[simion314]

>Isn’t this a pretty much solved problem though? Just add a battery to your house?

In winter the days are short, the sky can be covered in clouds for an entire week, the solar panels can be covered in snow also. I have solar panels but I do not have a way to export my data to show you the summer vs winter GIANT difference.

So people like me with solar need the other people in the area not to all go for solar, then we will need to find a way to burn the excess. Is the same with a country, we can't store the energy from summer for winter and also resist for say 2 weeks of snow and clouds. The EU market might be so in demand that the rich countries will bid for the energy and the poor will have to burn their things to survive.

I am wondering if it would happen that with so many solar roofs we will either have to pay for people to use my energy or I will need to actually throw the excess in the ground safely somehow.

[ben_w]

> In winter the days are short, the sky can be covered in clouds for an entire week, the solar panels can be covered in snow also. I have solar panels but I do not have a way to export my data to show you the summer vs winter GIANT difference.

Short days, but still enough to make a lot of juice in Italy. Scotland and Scandinavia get issues, but Italy's basically OK for winter: https://www.wolframalpha.com/input?i=%28sunrise%2C+Rome%2C+2...

And: https://www.sciencedirect.com/science/article/abs/pii/S09601...

> we can't store the energy from summer for winter and also resist for say 2 weeks of snow and clouds

You, personally, can't store 2 weeks of energy (though it's closer than you may expect, 1 person-week of Italian average electrical consumption is ~= 1 EV battery*). But you personally don't have to, transmission to another part of the country (or continent) has a huge impact on how much storage you need.

Basically, this problem is known, it's not all that difficult to work around — everything on the scale of "national power supply" is expensive and has pros and cons, PV isn't particularly remarkable in the scale or cost of those pros and cons even with current solutions and assuming no R&D effort can improve the trade-offs, they're just different than the pros and cons of the other options.

* https://www.wolframalpha.com/input?i=%28%28%28300+terawatt-h...

[simion314]

The real life is not as simple as you wish The energy I produce can only go to my neighbors, it can't be sent to a different region in the same village it is a grid limitation.

Also when the weather is bad it is bad in a big chunk of Europe, sure in the South they will probably have nicer weather.

What about the issue when everyone has solar? then who buys my extra production? Or if there is someone that can buy it because of too much solar the prices would be close to zero then the solar panels investment will not be worth it since you could be cheap energy from the people with solar panels when the weather is good.

My gut feeling is that 100% solar is stupid, it is like the 20-80 problem we see now a lot of growth since it is very profitable, when more grid investment is needed and profits will go down this growth will stop.

[ben_w]

> The real life is not as simple as you wish The energy I produce can only go to my neighbors, it can't be sent to a different region in the same village it is a grid limitation.

I would need to write something the size of a PhD thesis, not a comment, to fully describe the various possibilities and their trade-offs for even just the Italian grid, let alone the whole of Europe's.

But to keep it simple, I can say that limits of your grid can be re-engineered, and even for unrelated age and capacity reasons people are already planning to spend more on upgrading the European grid anyway, than it would cost for the material to build a global high-power DC backbone that would let the EU be lit in the middle of night, in the middle of winter, without any batteries at all, by panels in the Australian outback — and I have in fact done the maths on that.

(Only China is actually making enough aluminium, there's geopolitics even before Trump happened, but the price tag to get a single ohm of resistance around the entire planet is actually fine).

> Or if there is someone that can buy it because of too much solar the prices would be close to zero then the solar panels investment will not be worth it since you could be cheap energy from the people with solar panels when the weather is good.

Such investment is still generally worth it, because you don't need to actually sell anything when the price is low (or even negative), and even if it was zero the whole time forever, you've saved 100% of the current cost of supplying yourself with electricity.

> My gut feeling is that 100% solar is stupid, it is like the 20-80 problem we see now a lot of growth since it is very profitable, when more grid investment is needed and profits will go down this growth will stop.

100% anything leads to correlated failures.

But there's several other renewables.

[simion314]

So are you expert in grids? is it cheap to make it possible to get the electricity from homes, and resue or add new transformers to raise the voltage to medium then high voltage and use the same high voltage lines and whatever they use to get the energy from homes in Italy to homes in Romania ?

About costs, if the solar panels will cost me 20 years of paying my bills but they will maybe break in 10 years then it is a waste of my money, I can buy the energy directly and lose less money.

I bought the panels because they were subsidized otherwise there would be more profitable to buy the energy, without subsidies and if energy will be cheaper or I would get paid to use it then solar panels would make no sense .

Imagine then a country that needs to over build solar panels, why would private sector accept this?

[ben_w]

> So are you expert in grids?

Interested amateur. I skim read the actual government and industrial reports, and know enough to be able to roughly estimate the effort required to construct precise answers.

> is it cheap to make it possible to get the electricity from homes, and resue or add new transformers to raise the voltage to medium then high voltage and use the same high voltage lines and whatever they use to get the energy from homes in Italy to homes in Romania ?

"Cheap" is already the wrong question: on this scale, energy is measured in percentage points of the economy, opportunity loss from what else can be done with the same resources, geopolitical exposure, not pure €, and that means questions like "is it cheap?" can only be considered against everything else the governments can do with the same resources — not even just other energy projects, absolutely everything, and how everything interacts with everything else, has to be taken into consideration.

Consider this: https://eepublicdownloads.blob.core.windows.net/public-cdn-c...

If you limit yourself to just €, the scenarios on page 7 say that improving the grid would:

• 2030: reduce wasted power by 2 GW while saving €5 billion per year in wasted energy

• 2040: reduce wasted power by 4.8 GW while saving €9 billion per year in wasted energy

While another pair of options on page 22 shows:

• €5.6 billion per year invested, returns of €9.4 billion per year

• €3.6 billion per year invested, returns of €8.6 billion per year

But! The report is also has a section header titled "Does the study consider the EU’s goal to reduce dependency on gas imports?" with several specific mentions of Russia throughout.

> About costs, if the solar panels will cost me 20 years of paying my bills but they will maybe break in 10 years then it is a waste of my money, I can buy the energy directly and lose less money.

When did you buy?

I think you're over-estimating the current price of PV by a factor of about 15-25 — here's one of my local supermarkets, this price pays for itself in about *one* year: https://www.kaufland.de/product/456527791/?search_value=phot...

I believe Italian electricity (you are in Italy, right?) is slightly cheaper than German electricity, but that's more than compensated for by having more sun.

[account42]

> I am wondering if it would happen that with so many solar roofs we will either have to pay for people to use my energy

This is already the case - Germany ends up paying for both electricity exports and imports.