Cold winter days don't represent peak consumption for the grid, there is no capacity being built specifically for cold winter days. In contrast there is capacity being built to offset everyone turning on the A/C during summer heatwaves, and solar has high power output during those periods.
Your argument is specifically called out as being a misuse of the "duck curve" concept.
> Common misconceptions
> One misconception related to the duck curve is that solar photovoltaic power does not help supply peak demand and therefore cannot replace other power plants. For example, in California, solar output is low at 7 pm when daily demand usually peaks.[19] This fact leads some to believe that solar power cannot reduce the need for other power plants, as they will still be needed at 7 pm when solar power output is low. However, California's annual demand peaks usually occur around 3 pm to 5 pm,[20] when solar power output is still substantial.[19] The reason that California's annual peak tends to be earlier than the daily peak is that California's annual peak usually occurs on hot days with large air conditioning loads, which tend to run more during midday.[21] As a result, solar power does in fact help supply peak demand and therefore can substitute for other sources of power.
https://www.caiso.com/todaysoutlook/pages/supply.html is pretty good for total energy used and sources. In the Summer 3-5pm could be demand peak, but looks like the total energy used is high over a few hours, even after sun down.
That might be true in California, but in Europe that's where the peak demand was before AC got popular. And it can easily go back to that with the spread of heat pumps.
And actual usage of that capital often has peak usage much more extreme than a typical 90/10 rule, meaning that the vast majority of that fixed cost is mostly unused.
The key to decreasing that peak is the distributed storage that's paired with distributed solar. It allows massive amounts of cost savings, despite needing to beef up the distribution side of the grid for this to work.
Utilities are gonna charge you 25c a kWh extra for peak demand delivery, and then be paying the actual people delivering it like 1c a kWh, you can book it.
This is true if you're not connected to the grid. However if you use power on those cold winter cloudy days you need all that infrastructure still. The difference is when you used the grid's power every day that cost was spread over the year. If you only use grid power 20 days a year that grid infrastructure is very inefficient and costly.
Net metering is an anachronism. You should pay and receive the current spot price which is near zero on Spring/Fall sunny days and super high in Summer evenings and Winter nights.