Harder mostly, See the frequency is set by huge rotating masses in the form of generators, and when the supply and demand is matched the frequency and voltage are stable, when demand dramatically increases it pulls the frequency and voltage down, which is effectively slowing the generators down as load / magnetic drag increases with current drawn. Having large inertial masses spinning actually helps smooth out frequency changes. whilst large solar farms can and do syncronise with the grid, they are reactive and do not add the same smoothing effect as humungous spinning masses.
Low Grid frequency & voltage can cause an increase in current & heating of transmission lines and conductors and can damage the expensive things, this is why these systems trip out automatically at low frequency or low voltage, and why load shedding is necessary
> Harder mostly, See the frequency is set by huge rotating masses in the form of generators
I'm not saying you're wrong, but this isn't obviously correct to me.
Since solar going to a grid is completely dependent upon electronic DC->AC conversion, I would expect that it could follow a lot greater frequency deviation for a lot longer than a mechanical system that will literally rip itself apart on desync.
The real reason that small scale solar PV is grid following (i.e. it depends on an external voltage and frequency reference) is that this ensures power line safety during a power outage. That's it.
An inverter can be programmed to start in the absence of an external reference and it can operate at a wide range of frequencies.
About 10 years ago I had a chance to work in the Utilities vertical for a power producer. I asked the same question: how is the frequency set and the answer was that the biggest power plant sets the frequency because they can produce a lot power and any other smaller generator would not be powerful enough to change the frequency.
Sure, the smaller plant gets pulled into the larger plant's inertia.
However, DC-AC converters don't have an inherent inertia. They can follow almost any frequency and phase within reason. Certainly a DC-AC converter should be able to respond way faster than any frequency/phase changes that a mechanical system can generate.
In theory, they should be able to set themselves to be ever so slightly closer to ideal so that the amount of power they have to sink is limited but are still exerting a very slight force to bring the grid back into compliance rather than continuing to add load which propagates the collapse.
Low Grid frequency & voltage can cause an increase in current & heating of transmission lines and conductors and can damage the expensive things, this is why these systems trip out automatically at low frequency or low voltage, and why load shedding is necessary