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The reason they are tilted is to maximize irradiance hitting the panel. At a 0 degree angle (flat on the ground) you get a a lot around noon and then very littl

The reason they are tilted is to maximize irradiance hitting the panel. At a 0 degree angle (flat on the ground) you get a a lot around noon and then very little. This approach surely reduces land usage but what is the output per acre? I’d be really surprised if it’s higher than with tilted modules.

mkl 4y ago
The article claims it's much higher output per acre: > conventional solar technologies, which typically require five to 10 acres of land per megawatt of capacity. Erthos claims that its mounting scheme requires less than 2.5 acres per megawatt.
avip 4y ago
They don't claim to outperform fixed-tile or SAT on that KPI. They claim to reduce upfront cost of installation, construction time, and general project risk.
celtain 4y ago
I expect that they are getting lower output per acre, but in places where land is cheap and as solar panels continue to get cheaper, the money saved on building the support structures could be worth those losses.
- rootusrootus 4y ago
  They're getting quite a lot more output per acre, by being able to use more panels.
s1artibartfast 4y ago
They claim the power per acre is 4x higher than tilted panels. Seems like a stretch, but I don't know how bad the density is in tilted installations. I guess I have seen some where you can drive between rows
- sacred_numbers 4y ago
  Density in tilted installations is quite bad. If you want to capture morning and evening sun at an optimal angle you have to space the panels out a lot, like 5-10 panel heights. You can have them closer, but then you get shading, which defeats the purpose of tilting the panels.
whatshisface 4y ago
The amount of power landing on an acre is fixed, what you can achieve by tilting is having less solar panel surface area per ground cover area. If solar panels are cheaper than the mounting hardware (wow) then there is no reason not to let them lie flat on the ground (it's not as if the racks were holding them above tree shadows, or anything).
- guerrilla 4y ago
  > If solar panels are cheaper than the mounting hardware (wow) I'm surprised this surprises people... Every electronics hobbyist knows that electronics are cheap as dirt while any kind of box, mount, rail or whatever is BY REALLY FAR the most expensive part of a project, even when buying massivly mass produced cheap Chinese junk.
  - whatshisface 4y ago
    The electronics you're talking about are rice grain sized little things, while the solar panels are big sheets of silicon inside of glass, etc.
    - guerrilla 4y ago
      Economies of scale make that irrelevant.
    - imtringued 4y ago
      Those grain sized things have pretty high packaging costs in relation to what you are actually buying.
  - DoesntMatter22 4y ago
    You are surprised that this surprised people because electronic hobbyists know this? Most people are not electronic hobbyists so this should probably not surprise you
    - guerrilla 4y ago
rootusrootus 4y ago
> you get a a lot around noon and then very little. That's a little harsher than reality. You get a very pretty bell curve. I have a flat panel on the roof of my RV and I track the output over time. I'm not 100% how much of the loss in output is because the incidence to the panel is changing, or because the light from the sun is going through more atmosphere. Probably a little of both, but in any case the panel is still plenty useful even when not pointed directly at the sun.
hindsightbias 4y ago
Seems like they would have to do some grading to clear anyway, why not grade with some tilt.
elihu 4y ago
With tilted modules, you'd normally space them out quite a bit so the shadows of one aren't falling on the module next to it. If they're all flat, that's not a problem so you can space them closer. So, it makes sense that they'd get more power per acre than the conventional approach -- the panels are individually less efficient, but there's a lot more total solar panel area per acre. That might not always be a good tradeoff, but maybe at least some of the time it is.
nimos 4y ago
Texas is pretty far south. If you use https://pvwatts.nrel.gov/pvwatts.php https://pvwatts.nrel.gov/pvwatts.php there is about a 9% increase in total output over the year for optimal tilt(27 vs 0) but then you also need to space modules. There is hourly data if you are interested but even Jan 1 the panels produce for ~7-8 hours. The 3 hour around noon it's about 1/2 the output for the day (for Jan 1).
HellsMaddy 4y ago
Seems lying them flat also makes their cleaning robot able to easily maneuver, meaning they don't need to leave any space in between panels for humans to perform maintenance. Pros: reduces land usage as you mention, but also less humans needed for maintenance.
fulafel 4y ago
Going to the other direction, I wonder what would be the maximum archieveable output per acre without height limitations. Would you have a forest of tall towers, or one really tall panel covered building, or something in between?
JoeAltmaier 4y ago
Per day? Per acre? Per dollar? It's all about the metric you choose. That's the true issue.

mkl 4y ago

The article claims it's much higher output per acre: > conventional solar technologies, which typically require five to 10 acres of land per megawatt of capacity. Erthos claims that its mounting scheme requires less than 2.5 acres per megawatt.

avip 4y ago

They don't claim to outperform fixed-tile or SAT on that KPI. They claim to reduce upfront cost of installation, construction time, and general project risk.

celtain 4y ago

I expect that they are getting lower output per acre, but in places where land is cheap and as solar panels continue to get cheaper, the money saved on building the support structures could be worth those losses.

rootusrootus 4y ago
They're getting quite a lot more output per acre, by being able to use more panels.

s1artibartfast 4y ago

They claim the power per acre is 4x higher than tilted panels. Seems like a stretch, but I don't know how bad the density is in tilted installations. I guess I have seen some where you can drive between rows

sacred_numbers 4y ago
Density in tilted installations is quite bad. If you want to capture morning and evening sun at an optimal angle you have to space the panels out a lot, like 5-10 panel heights. You can have them closer, but then you get shading, which defeats the purpose of tilting the panels.

whatshisface 4y ago

The amount of power landing on an acre is fixed, what you can achieve by tilting is having less solar panel surface area per ground cover area. If solar panels are cheaper than the mounting hardware (wow) then there is no reason not to let them lie flat on the ground (it's not as if the racks were holding them above tree shadows, or anything).

guerrilla 4y ago
> If solar panels are cheaper than the mounting hardware (wow) I'm surprised this surprises people... Every electronics hobbyist knows that electronics are cheap as dirt while any kind of box, mount, rail or whatever is BY REALLY FAR the most expensive part of a project, even when buying massivly mass produced cheap Chinese junk.
- whatshisface 4y ago
  The electronics you're talking about are rice grain sized little things, while the solar panels are big sheets of silicon inside of glass, etc.
  - guerrilla 4y ago
    Economies of scale make that irrelevant.
  - imtringued 4y ago
    Those grain sized things have pretty high packaging costs in relation to what you are actually buying.
- DoesntMatter22 4y ago
  You are surprised that this surprised people because electronic hobbyists know this? Most people are not electronic hobbyists so this should probably not surprise you
  - guerrilla 4y ago

rootusrootus 4y ago

> you get a a lot around noon and then very little. That's a little harsher than reality. You get a very pretty bell curve. I have a flat panel on the roof of my RV and I track the output over time. I'm not 100% how much of the loss in output is because the incidence to the panel is changing, or because the light from the sun is going through more atmosphere. Probably a little of both, but in any case the panel is still plenty useful even when not pointed directly at the sun.

hindsightbias 4y ago

Seems like they would have to do some grading to clear anyway, why not grade with some tilt.

elihu 4y ago

With tilted modules, you'd normally space them out quite a bit so the shadows of one aren't falling on the module next to it. If they're all flat, that's not a problem so you can space them closer. So, it makes sense that they'd get more power per acre than the conventional approach -- the panels are individually less efficient, but there's a lot more total solar panel area per acre. That might not always be a good tradeoff, but maybe at least some of the time it is.

nimos 4y ago

Texas is pretty far south. If you use https://pvwatts.nrel.gov/pvwatts.php https://pvwatts.nrel.gov/pvwatts.php there is about a 9% increase in total output over the year for optimal tilt(27 vs 0) but then you also need to space modules. There is hourly data if you are interested but even Jan 1 the panels produce for ~7-8 hours. The 3 hour around noon it's about 1/2 the output for the day (for Jan 1).

HellsMaddy 4y ago

Seems lying them flat also makes their cleaning robot able to easily maneuver, meaning they don't need to leave any space in between panels for humans to perform maintenance. Pros: reduces land usage as you mention, but also less humans needed for maintenance.

fulafel 4y ago

Going to the other direction, I wonder what would be the maximum archieveable output per acre without height limitations. Would you have a forest of tall towers, or one really tall panel covered building, or something in between?

JoeAltmaier 4y ago

Per day? Per acre? Per dollar? It's all about the metric you choose. That's the true issue.