DOORNHOEK
Solar Farm Cellular Coverage
—– Goal —–
The task required from SDE: cellular coverage over the solar farm for communication with office personell, workers as well as security patrolling aprox 10km perimeter.
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What is this project about?
Situated around 11km outside Klerksdorp, this new 120MW solar addition to South Africa’s electricity provider, Eskom, is on the verge of handover in May 2026.
There will be personnel working over this vast area who require communication via mobile or PTT 4G radios, as well as office personnel with 4G/LTE data requirements.
The closest base stations (BTS) are Brackspruit which is roughly 6km from the solar site.
The high powered Amplitec system recommended by our RF engineer was the 43dBm “20 watts” O43J fibre optic tri-band repeater.
Using 1 of possible 4 x RU’s (radio units) each capable of 2-2.5 km radius.
The MU is installed where the signal is received which can be up to 15 kilometres from the RU using fibre cable. The RU is the coverage unit.
The O43J is a tri-band repeater which in the case of Doornhoek amplifies B8 the “900MHz”, B3 the “1800MHz” and B1 which is the “2100MHz” spectrum.
A full house OMT “onboard monitoring terminal is available with all Amplitec high powered cell extenders.
The settings are accessed on site using a usb cable via a pc with software, to adjust and read all the parameters of the repeater and to monitor them.
With the OMT installed these setting and readings can be done wirelessly from anywhere offsite via the built-in router with a sim card.
Amplitec engineers are always available to assist via the OMT’s option for set-up, guidance & advice. Monitoring and adjustments can henceforth be done from anywhere offsite.
SDE has the privileged assistance of a South African based RF engineer with years of experience working for CSNR and network operators to consult and make presentations.
High-Performance RU Coverage & Fibre-Connected Cellular Repeater Deployment
The RU, when its parameters are set up correctly is capable of good coverage through a high gain broadband omni directional antenna or a set of sector antennas.
More RU’s can be used for larger coverage in or outdoors – obviously fibre optic cable trenching must be considered. An alternative is to use overhead fibre cables as used in established suburban areas on farms, lodges, mines and large production areas such as vehicle manufacturing plants. Small towns that are in valleys or behind ridges, hidden from base stations can benefit. Indoors, existing fibre can be used.
Most cellular repeaters have AGC protection. If the MU is a good distance from the RU, the horizontal separation acts as isolation. This can be 600m -15km. Any structure in between acts as added isolation. If ideal isolation can not be achieved, an isolation grid can made from welded mesh with 13mmx13mm apertures and used to great effect when installed between the MU antenna and the RU antenna.
The choice donor antenna used is the SDE ultra reliable and study 25dBi grid with a wide band range of 698MHz to 6000MHz affording coverage to all the bands made available in South Africa and abroad.
Brakspruit BTS Services
The Brakspruit BTS can provide the
following MNO (mobile network operator) services :
MTN-SA 4G 1800
SA 03 4G 1800
CellC 4G 1800
SA 08 4G 900
MTN-SA 2G 900
V/C 2G 900
V/C SA 2G 900
SA 03 3G 1800
SA 05 3G 1800
TELKOMSA 3G 1800
MTN-SA 3G 1800
Brakspruit MTN BTS on the left and Vodacom on the right
On-Site Challenges
To establish reliable coverage at Doornhoek Solar Farm requires more than software planning alone. While LoS routing tools help predict signal performance, real on-site surveys often reveal challenges that software cannot detect.
Terrain, solar infrastructure, reflections, and remote site conditions can all affect signal strength and network reliability. Physical testing helps identify dead zones, interference, and connectivity issues that may impact operations, SCADA systems, security, and remote monitoring.
Proper planning and on-site testing are essential to ensure stable and effective cellular coverage across the facility.
Software Challenges
Another aspect that software often does not take into account is natural environmental changes over time. For example, trees along the communication path may have grown more than 20 meters over the past 10 years, creating new obstructions that were not present when the original network planning was done.
These changes can significantly impact signal strength, Line-of-Sight (LoS) performance, and overall Doornhoek Solar Farm cellular coverage, making physical on-site surveys essential for accurate network design and reliable connectivity.
Real-World Site Challenges Beyond Software Planning
On site there is constant change, and conditions can vary significantly from day to day. Teams have to contend with rain, mud, difficult terrain, and strict Health and Safety requirements while working within an active solar farm environment. Due to safety regulations, only approved contractors are permitted to work at height on the terrain.
As a result, all work involving scaffolding and elevated installations must be carried out by these certified contractors under close supervision to ensure compliance and safe working procedures at all times.
Another challenge that is not always obvious during planning is the density of surrounding vegetation. From ground level, the true thickness and impact of the trees may not appear significant. However, once positioned on the scaffolding and looking directly towards the BTS over the donor antenna, the extent of the obstruction becomes much clearer. Tree growth and dense vegetation can have a major effect on signal strength, Line-of-Sight performance, and overall cellular coverage reliability.
Before the trees were cut
After 96 trees were cut.
BTS seen in the distance
The Main Unit, trenching to the enclosure and the solar powered installation.
The entrance and offices give indication as to the enormaty of the site, even though this a one of the smaller solar farms.
RU Radio Unit & the mast – the installation – the ventilated enclosure – coax cabling & fibre
O43J B1,B3,B8
Fiber Optic repeater
Trenching and storm water
run-off
Fiber switches and data points
COVERAGE TEST POINTS ALONG THE PERIMETER AND AT OFFICES, MU & RU AMPLIFIERS - IN YELLOW.
The RSSI or “received signal strength indication” on GSM 900 was measured at the MU mast @ TP11:44. The measurements were taken at this point after trees were removed to establish LoS to the BTS.
Once the tri-band system was switched on, the RU‘s coverage at the centre of the farm greatly improved.
Measurements taken across the farm not only improved drastically but LTE on other networks on the MTN-SA & Vodacom-SA shared BTS’s were at excellent levels for communications across the farm and perimeters.
MU master unit below after amplification. RU radio unit to the right after amplification
Goal achieved and surpassed: Coverage over the whole solar farm with coverage over the farm house.
