Renewable sources suffer from intermittency and variability in time and amount of power, causing problems of integration with the grid. Field experience in deregulated systems has occasionally shown that increase of renewable injections such as wind, solar etc. to the main grid depresses voltages at the point of interconnection. We pose the question: is it possible to analytically predict such behaviour at the planning stage? Conventional analytical techniques (load flow) do not seem to address this issue effectively. Bus classification of renewable generators and apriori specification of their voltages are difficult, and at times impossible. Conventional load flow techniques therefore fail to analytically construct future scenarios. We show that the behaviour mentioned above can indeed be predicted and online scenarios constructed with Modular Load Flow — a new load flow method reported in the recent past. With Modular Load Flow, time varying power flows and voltages can be calculated with time varying injections. We hope these studies to be useful in planning integration of renewables. To the best of authors' knowledge such ‘tracking load flow’ has not been reported earlier. A field experience has been explained analytically.