Recently i was reading  a paper entitled "Weighted efficiency oriented design methodology of flyback inverter for AC photo-voltaic modules". The word weighted efficiency was new for me so i searched about it. Here is what i found about it

• Weighted efficiency is a term used for European efficiency and Californian efficiency formulas. The California efficiency formula is given below
• η_cec = 0.04 η_10%load +0.05 _η20%load +0.12 _η30%load + 0.21 η_50%load + 0.53 η_75%load + 0.05 η_100%load 
• As seen in the above formula the efficiency is not measured as peak value but different values are obtained to calculate the efficiency.
• The above formula is a weighted efficiency and hence the term implies to the California efficiency formula.