Again, the article is misleading and fails to understand the German electricity markets (!), how the EEG works, how the electricity production/distribution/sales works in Germany, the pricing and how consumers buy electricity.
For example: the renewable produced electricity is delivered onto the grid and the distribution takes it. As much as is possible. This is mixed with non-renewable electricity. The consumer then gets delivered the mix. The normal consumer has no choice - he always gets the mix. He/she can't prefer fossil fuels or renewable. If there is more coal generated electricity, the renewable energy electricity has a preference. By law:
https://www.buzer.de/s1.htm?g=eeg_2009&a=8
'Netzbetreiber sind vorbehaltlich des § 11 verpflichtet, den gesamten angebotenen Strom aus Erneuerbaren Energien und aus Grubengas unverzüglich vorrangig abzunehmen'
translates: 'Grid companies ... are required to take all provided electricity generated from renewable energies ... immediately and with preference.'
That's the German law, the EEG, the renewable energy law.
Thus there is simply no choice: ALL AVAILABLE RENEWABLE ENERGY IS PUSHED INTO THE GRID IMMEDIATELY WITH PREFERENCE.
The provider of renewable energy gets a guaranteed price, based on some calculations. The goal is that this price goes down over the years.
Additionally coal gets further price burdens, which last year had an effect that a lot of coal was driven out of the market, because coal generated electricity was suddenly much less competitive.
Currently there is no time in Germany when renewable energy electricity drives the country 100% or more. There are weekends with lots of wind where we reach 60%. These days are still relatively rare.
On these days the consumer can not choose to get more wind electricity, since he AUTOMATICALLY gets as much as possible via the mix provided by the grid.
The producer gets his price. Now there might be additional capacity available and there might not be a buyer for it. Thus the price on the spot market gets zero for some short period of time or even negative.
But for me as an end consumer I can't choose what kind of electricity I get delivered. What I can influence is where I buy the electricity from and where the profits from that are invested. For example I buy my electricity from a local provider, which invests in renewable energy. The company not only buys renewable energy on the market, but also has its own renewable energy production. The provider invests their profits into more renewable energy production.
For coal its currently tough to make any profits and they are slowly driven out of the market:
https://www.tagesspiegel.de/wirtschaft/hunderte-millionen-ve...
Last year in the first half brown coal power plants were 650 Million Euros in the red.
Thus the consumer doesn't give the coal power plants any advantage.
The added capacity of renewable produced electricity is each year planned (but not completely determined) and the government has instruments to influence that.