power factor measurement for single phase supply at any power point ?

Hi, is it possible to measure power factor on the single phase supply at any single power point ? I need to make a simple PF electronic circuit with capacitor to save energy on my house by 24 hours without worried about over compensated which may cost my electricity bill more. I use less energy at home during daytime and more on the night time but using single capacitor would sometime over compensated during day time since it is not regulated automatically. My house is 240V, single phase with 30A suppy, during day time using 6 A and nigth time using 15A. How many microfarad needed ???