In this situation, are allowed to stop the vehicle on the hard shoulder?

In the photo you are driving along a road through a forest which bends to the left; the bend is marked with red and white guide boards, and the right-hand edge of the roadway is marked by solid edge line P-7b, beyond which there is a shoulder. You are not allowed to stop your vehicle on this shoulder. The answer is: no.

The Road Traffic Act prohibits stopping a vehicle on the roadway and on the shoulder next to a solid line marking the edge of the roadway, and the Regulation on road signs and signals states that marking P-7b "solid edge line" marks the edge of the roadway and also means that the driver of a motor vehicle is not allowed to drive onto the shoulder. A solid edge line is painted where driving onto the shoulder is dangerous - on bends, next to a soft or narrow shoulder, in places with limited visibility. A car standing on the shoulder after a bend would surprise approaching drivers, and a driver going around it would move into the opposite lane at a place where you cannot see what is coming from the opposite direction. If you have to stop, you drive on to a section with a broken line or to a lay-by.

Legal basis: Art. 49 para. 1 point 5 of the Road Traffic Act (Prawo o ruchu drogowym); § 86 para. 8 of the Regulation on road signs and signals