Hi All,
For a couple of days my RS450/100 MPPT has been going into voltage or curent limited mode for no apparent reason. Only for minute or two at a time but several times a day. Usually it only did this first thing in the morning when switching on and also when the battery cannot receive full output from the MPPT.
Not updated firmware or anything as far as I know.
What could be the reason ?
Reason’s could be many.
I’m afraid my crystal ball currently has a flat battery, so without further details such as whats in the system / how its wired / what settings it has / logs of issues / voltage of pv / current of pv / ect /ect, the only thing that anyone can say it at best a guess.
My guess is mppt is clipping the pv due to voltage or current.
I suppose I’m saying there is no obvious reason why it’s clipping.
The moments at which it happens have been in the mornings, battery around 50% SoC, approx 2000W production, batteries can accept 4x that charge.
Set up is 4.5kw array, 1x RS450/100, 2x MPII 5000/48 (tandem), 8x Pylontech US2000c
It’s never done this before except as stated, when battery is near to full and won’t accept the full output.
Please instruct me how to get logs and I will provide them on here.
Thanks,
That could indicate overvoltage on the PV side. Cold Panels have a higher voltage. So coming out of a cold winter-night into a sunny day basically makes them show their maximum daily voltage right away.
And if that may exceed the inputrange of the MPPT, it will throttle production to protect its circuits.
The problem is, this is hard to see, because that measure will exactly bring voltage down into the allowed range.
So best is to use the mppt calc and see if your exact panels may come close to the limit under these circumstances. Because there are also deviations of +/-2 or 3% by the manufacurers. And if you have a batch, all doing +3%, a too close designed array could yield too much.
Forget the first thing in the morning, it’s around 7am and I think it’s just the thing switching on.
I’m talking about 10am, 10.56am, 11.40 am, sun is of course up but not full production by any means
Go onto vrm / console / pv / mppt / history, this should show max voltage ect.
As above use MPPT Calculator - Victron Energy to check panels / mppt are within tolerance.
Also in vrm what does alarm log indicate as the alarm?
240.06v is well within specifications.
But 5074w / 240.9v = 21a, is in excess of mppt 20a max short circuit limit / max pv array size per tracker.
Reduce amperage( reduce panels in parallel) or increase voltage ( increase panels in series).
Before that run any proposed layout through MPPT Calculator - Victron Energy.
Running in excess of limits may cause damage and invalidate warranty.
I have over current every now and then, its anoying, but my panels are within mppt max amperage limit, so all good.
Im not familier with rs450/100 and i presume screenshot you posted is one of the two mppt trackers?
If its single tracker information, panel reconfiguration may be required to ensure mppt limits are not exceeded.
What are the panels and how are they configured, spec / number / array orientation ect.
It should be the two trackers as I don’t think one string could produce 5kw.
It is 5x 400W on tracker 1 and 6x 400w on tracker 2.
That’s a bit worrying if it could cause damage, I thought everything was safely within the spec.
It must occur when the sky is pretty clear and we have a gust of very cold wind bringing panel temps down.
Hmm, what to do ?
Once the ambient temps go up there will be no isues I’m sure, but still..
So you have approx 2000w on tracker 1 and 2400w on tracker 2, this being well within specs.
Post alarm log details.
As stated i’m unfamiliar with rs450/100, i did run it on a demo and got the below which shows both trackers, maybe worthwhile for you to get same view to check your system.
Could try advanced on vrm, you can then have custom widget to show info on trackers and see where potential issue is.
No alarm logged since October last year.
For the VRM advanced widget suggestion, I can’t have MPPT operation mode, it’s not one of the options offered. I can have tracker voltage or current but as these issues occur for only a short time I don’t know whether it would be very visible on the graph output.
Sorry i have no other suggestions, especially if you have no alarm logs such as " Error code: #18 - Charger over-current"
If you have no alarms, then don’t be alarmed!!!
Ps what do you mean by or how do you know inverter / charger is in “voltage or curent limited mode”.
I have a node-red node which shows MPP operation mode. 1 = voltage or current limited
An mppt can be limited for many reasons, such as ESS / DVCC / BMS / temp / set charging paramitors ect ect.
Throttling of charge amperage is nothing to be worried about, its normal.
In my system i have four mppt’s that have max amperage set to 38a each, but this is regularly alterered by the system / settings to a lower figure.
Sounds like if you not happy with the way the system is throttling the mppt’s, you need to go over mppt’s / ESS / DVCC / BMS settings to check all set paramitors are how you want them.
Ps it took me quite a while to get my head around the BMS config settings file to get my system how i wanted it.
Everything should be set correctly with no reason to throttle unless battery is balancing/nearly full which would be the BMS operating correctly.
It hasn’t done it for two days, maybe it was just a “glitch”… or cold gusts causing momentary over-current on one of the trackers. I have activated widgets for MPPT mode, plus voltage and current on individual trackers so might have a chance of spotting something if it reoccurs.
The datasheet for the MPPT RS states 5760W total - but this is at 57.6V charge voltage (So that’s the 100 Amp limit)
Your highest voltage was 51.3V, that lowers the maximum to 5130W - and you can also see that the 93.9A are quite close to 100A.
So, it may well hit that limit there from time to time and seek for a sweetspot around that 100A.
Depending on how often that occurs, I wouldn’t mind it all too much. Everything is build and designed to even go beyond certain nominal limits (while some are super strict) as long as all parameters allow for it. So, if the MPPT is occasionally throttling for no apparent reason - something is a bit off and it does that to prevent damage.
If it’s not like several hours a day, you also won’t loose a mentionable amount of solar there.
Yes I suppose it’s nothing to worry about.
