I wonder if they have had issues trying to solve a problem so many people insist doesn't exist.
Solar PV is very reliable year long. It is the day-night cycle that requires batteries, for seasonal offset they do not work and probably never will.
In the off-season they still work just fine, they just make much less power. Which you can offset to some degree by a good balance between wind and solar at the grid scale (not at the private dwelling scale, unless you live rurally).
I'm on PV during the day time all year round in a densely built up region in Western Europe. In the summer we overproduce a ridiculous amount that we can't consume ourselves (though I'm getting better at finding good uses for it), in the winter it is touch-and-go during the day. Netmetering is enough to give me a negative electricity bill which goes towards paying whatever NG we still buy (which isn't a lot, we spent a good bit of money on insulating this house as much as we could without rebuilding it).
> I wonder if they have had issues trying to solve a problem so many people insist doesn't exist.
Nobody who knows anything about PV is going to insist the problem does not exist.
You acknowledged that you're wrong in the very same paragraph.
I suspect you're misunderstanding what the word reliable means in this context.
PVs are very reliable at converting photons to electrons. However if they don't get enough photons, like during night or winter up north, they're not a viable energy source for many uses.