With the escalating costs of grid supplied electricity becoming a reality in South Africa we are often asked about using solar energy as a source of power for water pumping systems. The truth is that solar energy systems remain a costly capital investment and when compared against the current grid supplied electricity tariffs, it remains largely unfeasible to switch to using solar. Other factors such as the limited daily pumping time when using solar can also lead to increased overall system infrastructure costs when comparing against 24 hour daily available pumping time that grid power supply has to offer. Solar powered water pumping does however have its place typically on projects where the capital outlay for grid supply infrastructure is too costly. Inevitably solar will become more competitive as grid supply electricity tariffs increase.
As a serious roll player in the irrigation water pumping control sector, we at Irri-Gator decided to invest in suitable solar photo voltaic (PV) equipment that would allow us to carry out extensive testing of our variable speed drive ranges using solar energy as a source of power. We installed a 5 kW solar PV system on the roof of our Brackenfell premises which was split into two arrays allowing us to provide a voltage and power source to test conventional 230 VAC and 400 VAC single and three phase variable speed drives. The DC power source from the solar PV system is applied directly to the DC bus on our conventional AC variable speed drives which in turn are powering stock standard 230 VAC single phase or 230 and 400 VAC three phase motors. We went a stage further and develop an in house Maximum Power Point Tracking (MPPT) controller to automatically regulate the speed of the motors based on the available solar irradiance at any given time during the day.A further article in an upcoming edition will cover an explanation on this product.
We can categorically report that our product range performs well above expectation and we will be announcing our intentions to offer complete turn key (supply and installation) solar power VSD solutions to our clients in the very near future.