On grid systems in Europe are regulated in the following way:
You produce energy when the conditions allow it and you feed the energy into the grid right-away. The energy company buys your energy at 1/3 or even 1/4 of the price you pay for the same energy from them. You don't use your energy, you are unable to.
This is because the EU is a shmuck and lets its people be bullied by the energy companies. You can never break even if you use on-grid systems. I guess in the US or other places, the rules are similar.
This is why I presented an off-grid system, it is the only one breaking even (currently in 7-10 years, dropping from 15 years a few years ago). Maybe in 5 or 10 more years the price of renewable systems like wind or solar will drop enough so that you can break even in under 3 years, which is what extended warranty can offer. This will make more people invest in it.