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Various small off-grid PV systems, also referred to SHS (Solar Home Systems) have been supplied country wide. These systems are typically based on small high efficiency lithium ion batteries as storage solution and Victron components such as solar charge regulator, inverter and monitoring devices.

Based on our excellent service and knowledge we have rendered to the Botswana Meteorological Department as well as University of Hamburg, CTS was able to secure the 2nd Phase of the manufacture, supply and installation of automatic weather stations in Botswana.

The stations supplied to make use of satellite communication due to the extreme remoteness of the sites, these were:

• Mababe (Savuti Marsh)
• Tubu (Okavango)
• Baines Drift (Eastern Botswana)
• Xade (Central Kalahari Game Park)
• Ngwaltle (Western Botswana)

These stations are not located at any Meteorological Department property, thus fences had to be erected for protection against animals.

Station design is based on our well proven tripod mast with all relevant sensors and a CR1000 logger as the processing unit. Data is transmitted at fixed timeslots allocated by EUMETSAT (Germany) on an hourly basis. Satellite transmission is based on a fire and forget principle, thus no remote maintenance can be done.

Weather data can be found at: http://www.sasscalweathernet.org .

An existing off-grid solar PV system was expanded to a total of 4,44kW on the farm Ombirisu north of Okahandja and the battery was upgraded to a Lithium-ion technology.

Final System Specifications:

• 6 x 295W Canadian Solar have been added to an existing PV array to deliver a final capacity of 4,44kW
• Replacing old charge regulators with 3 x Victron MPPT 150/70
• Replace old battery with 1 x BlueNova Lithium-ion battery 24V-24kWh
• Pole mounted solar array
• Online connection with remote access

After successful completion of the Omusati off grid electrification project, CTS was successful in winning the bid for the second phase of containerized PV solutions for the Kunene region. With the experience gained from phase 1, the containers were optimized in many ways. The final design consisted custom build 20ft container by Namspace in Swakopmund.

Sites that were electrified in the Kunene region are:

• Otjitjekua School
• Otjiu School
• Otjiu Hostel
• Epupa School

The project included the following:

• Upgrading of all government building wiring as per national standard for 4 sites in the Kunene region:
• Manufacture, supply and install container power units for these sites.

The power containers consisted of ca 2.8kW of PV modules installed on the roof as well as 4,500 Ah of battery capacity. Five kVA inverter charger and two 70A BlueSolar Charge regulator all from Victron Energy complete the system. Remote monitoring of all sites is achieved by using the Victron Color Control GX unit.

National Botanical Research institute approached CTS to upgrade two of their existing AWS to satellite communication and subsequent installation at Kanovlei in the Tsumkwe Area as well as Koichab Pan close to Lüderitz.

Communication is via Meteosat satellites and based on a “fire and forget” principal which unfortunately does not allow remote maintenance procedures.

The stations form part of the SASSCAL Weathernet and measure all important meteorological parameters.

Weather data can be viewed at: www.sasscalweathernet.org 

Central Technical Supplies (Pty) Ltd. – Geiger Engineering (CTS) was approached by Farmers Meat Market Mariental to design, supply and install a solar water heating system with the aim to reduce the monthly diesel consumption as two diesel boilers are operated to heat water up to 82 deg. C for production purposes.

The water requirements of the abattoir are as follows:

1. 2,000 liter/hour @ 45 C°
2. 3,000 liter/hour @ 60 C°
3. 500 liter/hour @ 82 C°

This adds up to a total daily water requirement at 60 deg. C of roughly 25,000 liter.

The system is design such as to preheat water from 18 deg. C to between 50 deg. C and 60 deg. C before supplying the diesel boiler system, thus reducing runtime and diesel consumption of the diesel boilers. A 20,000L stainless steel tank (non pressure tank) manufactured locally according to CTS design, acts as the buffer tank for the daily water requirement. A total of 120 flat plate collectors supplied by Solsquare Namibia with a total surface area of 300 m2 are connected by means of a 450kW Alfa Laval flat plate heat exchanger to the water tank.

A set of two Calpeda circulation pumps connected to Danfoss variable speed drives and a timer circuit guarantees at all times that the heat from the collectors is effectively transported to the water tank. Flow as well as temperature monitoring on all four ports of the heat exchanger make it possible to determine the instantaneous as well as accumulated kWh produced from the collector field.

Furthermore additional heating energy is obtained from the ammonia refrigeration plant. A heat exchanger is installed on the ammonia discharge side before the existing cooling towers to be able to heat the water during night time as well, as this is the time when the refrigeration plant runs at full capacity to cool down the newly slaughtered meat in the cold rooms. Again flow control and temperature monitoring on the hot water side of the heat exchanger accurately indicate heating energy obtained from the refrigeration plant.
A total of four pump sets have been installed and pumps are cycled on a 24 hour basis in automatic mode. Should at any given time a pump fail, the system can be switched to manual mode to be able to repair the pump without system down time and a resulting increase in diesel consumption.

All systems components are sized such as to allow for future heating capacity upgrades should it be required.

After a year of operation, the plant is performing better than expected and the client is able to safe nearly N$ 60,000 per month on diesel costs, bringing the payback period of the entire system down to below two years. This clearly shows that solar energy, be it for heating or for electricity production, surely is the way forward for a cleaner and greener future for generations to come. CTS is proud to be part of making Namibia and the world a better place for our grandchildren to live in.