Overview of the Elexpert LED Lights


High bays, low bays, bulk heads, floodlights and streetlights have been popular lights for application in large industrial and commercial applications and public area in South Africa. The electricity usage of these are astronomical. Many of these lights use typically 1000, 400 and 250 Watt light globes. These use high intensity discharge globes (HID) typically High Pressure Sodium Vapour (HPS) or Nickel Halide.

These light fittings involve a basic fitting with some form of reflector, a fitting for a screw in type light globe and a compartment for the control gear. The total electricity consumption of these lights is the capacity of the globe plus 10% for the power supply. In other words the 400 Watt light will use 400 plus 10% = 440 Watt. The power factor ranges from o.6 to 0.9 which means the kVA can exceed 500 VA.

To date various technologies have been explored to replace the HID lights currently used in these fittings. So far these have proven very expensive, too difficult to change or not providing adequate light.

With the rapid development of LED’s, options are now becoming available to replace the current less efficient lights. New lights have now been developed that capture various features in meeting various customer needs in the market. This paper sets out the features of the new Elexpert retrofit LED lights with various features.

Light options

Elexpert has developed solutions to meet various demands in the market. It realises that in some cases there are cheap alternatives available (many not proven), but in other cases our solutions are unique and lowest cost. Our current products with the respective powers are shown in the table below:


Elexpert is a small company with flexibility to develop unique solutions to meet customer needs.

New Light Design

The basic idea of the retrofit lights is the retrofit of current lights with a much more energy efficient LED light or installing new LED light with fitting. The product basically has the following components:

A power supply:

  • A low voltage constant current supply.

A screw in light:

  • Screw in fitting with structure to hold the various components.
  • A cooling fan.
  • The heat sink.
  • The high power LED/s.

Some units the power supply and the light are integrated into one unit.

The whole idea is that the Power unit and the light fitting are all modular. If any of these fail it can be replaced under guarantee or the faulty component need only be repaired.

Features of the light

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

  • Retrofit: high bays, low bays, bulk heads, floodlights and streetlights from power ratings of 125 Watt up to 1 000 Watts.
  • Much more efficient use of electricity to provide the light. (up to 75% saving)
  • Better light utilisation due to display LED angle.
  • SABS approved and Qualify for Eskom incentives.
  • Competitive price achieving breakeven of 6 to 24 months.
  • Lifetime up to 10 years ensured by using forced cooling.
  • Few basic components for improve reliability and easy repair.
  • Much lower heat generation thus increasing comfort or decreasing air conditioning costs.
  • Completely modular and all components are replaceable.
  • Local manufacture – future replacement / repair is thus easy.
  • No warm-up time required like the old HID lights.
  • Up to 80% light output maintenance after 40 000 hours operation.
  • Immediate light, no 10 minute heat up and cool down, that cuts down production time.
  • Good power factor of at least 0.92.
  • Change Hi-Bay light with telescopic stick without scaffolding or switching off the power.


The idea of the retrofit is the following:

  • The old power supply and starter be removed.
  • The new power supply be installed in the same compartment.
  • The old globe be unscrewed and the new screw in type LED light be screwed into the existing socket.

Where possible the power supply to the light should be switched off when doing the retrofit. In cases where this is not possible, the retrofit can be done while the supply remain switched on. This would require extra retrofit costs as live LV work will have to be performed by an appropriately certified electrician.

Maintenance / Failures procedures

The maintenance on the light is very simple:

In very heavily dusted / polluted environment:

  • The LED can be wiped with a cloth.
  • The fan can be wiped clean of any dirt.
  • The cooling fins can be blown clean of any collected dust.

If the light goes off or dims:

  • This could indicate a problem with the power supply or the LED.
  • Change the light with a spare one.  If the problem is solved – replace.
  • If the light remains off / dim, return the old light and change the power supply and replace.

Light intensity

The Elexpert LED lights comes in various options to meet different lighting needs.  They have been developed to meet different customer needs in different ways as cost effectively as possible.  The following options are compared below:

  • Sodium Vapour (400 + 20 Watt) at 220 Volt.
  • Metal halide (400 + 20 Watt) at 220 Volt.
  • CFL 85 Watt.
  • Elexpert LED light (50, 100 and 150 Watt).

This is done for high bays, low bays, bulk heads floodlights and streetlights.  The characteristics of fittings of different manufacturers differ significantly.  These comparisons are for illustrative purposes.

The comparative light spectrum for different lights are compared in the figure below for high bays with aluminium reflector:


The comparison below is for a Low bays.


The comparison below is for a Bulk head using 50 Watt LED light.


The comparison below is for a Streetlights.


The comparison below is for a Floodlights.


The table below shows the distance light attenuation for LED and HPS lights.


It is clear that the LED lights and HPS lights have a very similar distance light attenuation characteristic.  The comparative light output should thus remain comparable at the full range of distance from target area.

It is clear from these graphs that the LED lights can provide the similar light as the HPS and the Metal Halide lights with much lower power.


The bottom line is that each individual application need to be determined and the power output and light design be done to ensure the customer’s light needs are met.  The comparisons were done using 150 and 50 Watt LED options.  These can be adjusted to meet any specific need.

Daylight Harvesting

One of the innovative strategies being applied to save even more electricity, which is possible with LED lights is daylight harvesting.  Many buildings allow a lot of sunlight into the buildings.  On sunny days, the light output from the lights can thus be reduced to still sustain the required light output on the target areas.  Buildings are now also being equipped / retrofit with special skylights which produce even light from the outside into the building.

The Elexpert lights also offer this feature. This is provided on each light and thus don’t need any changes to the wiring in the building.  The extent of dimming to be applied needs to be customised per customer.  In general the dimming to be applied is as follows:


In other words the following can be said in this respect:

  • The change in light output will be relatively gradual as the extent of ambient light changes.
  • On an average sunny day the LED lights will only be using 20% of power if adequate light entry is allowed in the building.
  • It is considered important not to switch the lights off completely to ensure the atmosphere in the building is retained and not to have lights switch on and off all the time.
  • On a cloudy day, where the ambient light in the building is about 100 Lux, the Led lights will substitute with 75% power.
  • Because South Africa is such a sunny country with more than 90% of the days having ample ambient light, consideration could be given to even consider reducing the light requirement slightly below the ideal requirement for these few day, obviously still within safety standards. This strategy is supported by the customer perception as the experience of light in the building would be relative to the ambient light outside of the building.

The extent of dimming can be customised as per customer requirements.

Radiation characteristics

The radiation characteristics of the Osram LED without any reflector is shown below. It shows the very even reduction away from the centre


It shows the very even reduction away from the centre.

LED characteristics

The Osram LED’s: GW KALRB3.EM delivers close to 100 lumens per Watt at the point of power utilisation used.  Although this is not that much more than the current lights, there is very little waste as almost all the light is directed at the target area.

The table below shows the Efficiency comparison table. The forward current on the LED’s are 1Amp with a Voltage of 48V. So that means the Luminous flux is 5030lm.

At a temperature of 85 degrees, the Lumens per watt is 102 lm/Watt.  Due to the efficient cooling of the Elexpert LED’s the temperature would be retained far below the 85 degrees thus ensuring closer to 105 lm/Watt.



The prices have been set to reflect the payment terms with suppliers and the payment terms with customers.  Payment for the lights are therefore required as follows:

  • 30% of light price on placing the order.
  • 50% before delivering of lights to site.
  • Remainder 30 Days from day of completing the delivery /  installation.

Any extended payment terms will require change in price


The light contains the following separate parts namely:

  • The power supply.
  • The LED light unit.

All these units will carry a minimum 3 year exchange warrantee.  Additional warrantee periods can be provided in certain cases.  To facilitate this process customers will be provided with some additional units (charged) which can be exchanged by the customer.  The faulty units will then be replaced free of charge.  This will be on site within one month.  The cost of changing the light, power supply or backup unit will be for the account of the customer.

If any of the units fault after the warrantee period, the same process will apply except that a fee will be charged to collect / install / replace / repair the faulty components.  It is important to note that only the faulty components will be replaced and be charged for.

Life / Lumen maintenance

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


  • The Power supply – 10 years plus continuous.
  • The fan – 5 years plus continuous.
  • LED’s – <10% failure 50 000 h. (temp. dependant)

The LED’s are so mounted that it can easily be replaced. Therefore, when the LED goes faulty, only that has to be changed.

The Lumen maintenance projection of the Osram LED’s: GW KALRB3.EM is shown in the figure below.  The Elexpert design ensures  the following surface temperatures:

  • In the open mode (hi-bay and low-bay) will be not more than 10ºC above ambient thus less than 55°C in most cases.
  • In closed mode 50 Watt (Bulk Head, Streetlight, Floodlight) will be not more than 20°C above ambient thus less than 65°

In closed mode 100 Watt (Bulk Head, Streetlight, Floodlight) will be not more than 40°C  above ambient thus less than 85°C


This shows the following:

  • Open mode: Expected 80% of the light output should be maintained after more than 5 years of continuous operation or 20 years for 8 hours per day, 5 days per week.
  • Closed mode 50 Watt: Expected 75% of the light output should be maintained after more than 5 years of continuous operation or 20 years for 8 hours per day, 5 days per week.
  • Closed mode 100 Watt: Expected 80% of the light output should be maintained after more than 10 years of operation for 8 hours per day, 5 days per week.

The Chromaticity maintenance over time is shown in the figure below.


Ultra violet (UV) radiation

UV rays are defined as those in the range between 10 nm and 400 nm.  The body and some biological processes (such as brewing of bear)  are subject to various different impacts from UV rays.  It is therefore a requirement that the amount of UV rays be known and be kept within acceptable limits.  The Figure below shows the light spectrum for the Osram LED’s used at the extreme light spectrum levels namely 6500 and 2700 K.


It is clear from this that the amount of UV rays from the Elexpert LED’s are almost negligible and suitable for all applications involving human beings and biological processes.

The graph below shows the Light spectrum of a Metal Halide lamp.  This shows a significant amount of UV light output.  The Elexpert LED lights is thus a much safer option in this respect.


Power Factor

The following should be noted in terms of power factor for the new LED installation:

  • The power factor of the new LED with its power supply is better than 0.92.
  • The power factor of a new Sodium Vapour light is close to 0.6.
  • When the power supply of the Sodium Vapour lights become faulty, the power factor could be even worse.

Because the power consumption of the new LED’s is so small compared with the existing lights, the total vars consumption would always be less as illustrated below.


This clearly shows that the total amount of vars are reduced significantly even if the new power supplies become faulty.  The important factor here however is the fact that the Total Power in kVA is increased drastically because of the bad power factor of the existing HPS lights.  This has a major impact on the bill because large customers are charged for kVA not kW.  This impact is included in the return calculations.

Electricity Savings

To calculate the electricity savings it is important to first understand the impact that the installation of the new LED lights will have on the electricity bills of customers.  The following should be noted in this respect:

  • The prices for customers differ all over South Africa.
  • Eskom’s prices for large and industrial customers are generally the lowest in RSA.
  • Different tariff structures are offered namely:
    • Maximum demand tariffs with demand / access charges. These will charge for:
      • the maximum demand taken in each month / year
      • and will also penalise for a bad power factor
    • Single or 2 seasonal energy charges.
    • Or Time of use energy charges.
    • Reactive energy charges.

The impact for every customer will be different and therefore a study has to be done for each customer individually.  The impact that has to be determined is the following:

  • To what extent is the energy reduced.
    • This has to be done for kWh per the relevant period in the case of TOU and seasonal tariffs.
    • The extent that the reactive energy charge (c/kvarh) is reduced.
  • The extent that the maximum demand is reduced.

For the examples the following has been assumed:

  • For the 24 hour operation the price would reflect all the charges as for a 100% load factor customer. This was calculated at a typical municipal large customer tariff at 400V.
  • For the 9 hour per day 22 days per month operation it was assumed that the full demand would impact the saving in maximum demand because the times that the lights operate would co-inside with the operation of the business. (This would not necessarily be the same for security lights burning at night only.)
  • The impact on the reactive power is neglected because it is small.
  • The impact of the Eskom standard product incentive has been included.

The financial break even were analysed for four options using the City Power TOU tariff:

  • Option 1.  24 hour operation 30.4 days per month.
  • Option 2.  12 hour (Day) operation  30.4 days per month.
  • Option 3.  9 hour operation 22 days per month.
  • Option 4. 12 hour (Night) operation 30.4 days per month.

The average energy price firstly need to be calculated.  This is done by first determining the ratio of usage during the various TOU periods as shown below.


The key assumptions relating to each option is shown below.


The annual NPV’s for 24 h operation for 30.5 days per month are shown in the table below.


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


It is thus clear that the various options break even as follows:


Option 1.  24 hour operation 30.4 days per month. – 7 months.

Option 2.  10 hour (Day) operation  30.4 days per month. – 14 months

Option 3.  8 hour operation 22 days per month. – 20 months


Provision has been made to replace 20% of the OSRAM within the 10 years.  In all cases the expected NPV over 10 years exceeds R10 000.  This is excellent considering all the environmental advantages and the small investment required.

Tax Incentives

Government has made available a tax incentive for energy savings.  This equals 99 c/kWh saved.  It only offers potential for very bigger projects.  The constraints are as follows:

  • It is only applicable for savings in a particular financial year.
  • The measurement and verification cost is from R20 000 per site.

For 8 hour operation this equals to almost 8 kW of savings which is equivalent to 26 hi-bays.


The new Retrofit LED lights provides the first real alternative to the high output HID lights used extensively in South Africa.  It reduces electricity consumption by about 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.

Why change

The main drive for the installation of the new more efficient LED high bay lights are as follows:

  • Savings in electricity:
    • Lower usage of the LED light compared with other lights.
    • Lower usage on air-conditioning where applied.
  • The ability to switch on and off in very short periods compared with Sodium Vapour / Nickel Halide.
  • The backup supply features during power failures / interruptions from utility.
  • The retrofit design means simpler replacement, cutting down on electrician bills

The new LED light with its power supply will use about 30% 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.