> You haven't linked the photo…

The one at the top of the article.

> They wouldn't, they'd just put more panels on a bigger surface.

Given a specific budget they can only buy so many panels. Free land would change the tradeoffs.

> And again, industrial actors are maximizing the economic output they can make.

Based on current costs. Change the costs and the methods change too.

> Whatever decision you take at your level, it's going to be more expensive than what they are doing, and more efficient.

No. I already have the land and the house. That means most efficient for me is different.

I don't want to waste any more of our time arguing about how to define X so I'll skip the rest.

▲

littlestymaar 3 days ago | parent [-]

This makes no sense: solar plants in the deserts have the same shape yet even though the land is pretty much worseless.

Where did you get your morning shade fixation from?

▲

Dylan16807 3 days ago | parent [-]

They don't build them in deserts that far north, do they?

I got this "fixation" by doing the math to figure out why panels do so badly when there's still seven and a half hours of daylight.

The insolation per square meter of ground is very low when the sun is near the horizon. But the insolation of a flat surface at 60 degrees of tilt is still pretty good. If you avoid shade.

Please tell me you have no disagreements with that. It's basic math.

So as you said with basic panels "one cell being shaded criples the output of the entire row". Normal commercial installs don't try to capture the morning sun. But in the middle of winter in Denmark the "morning" sun is basically all you have access to.

You said "They don't care about shade when the sun is low because when the sun is low the incidence angle is terrible in the first place."

If you tilt really far and avoid shade, you counteract the bad incidence angle. A single square meter of panel can absorb the light that would have hit 6 square meters of ground.

▲

littlestymaar 3 days ago | parent [-]

> They don't build them in deserts that far north, do they?

I'm not aware of any desert in Denmark…

But you say the design is driven by lack of space, then why do they use the same design in deserts?! That's my question. Denmark doesn't have much free space, but Sweden do, land is cheap in many places there, yet the Swede don't design their plant differently.

> Normal commercial installs don't try to capture the morning sun. But in the middle of winter in Denmark the "morning" sun is basically all you have access to.

And yet you insist commercial plants don't do that? Why? Are they stupid?

> If you tilt really far and avoid shade, you counteract the bad incidence angle.

Only the vertical angle, not the horizontal one… And again it makes no sense to optimize for winter morning sun when there's only 2 hours of sunlight per day in average during winter…

You could set up a football field of our perfectly optimized morning sun solar panels, plus the same for evening sun, and you'd still have failed to power a house for the full month between January and February where the sun often don't show up once, and in that time span you've already exceeded the 10% non-solar budget in that mental exercise…

▲

Dylan16807 3 days ago | parent [-]

> I'm not aware of any desert in Denmark…

Right! A lack of places with such super free land that also have horrible sun angles.

> But you say the design is driven by lack of space, then why do they use the same design in deserts?!

The desert builds don't have to deal with the same horrible sun angles.

But whatever, I might be wrong on what they would do with free land. That was a guess, I admit it. That guess was to illustrate my point about angles. It's not a critical part of my argument.

It's a fact that solar panels on a roof avoid the shading problem, while a normal commercial layout does not. Pure mathematics.

> Only the vertical angle, not the horizontal one…

The horizontal angle doesn't change very much. If you point flat 50-60 degrees south (the year-round optimal angle for Denmark) you will get a significant amount of sun no matter the season if you avoid shade. Winter sun is less than average but it's close to 50%, not 5%.

> And again it makes no sense to optimize for winter morning sun when there's only 2 hours of sunlight per day in average during winter…

That's so close to understanding my argument!

Commercial plants don't bother. They're not optimal for winter. But if you build on a slanted roof you get that optimization for free. So a home install actually becomes better than a commercial install for this specific use case.

But it's not 2 hours of significant light, it's more than that. Clouds don't make the sun useless.

> where the sun often don't show up once

Nah.

▲

littlestymaar 2 days ago | parent [-]

> The horizontal angle doesn't change very much

Yes the range reduces in winter especially when you go north, but you still get at least 45° of incidence angle in the best case scenario.

> Winter sun is less than average but it's close to 50%, not 5%.

How can it be 50% when the sun is beyond the horizon for 17 hours straight?! For some reason you obsess with shade, but disregard the most important one: the one caused by earth moving in front of the sun (also called “night”)…

> That's so close to understanding my argument!

> Commercial plants don't bother. They're not optimal for winter

I see what you mean, but plants optimize for electricity value, not rough output, and electricity is more expensive in winter, if they could get good yields at that period, they would actually make more money than the one they get by selling excess electricity in summer…

> But it's not 2 hours of significant light, it's more than that. Clouds don't make the sun useless.

For regular solar panels, they pretty much do, especially in the north (because the cloud layer is effectively much thicker due to the high sunlight incidence angle). Amorphous panels have better performance in these scenarios but it's still far from good, especially if you tilt them heavily to face the sun as these panels need to be facing the sky to get as much diffuse daylight as possible.

As a result, the sunny hours, even though rare, are going to dwarf the others in electricity production, even if there's few of them.

But if you believe you can sustain 90% of your electricity consumption from solar in Denmark, go ahead, I'm not going to convince you otherwise and I'll have no guilt if you lose your shirt in the process.

	▲	Dylan16807 2 days ago \| parent [-]
		> How can it be 50% when the sun is beyond the horizon for 17 hours straight?! 50% of the average. The average being a day with something like 12 hours of sunlight. Sorry to be unclear. > I see what you mean, but plants optimize for electricity value, not rough output, and electricity is more expensive in winter, if they could get good yields at that period, they would actually make more money than the one they get by selling excess electricity in summer… One important factor is that they're not optimizing for power per panel. Panels are pretty cheap, and filling the land with panels makes sense as an overall decision. Let me reframe things. For a commercial plant it's not that they could get significantly more power in deep winter, it's that they could get the same power with 20% as many panels. But spreading panels out that far would be worse the rest of the year. Many home installs can get that "spreading" for free. So to redo my claim from earlier, if there was a magic button to put 50 feet between each row of panels with no downside, I strongly bet commercial installs would pay to press it. And it should take the winter output up from "useless" to "bad". It's possible I'm still severely underestimating the clouds. But when there is light, there's this interesting advantage small/widely-spaced installs get in winter. Or rather, they have a much smaller disadvantage.