04/02/2021

Nearly every time I investigate remote area power supplies for low income areas, the power supply is either unreliable or has failed.  Typically in remote areas, renewable energy is used as the source.  Even in non remote areas, the cost of grid connection can be prohibitive for a low income population.

But due to the often variable nature of the energy supply, batteries are used to store the energy for times of shortage of supply.  But batteries wear out.  Unless the user is actively using the electricity to earn enough, usually they will never be able to afford to replace the batteries.  They often needing replacement after 2-3 years.  The batteries also form about 50% of the total cost of a photovoltaic system.

Earning incomes happens mostly during the daytime, which is when solar power is most available.  Many remote and low income communities are in very sunny climates, hence they could potentially earn an income without battery energy storage, which makes the whole system much cheaper and more reliable.  Without a battery, the amount of power available does vary widely, so the problem is to stabilise the electricity so that it is useful, how to use excess power whenever available, and what to do when the load is greater than the power available.


Because hot water is always needed, whenever there is spare power, it is fed to a power controlled, water heater.  The other loads connected all have different levels of priorities.  So as the amount of power available reduces, at first the water heater gets reduced power until it is off, then the loads get switched off, starting from the lowest priority loads.  For example, the lowest priority load may be a battery lamp, as it does not need to be charging all the time.  This concept has been developed by postgraduate student, Edwin Ribisi, and myself for which we have been granted a South African patent (2019/04750).  I am most grateful to the Ms Mante Kgaria and the NMU Innovation Office for their efforts in this regard, and, also to the Dept. of Physics; Professors Ernest van Dyk and Freddie Vorster for allowing us to use some space in their Outdoor Research Centre for this work, and assistance from Dr Ross Schultz.

An angle grinder powered from the batteryless photovoltaic system cutting steel.

Edwin Ribisi

Prof Peter Freere

Contact information
Prof. Peter Freere
Associate Prof.
Tel: 27 41 504 3577
peter.freere@mandela.ac.za