The reason why it totals 1.5% is because it costs money to replace existing power sources and the lobby power of the coal industry is still huge. It has nothing to do with solar energy itself.
You may call it "the lobby power" but there seems to be no choice for the heavy industry than to use coal, thanks to nuclear phase-out.
It's actually become something of a political issue (because of the lost jobs).
In 2010-2013 renewables apparently couldn't keep up. Since 2014 they appear capable of replacing all other end of lifed power plants.
The renewable parts of that is bound to go down: As part of the push to renewables, when spinning up capacity, you get prices guaranteed for 20 years. The different to market rates is spread across the whole market ("EEG Umlage", "renewable energy law contribution").
But: that law is approaching 20 years now and so in 2021 the first installations will drop out of that subsidy scheme. Prices and guaranteed rates were dropping ever since, and so will the subsidies - with a delay of 20 years.
> there seems to be no choice for the heavy industry than to use coal
Comparing the numbers in 2000 and 2017 (https://de.wikipedia.org/wiki/Stromerzeugung#Bruttostromerze...), coal used to account for more than 50% of power generation in 2000, down to 36.6% in 2017. Even in absolute numbers to account for the rise in total power production, coal is less in 2017 than in 2000. Petrochemicals are up from 9.5% to 14.1% though.
Non-regenerative power was 436.5 TWh in 2017, down from 538.7 TWh in 2000.
And no realistic fuelcell technology or disrributed grids.
If France were forced to disconnect from its neighbors, its electricity would be more expensive and/or more emissions-intensive. It would need more fossil combustion to deal with seasonal demand swings and/or it would get less utilization out of its nuclear reactor fleet. The same goes for Germany, of course: electrically isolating itself would also increase costs/emissions. Germany and France both rely on international electrical connections to improve utilization of their non-combustion electricity sources. Both use imports to meet part of their electricity demands. Both are net electricity exporters over the course of a full year.