r=0.05;

A=(((((1+r))^(40 ))*r)/((((1+r))^(40 ))-1));

a10=(((((1+r))^(10 ))*r)/((((1+r))^(10 ))-1));
a20=(((((1+r))^(20 ))*r)/((((1+r))^(20 ))-1));

CenaDC=(3621.32*vt+1571.71*nt+9227.16+min1);

rcf=180000*a10+150000*a20+24885*A+40000;
vt=0.75*el1;
nt=el1-vt;

min1=Min[30754.08, (el1)*495];

30754.08/495;

d1=Plot[{(((3621.32*vt+1571.71*nt+9227.16+(el1)*495)+rcf)/(el1*1000))},{el1,0.01,30754.08/495}, AxesOrigin->{0,0}, Filling->None, PlotStyle->{Magenta} , GridLines->Automatic, PlotRange->{0,20},AxesLabel->{"Dodaná energie [MWh]","Náklad na 1 kWh [Kč/kWh]"},PlotLabel->"Závislost ceny 1 kWh na dodané energii DC nabíječkou"];

d2=Plot[{(((3621.32*vt+1571.71*nt+9227.16+30754.08)+rcf)/(el1*1000))},{el1,30754.08/495,100}, AxesOrigin->{0,0}, Filling->None, PlotStyle->{Blue}, AxesLabel->{"Dodaná energie [MWh]","Náklad na 1 kWh [Kč/kWh]"}, PlotLabel->"Závislost ceny 1 kWh na energii dodané DC nabíječkou", GridLines->Automatic, PlotRange->{0,20}];

Show[d1,d2, PlotRange->{0,20}]