Unfortunately, being your site is in a different language I can't help too much as content has a lot to do with how a site is perceived as well.
Two things I did notice...
=> Copyright notice states 2014.
=> Featured images on the homepage are redundant and fuzzy. Others don't seem to be sized for that space. It is recommended to have unique images that apply specifically for each post and to make sure that the size/orientation fits where they will be used.
I also ran a quick performance test and there is some work to do.
@Kamelalhomsi It was not bad. I had to translate it, but one thing I did find out, that only people involved with Electricity would understand that.I like that fact that you do direct them to You Tube.