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Outback charge controller not using all of the arrays volts
#41
Daromer, I meant does your controller have 120v input sustained max power (not a brief period) at full battery voltage? or does the input voltage drop to roughly 92v sustained when battery is close to full charge. Also to see only 92v sustained,, the charge controller has to acting like it’s getting max from panels when panels should be able to produce their max,
that’s if anything I said on this topic is correct. If u do not see 92v sustained at 58v battery with all other parameters just mentioned met aswell, then I’m wrong.
I suspect u will be seeing roughly 92v.
I just read what u said again and it appears as if 58v is the max the controller can charge too, not your batteries top voltage?
What is the max voltage u charge your batteries?

(06-01-2020, 02:12 AM)OffGridInTheCity Wrote:
(06-01-2020, 01:12 AM)Doin it Wrote: Red, I understand that it’s normal for the amps to lower when battery is full. I don’t understand why the charge controller can use 100v from array when the amps the controller is charging with are lower. Shouldn’t the controller be able to use 100v if at the time the panels are capable of 100v?,, regardless of the amps being used from the array..  Is there a maximum amount of volts that the mppt can use depending on what battery voltage is? Even tho I’m well under the 150v the controller 
It sounds like you're focusing on voltage - but voltage, by itself, is not the issue.   The issue is *power* = e.g. watts.   Note that 100v * 30a = 3000w  and  90v * 35a = 3150w.  In this example, 90v is giving more power than 100v.   The Outback MPPT algorithm is raising and lowering the voltage (and correspondingly raising and lowering the amps) every few seconds to find the maximum power point - e.g. the combination of voltage * amps that brings in the most power.      A lower voltage (than panel max) will result in greater amps / power - you can trust the Outback to find the sweet spot on this.

I've seen videos explaining the 'maximum power point curve' concept - but don't remember the details.  You might want to search one out to get more info.   But the idea is that there is a curve of volts/amps that determine max power (max watts from panels) that changes from moment to moment as the panel output changes from moment to moment due to clouds, temp, sun strength etc.  

As a side issue - as the battery fills and it goes into absorb/float, the Outback will limit the output current to the battery..  because its in CV (constant voltage / declining amps) mode as the battery fills.  This in turn will cause the Outback to accept less input power or shunt aside excess power - because its the output that is the overriding issue - e.g. to avoid overcharging the battery.    Ultimately, if the battery reaches 100% full, the output will go to 0 and the input power will go to 0 as well...   even thought the panels are still producing power.    
Example from my own system on output affecting PV input power:
Midnite Classics let you set the max output amps and I had to set mine to down to 80a because at 86a (the max the controller supports) my 80a circuit breakers trip.  This actually happened and I was going crazy trying to figure out what happened.  This means my input power is limited to 80a * battery-voltage which means that when my battery is low (say 50v), I can actually loose some PV input power because the input cannot exceed the 80a * 50v = 4000w output whereas my array can produce 4275 watts at 100%.    As soon as my battery reaches 53.5v then 53.5 * 80 = 4280watts and I'm good to go.     


This is all 'as is should be' and why you buy an expensive controller like Outback or Midnite Classic (or others) because they are quire sophisticated in getting every bit of power (e.g. watts) that it can and constantly check for the best solution.
Offgrid..(or anyone) my understanding was that the input amps into controller at max array production is just the amount of max amps that the array can produce and is not changed by the charge controller?
Also when full power is needed from an array that should be able to produce max at that time, the voltage used from the array is the highest voltage the controller can use to create more amps, meaning the amount of volts the controller accepts from array is limited by how many amps is can create OUTPUT into the battery. Like for a 60v battery the array voltage is lowered to roughly 80v so the charge controller can then use that amount of volts over 60v (20v) to THEN create more output amps to charge battery? I’m saying the mppt charge controller DOES NOT raise the amps getting input from array and then again raise the amps from input amps to output amps to charge?
Is this way of thinking correct?
Offgrid, I think u are saying that the controller finds a max power point and all the voltage above what the controllers displays as input that the array could have possibly supplied is used to create more INPUT amps and then those INPUT amps are then raised again to a higher amperage to OUTPUT into the battery, therefore u are saying the amps get raised twice?

To clarify, I do see input voltages from array up to max Vmp and higher sometimes.. like when my battery is low on voltage (58v) then I can see real close to 100v input from array (100v + 58v =158v) which happens often but as the battery voltage rises the input voltage lowered by the same amount, staying below like 158v combined max. Exceptions are when my controllers doesn’t need to (not much loads) or can’t supply much power ie batteries full and low loads or cloudy, at those instances I also see max Vmp from the array.
#42
(06-04-2020, 03:18 PM)Doin it Wrote: not2bme, I’d assume since the volts would stay the same that I would see the same results, with just 6 panels I’d see half of the loss of wattage with 12 panels, and with 3 panels I’d see 1/3 the loss..

I'm more curious of the fact that you have two different manufacturers. So it would be easy to see if the two panels are not as equal as you think so there's a slight loss there. You cannot mix one brand of 250w with another brand of 250w without seeing some loss. By testing one string at a time or one manufacturer at a time and seeing if there's any differences between the strings. Adding all that up separately should equal all your total value. If not then you just proved there's losses between panels.

The Voc of 150 shouldn't be an issue since your panels never reach that value, plus it only gets that high when your batteries are full. Speaking of which, I hope your batteries are still discharged below 80% SoC during your 'test'. Most of the time my panels already charge my batteries by noon, so even before I hit peak wattage it's already switched to CV and decreasing the wattage to the battery.
#43
The panels spec are within hundredths of each other both in volts and amps, I think they are actually made by the same manufacturer with different labels on them, they are both made in Korea. They look identical in every way aswell. Anyways it’s easy for me to disconnect one brand of panels from the other since they are on separate breaker-strings so I’ll do that. I’m thinking max a 50w difference between the strings

I think the 150v is the issue.. no my panels are not over 150v so the controller is not damaged by my panel voltage and controller still works.. but for instance if my panels were 120vmp, there is no way the 150v controller can take that amount of voltage over the voltage needed for input to charge battery and create amps (in my case roughly 84v input at max production)... the controller can only create x amount of amps by lowering the voltage that the controller allows in due to not being able to go over roughly 150v combined (battery + array) voltage and any voltage above that (I’m thinking) is just simply not used when the controller thinks it’s getting everything from the panels that it can. But the controller can still be used with a 120vmp array to charge a lower voltage battery but the controller can only create so many amps and it can only use so many volts to do so. This is why if a person is using the highest battery voltage the controller can charge (60v for outback) then I’m seeing that roughly roughly the difference between 150v and battery voltage is the amount of volts the array should be so the controller can use all of the volts array has available to create the max amps the controller can create


U said I hope your batteries are discharged below 80% when doing the test.. well, no and yes.. the input voltage from array will never (in cc or cv) go above the difference between 150v and the battery voltage at any time, unless it’s cloudy or the controller isn’t trying to get everything from array that array has to give (low loads and more solar available than loads) then I’ve seen combined voltages of 165+ ,,input voltage of around 100v
#44
doin it NO. The controller have 150VDC max input. It stays at the vmp where the max wattage is produced no matter what the battery voltage is as long as its LOWER than the input is. I have never ever heard of a controller like you talk about. ALL systems i have set up here always have the input isolated from the output in terms of being buck or boost converter. There are even buck&boost converters where you can go both ways.

I would say that the controller you are using have this limitation only. You can look at Vitron or any other brand and you will see that there are no limits based on a total voltage differential.

Here is as an example the recommended range for the PCM60x
System Voltage 12V 24V 48V
MPPT Range 15 ~ 115VDC 30 ~ 115VDC 60 ~ 115VDC

So if you run 48VDC battery bank (Thats max 58v). The minimum input is 60VDC. Its logical due to being buck converter. The 115VDC is their top voltage where they are the most efficient. Their top voltage is 145V. and thats the VOC and not the total voltage battery + panel.

Note that there are also users here that have run them closer to 140VDC with 4 panels in series...

Same goes with Victron chargers.
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#45
Daromer, Your telling me that if I had a higher than 100vmp array (and amps were the same as they are) that I would be have a higher than the 84v input that I’m seeing?
So then the controllers do create-raise amps twice?
My panel Vmp 100, imp 38,
The controller uses 84v input from array and then what? Does it raise the input from array amps from 38 when the arrays capable of max imp amps and max Vmp volts since it’s only using 84v of the possible 100v.
If so the amps are raising twice.. 84v and the amps raised to above 38v.. then those input amps get raised again to the amps that are output to battery, so that’s twice the amps are raised?
If this is so then your telling me that it’s just a coincidence that my battery voltage + array input voltage on controllers screen = roughly 150v everytime the controller is trying to get the max power it can from the array? And that it’s just a coincidence that I am using the max battery that the controller can charge?..

using the max battery voltage that the controller allows actually should be pushing the controller near its max voltage limits.. if we could actually have a 145v array (and use all of its power) then we should be able to charge a much higher voltage battery than a 60v with a 145v array..

In your example above: if u were using a battery that is at a voltage of 48v then yes I’d say close to a 115vmp array could be used and be ofcourse very efficient due to that voltage being the highest voltage that would allow the controller to get max power from the array... ie higher voltages =less amperage for better efficiency... 115v+48v = 163v really close to 150v and as I said I’ve seen 158v (combined) sustained on the outback 150 so there is a little head room above 150v.. your example says that 115v is most efficient mppt voltage..,, but the input voltage would not always be 115v as the battery voltage rises..
So what I’m stating from the start is that my battery 65.6v + 84.4v array input (when controller is trying to pull max it can from panels)= 150v.. like I said I’ve seen as high as 158.
In your above example I’d suspect that if the 48v battery got charged and was 58v then it would no longer be able to use 115v input from array, but instead would have an input from array voltage of roughly 92v - 100v, maybe even 104v but probably more toward 92v when battery is at 58v
#46

On this graph it can be seen that the voltage cannot go over 150v combined depending on amperage of array..
Look at the circled part, 100v mppt from pv and 4438w max controller can produce. This means that an amperage of 44amps is they highest the array can input to controller 100v x 44amp= 4400w. The controller can produce up to 76amps x 58v battery voltage which equals 4400w. So if a person wanted a higher mppt from pv voltage then the amps from array would have to be lower to still get max power from the panels..ie 120v mppt from pv means that the highest amps the array can put into the controller is 36amps,, 120v x 36amps = 4400... problem is that these controllers are only capable of creating x amount more amps from the input amps. Using 120v pv mppt input the controller would have to convert the 36amps from the array and convert that to 76amps to get 4438w.. it would have to raise the amps by 30amps!! I don’t think they are capable of raising the amps that much, so then full output isn’t seen from my array like what I’ve been explaining is happening to me.

So now how that ties in with the roughly 150v combined battery + array... If the pv mppt voltage for that 58v battery was only 92v instead of 120v then the array could supply 48amps, 92v mppt pv input x 48amps = 4438 (instead of 36 amp like with the 120v pv mppt input) 48amps to 76 amps is much more achievable for these inverters and then close to 4438v can be seen. So it can be seen how the voltage of the array directly affects how much power the controller can produce.
A 92v array Vmp- mppt pv input + a 58v battery = 150v. With an mppt pv input voltage of 120v instead of 92v, the combined 120v +58v=178v and is a lot more than 150v so not all the arrays power will be used because with 120v mppt pv input the array can only be 36amps which is then to many amps needed to be converted to the 76amps needed to get 4438v at 58v...
this is also why the lower mppt pv input voltages on the graph actually allow the 150v charge controller to produce more power at the same battery voltage.. it’s because the amperage of the array can be higher and the charge controller has less of an issue creating enough amps to get to 76amps from the higher amps coming from the lower voltage array.
So considering all of this It still seems like having battery voltage + array voltage around 150v-158v is needed to receive all of the power from the array.. my combined is 166.1v, 100vmp + 66.1v battery and I’m not getting all of my power from the array. I’d say my array is roughly 10v to high to get all the power from it for a 65.1v battery
#47
Simple version:
The panel volts must be < 150V or the MPPT shuts off (some may be damaged too).
The panel volts must be > battery volts for the MPPT to work (some have a max battery voltage eg 58V).
More volts only does not = more power from your panels, it might = less.

So you know how an MPPT works right?
It's about constantly calculating & adjusting to get the max POWER out of the panels, not just volts.
All while the sun rises, sets, middle of day, clouds & shade go past, etc, etc
Eg: draw some current from panels, measure panel volts, calc V x I = Power1
draw a bit more current, measure panel volts, calc V x I = Power2
better or worse? eg better power so
draw a bit more current, measure panel volts, calc V x I = Power3
better or worse? eg better power so
draw a bit more current, measure panel volts, calc V x I = Power4
better or worse? eg no it got worse so
draw a bit less current, measure panel volts, calc V x I = Power5
hover around trying more/less to get the most power out for any given situation
etc, etc

On cold days (< 20degC) the power you get may be a bit better than NOCT values.
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#48
Yes red I understand all of that.. the controller should still give me max volts (100vmp) if they are available and max amps (36imp).. for instance my controller will show 36amps at max when panels can supply 36amps, but will not allow input from array voltage over the difference between 150v and battery voltage when controller is trying to draw max power from the array
#49
Does anyone here have a 150v mppt charge controller with an array Vmp voltage + battery voltage over roughly 150 -160v. If your combined voltage is higher, are u getting a good bit less from your array than Vmp x imp from your array?
#50
YES I have including many.

What is it that you dont understand ? The input side on for example Victron and PCM60x is isolated from the output. It is MAX 145VDC input on the input side and it will work fine above 115VDC. IF the VMP is 120Volt the PCM will stay at that IF the wattage is better than at 90V or whatever.

Same goes on my big unit...

MPPT is a system where it tracks the best power point and holds the input side at that voltage/current. Then it bucks it down to the battery side and thats why it need to be +2v Battery side.

The PCM is the most efficient at max 115Vdc. BUT it works fine up to 140VDC. And 140 + 60 = 200V combined. Way above...
So once again the issue you seem to have must be limited to that controller and design. It havent existed on any other controller i have installed. ALl other controllers have its input range defined as we have stated many times already. Input to be higher than battery but lower than max. And then the tracking point have its area where it works the best.

And then of course most controller have a MAX wattage they can convert.

I leave this thread now because it goes no where. Sorry.
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