150kw is getting into 3-phase territory but still very practical for single phase service. It comes down to cost of the panel (size and amount of copper in it) and if the power company needs to supply you with a different service transformer to feed the building. As Mikey said, go with what is cheaper.
Is drawing 150kw on a single phase an issue for the TDU since it is extremely unbalanced on the transmission lines, right?
I assume that "TDU" is your utility supplying power to the building?
If so, yes and no. Yes it is a load on only 1-phase of their (usually 3-phase) transmission lines BUT it is THEIR job to monitor the lines and divvy up the loads on them between you and other customers so no it is not really an issue for them.
Would they prefer a 3-phase load? Sure, but it should make no difference in what you pay.