This is unfortunately not true.
Panels supply the home first and put excess into the grid, sure. But this will have limited effect on blackout frequency.
Let’s be really clear here - it’s been a LONG time since blackout have been caused by a simple lack of supply. The current rooftop PV generation capacity has seen to that. Blackouts have been caused by abrupt changes to supply or demand and the inability of the distribution system to keep up with them.
To oversimplify massively, the grid is basically a giant electrical circuit. You have generation capacity X, and you have load Y, and it’s the responsibility of grid management to arrange things that the two are approximately equal so that the voltage/waveform that gets delivered to premises is close enough to 240v/50Hz for applicances to run without damaging themselves. If demand suddenly spikes or supply drops (or vice versa) then the system needs to be able to bring more power into the grid (or disconnect excess from the grid) fast, or else things start getting bad. There are series of safety interlocks in the grid designed to flip and disconnect if the grid gets into a crisis state, on the reasoning that shutting down the grid temporarily is better than having short circuits, melted appliances and wires, blown fuses, and electrical fires all over the place.
In an theoretical ideal fossil fuel/hydro grid, supply is generally completely under the control of the grid managers. Demand goes up? Bring another generator online or start releasing water through one of the turbines? Demand goes down? Unplug a generator and you’re golden. this is possible because there are a small number of centralised generators which have predictable output.
In a renewable grid, generators are widely scattered and do not have consistent output. You now have to manage for unpredictable fluctuations in supply as well as demand, and there are so many small generators that it’s more difficult to manage them individually. Note that this does NOT mean that this is impossible, it just means that more sophisticated management systems than those currently in place are required, and the current grid setup (a series of high-tension cables radiating from centres of generation like the Latrobe Valley) are often in the wrong places.
What this means is that you have more fluctuations in a system that is ill-equipped to handle them. And fluctuations WILL happen. The big SA blackouts from a couple of years ago happened when storm winds blew down major high-tension lines. The system could not compensate fast enough, and safety interlocks tripped, cutting off big parts of the grid (all of which took time to fix). There were a couple in Vic this summer that were due to elderly coal plants breaking down. Abrupt changes in supply that the system could not compensate for quickly enough. THERE WAS NO LACK OF POWER - the grid just was not able to get the power from where it was generated and distributed appropriately around the grid.
And the ‘distribution’ thing is key. Just cos your solar power is consumed by your house first, does not make you immune to blackouts (unless of course you’ve bought a battery and gone completely off-grid), nor does it make blackouts less likely. Even houses that generate more solar PV than they consume (like mine) will still experience blackouts when the grid is down. This is deliberate - in an emergency it’s hopelessly dangerous for sparkys or firefighters to be wandering through a disaster-affected area trying to do their jobs, not knowing from house to house whether the power is still on. That means that when a blackout happens in your area and you;re on the grid, you’re affected regardless of how much solar you personally are generating. And an increase in gross solar PV generation capacity is not going to change this. In fact, it may make things worse until the distribution system is improved, because solar has higher variability. I know for a fact that AEMO is already planning ahead for problems in 2023, because there’s going to be a total eclipse and the grid is not yet ready to deal with GW of generating capacity going offline all at once because of a random astronomical event. But hell, even clouds passing in front of the sun could have similar effects. These events cause rapid fluctuations in supply, which is what the grid cannot currently deal with. The more solar you have, the greater % of your generation capacity is subject to fluctuatioh, so the better your systems have to be to deal with it or else you’ll have more blackouts.
It’s not a matter of power, it’s a matter of control.
Look, I love that we’re increasing the amount of renewable generation. It’s great for the emissions problem, but in itself this will not solve the blackout problem (and may make it worse unless further steps are taken). And if these blackout problems DO happen, it’s just handing ammunition to people who’d love to shut down renewables purely out of ideology.
Increasing PV generation capacity in a coal-optimised grid is like putting a v8 engine in a bald-tyred Mazda 323. Sure, you’ve got more grunt, but can you control the result?