207kWh System... In 12V??? 😬

[MattiFin]

Hi, Im not sure about your background but I am a mechanical engineer and have constructed all kind random products for a profession. I'm sorry to say but a HEB600 by itself would never ever be used for a tall bridge You usually have either massive towers with wires helping with the support between towers or you use a structure below road surface so the total thickness of the surface below the car is way more than 600mm. I dont have Inventor on this Computer so I didnt do a FEM analysis myself, Ijust calculated with E module as 2.1x10^5 which is common for normal steel and used Eulers case with 1 fixed point and the second free hanging. If you show me your calculation I guess we can see where it has been wrong. But the whole area of the thing blowing with a pressure of +110kg/sqm will be 2.4x2x6x110 = 3200kg and to simplify you can put that as one force on middle of beam = 3m up on the beam. And you can load it some more before plastic deformation occur but not much and the HEB 500 will not handle the +3000kg load. Can you show your calculation and we can compare?

Small bridge is not same as tall bridge
Different sort of engineer (EE-ish) here but can calculate enough to tell that HEB600 is not going to bend by couple solar panels.
I did my crude calculation from HEB600 flange dimensions, flange distance and calculated tensile stress in the beam flange.
30x300mm flange, S355 steel gives us 3195 kN tensile yield strength for the flange. Distance from flange to flange is abouts 600mm and assuming that the flange handles 100% of the load and web is just dead weight.
600mm distance from flange to flange and 6000 mm beam length gives nice round 1:10 ratio on lever arms and torque.
320kN at 6m is 1920 kNm, with 0.6m meters between the flanges it translates to 1920 kNm/0.6m=3200 kN tensile stress on beam flange.

Just to make sure that we are talking about same HEB600 here:

https://www.dlubal.com/en/cross-section-properties/heb-600-euronorm-53-62-din-1025-2-szs

If you mixed up HEB600 and HEB60 I'd buy it but then on the other hand I hope I don't cross too many bridges that are your design.

 

[Watts Happening]

This is what you get when you pick the wrong installer.

Believe it or not, I know the installer. I control the network for that home in the video.

I wired his RV probably 5 years ago, he was totally green in the field. He still calls with questions.

I can all but guarantee you the batteries were heavily subsidized by Battle Born. I can’t believe the route they went, not something I’d have done at all.

But I’m sure someone in marketing thought it was a great idea. I’ve worked with them on projects in the past, we’re now to a point it’s hard to argue the cost difference. I do however appreciate them bringing jobs and work to our area. They’ve always been nice folks.

 

[Watts Happening]

Holy cow, where do we start...

$149,000 of batteries... are they unaware of other options on the market today? 12V batteries in series? Yikes...

Again I know the installer, a lack of experience tied with “likely heavily reduced pricing” for that project to be used in marketing, equals what you see.

BB simply doesn’t offer anything in 48v, I’ve spoken to them many times face to face about entering that market, it doesn’t seem to be a priority. I wouldn’t be surprised if the batteries weren’t top balanced.

Scariest thing to me is that he’s not a licensed contractor in NV, let alone CA. I’m sure most of the work was outsourced, but damn, not something I’d put out on the internet for prying eyes.

 

[jonasgranlund]

Small bridge is not same as tall bridge
Different sort of engineer (EE-ish) here but can calculate enough to tell that HEB600 is not going to bend by couple solar panels.
I did my crude calculation from HEB600 flange dimensions, flange distance and calculated tensile stress in the beam flange.
30x300mm flange, S355 steel gives us 3195 kN tensile yield strength for the flange. Distance from flange to flange is abouts 600mm and assuming that the flange handles 100% of the load and web is just dead weight.
600mm distance from flange to flange and 6000 mm beam length gives nice round 1:10 ratio on lever arms and torque.
320kN at 6m is 1920 kNm, with 0.6m meters between the flanges it translates to 1920 kNm/0.6m=3200 kN tensile stress on beam flange.

Just to make sure that we are talking about same HEB600 here:

https://www.dlubal.com/en/cross-section-properties/heb-600-euronorm-53-62-din-1025-2-szs

If you mixed up HEB600 and HEB60 I'd buy it but then on the other hand I hope I don't cross too many bridges that are your design.

I asked Chat GPT and he came to similar solution, at 3000KG 6m out of a HEB 600 will plastic deformation occur (that is 2 random smaller cars at edge of beam). I have no idea how you can think it would hold for 32000kg (320kN) when one edge i free in the air. You have probbably made a 10x error somewhere along the way, maybe you saw the Moment of Inertia at cm4 and didnt change or something. Also in my second post I just commented clearly that the top row alone will push with over 600kg (closer to 700kg at 150mph), there are 4 more rows of panels in the setup so total evenly distributed will be well over 3000kg, but the further towards top the larger bending moment it will create obviously

 

[MattiFin]

I asked Chat GPT and he came to similar solution, at 3000KG 6m out of a HEB 600 will plastic deformation occur (that is 2 random smaller cars at edge of beam). I have no idea how you can think it would hold for 32000kg (320kN) when one edge i free in the air. You have probbably made a 10x error somewhere along the way, maybe you saw the Moment of Inertia at cm4 and didnt change or something. Also in my second post I just commented clearly that the top row alone will push with over 600kg (closer to 700kg at 150mph), there are 4 more rows of panels in the setup so total evenly distributed will be well over 3000kg, but the further towards top the larger bending moment it will create obviously

beam supported from both ends but you get the idea:

Beam deflection and stress calculator

sunsetpatios.com.au

12m span 610UB125 beam supported from both ends and 36 000kg load on middle: The total maximum stress in the beam: 342 MPa

Single span beam (IPN / IPE / IPB / HEA / HEB / HEM)

12m span HE600B σ0.5L outer fibre: 197 MPa

and third one for beam supported from one end:

Bending Stress Calculator

Use this bending stress calculator to help you find the bending stress on a beam of any typical cross-section and dimensions, given the bending moment it experiences.

www.omnicalculator.com

HEB600 beam, 1920000Nm bending moment and we get 350MPa bending stress. Close enough to my initial calculation.

 

[MattiFin]

Bending Stress Calculator

Use this bending stress calculator to help you find the bending stress on a beam of any typical cross-section and dimensions, given the bending moment it experiences.

www.omnicalculator.com

 

[jonasgranlund]

beam supported from both ends but you get the idea:

Beam deflection and stress calculator

sunsetpatios.com.au

12m span 610UB125 beam supported from both ends and 36 000kg load on middle: The total maximum stress in the beam: 342 MPa

Single span beam (IPN / IPE / IPB / HEA / HEB / HEM)

12m span HE600B σ0.5L outer fibre: 197 MPa

and third one for beam supported from one end:

Bending Stress Calculator

Use this bending stress calculator to help you find the bending stress on a beam of any typical cross-section and dimensions, given the bending moment it experiences.

www.omnicalculator.com

HEB600 beam, 1920000Nm bending moment and we get 350MPa bending stress. Close enough to my initial calculation.
View attachment 210718

What are you talking about, the beam is obviously only supported on the ground, do you think it is some kind of invisible thing at the top of the tower holding it fixed in that edge too? :D Do you know how big difference it would be if the beam actually was supported at the top of Solar tower also? Try it again but as free hanging in one end and fixed in th other, then you get a bit closer to reality. Edit: I see now that you also calculated with free in one edge (I have no Idea why you would mention supported from both ends when that is a totally different case and handle an insane amount of more force before deflekting the same. Usually it is good to calculate a deflection of L/360 and ifyou want it really stiff L/500. with my 3 ton it will be a deflection of around L/500.
Since you know the beam you already have the moment of Inertia, it is 171040 cm^4 so their is no need of calculating that part since all the small radious also make a difference. Also 350MPa is way to much for normal steel, you should keep it around half of that if you want to be sure of no plastic deformation.

But I dont think we get further than this. a final conclution from me is that a 6m high tower that will have a surface of 30 square meter evenly along the 6m need to be a HEB 600 Beam to be sure not to be deflekted, and as a HEB with the full force it will deflect around 8mm and with going down to a HEB 500 it will deflect around 12mm and with a HEB 300 it will deflect 30mm. So if you think it is ok in your scenario that it deflect 30mm on you go for a HEB 300, but the HEB60 that you mentioned will be along the ground before it start to blow

 

[Zwy]

This is a really neat setup, especially with bifacial for the sonw to beam in from all angles. But if we calculate with a large sized panel of 1300x2400 it will be an insane power at the shaft/Beam If the beam is mounted in strongest direction perpendicular to the panels and the force will be around 100-120kg/sqm. You are looking at a single HEB 600 to manage the wind force with tolerance and without any plastic deformation. What beam is it right now?

The beams on my current MT Solar mount with 16 530W panels is 4x6 with 3/16" flange and beam and is referred to as SD, Standard Duty. The array is 34 feet long, panels are mounted landscape in a 4x4 pattern.

The larger used arrays have 4x8 with 3/16" thickness. Those are referred to as HD, Heavy Duty.

MT Solar makes these in 7.5 foot lengths and you end up with 15 feet between poles. The 7.5 foot length is so it can be shipped on a pallet. If you can source beam in one piece for the length you need for the arrays, it would work better. MT welds a flange on the end with some tolerance and so you have to run a string line and there are set screw adjusters to adjust the space top and bottom of the flange to make a straight assembly.

There is a XHD, Extra Heavy Duty and I believe it is a 4x10 beam.

I have been thinking of building a 10m long fence with bifacial pointing east/west to get some moringin evening power and also extra power during winter when beaming from snow, but I think this is a better idea, with a tower. But the vertical beam need to be very powerful as shown above.

Rails on used mounts were Ironridge. Later years went to Tamarack. The array I purchased new was Tamarack. I prefer the Tamarack but the Iron Ridge works fine. The Iron Ridge are the XR1000 rail.

Poles on my 16 panel array are 6" SCH80. The used mounts will be 8" SCH40. I ran the numbers thru the MT Solar calculator and the 8" SCH40 will work fine. Poles are 8.5 feet in the ground with a 36" diameter hole filled with concrete to ground level. Takes less than 3 yards to fill a hole if I remember right.

I did a review on the MT Solar mount, the link is also in my signature below.

Go to the MT Solar site and use the calculator tool for determining dimensions, pole size, and whether it needs to be SD, HD or XHD.

 

[Zwy]

600 kg load is a lot but you were talking about frikking HEB 600. You would use something that size to build small bridges for 60 ton semis!
6 m tower built from HEB600 can handle around 320kN wind load at the 6 meter lever arm. 600 kg is only 6 kN

6 meter section of HEB600 alone would weight around 1300kg, that aint fly very far even in windy weather.

HB600 would be slight overkill for this application.

MT Solar mounts are designed for rated wind for the area, here it is 105 mph.

 

[MattiFin]

What are you talking about, the beam is obviously only supported on the ground, do you think it is some kind of invisible thing at the top of the tower holding it fixed in that edge too? :D Do you know how big difference it would be if the beam actually was supported at the top of Solar tower also? Try it again but as free hanging in one end and fixed in th other, then you get a bit closer to reality.

Did you bother to read? Cases with support on both ends were for 12m beam making it similar-ish to 6 meter beam fixed from one end.
Also the last link was for beam supported from one end.

Mechanical engineer…

 

[jonasgranlund]

Did you bother to read? Cases with support on both ends were for 12m beam making it similar-ish to 6 meter beam fixed from one end.
Also the last link was for beam supported from one end.

Mechanical engineer…

I added an edit after the text, I dont understand why you discussed something totally different then the load case here, but I saw that your last case came closer to what we are discussing

 

[jonasgranlund]

Did you bother to read? Cases with support on both ends were for 12m beam making it similar-ish to 6 meter beam fixed from one end.
Also the last link was for beam supported from one end.

Mechanical engineer…

Hehe, so you say that if you fix both ends to a wall it will be the same thing when you double the length? And then complain about me being a mechanical engineer? It is far from the same thing... In one case with 1 edge free the formula for deflection is PL^3/(3EI) and where it is 2 fixed edges the formula for deflection is: PL^3/192EI So what you basically are saying with your comment that double length of beam will compensate for that one edge i free means that you think that 2^3 makes up for the 192/3, but 2^3 = 8 and 192/3 = 64 so you are waaaay off. However 4x4x4 = 64, so if you make your beam 24 meters instead it will actually be really close, atleast up to when deformation start to occur.

Can you explain how you calculated when you came to the conclusion that double length and 2 fixed edges give the same deformation?

P = Force at edge of beam when free and at middle when beam is 2 times longer so still 6m from the edge.
L = length of beam

 

[robbob2112]

I asked Chat GPT and he came to similar solution, at 3000KG 6m out of a HEB 600 will plastic deformation occur (that is 2 random smaller cars at edge of beam). I have no idea how you can think it would hold for 32000kg (320kN) when one edge i free in the air. You have probbably made a 10x error somewhere along the way, maybe you saw the Moment of Inertia at cm4 and didnt change or something. Also in my second post I just commented clearly that the top row alone will push with over 600kg (closer to 700kg at 150mph), there are 4 more rows of panels in the setup so total evenly distributed will be well over 3000kg, but the further towards top the larger bending moment it will create obviously

Having used chatgpt since it was released one thing I can say for certain is everything it says should be verified. Another thing I can say is that it is lousy at math, especially if there is any sort of unit conversion. I tend to think of it as as an eager 10 year old who is certain they are right, but is absolutely wrong.

 

[jonasgranlund]

Having used chatgpt since it was released one thing I can say for certain is everything it says should be verified. Another thing I can say is that it is lousy at math, especially if there is any sort of unit conversion. I tend to think of it as as an eager 10 year old who is certain they are right, but is absolutely wrong.

Since it came to same conclusion as me I think it is a good safety check, but I agree, I use both Grok and Chat GPT quite a bit when programming and it is far from accurate all the time

 

[Watts Happening]

Anyone else take issue to the “400 amps” claim?

 

[timselectric]

Anyone else take issue to the “400 amps” claim?

That's combining the inverters with the generator.
It didn't benefit their story to explain that part.

 

[robbob2112]

Since it came to same conclusion as me I think it is a good safety check, but I agree, I use both Grok and Chat GPT quite a bit when programming and it is far from accurate all the time

And it is a hundred times better at helping with programming than bingchat. That stupid thing gets it wrong then flips between 2 wrong answers

 

[Hedges]

Hehe, so you say that if you fix both ends to a wall it will be the same thing when you double the length? And then complain about me being a mechanical engineer? It is far from the same thing... In one case with 1 edge free the formula for deflection is PL^3/(3EI) and where it is 2 fixed edges the formula for deflection is: PL^3/192EI ...

Can you explain how you calculated when you came to the conclusion that double length and 2 fixed edges give the same deformation?

Yes, it should be clear that a beam supported at only one end will have the other end rotated downward, while double length beam supported at both ends is more like the single beam with end fixed horizontal, unable to rotate downward.

At some level of force it will be more like a cable, under tension (if the restraints on the ends can hold it back) but we aren't anywhere close to that yet.

 

[Watts Happening]

That's combining the inverters with the generator.
It didn't benefit their story to explain that part.

Of course, I had talked to him about that originally, it seems to have been skipped over.

 

[ksmithaz1]

I'm designing my refresh to scale up to 200KWH of batteries if desired. It would be 4 racks of 10 51.2x100AH. About $13K for a 50KWH in a nice standard equipment rack, capable of running in closed loops with 10-20 batteries in each loop. There was another thread on 12x4 vs 3x16. I mean before I would start rolling out busses and harnesses at this scale in a dedicated space with a bunch of 12v batteries, I would have engineered for some standard 3v x 280/300AH prismatic's built out custom shelving, mounts, and trays, or just gone for standard equipment racked gear. It's like doing a bunch of DIY work, and then still spending almost as much as if you would if you would have just grabbed 4 racks of pre-made 48v units. Makes no sense. I made it complex, with a generally inferior overall design but at least I spent as much as I would have just buying rack mount units to begin with, while making it look like I rolled my own thing.