No, that's a silly way to compare renewables with other energy sources. You could pick another arbitrary comparison, say ability to respond to load, and point out that nuclear is extremely slow and coal isn't particularly brilliant either. In either case the comparison would be dishonest.
It's a valid comparison, especially if the goal is to switch to renewables completely, as is the case here in Germany. And it is true, coal and nukes are rather slow when it comes to load changes. Gas is much faster. But they all can deliver at any time when there is demand, since they can run 24/7 (not accounting for service/maintenance time here). Wind and solar can only be used when there is wind and sun, unless you add enough storage.
You can't use renewables the way way you use a nuclear plant. They are not the same, and direct comparison is pointless at best.
If you want to go off grid, battery packs are pretty cheap now. I don't think anyone is advocating self sufficiency though.
Well, and here is the point. Assume you take the simple way with no storage. That means you can only use the energy it produces _when_ it produces any. You still need to be connected to grid for the times where it doesn't produce. This means you still have the same amount of base price for regular electricity, all you save is the kWh's that you can get from a solar installation, for example.
Now, here is the question: If you pay, lets say, 10 thousand Euro upfront for the install, how long would it take you to get even, when compared to using regular electricity? Since, in most places on the world, you have only a few hours of solar available for any decent amount of electricity generation. Plus, you don't have that all around the year either, winter in Europe and you produce little to nothing.
Projected life time of installed solar panels is between 20 and 30 years nowdays. Let's take the middle and say it's 25 years. That makes 400 Euro per year, or roundabout 33.33 Euro per month. At an average price of 25 Cent per kWh (it's expensive here in Germany), that makes roundabout 133 kWh per month that you must be able to use from that solar installation to break even. And mind you, this assumes 12 "usable" months per year, which is often not the case. The statistical avergae consumption per household is in Germany is about 3359 kWh per year, which results in roughly 280 kWh per month. You can already see that it's almost impossible to get even here throughout the lifetime of the panels. Thing is that during the time that solar is most productive, people are usually not at home, while the times when most electricity is used in a household is when there is very little to no solar to be useful for PV.
Really, such things have to be considered. I hear things like "sun and wind dont send an invoice" as justification for claiming that it would be super-cheap. But that's just too short sighted a view. To make it really feasible one _must_ include things like storage into the calculation. If i were to install a 10k Euro system here with no storage, and only to use it for myself, it would never ever pay for itself, let alone save me any money. My monthly electricity bill is just too low for that to happen. And i'm working at home, so i'm at home pretty much always. Heck, even if it were only 5k it would be hard to get even. And 5k isn't that much when it has to go into panels, electronics and installation. Oh, and electricity is, as said, expensive over here. For anyone where it costs less, getting even is much harder.
But then, i guess this starting to get way too off-topic here now anyways. It just irks me when people claim that electricity from PV is basically free, and then refuse to consider the details.
Greetings,
Chris