As you have 3 bar static pressure, an accumulator should be suitable. Only where your static pressure is very low is the extra expense of a pump required.
I'm not a plumber or expert btw - this is just what I picked up from reading around when considering an accumulator myself. Also keep in mind that an accumulator can only be filled to roughly half of it's capacity (there's a formula available if you do a search - i posted it a few months ago). This means a 500L accumulator will only contain around 250L (usually less) water, and the rest will be air.