[triceratops]

> And batteries aren’t an option either, because I can’t generate any excess electricity during the day

You can't generate excess electricity because you don't have enough land or rooftop (I mean maybe you do, I'm talking about the typical homeowner). Utilities can overbuild panels because they're extremely cheap.

LFP batteries have a self-discharge rate of 2-5% per month. Once they're cheap enough, over-building batteries to move summer sunshine into the winter months also becomes an option*. At $100/kwh, you could power Sweden 6 months a year for about $60bn (EDIT: $6tn, sorry) in batteries (yes labor and everything else will probably double that cost). And that doesn't even account for recent advances in sodium batteries, which reportedly bring that price down to $20/kwh

* (Any battery experts know why this might be wrong? I'm using basic arithmetic, not physics. That tells me a battery charged to 100% in July or August will still have > 70% charge left in December)

[looping__lui]

Germany would require a ballpark of 100 MILLION tons of Teslas Megapack grade batteries to run on battery for 2 weeks - which is even shorter than what we had to endure due to “Dunkelflauten”.

[triceratops]

Why would Germany need to run solely on battery for 2 weeks? Do you expect 2 weeks with 0 sun and wind all over continental Europe?

In any case, at $100/kwh, it would cost $250bn (EDIT: $25tn sorry) in batteries and maybe the same in installation costs to power Germany for 6 months a year. At the lower $20/kwh price tag it would be more like $5tn, compared to Germany's ~$4.5tn GDP. Over 10 years it could be done.

(And 6 months' storage is maybe too much anyway)

[looping__lui]

Because historically we had periods of a couple of days or weeks in a row where wind and solar were essentially non-existent:

https://www.tech-for-future.de/dunkelflaute/

[input_sh]

I mean not the whole Europe and this is obviously geography-dependent, but those "dark periods" are fairly common for Germany, as in there are weeks-long periods where Germany itself produces basically no electricity from wind or solar. In the most extreme case some years back, that "dark period" lasted almost two months.

This isn't to say they can't import it from elsewhere, they just can't make any of their own. Adding more capacity wouldn't do anything, it would take an incredible amount of batteries to handle the more extreme end of those "dark periods".

[triceratops]

But that's my point. It would cost 1 year's worth of German GDP in batteries to power Germany on batteries for 6 months. No one would ever need that much battery backup. And while it's a huge number, it's not an unfathomably huge number.

[looping__lui]

So, just jack up the debt from 60% of GDP to 160% for battery packs?

[triceratops]

That's the absolute most that handling the absolute worst case could cost today. It can only get cheaper from here. And there's no need for government debt.

[looping__lui]

Yes, we had these scenarios of 2+ weeks w/o sufficient renewable energy source MULTIPLE times: Google “Dunkelflaute”.