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Central Technical Supplies was once again awarded the tender to electrify 4 remote localities in the Otjozondjupa Region of Namibia. Custom build containers where installed on site with SMA Sunny Island 8.0 inverter installed. In addition the offered lead acid battery technology has been replaced by state of the art lithium batteries reducing system maintenance. The use of AC coupled technology did allow for the SunnyBoy solar inverter to be in installed inside relevant buildings on which PV modules are mounted. All components are interlinked by means of wireless technology to allow for remote monitoring where GSM signal is of sufficient strength. System sizes vary form 3kW, 12kW, 15kW to 20kW of PV power while inverters are as much as 3 in a single phase cluster.

Sites that were electrified are:

• Nhoma
• Aasvoel Nes
• Kanovlei
• Grashoek

A 7,3 kWp off-grid PV system was installed at the farm Heinrichsfelde in the Aus area with a Lithium-ion battery. The system is able to power an entire farmhouse. Remote monitorng and supervision is included.

System Specifications are:

• 24 x 305W Renesola PV modules
• 2x Victron MPPT 150/85
• 1x Victron Quattro 48/10000
• 1x BlueNova Lithium-ion battery 48V-24kWh
• Roof mounted with structure for IBR roof sheeting
• AC surge and lightning protection

This is a typical photovoltaic (PV) medium scale farm system found on many farms around Namibia. Over the past three years this system grew in PV size from 350Wpeak to ~1200Wpeak.

System specs are:

• PV modules with a total capacity of 1220Wpeak
• 1200VA, 24V Inverter charger
• 40A Solar Charge Regulator
• 360Ah battery bank@24V
• Battery Monitor showing: state of charge (%), charging/discharging current (A), Battery Voltage (V) and time to go (h)
• Switchgear for submersible pump control

The PV modules are mounted on frames facing true north for optimal energy harvesting. During times of limited sunshine, especially the rainy season, battery charging can be increased by starting the generator. Should the AC load increase behind the inverter rating, the generator can support the system to cater for the increased load. No automatic generator start function is included.

Furthermore a second PV system for the Farm workers has been installed to cater for lighting and a TV.

• 2x 90Wpeak PV modules
• 20A Solar Charge Regulator
• 2x 105Ah batteries
• 350VA, 12V inverter

CTS was awarded the tender to install a water heating system for the Hilton Hotel Windhoek.

The system was installed according to the following specifications:

•    2x 250kW gas fired hot water boiler

•    2x 6800 liter hot water storage tank (also known as calorifier)

•    1x Danfoss Aqua drive 11kW for glycol circulation pump control

•    2x Automatic bypass valves to control water temperature inside tank

•    4x Hot water circulation pumps

The boilers as well as glycol circulation pumps and one hot water storage tank were installed in the boiler room located in the upper basement of the hotel. The second hot water storage tank is installed on the 9th floor of the Hilton Hotel. A glycol circulation system connects the two calorifier with the two gas fired hot water boilers. The glycol circulation pumps are controlled from one Danfoss Aqua drive with cascading functionality to control the pumping speed depending on the temperature in the glycol line.

Each hot water boiler is cycled on a 24 hour basis, should the glycol temperature fall below a predetermined threshold for certain period of time the second boiler will start automatically.

Automatic bypass valves guarantee that the water temperature of each calorifier is kept at a constant 60 – 65 degrees Celsius.

Central Technical Supplies was approached by the University of Stellenbosch to take part in a tender to supply a solar resource measurement station to the Namibia University of Science and Technology in Windhoek.

We were successful in winning the tender. The station is based on the Kipp and Zonen Solys 2 sun tracker with CMP 10 Pyranometer and CHP1 Pyrheliometer.

The station is based on the CR1000 logger from Campbell Scientific and measures wind speed and direction as well as ambient temperature, humidity and rain in addition to the solar resource data.

CTS removed old and obsolete laundry equipment and installed new machines.

The installed equipment consisted of:

1. 2 x new Primus FS40 high speed washer extractors
2. 2 x Maytag energy saving tumble dryers
3. 1 x Miele through-feed drying ironers
4. inculding laundry trolleys, ironing trolleys and other small accessories