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Outback charge controller not using all of the arrays volts
#61
(06-05-2020, 09:49 PM)Doin it Wrote: Yes I understand that the voltage I should get from array is not the voc but is the Vmp which is 33.3v for my panels
Wrong. The Vmp for your LRE-60PE-305 "305W" (STC) panels is 30.3 (NOCT) not 33.0V (STC)
Numbers from the manufacturers spec sheet. You keep denying this. Not sure why.
I posted the calcs showing this works nicely on page 2, post #17.

(06-06-2020, 01:26 AM)Doin it Wrote: the 60v battery voltage + array Vmp voltage combined....
This is all nonsense like we've said many times it doesn't work that way.
All that matters is Vbattery < Varray < Vcontrollermax

(06-06-2020, 01:26 AM)Doin it Wrote: a Vmp of 90v (instead of 100vmp) would have enabled me to have roughly 200 more watts, because of efficiency losses when array start going over the optimal 30%....  and becoming more inefficient by every volt over the actual array Vmp volts ...
Again this is all rubbish. You are not loosing 30% of anything.
Your FM60 is about 90% efficient for a broad range of inputs. Read the specs.

We've tried to help you from years of experience here & we're not getting anywhere.
I don't think we can help you any further because you keep denying the manufacturers specs + physics & engineering in panels & MPPT units like yours.
Running off solar, DIY & electronics fan :-)
#62
Everyone is saying the right things. On a perfect world you might get the perfect conditions. I see my peak typically during very cold days at the optimal angle. Even a slight angle is enough to throw the numbers off. Your mppt controller is efficient between 93-97%. Here's how I would break down your losses.

Cable loss through voltage drop: 2-6% (depending on awg/distance/temp/current/voltage)
MPPT losses : 2-6% (input voltages do matter but not all that nonsense you're talking about 150v+panel+battery getting you 20% loss. You also lose some percentage points on higher total wattage. Check your manual, there is an efficiency graph)
Panel losses : 0-10% or more (mismatched panels/ideal temp and angle makes all the difference here so that NOCT vs STC is valid and published)
Connector losses : 1-10% (bad connections creates resistances and often overlooked. Or too many connections also creates losses)

So adding it all up you will have anywhere from 5% up to over 20% losses. So before trying to hypothesize about things, test your environment.
#63
I didn’t say I’m losing 30%,,,30% is the amount of volts the array should optimally be over battery voltage.. anything over the amount of volts needed to charge the battery (90v for a 60v battery )has to be knocked down to mppt voltage by the controller creating losses... yes the controller is 90% efficient using many array voltage input, but that depends on what battery voltage is being charged.. for instance a 100v array would be more efficient charging a 60v battery than a 12v battery because of how much higher the array voltage is from the 12v battery... mppt controllers are great because we can use an array higher than battery voltage to charge the battery,,, but the further the arrays voltage is from the battery voltage the more losses that are seen..

the 150 combined is what an array 30% higher than a 60v battery and the 60v battery equals... there is a recommended amount of array input voltage over battery voltage for reasons (30%) and one of those reasons is efficiency and that efficiency will get worse above 30% because right at 30% (for 60v battery) above battery voltage is where the mppt voltage wants to be..

I’ve seen many ppl get the Vmp x imp sustained (that specs on panels say) minus typical loses.. so I am not ignoring the 30.3v instead of 33.3v. I myself seen the Vmp x imp (that the panels say) sustained when my panels were wired 2s like I explained.. not everyone is going do have their arrays get less power than the specs on the panels say..

As for testing to see what my basic loses are... for me is kinda impossible and at best a guess due to many things even after testing.. best I could do is not have long wires, have proper ventilation under panels, use correct wire gauge, keep connections to a minimum, not live in the middle of a hot desert, not live in extreme cold, etc etc and I have done all of this..

Furthermore I am very positive that if my panel voltage was 90vmp instead of 100v that I would see more total production dueto 100v being so much over the optimal voltage to charge my battery. I believe the amount that the array voltage is over the battery voltage effects efficiency the most when using a 60v battery due to a 60v battery being at the max voltage battery the controller can charge..

I know a ruffled a few feathers and I apologize for that. In an attempt to pat down a few of those feathers: 48v battery users do not have to be concerned as much (if at all) with the issue this post is about due to 58v - 160v (close to 150v)= 102v so not many 48v users will have arrays larger than 102v so very minimal if any loses will be seen,, plus the arrays voltage mppts at 64v and 64v+58v= 122v which is well under the 150v so the controller isn’t being pushed to its max because it’s not charging the max voltage battery (60v) that the controller can handle.. although there is some loses dropping the battery voltage from 102v to 58v vs 75v to 58v

I would also say we are all saying the right things, and I might have even said some things that are not typically thought about.. so in conclusion I guess we should end this discussion ,, and like I said I’ll report back years from now when I get better efficiency-higher wattage from a 2s 90v array instead of 3s 100v when charging a 60v battery. I appreciate everyone’s research and assistance..
I would still like to here from anyone that is charging a 60v battery with these 150v controllers..
#64
Once again you are wrong in what you think you found. Go back and Read what we have added on what your issue is.


Me and maqaany other Charge with 150v controller... Dont you listen? Everyone that have the pcm60x as example. Some runs Them on 3s with 60cell
.some.4s. some.with 3s 72cell
All work as we have explained to you. Same goes with victron and the other brands.

Its not our research. We point out fact from the datasheet, the real world and tell you what is wrong with your assumptions that are based on your setup.
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#65
Daromer, do u think a setup that has a 4s (as u describe) 33vmp = 132v array, will have more power lost than a 2s 90v setup that is charging the same battery bank? To me since the array voltage is higher using 132v array, that the mppt has to lower that voltage a lot more than from the 90v array to the same battery voltage so more losses would happen with the 132v array.. I know the controller raises the amps when it lowers the volts but the more the controller has to do that (due to voltage being much more higher than battery voltage) then the more losses that occur... to further those loses if a person is using a 60v battery (max battery voltage the controller can possibly charge) and that the 132vmp is at the highest (actually over) array voltage that should be used, then there would be more losses. It just makes common sense to me that when a system uses the max voltages (or close) the controller can handle (battery voltage and array) that there would be more losses than a slightly lower than max battery (48v) and lower than max array Vmp.. do to everything I just said it makes more sense (to me) to have array Vmp closer to optimal mppt voltage for the battery voltage. I’m my case optimal mppt voltage is 78-86v for my (60v) battery, so an array of 100vmp (like I have) is slightly to high for best efficiency and more losses would happen than if my array was 90v.. 90vmp array + 65.1v battery = 155.1v
I understand all the rest of the losses everyone has described.. I have not seen a data sheet with the max battery voltage (60v) that the controller can charge. I think at this voltage the max array Vmp that is accepted for other battery voltages should be avoided due to everything I said in this post. For best efficiency from the controller, a voltage close to but slightly above the best mppt voltage for your battery is best.. so for a 48v battery wouldn’t the best array Vmp be roughly 75v,, for 60v battery best array Vmp is roughly 90v.. unless a person lives in an area that is usually cloudier than higher voltages might still yield more power but that’s a different discussion all together

Not2bme, just to clarify, I don’t believe I said that I’m getting 20% losses due to these issues.. I think I said 600w max loss from a 3660w array (that included basic losses) and roughly 200w of those losses (u called it mppt losses) being from what this post is about,, Starting off this post I was thinking more of my losses were coming from the issue I described, but from all the helpful info that everyone has posted, I ended up saying that roughly only 200w of the 600w below 3660w was coming from the ”mppt losses” because of having an array well over the optimal voltage needed to charge the batteries..
#66
You are still doing nonsense math with your numbers.

Experiment for your self. That's the only way you're going to accept how it works.
Change 3s to 4s.
Go buy another brand contoller, try it out.
Or whatever else you want & measure the results.

Even if you change the Varray at Vmp into any MPPT controller from ~80V now to 90 or 120V it will only change the controllers efficiency very slightly, eg maybe 2% so for your FM60 from about 98% to worse case approx 96%

Here's my system this morning:
I have strings of 2x 72 cell panels (8 panels to one MPPT, total 24 panels) with
STC Vmp = 37.1
NOCT Vmp = 34.4
Outside temp here now is 14degC, partly cloudy some shade on some strings.
Here's my systems voltages:
 

Here's another screen shot after the cells have warmed up a bit more, voltages dropped.
 
Doin it likes this post
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#67
Nice monitoring of your controllers Red, is that something thru victron? Yeah I understand that when panels heat up there’s losses in voltage and power output..

Red u said 2% so is that 2% from 80v to 90v and another 2% from 90v to 100v? If so that’s roughly a 4% loss so that’s roughly 150w from my 3660w array.. I’m saying I’m losing 200w from my array being higher than optimal so our maths are not that far apart. Even though I could only lower my arrays voltage by like 13v for it to be optimal for my battery.. so maybe not quite 4% in my case but my point still stands that it’s not as efficient to have combined voltage over 150v when charging the max nominal battery voltage the 150v controller can charge..
I wouldn’t call it nonsense math, due to simple fact that I’m using the max nominal (60v) battery voltage the controller can handle (I charge it to 65.1v) and the optimal mppt voltage for that battery is 80v and those 2 added together equals 145.1 so having an array roughly 10v higher gives some room = so that’s 155.1v combined for when using the max battery voltage (60v nominal) that the controller can handle-charge. Or the math can be done 60v nominal battery + 80v optimal mppt voltage + 10 extra array volts= exactly 150v and to me is not a coincidence.. I’m saying the max COMBINED OPTIMAL (for best efficiency) voltage when charging a (max controller can charge) 60V battery, is right at 150v. So no all isn’t lost above 150v like I previously said but there’s still losses above 155.1v combined when charging a 16s 60v battery. 155 or so being the optimal combined voltage to have the least amount of losses.
#68
We've repeatedly explained how this works.
Your thinking & math is still wrong - based on guess work not engineering.

I would expect the FM60 to be >96% efficient for all normal operating conditions Vbattery (yours max 65V) < Varray < Vcontrollermax (150V).
This is based on the spread of numbers in their spec sheet, lowest being 97.5%.

As I said before your array is not a 3660W (STC, "sold as", "name plate") array in the real world, it's really a 2690W (NOCT) array for what you'll actually get sustained.
The screen on the FM60 already shows you that. Any difference is due to cell temps, nothing else.

Go ahead & experiment with some other configs, eg 4s panel string & see what happens for yourself.
It's the only way you'll accept & learn how it actually works.

Please post a screen shot of your FM60 showing anything like 3,000W sustained for 15-30 mins
Running off solar, DIY & electronics fan :-)
#69
(06-06-2020, 05:39 PM)Doin it Wrote: 90vmp array + 65.1v  battery = 155.1v

This part of it is just pure nonsense. You repeat this in every one of your posts and that's what's driving everyone up the walls.

Ideally you want to be around 10-20V above your battery voltage to be optimal. Any more just make it less efficient. So for a 24V system the ideal panels should be around 40-50V yet I run mine at 3S for around 90V. Still fine. Using your maths of 90V+30V batt= 120V, so it doesn't add up at all. You have to just give up on that.

The 150V is just the max of the controller. Any higher than that the electronics might get fried. And the max the panel can produce (the Voc) must not exceed that number. So that's why that's there. Nothing to do with your other math.
#70
(06-07-2020, 04:46 AM)not2bme Wrote:
(06-06-2020, 05:39 PM)Doin it Wrote: 90vmp array + 65.1v  battery = 155.1v

This part of it is just pure nonsense. You repeat this in every one of your posts and that's what's driving everyone up the walls.

Ideally you want to be around 10-20V above your battery voltage to be optimal. Any more just make it less efficient. So for a 24V system the ideal panels should be around 40-50V yet I run mine at 3S for around 90V. Still fine. Using your maths of 90V+30V batt= 120V, so it doesn't add up at all. You have to just give up on that.

The 150V is just the max of the controller. Any higher than that the electronics might get fried. And the max the panel can produce (the Voc) must not exceed that number. So that's why that's there. Nothing to do with your other math.
This 150v total is roughly the best-optimal combined voltage for the 60v battery....maybe 160v but thats pushing it... nobody can argue that.. anything over is making the controller do more work-more losses.. this is not guess work.. due to the incoming voltage being more than the optimal 30% higher than battery voltage if the combined voltage is over 150v...
I didn’t make this stuff up.. 80v is the optimal mppt voltage for the 60v battery, so having array Vmp 10v higher than 80v gives room to make sure 80v can be acquired from the array.. that equals 160v... and anyone with a lower (than 60v) voltage battery should absolutely make sure they do not have a combined voltage over 150v or they would have even more losses than a 60vbattery user due to the controller having to do more work- controller has to drop the arrays incoming volts more to achieve a lower battery voltage therefor more losses..
so for a 24v battery the array should only be about 10v higher than the optimal mppt voltage for that battery so there’s less losses, because then the controller doesn’t have to lower the voltage as much as it would with a higher voltage array.. I realize that with only a 10v higher array than the 24v battery isn’t giving enough volts to supply enough amps so arrays volts have to be higher.. so this is why there’s more losses with a 24v battery than a 60v battery, because with a 24v battery the array voltage has to be higher to supply more amps and controller has to make more amps, therefor have to have an array much higher than the optimal mppt voltage for the battery so more amps can be created = more losses.. more amps have to be created to have enough power to do anything with because 24v is so low
An mppt controller is made to use higher voltages than battery voltage and still be able to charge the battery.. but a pwm controller is more efficient because it doesn’t have to lower the voltage.. but a pwm controller cannot get more power (than mppt controller)in the beginning and end of the day during low light conditions therefor making the mppt controller more efficient overall,, but again when an mppt controller has to lower voltage it is not as efficient as a pwm controller, so keeping the array voltage for a 60v battery close to the optimal mppt voltage is best to keep the mppts efficiency high so the controller doesn’t have to lower the voltage as much.. and this number is 90vmp array for a 60v battery..
So in my opinion go-ahead and use an array a lot higher than battery voltage, higher than the 30% optimal,, really isn’t going to hurt anything but it will not give u as much power from the array as an array that is optimally sized above the battery voltage..

Btw Red, I can’t wire my panels at 4s as u have described because that would be 33.3vmp (on back of panels) x4= 133.2 Vmp and that would exceed the 150voc limit of the controller with a voc of over 160v. But I will try 2s with 45ish Vmp panels like I explained I will when we move into the next house. And since the Vmp would be closer to the optimal mppt for the 60v battery, I’m sure I will get a better percentage of the power that the label (Vmp) on the panels says. How much more...?..probably not much but anything helps. I’m hoping to gain back 200w from having less panels in series and closer to optimal mppt voltage for the battery.


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