now i dont get much?! BUT

[100kwh-hunter]

I see no mention of your solar charging power but the 20 amp controllers seem a little small for this much battery. Can you describe your solar array, solar panel specs and how you have it wired?

The panels on the south west roof: 6* 100wp 34,4v and 2.9A connected in 70v * 3
The panels on the east south roof are the same.
I am planning to put them all in one controller.
The reason for this is that from the local goverment i could not put all the panels on my south west roof(monumental state house).
So i had to place the other six some where else, but connecting them to one charge controller i think that can be done, all panels have diode's

I bought last week 12 panels 88v each and 2.6a 165wp.
So for this set i am 1 controller short.

I am currently building up btw, the first set of 12 100wp/34,4v i bought last year and are on the roof for just a month now.

Thanks in advance.

​

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[OffGridForGood]

Three levels of protection for the cells:
Think of the Inverter/charger settings as "normal day to day range of battery voltages/currents. Daily cycles.
Think of the BMS settings like a protection system in case the above fail, or a single cell 'runs away' in voltage from all others.
Think of the Fuses as the final measure - all else has failed or can't control the current flow -ultimate protection.

 

[HarryN]

In a perfect world, the solar power being captured would be roughly at the same time as the power being consumed.

When solar panels were expensive and really no one had battery packs, then people were encouraged to mount panels to produce maximum total power and just dump it into the grid.

Now that solar panels are relatively inexpensive, and people have large battery packs, consider to think about having solar panels positioned to capture sunlight during 3 times of day:
- Morning ~ 8 or 9 am
- Mid day - conventional positioning ~ 1 - 2 pm
- As late in the day as possible - 6 pm

The morning positioning helps with breakfast and recharging from the long night of no solar power.

The late afternoon panels help cover what is often the largest power usage time for many homes, as well as charge up the batteries as much as possible so that they are ready for the long night period.

 

[DougfromdaUP]

Start by setting your high voltage disconnect at 3.55V per cell or so - 3.3V is nowhere near charged. Remember the charge curve:

Also, stop worrying about DOD as such. Put a high voltage protection at 3.55V, low voltage at 3.0V and call it a day. So for a 16s pack that's 56.8V at the high side, and 48V at the low side.

This is a great resource! Do you have the dataset, or maybe curves for other cells?

 

[upnorthandpersonal]

I think Andy from @Off-Grid-Garage has a few on his website: https://off-grid-garage.com/battery-data/

 

[TorC]

In a perfect world, the solar power being captured would be roughly at the same time as the power being consumed.
...snip...

Now that solar panels are relatively inexpensive, and people have large battery packs, consider to think about having solar panels positioned to capture sunlight during 3 times of day:
...snip

In a grid-tie situation I believe this does help. However, my calculations indicate that, with a reasonable battery bank and PV array size, there's plenty of power on days when you get the most benefit from this. The days when you're running short on power are the cloudy ones, and it's total input to the system, not time of input that matters most. I concluded that for an off-grid system, a single south array was still better than the same panels split into one east and one west.

On reading this, I realize I haven't checked SE/SW, but my first guess is the above still holds. That said, if south only is unavailable, I expect a split to beat all on one roof unless shading is involved.

Here is a link to the tool I wrote to come up with the above conclusion: https://diysolarforum.com/threads/multi-array-performance-calculator.54631/

 

[Delphinus]

My uncle has his own scrap/old metal yard. this is what he had in 25mm2, but agree it should have been red and blue (and black between bms and batt.)

That cable is not correct, the wires are too thick so high resistance and lower A, those 25mm2 are rated for less than 100A, You should use a proper cable and build the system for a single battery be able to handle all the load.

The inverter fuse doesn't look to be in a fuse holder, you must use one.

You have a good bus bar and fix de cables with wood screws, use proper metal bolts and a good isolator between the wood and copper bar.

The positive and negative bars are screw to the same board did you consider what could happen if you have humidity and all that energy short circuit.

Like you wrote you have a lot of money in batteries so don't be cheap in the remain, build it to last and be has much has secure has you can.

 

[100kwh-hunter]

Three levels of protection for the cells:
Think of the Inverter/charger settings as "normal day to day range of battery voltages/currents. Daily cycles.
Think of the BMS settings like a protection system in case the above fail, or a single cell 'runs away' in voltage from all others.
Think of the Fuses as the final measure - all else has failed or can't control the current flow -ultimate protection.

I have fuses on all levels. except individual cell level as you do with second hand li ion cells.
Thanks for your explanations, makes al lot clear.
But my inverter is just a stupid thing, min 42v max 58v, in that range he operates....
So i use the bmses to cut off the power under 48v, when the inverter receives no power it will shut down, (48v in my case) and will be active when there is 48,1v
However i placed a switch when the inverter is off, the switch will not go back to the inverter, but be on the grid, until i switch it back to inverter
The switch is grid and inverter tied.

Thanks

 

[100kwh-hunter]

sunlight during 3 times of day:
- Morning ~ 8 or 9 am
- Mid day - conventional positioning ~ 1 - 2 pm
- As late in the day as possible - 6 pm

The morning positioning helps with breakfast and recharging from the long night of no solar power.

The late afternoon panels help cover what is often the largest power usage time for many homes, as well as charge up the batteries as much as possible so that they are ready for the long night period.

Bingo, and this is why my house is idly for this....we come home and charge the ev's and start electric cooking......
The best roof is at 14:00 to 18:00.
In summer time 15:00 to 19:00
This is also the roof i have the most room to place panels.
Considering the time when we are stil at work and the roof that has the most sun in the morning, we need 100kwh of storage to make it real easy for us(and the batts of course)

 

[100kwh-hunter]

This is a great resource! Do you have the dataset, or maybe curves for other cells?

There is a link in this thread somewhere that leads to a page written by will prose. it is a good read!
Go with that one on youtube university and make up your own mind....
Speaking for myself incl after what i read and learned here....Will is on a good spot...
BUT there are to many differents in batt chemistry and too dam many different charge charts...this is why i came for help here....
Oke maybe (no oke not maybe...just say it....sigh) i am to carefull with my own stuff, but ust like my cadillac from 1949...its made to drive....
I hope you get my drift(in my bad english)

With best regards Igor

 

[100kwh-hunter]

I think Andy from @Off-Grid-Garage has a few on his website: https://off-grid-garage.com/battery-data/

Andy...yes also a good one. i did not know he had a website, i will check it out, thanks.

 

[100kwh-hunter]

On reading this, I realize I haven't checked SE/SW, but my first guess is the above still holds. That said, if south only is unavailable, I expect a split to beat all on one roof unless shading is involved.

Oke good point!
But, the ever enoying but...we have some clouds in the morning...that array does nothing...really nothing
Oke we have clouds in the afternoon....that other array does nothing.....
But those two arrays(up til now!) can keep us going after! expansion.
But there is a problem:
The two array are giving not enough to meet the max of one mppt controler(seperate)...so i plan to connect those two arrays into one controller, i think it can be done because my panels have diode's. but i would like some opinions for/about this one....

Thanks

 

[100kwh-hunter]

However, my calculations indicate that, with a reasonable battery bank and PV array size, there's plenty of power on days when you get the most benefit from this. The days when you're running short on power are the cloudy ones, and it's total input to the system, not time of input that matters most

Agree...
Short of storage....need more cells...
Short of harvest....need more pv

Oke i have easy talking, i have room enough, for batts and pv(130m2 can be covered in pv, and more if must) so i can do it with "old" panels.
Panels from 25 years ago! give an average if they are good of 120wp per squire meter....the really new and expensive ones gives 190wp per squire meter...
Oke i can fill my roof with 100w per m2...times 130...
I think i made a calculation error....20 meters * 8 meters + 5*6 m2 + 8*3...
But oke, i could be the left over roof after i install all the new panels.....Oke i lost track....

But again:
Short of storage....need more cells...
Short of harvest....need more pv

I am busy with this for over 5 years now....i just made myself a 28 euro profit....investment up to now...15000 euro...
Operational...3 weeks.
Pv is waiting to put on the roof
Ect

 

[100kwh-hunter]

That cable is not correct, the wires are too thick so high resistance and lower A, those 25mm2 are rated for less than 100A, You should use a proper cable and build the system for a single battery be able to handle all the load.

DC Wire Size Calculator

Use our DC Wire Size Calculator to know the wire size needed for your DC electric application.

www.omnicalculator.com

I used this one for all my wires.
For 50V and 100A it spits out 26,7mm2
I am way not close to capacitor capacity.
So i really hope you can explain this one to me, cous i dont think i understand it, sorry.

The inverter fuse doesn't look to be in a fuse holder, you must use one.

I will do that!

You have a good bus bar and fix de cables with wood screws, use proper metal bolts and a good isolator between the wood and copper bar.

I just did all with wood screws?
As a carpenter for over 40 years i thrust screws more than nuts and bolts.
The beam you see is screwed seperatly on the "back wood sheet"
The screws that are attaching wires to the bus bar are screwed with screws that are shorter than the piece of beam is thick
So the bus bare screws will never connect the "back wood sheet"
When i take my yr meter i can not even measure the resistance on 1cm of space on really (soaked) wet wood, not even the plywood or the beam.
oke fair is fair....a yr meter is something different than running 300A 56V to a wet piece of wood, to a short circuit
I am very curios to hear your thoughts about this one.
I will do a experiment on this one...really wet wood and just dead short the busbars....on the wet wood, the best i can hope for is some steam, so it is going to prove your theory.(i hope...better save than sorry)

The positive and negative bars are screw to the same board did you consider what could happen if you have humidity and all that energy short circuit.

I made every efford that the construction of this wall is going to be water/damp proof....
This whole room is a room in a room in a room....incl insulation and 3 times water turning. shoot how do i must explain/translate my work "slang" in to English.
Dip this one into a pond....wont leak and stay's warm?
I hope you understand, sorry for my bad english.

Like you wrote you have a lot of money in batteries so don't be cheap in the remain, build it to last and be has much has secure has you can.

That is one of the reasons i am here, to receive comments and learn....and hopefully to be able to help others with there projects.....
And i am not cheap, i make mistakes...so yes fuses of 1.25 each are going to be replaced with breakes of 8 euro each....
It must be good or i wont do anything.....

 

[100kwh-hunter]

Thanks for all your input, it is really appreciated, just like every one elses input.....
Long way from being done the correct way.
But with you guys....i will have a dream system...learn me as much as you can so i can hopefully help others.....
Again sorry for my english, it is not my native language, and i refuse to use google translate or simulair...

Btw i received today my breakers

 

[Delphinus]

So i really hope you can explain this one to me, cous i dont think i understand it, sorry.

You use this cable, it's rated for 89A and that is for AC, for DC the A will be lower.

Fuses are faster than breakers, use both, if you want only one go for fuses.

Tested the resistance of pine wood, probes 12cm apart measure 800 mega ohms, was dry didn't bother to measure humidity but probably was arround 70, diferent type of wood will give another value.

You can get away without isolators, thin wires, wood bolts and your system will work but wont be to code and when something go wrong usualy fails in the weaker point and you have several.

Your 8€ breakers are very inexpensive, I don't use them because couldn't found good ones for DC, it's not correct but for maintenance I turn off charge and discharge in the BMS and open fuse holder.

 

[HarryN]

In a grid-tie situation I believe this does help. However, my calculations indicate that, with a reasonable battery bank and PV array size, there's plenty of power on days when you get the most benefit from this. The days when you're running short on power are the cloudy ones, and it's total input to the system, not time of input that matters most. I concluded that for an off-grid system, a single south array was still better than the same panels split into one east and one west.

On reading this, I realize I haven't checked SE/SW, but my first guess is the above still holds. That said, if south only is unavailable, I expect a split to beat all on one roof unless shading is involved.

Here is a link to the tool I wrote to come up with the above conclusion: https://diysolarforum.com/threads/multi-array-performance-calculator.54631/

In California we are rapidly shifting toward the grid essentially not wanting to buy roof top power / viewing it as having very little value, and charging quite a premium for power during peak hours. ( 2 - 5x vs off peak )

So if the prices are ~ $ 0.20 during off peak but closer to $ 0.50 - $ 1 / kW-hr during peak, does this shift the economics related to putting 50% of the panels facing 18:00 ?

I know for my off grid work shop - this makes a big difference in the ability to work later into the afternoon and evening with a minimalist battery pack size.

In the summer it is too hot to work in the ship mid day, so I end up working later into the evening.

 

[TorC]

I know for my off grid work shop - this makes a big difference in the ability to work later into the afternoon and evening with a minimalist battery pack size. [emphasis added]

There's your reason, right there. All the systems I've been playing with in my calculating have enough battery that the time they fall down and can't keep up is when there are days in a row of zero or near zero solar input. I still was using a usage pattern that was higher morning and evening when I did those calculations. If you've got only just enough battery to barely make it through one night, then yes, it makes sense that matching some panel orientation to a later high demand would be of some use. That's something I, here in a rainier place, don't consider enough for any off-grid use.

 

[HarryN]

There's your reason, right there. All the systems I've been playing with in my calculating have enough battery that the time they fall down and can't keep up is when there are days in a row of zero or near zero solar input. I still was using a usage pattern that was higher morning and evening when I did those calculations. If you've got only just enough battery to barely make it through one night, then yes, it makes sense that matching some panel orientation to a later high demand would be of some use. That's something I, here in a rainier place, don't consider enough for any off-grid use.

Yes - well necessity is the mother of invention.

I originally used my van that had a pretty large battery pack, inverter, etc plus a modest amount of solar more or less pointing up.

When I got to the shop I would plug in additional fixed panels that faced morning and evening, so fairly healthy setup.

One night on the way home, a guy ran a red light and took out the van and I was in the ER. Took a long time to recover - still at about 70 - 75%. Of course he had no license or insurance but that is a different topic.

Anyway, so my replacement vehicle (older explorer) is smaller. I took out the 60 part of the 60 / 40 seat and that was all of the room that I had for the power system - so it's now a minimalist system.

Not disagreeing with you - just working with what I have.

_____________

As far as CA, homes with large, grid tied solar systems facing the sun at 14:00 are about to loose much of their ability to sell power to the grid, and are going to be paying a LOT for power purchased from the grid during the 16:00 - 20:00 time period in the summer.

Many of those homes do not have any kind of battery pack so unless they move around some panels, they are going to be real unhappy this summer.