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30 Watt Integrated

100 Watt Integrated

Overview “Streetlights”

Background

 

Streetlights are applied in most high density residential and commercial areas in South Africa.  This is done by Eskom, Local Authorities and private complexes.  The lights vary from more commonly 125/150 Watt in small low traffic roads to 250/400 Watt for main arteries.  These use high intensity discharge  (HID) globes typically High Pressure Sodium Vapour (HPS) or Nickel Halide. The total electricity consumption of these lights is the capacity of the globe plus about 10% for the power supply.  In other words the 400 Watt light will use 400 plus 10% = 440 Watt.  The power factor ranges from 0.6 to 0.9 which means the total power can exceed 500 VA. The electricity usage of these are astronomical.

New Light Design

The basic idea of the new LED Streetlight is the retrofit of current Streetlights with a more energy efficient LED light or installing new fitting with LED light.

The product basically has the following components:

  • A screw in light:
    • Driver (Constant current)
    • LED/s
    • PC board/s
    • Lense/s
    • Heat sink
    • Thermostat
    • Fan
    • Basic strew structure
  • Optional retrofit kit plus lightning arrestor.

The whole idea is that the driver and light are modular simplifying storage and replacement.  If any of these fail it can be replaced under guarantee or only the faulty component be repaired.

Features of the Light

The features of the new light can be summarised as follows:

  • Much more efficient use of electricity to provide the light. (70% saving)
  • Easy change of components.
  • Better light utilisation.
  • Immediate light, not 10 minute waiting period.
  • Only 10% failure expected in more than 50 000 hours.
  • Excellent power factor.

Elexpert LED Streetlights

With the rapid development of LED lights, options are now becoming viable to displace the current inefficient lights.  A new light has now been developed which capture various features in meeting various customer needs in the market.  This paper sets out the features of the new LED Streetlight with retrofit and possible backup features.

Basically two options are offered:

  • For replacing 400 and 250 Watt HID lamps: Up to 90 Watts LED. The same unit can be set on the light at:
    • 90, 75 or 60 Watts.
    • E40 socket.
  • For replacing up to 150 Watts: Up to 30 Amps LED: Different units can be ordered to meet different needs.
    • 20 Watts, 30 Watts.
    • E40 or E27 Socket.

Retrofit

The idea of the retrofit is to fit the LED light into existing streetlight fittings as follows:

  • The old power supply and starter be removed.
  • The old globe be removed as well as the reflector (to provide for air circulation).
  • Clean the old fitting / glass.
  • Connect Live to the light socket centre and neutral to side.
  • The LED light be screwed into the socket and be aligned.

The following should be noted in this respect:

  • The retrofit is not recommended for PVC (non-metallic) fittings as these do not provide adequate cooling. (It can however be used up to 30 Watts max).
  • Some light fittings require some small modifications to install the globe.
  • Where the existing socket is faulty it should be replaced.
  • Where existing light fittings are in serious disrepair a new fitting should be provided.

The picture below shows the 90 Watt unit retrofit in an existing streetlight fitting.  Detailed retrofit instructions are available.

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Maintenance/Failures Procedures 

One of the big challenges of new LED lights relate to maintenance / replacement.  Eventfully all lights will fail.  The cost at which many LED streetlights are being changed in South Africa is ridiculous.  Many of them will never reach break-even.  The following problems are thus being faced by utilities in respect of the current complete LED streetlights:

  • Utilities are faced with replacing the complete light in the future at an enormous cost.
  • Utilities will have to keep complete units as spare. This is not just a small globe but a complete unit at high cost and taking much space.
  • When lights fail due to guarantee, old age, lightning or any other reason the complete unit need to be changed at high cost.

The Elexpert Globe approach overcomes all these problems as the cost is much lower as the light is a separate small interchangeable unit.

The maintenance on the light is very simple:

If the light goes on and off by itself:

  • The light is overheating. This will happen if the lights are on during the day (when day/night switch is faulty / bypassed).  Fix day/night switch.
  • This could indicates the fan has failed. Change the light with spare.

If the light goes off or dims:

  • This could indicate a problem with the driver or the LED.
  • Change the light with spare one.

To facilitate the process of fixing / exchanging faulty units Elexpert has made arrangements with courier companies to collect and return these to customers on site at a small fee.  It is recommended to buy some spare units as with HID lamps so that faulty units can be replaced immediately without having to way for replacements.

Light intensity

The various lights have been designed to meet different street lighting needs. The comparative light spectrum for a 150/400 Watt HID lamp compared with the Elexpert 30/90 Watt LED lights are shown in the figure below:

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Although the LED light gives less light close to the pole, it gives more light far away from the pole.  The LED light has been designed to meet the South African street lighting standard.  Many of the current lights do not meet these standards and in fact create dark spots at the points between poles.

The figures below shows the typical light distribution obtained with the Ledil / Gungtai lenses used for the 30 and 90 Watt lights respectively.

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Street Simulations

The table below shows the key values for a typical 2 lane sub-urban road.

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This shows that this lighting arrangement meets the S3 road standard.  The figure belowshows the light distribution (lux) for the case described above.

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Warrantee

The light contains the following separate parts namely:

  • The driver.
  • The LED light unit.

All these units will carry a 3 year exchange warrantee.  Can be extended to 5 years.

If any of the units fault after the warrantee period a fee will be charged to replace / repair the faulty components.

Life expectancy

The life expectancy of the various key components of the product are as follows:

  • The driver. – 10 years plus continuous.
  • The fan. – 10 years plus continuous.
  • LEDs – 1% failure after 50 000 hours usage.

The critical component of the whole light in terms of life is the LEDs

Lumen maintenance Lifetime.  The output of LEDs do reduce over time.  This is largely depending in the temperature of the LED.  The solution provided here will retain a surface temperature of typically  less than 60° C.  This indicates that 90% light will be retained after 50 000 hours of continuous operation.

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Electricity Savings

The electricity savings to utilities are twofold.  Firstly the savings in purchase costs and secondly the longer term savings in network costs.  Most municipalities buy on Eskom’s TOU tariffs either Megaflex or Miniflex.  The calculations were done on Megaflex.

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The costs applicable for a utility buying at the Eskom Megaflex tariff at 11 kV in 2017/18 is thus as follows.

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Four cases are analysed:

  • Whole night burning: Replace 150 Watt HID with 30 Watt LED with fitting.
  • Whole night burning: Replace 150 Watt HID with 30 Watt LED light only.
  • Whole night burning – 50% dimming after midnight: Replace 150 Watt HID with 30 Watt LED light only.
  • Whole night burning: Replace 400 Watt HID with 90 Watt LED light only.

The key figures relating to each option is shown below.

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A few typical breakeven situations are shown in the figure below.

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The following can be concluded from this:

  • The 400 Watt light hold the greatest returns.
  • The dimming option makes a small difference only.
  • The inclusion of the cost of a fitting on the 150 Watt units extends the break-even extensively.
  • Companies who pay company tax can claim a tax rebate from SARS. The value of this is equal to about R230 and R560 for the 150 and 400 Watt lights respectively.  There are however measurement and verification costs involved which need to be factored in.  This can have a big impact on the break evens.

The annual NPV’s are shown in the table below.

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This shows breakeven within the guarantee period and thereafter significant value.

Why change

The main drive for the installation of the new more efficient LED Streetlights are as follows:

  • Savings in electricity:
    • Lower usage of the LED light compared with other lights.
  • The ability to switch on and off in very short periods compared with Sodium Vapour.
  • Ability to dim the lights when there is very few traffic or say after midnight.

The new LED light with its power supply will use about 25% of the power of the existing light for similar usable light depending on the customers need.

This reduced electricity savings will off-course assist customers in the following respects:

  • Lowering their carbon footprint.
  • Moving towards achieving the 10% savings requested / required from key (eventually all) customers.

Conclusions

The new Retrofit LED Streetlight provides a first real affordable alternative to the high light intensity Sodium Vapour lights used extensively in South Africa.  It reduces electricity consumption by at least 70% and provides excellent return on investment.  The reduction in electricity demand offered by these lights can make a significant impact on the shortage of electricity supply in South Africa and a very significant reduction in impact on global warming.