207kWh System... In 12V??? 😬

[MattiFin]

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

The 2 first calculators I used are for "simply supported beam" with support on both ends so PL^3/48EI.
Thus cantilever beam has 2x deflection compared to simply supported beam with 2x span.

I throw the 2 first calculators just to trying to wake you up that you or ghatGPT made gross error somewhere.
Like I wrote: "beam supported from both ends but you get the idea:"

 

[Dagoth Ur Does Solar]

I wonder who the people are in the comments defending the choice...

 

[jonasgranlund]

The 2 first calculators I used are for "simply supported beam" with support on both ends so PL^3/48EI.
Thus cantilever beam has 2x deflection compared to simply supported beam with 2x span.

I throw the 2 first calculators just to trying to wake you up that you or ghatGPT made gross error somewhere.
Like I wrote: "beam supported from both ends but you get the idea:"

You used the wrong case then, it would be major problem if the solar structure was free to rotate around its own axis and also if both edge of the beam could rotate on your bridge example,
But do you agree that if you have two cases where the beam is fixed in one end and one where it is fixed in both ends you can make it 4 times longer to get the same deflection? So instead of a 6m standing beam with 3500kg force you can have a bridge of 24m and put the 3500kg on the middle to get the same deflection?

And what was wrong with my calculation about this: if 30 square meter solar panels was abused by a 150mph hurricane will the 6m HEB 600 beam fluctuate 6mm in each direction and if it is a HEB300 it will move around +-30mm. I saw so many different comments and calculations about all kinds of other things, but how many mm did you come up with in this exact case, I think it is good if we talk about the same thing.

I was unnecessary harsh on Monday evening and I'm sorry about that.

 

[jonasgranlund]

I wonder who the people are in the comments defending the choice...

I really hope you don't see me as a defender of the system,
I was merely pointing out that I would call it a 48V system.
In my system my base is a 16s1P with internal BMU to have it as a 48V battery. But I have 6 of those 48V "batteries" that are connected in Series with a central BMS, and I call my battery a 288V battery and not a 48V battery.

I also see the difference that in this system there is no way for a central BMS to balance between the 12V batteries, not to mention that it is an extremely expensive solution. So I am definitely not a fan. In my on the back of the napkin math I would go from 12V to 48V if I needed more than 2,5kW and from 48V to a high volt system if I needed more than 10kW in continuous power.

 

[Michelle Konzack]

I just came across this thread and I must say: US-American prices.

I am Victron/Fronius installer in Estonia and just wait for the outcome of a Lawsuit my (potential) customer filed against the Grid provider for fraud, because my customer has a Grid Connection 400V 3-Phase with 500A, but can use only the half because the GridProvider has connected too many private housholds on the power line.

The Investment for a bigger MAIN transformator is roughly 5,6mio Euro.

However, we proposed that the Grid provider take over the costs for a Battery Solar and Wind powered solution which contain:

12 Victron Quatro 48/15000/200/100-100
Ekrano GX
8 sets of SOPzS Batteries 4350Ah/48V (1600kWh in total)
6 Victron SmartSolar MPPT RS450/200-Tr (each 2 Strings with 9x 550Wp)
3 Fronius 20kW (each 36x 550Wp)

which cost roughly 350.000€ SIGH!

Compared to the 150k USD from the Video... I say only Oops!


Since the guy need anyway a heated house, he can simply install a SOPzS Batteries with 4350Ah (200kWh and 160kWh @20C) for just 18.000€.
For the 150k USD I would have installed him 4 of thoses sets and 4-5 Victron RS450/200.

Then he can have parties as long as he want.

Oh, my customer has already the permission, to install 2 Windmills (I do not know, what this two monsters cost) with 40kW each...
...and we want to couple them ACout of the Quatros, that we can have even in a total power cut energy.

Oh, 12 Quatro Inverter are 144kW or 180kVA, while the Windmills and Fronius have together maximal 140kW output.

Also my customer has the right to feed-in 250A (100kW).

This will be definitively the biggest private installation in whole Estonia.


We estimated, that with a second set of Victron Quatro Inverters and more Solarpower he can go probably Off-the-Grid, since in Winter the work in the enterprise is reduced to roughly 25-30%, hence the daily power consumption of 1100kWh will be reduced to 300-400kWh roughly


Mean, 4-5 days working on Batteries!

 

[MattiFin]

You used the wrong case then, it would be major problem if the solar structure was free to rotate around its own axis and also if both edge of the beam could rotate on your bridge example,
But do you agree that if you have two cases where the beam is fixed in one end and one where it is fixed in both ends you can make it 4 times longer to get the same deflection? So instead of a 6m standing beam with 3500kg force you can have a bridge of 24m and put the 3500kg on the middle to get the same deflection?

Depends what you mean by fixed from ends.
If it has moment(torque) support both ends but floats axially?
If both ends are fixed for both moment and axial movement it works mostly like cable and deflection is something else.
Lazy to work out the numbers as both cases get bit more complex and are even less relevant than HEB600 for solar panel support

And what was wrong with my calculation about this: if 30 square meter solar panels was abused by a 150mph hurricane will the 6m HEB 600 beam fluctuate 6mm in each direction and if it is a HEB300 it will move around +-30mm. I saw so many different comments and calculations about all kinds of other things, but how many mm did you come up with in this exact case, I think it is good if we talk about the same thing.

I was unnecessary harsh on Monday evening and I'm sorry about that.

34.3kN load on HEB600 cantilever beam at 6m gives 6.9mm deflection so I think your number matches close enough on that.

---
for stresses:
Even better yet on closer look dlubal website seem to give "Plastic limiting bending moment" already, so no need for calculator.

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

1510.13 kNm / 6m = 251 kN or abouts 25 tons on 6m HEB600 beam supported from one end before the structure will yield totally and fail.
My crude "back of the envelope" calculation was 320 kN and for me(EE) that is sufficient level of accuracy. At least its not off by a factor of 10

IMO applying 1/100 or 1/500 or any arbitrary deflection is not really relevant, we are happy if our silly math example survives the hurricane.
Same goes for safety factors, once in a lifetime hurricane won't need same safety factors on design as elevator full of people.

 

[upnorthandpersonal]

8 sets of SOPzS Batteries

Why lead acid? You can get LFP even here in Europe for 80Euro/kWh cell price. And you wouldn't have to worry about 50% discharge etc.

 

[Michelle Konzack]

Why lead acid? You can get LFP even here in Europe for 80Euro/kWh cell price. And you wouldn't have to worry about 50% discharge etc.

How do you use LiFePO4 Batteries in a country where temperatures can go down to -42C and your installed underfloor Heating System can not get it above -10C?

ANY Lithium based Batteries can not be charged in MINUS temperatures.

Also, how should I design a system, where I have a 12kW 24V Motor installed?
I have for testing a 64 cells EVE 304Ah (= 51,2V with 1216Ah) with 4 JK BMS 250A here which I wan to install in my UAZ Buchanka 4x4 using a 20kW GoldenMotor, has cost me roughly 6400€ including shipping to Estonia, but they create problems in mass. I have put them into the same Battery Room where I have my 2000kg SOPzS Batteries, hence they are under the same conditions, but at -29C outside just 2 month ago and roughly -3C in the Battery Room, all 4 BMS have shut down.

LeFePO4 Cells are the worst ever!

 

[Michelle Konzack]

Why lead acid? You can get LFP even here in Europe for 80Euro/kWh cell price. And you wouldn't have to worry about 50% discharge etc.

80€/kWh?

plus shipping to Estonia result in 6400€ for the 62,kWh. (I bought them from the Netherlands because in Estonia they are 30€ more expensive)

 

[Michelle Konzack]

How do you use LiFePO4 Batteries in a country where temperatures can go down to -42C and your installed underfloor Heating System can not get it above -10C?

ANY Lithium based Batteries can not be charged in MINUS temperatures.

Also, how should I design a system, where I have a 12kW 24V Motor installed?
I have for testing a 64 cells EVE 304Ah (= 51,2V with 1216Ah) with 4 JK BMS 250A here which I wan to install in my UAZ Buchanka 4x4 using a 20kW GoldenMotor, has cost me roughly 6400€ including shipping to Estonia, but they create problems in mass. I have put them into the same Battery Room where I have my 2000kg SOPzS Batteries, hence they are under the same conditions, but at -29C outside just 2 month ago and roughly -3C in the Battery Room, all 4 BMS have shut down.

LeFePO4 Cells are the worst ever!

Forgot one thing:

I bought my 48 SOPzS Cells in 2018 and have payed 8000€. LiFePO4 Cells where nearly 4 times more expensive.
Currently the price for the 70,5kW is at 10500€ and they support without any problems a load of 1600A while the EVE cells have problems giving me 800A which I need for a peak of the 20kW Motor.

Oh the charger is a MultiPlus-II 48/15000 which allow me the charging from a 230V 32A CEE Socket and support my Electric tools if needed.

Also my Wind Chargers can only charge Acid Batteries.

 

[upnorthandpersonal]

How do you use LiFePO4 Batteries in a country where temperatures can go down to -42C and your installed underfloor Heating System can not get it above -10C?

I'm at 63 degrees north in Finland with 100kWh of LFP powering my off-grid house. You put them in an insulated box with a small 7W heater on a thermostat. We were at -34C in January.

 

[upnorthandpersonal]

80€/kWh?

Yeah, or even lower (71 Euro for Envision cells). Shipping from The Netherland to Finland is a few hundred Euro.

 

[upnorthandpersonal]

Currently the price for the 70,5kW is at 10500€

Of which you can use 50%, so 35kWh. That same 35kWh LFP costs me 2800 Euro in cells now.

 

[Michelle Konzack]

Why lead acid? You can get LFP even here in Europe for 80Euro/kWh cell price. And you wouldn't have to worry about 50% discharge etc.

Another thing is cabling!
If I need 1280kWh of usable energy, how do you make the Power rails?

The biggest 16S BMS I found is 500A.
12 Quatro Inverter can produce a load of 3750A without using the overload capability.
This mean I would need 8 BMS/BatterySets in parallel 11p16s?
How you you manage 1408 cells?

It is simply physical not possible

The SOPzS Cells have 4 poles hence I can use four 70mm2 Welding Cables (for PLUS and MINUS) Which mean, I need a power raill which support 32 connections for the Batteries, and in between (for balancing the load, see Wiring Unlimited) the 24 cables for the Quatros and 6 cables for the RS450/200

With the LiFePO4 Cells, the Cables would be much longer and and I do not know, how to get so high current over a distance of 5-8m out even if I use the bigger 120mm2 cables, I will run into a problem because two 120mm2 do not support the same current as the four 70mm2 it is nearly 30% lesser, because the bigger cable support lesser Amperes per square mm.

Hence designing a huge Industrial grade system is a real challange

 

[upnorthandpersonal]

The biggest 16S BMS I found is 500A.
12 Quatro Inverter can produce a load of 3750A without using the overload capability.

So simply put 8 packs (16 cells each, even say 15kWh each) in parallel. That's 4000A of current, and 120kWh of storage.

If I need 1280kWh of usable energy, how do you make the Power rails?

Energy and ability to supply current are not the same. Above I gave you 120kWh that can supply that current. Multiply the set-up by 10 to get 1200 kWh.

Or go higher voltage.

 

[upnorthandpersonal]

It is simply physical not possible

The 1MWh container made with LFP cells my lab just bought, with an ability to provide 200kW power output, tells me otherwise.

 

[740GLE]

For every problem there’s a solution, if you don’t see it yourself, just gotta ask around.

 

[Dave911]

Another thing is cabling!
If I need 1280kWh of usable energy, how do you make the Power rails?

The biggest 16S BMS I found is 500A.
12 Quatro Inverter can produce a load of 3750A without using the overload capability.
This mean I would need 8 BMS/BatterySets in parallel 11p16s?
How you you manage 1408 cells?

It is simply physical not possible

The SOPzS Cells have 4 poles hence I can use four 70mm2 Welding Cables (for PLUS and MINUS) Which mean, I need a power raill which support 32 connections for the Batteries, and in between (for balancing the load, see Wiring Unlimited) the 24 cables for the Quatros and 6 cables for the RS450/200

With the LiFePO4 Cells, the Cables would be much longer and and I do not know, how to get so high current over a distance of 5-8m out even if I use the bigger 120mm2 cables, I will run into a problem because two 120mm2 do not support the same current as the four 70mm2 it is nearly 30% lesser, because the bigger cable support lesser Amperes per square mm.

Hence designing a huge Industrial grade system is a real challange

Why are you trying to buss all the dc together at low voltage?
That doesn't make sense. Way too many amps. Huge amounts of copper. You want a higher voltage DC system. Id shoot for 300+ volts.
If your trying to control a large DC motor why is it 24 volts? You'd be better of going with an industrial inverter that takes in DC and outputs variable frequency AC. Then use a cheap to maintain AC motor with variable speed. The industrial companies, Siemens, ABB can supply you with an appropriate drive that can do this. The Siemens S120 system should be able to do that.

 

[Bop]

Rather than going the 'dozens of little 'batteries' tied together, do what I do- use a single series string of appropriately sized cells for the job...
The company that make my 400Ah LYP cells make them in single 3.4v LYP lithium cells, running from a tiny 40Ah, up to a huge 10000Ah single cell!!!
(plus LYP has an operating temperature of -45C to 85C)
A single string of 16s 10000Ah cells is a ridiculous half a megawatt-hour of storage in just a single 48v nominal 16s string (544000Wh or 544kWh)- with a continuous discharge of up to 10000A, and a peak impulse current of up to 200000A... (although I wouldn't even think of using a '48v' system for that size, commercial inverters and solar systems getting into that range are readily available in the hundreds of volts DC range, and here in Australia, 48v is left for pretty much the 'weekender cabin' stuff, with most offgrid house installs running at 96v (or even higher)...

So yes, there are lithium cells that can run down to the temperatures you described...
(We don't get low temps like that here in Australia, but LFP also doesn't like heat, with about 40-45C being their limit for charging at full power, and only up to 60C even at reduced power...
Where I live it regularly exceeds 43-45C for weeks on end in summer, and other places get far higher...

At those temps, both L/A and LFP suffer badly...

At these power levels, I'd suggest biting the bullet and get it done by a professional that knows what they are doing... any system of this power has a LOT of room for making mistakes, and a beginner can destroy hundreds of thousands of dollars worth of equipment (and possibly even an entire building) in very little time because they simple aren't trained to handle these power levels...
Even most trained electricians would back away unless they were trained in dealing with them...

 

[jonasgranlund]

Depends what you mean by fixed from ends.
If it has moment(torque) support both ends but floats axially?
If both ends are fixed for both moment and axial movement it works mostly like cable and deflection is something else.
Lazy to work out the numbers as both cases get bit more complex and are even less relevant than HEB600 for solar panel support

34.3kN load on HEB600 cantilever beam at 6m gives 6.9mm deflection so I think your number matches close enough on that.

---
for stresses:
Even better yet on closer look dlubal website seem to give "Plastic limiting bending moment" already, so no need for calculator.

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

1510.13 kNm / 6m = 251 kN or abouts 25 tons on 6m HEB600 beam supported from one end before the structure will yield totally and fail.
My crude "back of the envelope" calculation was 320 kN and for me(EE) that is sufficient level of accuracy. At least its not off by a factor of 10

IMO applying 1/100 or 1/500 or any arbitrary deflection is not really relevant, we are happy if our silly math example survives the hurricane.
Same goes for safety factors, once in a lifetime hurricane won't need same safety factors on design as elevator full of people.

If you were talking about a bridge (as you were) they are fixed in both ends, at least the one that are constructed with beams. But good, then we came to the same conclusion, a 6m HEB 600 will fluctuate 12mm end to end, no one have talking about the structure to yeild and fail, I dont think that anyone can have taken my first recommendation as if it was close to fall apart, in all construction you have a recommended amount of mm per meter that you can allow the structure to move as I'm sure you know. And I don't remember what I said but I think it was L/500 so if you just would have looked at that comment you maybe even wouldn't have started to complain about my recomendation. Or you could have said: "for me it is more than ok if the solar panels are swaying 100mm so a HEB200 would have been enough at my setup."

But you mentioned HEB 60 as a good size and now when you have calculated a bit more on it I'm sure that you would prefer a HEB 600 in front of a HEB 60 at these extreme weather conditions