First of all, that equation is not correct, which may be the reason
that you're having trouble assigning units to the quantities.
Power is defined as [energy / time], so [Energy] = [ power x time ],
and
[Time] = [ energy / power ].
Unit-wise, these equations are correct just as they appear here,
with no proportionality constants or conversion factors, when ...
[ Power ] = watts
[ Energy ] = joules
[ Time ] = seconds .
