Entry into force of the Solar Peak Law

Just a general question about throttling, there are already systems with 70% because of something. Does the percentage only refer to the kWp of the entire system, meaning the maximum capacity? Or is it always the case that only 70% (60%) of what is currently being produced is fed in?

Nope - refers to the maximum value.

You have 10 kWp, then you can feed in a maximum of 7 kWp. If you charge your electric car with 3 kW during that time, you are feeding in completely...

A general question about throttling, there are already systems with 70% because of something.
Does the percentage only refer to the kWp of the entire system, i.e., the maximum capacity? Or is only 70% (60%) of what is currently being produced fed in?

The throttling refers to the installed modules. If you have 10kWp on the roof, but the inverter can do more, the power of the modules is decisive.

Just a general question about throttling, there are already systems with 70% because of something.
Does the percentage only refer to the kWp of the entire system, i.e., the maximum capacity? Or is it always that only 70% (60%) of what is currently being produced is fed in?

Do you mean the 70% cap valid until 2023 (I have that too)? That refers to the feed-in. So if I have 10 kWp on the roof, which is throttled to 70%, it means a maximum feed-in of 7 kW (so always 70% of 10 kWp). Thanks to an 8 kW inverter (where the throttling is set in the software), I can then charge the car with 7.2 kW in summer and the still possible surplus of just under 1 kW goes into the grid.

Since we are supposed to receive remuneration for 20 years, the period of negative prices/no remuneration will be appended at the end using a somewhat complicated key. So, for example, one would receive remuneration for 20 years and 6 months.

I don't know the exact implementation, but that doesn't sound like a good deal. All remunerations expire on 12/31 after 20 years. However, curtailment occurs at the highest solar output in summer. For 24 best sun hours, I therefore get the feed-in remuneration for 1/1 paid as a replacement (i.e., regularly: €0). For the next 24 curtailed sun hours, the 2/1 (again €0) and so on.

I would rather say that one would then move from a time-based remuneration guarantee to volume (amount of electricity) (at least that's what I would find logical). But that would only be possible with a smart meter, which then costs a higher fee. One has to think that through carefully. We will see in the concrete law how exactly or have you already read it?