Paul you need to put mathematical signs on things to clarify what they are doing. Solar is positive because it additive, coal is negative because it is subtractive.
A small positive result is infinitely better than any negative result, because of the energy polarity multipliers which apply in each case (the subject of my first book!). It's why we can't carry on mixing them up, there is no halfway house, no "Net zero", the outcome is either all negative or all positive.