
    July 9, 2014

    >> LEDs has huge potential, and it may soon become the standard for most today's lighting needs, the problem is on production side.  

    You are correct. One thing that is missing in the LED business is the type of support government gave the solar panel business. Government intervention has been minimal in this area. We need government to say – let everyone throw away his tungsten filament and replace all with LED.

  55. goafrit2
    July 9, 2014

    >> The reality though is that as some products become commodities, there isn't much margin in there for any body.  So it becomes hard to make money under any model.

    Low margin is relative. A U.S. CEO getting $500k  a year will see things differentky to a U.S. CEO feeding on $2.5M salary. China can withstand that low-margin and supply to WalMart while Phlilips may find it challenging. Xiaomi – a smarthphone company is giving Samsung real problem on the phone business in China. Its product goes for $230 to Samsung comparable $299. They can live on that why it may be hard for South Korea owing to its cost model

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