without the controller fluctuations in wind power outputs caused stability issues resulting in the occasional need for turning off the wind turbines thereby increasing fuel consumption in combination with powerstore grid stabilisation system the mgc was able to manage the hybrid energy system delivering a increase in energy yield by maximising renewable energy penetration abb the mw project has an estimated payback period of years similarly the success of the solar pv plant at cronimet s thabazimbi mine in south africa with its payback period of less than four years is attributed aside from financial factors to the use of a programmable logic control plc system that helps achieve the solar penetration ratio of boyse et al