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Tesla's "solar roof" Event - Hosted at Universal Studios
- Thread starter AssortedBread
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Owner
Active Member
They already had solar panels but a shake roof. The additional weight of the steel roof was what caused the reinforcement problems.
A lot of the housing stock in the San Francisco Bay Area was built in the 50s, 60s and 70s before the earthquake prevention stuff came in.
Newer homes are a different story. But houses aren't like cars, typically they stay there for a really long time unless you are in a pricey area and they are bulldozed away.
Garlan Garner
Banned
No it doesn't. Sometimes the wind blows and it floats down like a feather.
I see this is a conversation about semantics. I'm done.
Garlan Garner
Banned
Solar panels aren't that heavy on a per sq. foot basis.
I person walking around on a roof is much heavier on a per square foot basis - than a solar panel.
That's the terminal velocity for that particle.
Hail doesn't fall at terminal velocity when it's being convected upward inside of the storm cloud, though. So technically it doesn't always fall at terminal velocity.
Owner
Active Member
In my hood we have very strict earthquake laws now. I actually have 35 pier and beams underground.
I don't think the laws worry much about someone walking on the roof in the middle of an earthquake.
Garlan Garner
Banned
Garlan Garner
Banned
Earthquakes were not being mentioned. Where did earthquakes come from?
He made the comment that California roofs were being load rated for solar panel weight.
Stay on topic.
Less crowd energy outdoors except with a lot of people. The stage was probably a mistake. With the small friendly crowd Elon could have even walked house to house and talked about each type of roof.
They will probably talk about the new charger when they unveil new powerwall/home software. Currently Elon probably doesn't want to talk about another piece of unavailable software. The short term goal is to get through the SCTY merger.
Actually, that was the entire context of the argument. Shear loads from roof weight during earthquakes. Original post for reference.
Sparky
Member
Yeah, I know.
I was standing in front of one of the houses (Tuscan roof I think) and asking how those tiles are interconnected and brought into the Powerwall.
1) I made the comment that according to the other engineer I spoke to, "since the Powerwall takes in DC; this system must be interconnected with some pre-defined series/parallel formula, How do you handle the interconnects between tiles?" The response was along the lines of "that's still under evaluation". I then asked "so currently you don't have a way to hook up this roof and make it function?" Unfortunately, when I asked that some guy the SCity engineer knew came up and said "hi" and I never got an answer.
2) I also asked the Powerwall engineer if I would be able to DC charge my Tesla with it. He said that's not part of the feature set. I said, "Yeah I know Tesla isn't real big on homeowner DC or V2G". He said, well actually it is something JB is interested in but hasn't moved on it yet.
Maybe I'm reading too much into this but this event was very quickly thrown together IMHO. Seemingly just a tasty morsel for the merger vote. The 3M guys commented that it was kind of fun to get thrown into a project where they had only 2-3 weeks to build the solution and integrate it into a product. It only came about because of a "CEO-CEO interaction". They were amazed how fast the roofs were put together since, up until the last minute, it hadn't been decided where the event would be held.
As someone else commented earlier, this event was much more about solar roof aesthetics than technology. Granted there's some serious tech behind the aesthetics but Elon's comments were clearly directed towards how to get a major chunk of the 4million new roofs per year to go solar. I tend to get down in the weeds with the engineering but he sees this stuff from the perspective of overcoming obstacles to every roof is an energy generator. That's all this event was about. If you want a great looking solar roof or can only put one on your house if the HOA approves it, buy a Tesla roof. Gee, "Tesla roof". That sounds weird.
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The cynic in me agrees.
I do appreciate the Powerwall 2 update, though - that's substantive.
Garlan Garner
Banned
I suppose when we talk about roof loads here in the north we are talking about snow weight loads. Actual measurements of weight. 24" of snow weighs a LOT. That's the default of the conversation here because we don't have earthquakes here. 40 years here....I've never felt one.
I work for a phone company and whenever we talk about California concerning earthquakes....we use the term "structural rigidity " or simply "earthquake proof".
Garlan Garner
Banned
Hmmm....good question.
I'm thinking that since these solar tiles are actually a part of the house...they will be warmer than the solar panels I use which sit 3 inches off of the shingles. Of course....my roof is 33.3 degrees and snow has a difficult time sticking to that grade. I also have another part of my roof that is 22 degrees and snow loves to sit on those panels. I heated those panels though because snow collects and sits on those for weeks.
I wonder if Teslas tiles will absorb heat from my house as my shingles do. Because I have solar panels - many days I am the only one with snow on my roof ( solar panels ) in the morning. Other homes in my neighborhood are clear of all snows on the roof by the time the sun comes up.
However when the sun catches even a small corner of my panels....the now is melted off (evaporated) in about 40 min - Even at 10 degrees F.
If I can purchase the tiles individually I will simply because I'm interested in how they will function.
Ulmo
Active Member
As a thought exercise, consider the additional distributed weight on the structure from solar panels (or multiple people, or heavier roofing (or ... other things*)) compared to the concentrated pressure of one person (walking or not) distributed through the structural members. Although each has its own structural effect, the single person can be weight distributed across many structural members. Their load capacity is not simply the one or two pieces directly at the person's feet; it's a system of structural members which can take and transmit the loads.
Although not directly about homes, I have an example of how seemingly small things can be structural members in a system supporting things far away. In carpentry class, one of the test questions is "What is the most important structural element in a tilt up?" (Tilt ups are (often large multistory) rebar reinforced concrete walls formed on the ground laying down, then tilted up into place, these days by various cranes or similar.) Answer: the nail. (The roof holds the roof and walls together, and the roof is composed of sheets attached by nails to horizontal members (which are often on columns inside in addition to the concrete walls). Take out the nails in those sheets, and the entire building falls down (usually with a little wind in an opportune direction); insufficient amount of strength is being transmitted without the nails in the wooden sheets.)
This solar roof is an engineering CEO's dream job.
* wind, dust, water, vegetation, soot, animals, birds, insects (especially insects, since wasps' nests can weigh tons (and have caused structural failures)), earthquakes, other member failures (termites, rot, corrosion, rust, fire, freeze damage, etc.), helicopters, etc.
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Garlan Garner
Banned
Solar panels are far lighter than shingles. Most roofs can handle 2 layers of shingles.
Ulmo
Active Member
I think Tesla is dealing with connecting solar roof shingles and connecting super chargers to cars, and soon, they may have very good connection engineers in their engineering departments, maybe making some new connection invention.
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