solo mining and low work utility output in miners

[nixifo]

Hello,
I am solo mining and I am unsure about my work utility output.
With every new reading it is getting lower constantly, for 5-10 min and then increases quickly sometimes to about my hashrate and this is repeated over and over.
So almost always it is way lower than my hashrate even at 1/3.
This happens with cgminer sgminer and all I have tried.
I know that with pool mining WU is best to be near your hashrate.
With solo mining is different?
Thanks