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Slightly off topic, but why is there so much discussion about fixed rooftop solar compared to a ground based system with tracking? Seems to me a ground based sy

Slightly off topic, but why is there so much discussion about fixed rooftop solar compared to a ground based system with tracking? Seems to me a ground based system would be easier and safer to set up, easier to keep clean, and easier to keep in an optimal position, even if it didn't have tracking. Why have this tight coupling to the roofing system?

cglace 8y ago
Because the roof structure already exists.
- dashundchen 8y ago
  Expanding on that, built up areas are where the demand and grid already exists, but not necessarily the clear space. Little added transmission capacity is needed. In a neighborhood in my city where a few large electric users have expanded, the utility has been subsidizing rooftop panels for residential users to minimize summer peaks and avoid having to upgrade the old undersized grid. So far it has worked pretty well - peaks usually line up with the hottest sunniest days.
bradknowles 8y ago
It develops that tracking systems are expensive, heavy, and take up a lot of space. In fact, so much so that the tracking systems rarely make sense with modern panels. You would usually be better off spending the money, weight, and space on more fixed panels than messing with the tracking systems.
- tejohnso 8y ago
  That's disappointing. It's too bad the tracking systems are such a burden. But what about a simple wooden structure to hold fixed panels oriented optimally? That's a few thousand dollars at most, for a twenty to sixty percent efficiency improvement. It would kill me to mount panels facing North at a 45deg angle.
walrus01 8y ago
A ground based two axis tracking mount that can take the wind loading of six 360W 72-cell (2.0 x 1.0 meter each) panels costs more than the panels. Foundation, concrete, pole, mechanism, etc. It is much more economical to just buy more panels and mount them at a fixed angle.
pjc50 8y ago
For urban areas the land costs far more than the panels. Utility scale has largely abandoned tracking as not cost effective.
alkonaut 8y ago
For urban residential I wouldn’t give up any area of my small plot of land even if it provided all my electricity and the installation was given to me for free.
- tejohnso 8y ago
  Okay, but in the suburbs I see every house with hundreds of square feet of unused lawn, which is useless at best, and and ecological disaster at worst [1] [1] https://earther.gizmodo.com/lawns-are-an-ecological-disaster-1826070720 https://earther.gizmodo.com/lawns-are-an-ecological-disaster...
  - alkonaut 8y ago
    Isn’t the point of a lawn that it’s “unused” space? That’s where kids can play soccer and all that. I have 10k square feet total plot, most of it not occupied by garden, buildings and would still not prefer to have panels there rather than on the roof where the space is “free” because I can’t use it for anything else. Even at 60 degs north lots of people do have solar on the roof here (but haven’t seen any north facing)
    - tejohnso 8y ago
      Oh, children actually play outside on the lawn in your area; that's wonderful. But using an inefficient roof angle isn't free. That loss of output has a cost. I would think that in some cases it is a significant cost, so I'm just surprised that ground based mounting is so rarely mentioned.

cglace 8y ago

Because the roof structure already exists.

dashundchen 8y ago
Expanding on that, built up areas are where the demand and grid already exists, but not necessarily the clear space. Little added transmission capacity is needed. In a neighborhood in my city where a few large electric users have expanded, the utility has been subsidizing rooftop panels for residential users to minimize summer peaks and avoid having to upgrade the old undersized grid. So far it has worked pretty well - peaks usually line up with the hottest sunniest days.

bradknowles 8y ago

It develops that tracking systems are expensive, heavy, and take up a lot of space. In fact, so much so that the tracking systems rarely make sense with modern panels. You would usually be better off spending the money, weight, and space on more fixed panels than messing with the tracking systems.

tejohnso 8y ago
That's disappointing. It's too bad the tracking systems are such a burden. But what about a simple wooden structure to hold fixed panels oriented optimally? That's a few thousand dollars at most, for a twenty to sixty percent efficiency improvement. It would kill me to mount panels facing North at a 45deg angle.

walrus01 8y ago

A ground based two axis tracking mount that can take the wind loading of six 360W 72-cell (2.0 x 1.0 meter each) panels costs more than the panels. Foundation, concrete, pole, mechanism, etc. It is much more economical to just buy more panels and mount them at a fixed angle.

pjc50 8y ago

For urban areas the land costs far more than the panels. Utility scale has largely abandoned tracking as not cost effective.

alkonaut 8y ago

For urban residential I wouldn’t give up any area of my small plot of land even if it provided all my electricity and the installation was given to me for free.

tejohnso 8y ago
Okay, but in the suburbs I see every house with hundreds of square feet of unused lawn, which is useless at best, and and ecological disaster at worst [1] [1] https://earther.gizmodo.com/lawns-are-an-ecological-disaster-1826070720 https://earther.gizmodo.com/lawns-are-an-ecological-disaster...
- alkonaut 8y ago
  Isn’t the point of a lawn that it’s “unused” space? That’s where kids can play soccer and all that. I have 10k square feet total plot, most of it not occupied by garden, buildings and would still not prefer to have panels there rather than on the roof where the space is “free” because I can’t use it for anything else. Even at 60 degs north lots of people do have solar on the roof here (but haven’t seen any north facing)
  - tejohnso 8y ago
    Oh, children actually play outside on the lawn in your area; that's wonderful. But using an inefficient roof angle isn't free. That loss of output has a cost. I would think that in some cases it is a significant cost, so I'm just surprised that ground based mounting is so rarely mentioned.