You don't even need to open up R or Pandas to understand that solar is not viable in the winter.

Here's the official meteorology insitutions sunshine data: https://www.ilmatieteenlaitos.fi/1991-2020-auringonpaiste-ja...

Here's some solar production data over the seasons in visual form: https://profilesolar.com/locations/Finland/Helsinki/

What is also important to know is during the winter is that while production on average shows numbers every day, in practice that production comes only during the few actually sunny days in December when the panels aren't covered in snow.

Go even a bit up north from Helsinki and unless you keep your panels clear of snow manually, you'll hardly make anything between Nov and April.

EDIT: Here's a reddit thread where someone shares real production data: https://old.reddit.com/r/Finland/comments/1i6onkk/solar_ener...

In case people want to play with a toy model: https://model.energy/

We have the problem of stable high-pressure polar air masses potentially parking over the country. Whenever that happens, we get 2 weeks of dead calm, coinciding with the coldest weather that occurs in the country. At the time of the year when there is no solar.

That's where inter-country interconnects, storage and gas come in, which can only be reasoned about through simulations.

> That's where inter-country interconnects

Recent experience has shown that we need to have our power generation on our soil. That is not something that can be compromised on.

> storage

Weeks of storage would be hilariously more expensive than just building more nukes.

> gas

Our main source of gas was Russia. Enough said.

These weather systems are quite big indeed. It's cold and calm in the neighboring Scandinavian countries as well and typically in Central Europe too.

Show one where it does work. Even in far souther countries like Poland solar production is 1/4 of what it is in summer. I'd have to fill my entire roof with solar and still would have to get some power from the network to heat my house