How can I get a stacked bar with single values and sum on the side

So this one is a bit tricky to solve from the doc's nodes near coords align in combination with visualization depends on should have been the silver bullet. Weirdly it fails.

Instead one must combine visualization depends on with every node near coord/.append style as a work around.

One must also include their data inline, as explained by @Symbol1, to prevent errors.

Package PGF Math Error: Unknown function `thisrow_unavailable_load_table_directly' (in 'thisrow_unavailable_load_table_directly')

I also had to restructure the data into a table form. I supposed one could have used meta tags with the original coordinate data but I haven't tried this.

documentclass[tikz,border=10pt]{standalone}
usepackage{pgfplots,pgfplotstable}
pgfplotsset{compat=1.12}

begin{document}
  begin{tikzpicture}
    pgfplotsset{
        show sum on top/.style={
            /pgfplots/scatter/@post marker code/.append code={%
                node[
                at={(normalized axis cs:%
                    pgfkeysvalueof{/data point/x},%
                    pgfkeysvalueof{/data point/y})%
                },
                anchor=south,
                ]
                {pgfmathprintnumber{pgfkeysvalueof{/data point/y}}};
            },
        },
    }

    begin{axis}[ybar stacked,
        nodes near coords,
        title={Energy spent},
        xtick={0,...,4},
        bar width=25pt,
        ymin=0,
        enlarge x limits=0.125,
        ylabel = Energy (J),
        legend entries={A,
            B,
            C,
            D},
        legend pos=outer north east,
    ]

    addplot+[visualization depends on={value thisrow{Ax} as xdelta},
              visualization depends on={value thisrow{Ay} as ydelta},
              every node near coord/.append style={xshift=xdelta,yshift=ydelta}] table [x={x}, y={A}] {
      x A      Ax Ay 
      0 0      0  0  
      1 0      0  0  
      2 20.544 0  0  
      3 21.192 0  0  
    };
    addplot+[visualization depends on={value thisrow{Bx} as xdelta},
              visualization depends on={value thisrow{By} as ydelta},
              every node near coord/.append style={xshift=xdelta,yshift=ydelta}] 
     table [x={x}, y={B}] {
      x B     Bx By    
      0 0     0  0     
      1 0     0  0     
      2 9.610 0  0   
      3 9.681 0  0     
    };
    addplot+[visualization depends on={value thisrow{Cx} as xdelta},
              visualization depends on={value thisrow{Cy} as ydelta},
              every node near coord/.append style={xshift=xdelta,yshift=ydelta}] 
     table [x={x}, y={C}] {
      x C      Cx  Cy 
      0 0.505  25  5  
      1 12.505 0   0  
      2 0.247  -25 -10  
      3 1.975  -25 -10  
    };
    addplot+[visualization depends on={value thisrow{Dx} as xdelta},
              visualization depends on={value thisrow{Dy} as ydelta},
              every node near coord/.append style={xshift=xdelta,yshift=ydelta},
              show sum on top] 
     table [x={x}, y={D}] {
      x D      Dx  Dy
      0 3.772  0   0 
      1 1.075 -25  0 
      2 0.439 -25  0
      3 2.066 -25  0
    };

    end{axis}
  end{tikzpicture}
 end{document}

Note pgfplots has sensible enough defaults so I inserted the + between addplot and the options [] hence the colours differ slightly.