Feasibility Study for 11.6MW Solar PV Plants

This study was conducted as part of a due diligence exercise for a client who was interested in investing in 3 separate projects spread across SA, and developed for the Small Scale IPP bid round. Grey Green completed a high-level concept design and costing exercise as part of this feasibility study in order to enable our client to determine whether the project was feasible, both in terms of the total EPCM costs as well as the long term returns from the PV plant’s generation over its 25 year lifespan. This project was completed with the assistance of our Spanish partner DISEPROSA.

Energy Efficient LEDs for Vector Logistics Cold Rooms

LED lights are a very good choice for cold room warehouses. After a very rigorous trial phase, Rick du Toit, regional plant engineer at Vector Logistics in Cape Town, decided on a LED light supplied locally by Lighting Revolution. The trial period involved testing different strength lamps with a various range of reflectors.

The light that was finally chosen was a 130W tunnel lamp, made up of two chips with separate cone reflectors at 120 degrees. These lights give a very even spread of light for warehouses with high ceilings of up to 13 meters.

The project was managed by Grey Green (as the ESCo), who made use of the Eskom Standard Offer Rebate Programme.  The project has been completed and the post assessment report has been published by the independent ESKOM appointed Monitoring and Verification team (M&V).

A summary of the changes that took place is given below:

  • 130 x LED Tunnel lamps were installed (130W each including electronic driver)
  • The lights are replacing 107 x 400W metal halide lamps (low bay fittings) and 23 x 1000W halogen wedge lamps
  • 27 of these lights are in areas where the ceiling height is 5 meters or less
  • 103 are in areas where the ceiling heights are between 11 – 13 meters high
  • Approximately half the lights are in cold rooms at between -4 and -6°C, the other half are in -25°C freezer rooms

Part of the project involved trialling the lights extensively, including switching tests as well as testing the lamp in the freezer rooms, which is the more severe operating climate. Based on the trial results the project went ahead using the tunnel lamp fitting from Lighting Revolution. The implementation was not without its challenges because of working in freezing room temperatures, but the installation team (FLASH Electrical) rose to the occasion. All battery operated equipment (lifting devices, drills and flash light) used needed to be warmed intermittently in order for it to operate correctly. This led to slight delays in implementation schedule, but overall the project went extremely well.  The results, measured in terms of increased lux levels on the plant floor as well as substantial energy savings, were quite incredible.

The M&V baseline report revealed that the metal halide lights consume on average 400W and the halogens 1080W. This fact may seem obvious but depending on the type of ballast and site’s average voltage the rated power drawn by a light fitting can vary by up to 50W or 10%.  The average lux within the plant rooms was between 70 – 100 lux before the implementation (due to degradation of the lux levels as the lights age).

After the post assessment measurements it was revealed that the LEDs performed better than expected in the cold environment. The 130W rated fittings on average drew 126W. The additional savings can be attributed to the cold climate within the cold rooms which helps dissipate heat from the fittings which is a typical weakness of LED lights. The average lux levels post the implementation was 180 lux even in the areas with 13 metre high ceilings.

The lights will thus save 51kW, equivalent to 447MWh per annum. This at current tariffs is equivalent to R 360 000 per annum. The Eskom rebates for LED interventions on the SOP programme are 0.55 c/kWh saved during the SOP qualifying times. This has resulted in the rebate subsidizing approximately 45% of total project costs!

The LEDs have IEC certification, and come with 50 000 hour or 3 year warranty. The indirect benefit of the LED lights is that they also have far less ballast losses and because of their lower operating temperatures there will be less heat dissipated into the cold room which should in theory lead to a slight saving in refrigeration load.

The project has served to demonstrate that using the correct light for a particular environment can be very effective leading to increased lighting levels as well as cost savings.