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I lived in a high-rise condo uptown for a few years, when you looked out over the city, the 6-7 story mid-rise condo building had the A/C units setup in little grids all around the roof.  And same thing for our building, at the top of our building there is a rooftop terrace and if you looked over to one side you would see the A/C units lined up in nice groups of 4-6 units. The picture of the Stonewall Station apartment condo's brought this back for me (see picture below)

When I was looking at it, each grouping almost perfectly corresponds to a footprint of a small 6-8 panel solar array.

Benefits:

  • With commercial solar panels at 21+% efficiency, a condo tower or mid-rise building could cover all the common electrical needs with these arrays + a decent battery backup.
  • No one can argue that it is ugly, because this would be about a 12-24 inches above the already ugly A/C units on the roof.
  • You are still connected to the grid for backup power.
  • (need to run some simulations) but COA (HOA for condos) costs could be tamed or even lowered based on actual design and sun exposure for a particular condo.

Drawback:

  • Initial cap-ex of construction is higher.

Would love your thoughts.

On 8/19/2017 at 8:57 PM, gman430 said:

DJI_0298.JPG

 

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The picture I quoted is a perfect example for implementation of my idea.

This is a primarily south facing building, with I-277 right below it - so very little chance of shade from another building blocking the sun.

And those black groups of squares on the roof are the A/C units - if it was not clear in my initial post.

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Only drawback is the owner of the building don't  pay each units power bill the renter does, so there is no incentive for the building owner to add solar except for the common area power needs that they pay.

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Oh, that is not even in scope. There is not enough area to capture enough sunlight to cover all the units. This would cover all the common areas.

The building has a garage that is lit, it has elevators, has hallway lighting, exterior/perimeter lighting on the building. Then there is the trash compactor, the central fire alarm system, the security system. (all these things consume electricity)
The cost for these items are rolled into the HOA/COA, for the owners to pay. In a rental building this is split across all the units in the cost of rent.

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These apartment structures are made of wood.  This would make it very complicated and expensive to retrofit to accommodate panels.

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1 hour ago, archiham04 said:

These apartment structures are made of wood.  This would make it very complicated and expensive to retrofit to accommodate panels.

A thin film system would probably be fine,  but their efficiency is a fair amount lower.

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So the wooden structure supporting the flat roof is less than that supporting all of the apartments full of people and furniture?   Surely the requirements far surpass the weight of solar panel arrays.  

 

I think the main impediment to this idea is that there are no longer state subsidies, so the benefits / payoff are too far out in the future for the builders or building managers to pursue it.  That might be a different story if Duke were paying the capital costs of the solar and immediately gave some benefit to the building manager in the form of air rights or some reduction in power costs, but it is Duke, so they are only really doing that on schools as part of halo marketing and not substantial conversion of the grid to renewables.  

 

I am happy they are at least doing white roofs, but I sadly I think until solar costs come down even further, this will not be worth the time given the developer's short term return needs for their capital.   If we had state leaders that believed in the value of renewable energy, we'd see it put in the building codes or subsidized far more.   Lacking that, we are unlikely to see it.   But the roofs will still be there in 5 or 10 years.  So if things do hit a turning point either in policy, energy cost, or global warming crisis reaction, then they can retrofit them nearly everywhere.  

 

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4 hours ago, archiham04 said:

These apartment structures are made of wood.  This would make it very complicated and expensive to retrofit to accommodate panels.

That is silly, the roof already is carrying the A/C units and not to mention a flat roof has to support decent live loads (sudden down pour, snow)

9 minutes ago, dubone said:

So the wooden structure supporting the flat roof is less than that supporting all of the apartments full of people and furniture?   Surely the requirements far surpass the weight of solar panel arrays.

Agreed ^^

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Around 15 or so years ago I read about a solar film that was in early stages of development. It was described as a thin, flexible, window tint-like material that was to be the future of high rise cladding material. Since then I have heard nothing. Reading this thread reminded me of it so I did a quick google search and found a German company that produces it.

http://www.heliatek.com/en/applications/buildings

This sounds like an amazing product and actually looks pretty good on the pilot projects they have completed. What do you guys think of this as a viable option?

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15 hours ago, dubone said:

So the wooden structure supporting the flat roof is less than that supporting all of the apartments full of people and furniture?   Surely the requirements far surpass the weight of solar panel arrays.  

 

yes. the structural requirements for a flat roof are much lower than the requirements for any of the floors that support apartments and people.  Adding any rooftop equipment to a roof usually requires supplemental steel be installed. A large scale solar array would certainly require concentrated loads on posts that would be very difficult to translate from the roof down to bearing walls below.

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So, the fact that there are concentrations of A/C unit clusters all around the roof means nothing. They just slapped them on there?

A solar panel canopy can have an aluminum frame that is anchored down on the same load bearing walls that the A/C units sit on.

Edited by Scribe

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An average residential panel is less then 50 lbs, lets say a commercial panel is about 50 lbs per panel. (source: http://news.energysage.com/average-solar-panel-size-weight/ )

A small cluster of 6 panels is 300 lbs, aluminum racking,  is 100lbs

That is 400 lbs per cluster - add any miscellaneous items at 100 lbs per cluster - still 500 lbs. Spread that over a 10ft x 10ft footprint and that is less then a 220 lb person walking on the roof. (think A/C repair person plus tools)

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The rooftop condenser locations are usually planned ahead of time.  If the solar arrays were planned ahead of time, it would probably be pretty easy, but a large scale retrofit application on these wood roofs is highly unlikely.  I designed a platform on a recent project, on a flat wooden roof.  The load was probably higher than a solar panel, but in this instance we had to carry steel through the roof, the walls, and floor all the way to the ground.  If you want to advocate for rooftop solar, I think that Steel and concrete roofs will be a much easier sell than multifamily wood.

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The point of this thread is to get people thinking about it. First for new construction, as it makes the most sense, then for retrofit.

There are condos that are not wood frame.  (Courtside and the Court 6 Condos on the other end of the garage)

Quote

If you want to advocate for rooftop solar, I think that Steel and concrete roofs will be a much easier sell than multifamily wood.

I wasn't trying to limit the discussion to either wood or concrete. I think these are valid points for wood frame. And we have a ton of it happening (and more will happen along BLE) so, it would be wise to add this to the calculations when doing a design, even if the project is started, they can still retrofit without massive expenses on a wood frame project.

Edited by Scribe

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My initial "Dead on Arrival" comment was probably a little too harsh.  It is definitely possible, and I am hearing of more and more lightweight solutions all the time.

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I prefer a good discussion over dead silence (or an echo-chamber for that matter). So, no worries. Keep poking holes in the proposal, I am sure people can find creative solutions.

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6 hours ago, go_vertical said:

Around 15 or so years ago I read about a solar film that was in early stages of development. It was described as a thin, flexible, window tint-like material that was to be the future of high rise cladding material. Since then I have heard nothing. Reading this thread reminded me of it so I did a quick google search and found a German company that produces it.

http://www.heliatek.com/en/applications/buildings

This sounds like an amazing product and actually looks pretty good on the pilot projects they have completed. What do you guys think of this as a viable option?

Thin film was/is a cool concept.  I really loved this type of system, but those thin film adhesive panels just were not efficient enough to compete:

solar-metal-roof.jpg

The investments in mass production of silicon cells and advances in efficiency have caused them to be the market standard if you're investing in solar.      

 

It doesn't mean that building developers want to built a power plant on their roof, even if it is a great idea.  It needs to be a decision by an ownership group that is thinking long term, has the up front capital, and usually has some qualitative benefits like marketing a building as green or LEED points or true savings long term.  Of course the Tesla focus on looks may lead to other soft/ qualitative benefits of roof durability, architectural aesthetics, and neighbor envy.  

For commercial buildings, a standard array would work.  Just need to have the right incentives for the right people. 

 

 

 

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