> the net result that it became cheaper to buy the power company supplied electricity than from your own solar.

I'm sure this is the way you remember it, and maybe even the way it was explained in that article but if you bought a solar panel the sunlight to power it is free, so your electricity from the panel is free. You're not "buying" that power and so the commercial supply can't be "cheaper".

Now if I've paid $5000 for a product which makes me electricity for free and then later you offer me the same amount of electricity for just $4000 you could say yours is cheaper, but, er, I already bought that $5000 product, I'm already out $5000 and my electricity is free, yours is not actually cheaper now. What we're seeing here is just "Did you know solar panels have become cheaper over time?"