• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

clouds parting overvoltage transients from MPPT controller algorithm--how to fix?

Iuval

New Member
Joined
Aug 19, 2020
Messages
22
I wonder if I need a low pass filter to filter out these annoying transients that trigger my inverter overvoltage protection alarm and shutoff when the voltage from the controller exceeds 15V. It only happens for a few milliseconds when a burst of sunshine from parting clouds hits my panels, during MPPT part of the cyle (not during float). Either the inverter or the controller should have a filter for this, but if they do, they are not working. I can make it better if I reduce the boost voltage to below 14.5V, but for my batteries I need it to be at least that high. Also, the internal resistance of the batteries is probably OK, not too high (inferred from density of electrolyte test with battery tester). I am considering getting a few inductors and capacitors and making a Butterworth filter, but maybe someone has a better idea. I already tried replacing the controller, no effect. Maybe I need to replace inverter?
 
Big electrolytic capacitor across the PV may slow it down or a diode in line with the PV to reduce the voltage by 0.6 volts.
 
There must be a resistance in the path from MPPT to batteries as well as inverter probably is connected closer to MPPT than batteries. If the wires are reasonably short and of correct gauge, connections tight and fuses/switches in good condition, the batteries must filter such spikes. It's hard to guess not seeing the layout and the parametrs of system, but in such situation I would reconnect the inverter (both positive and negative wires) on the battery terminals (or as close as possible) and see is there some change.
 
Big electrolytic capacitor across the PV may slow it down or a diode in line with the PV to reduce the voltage by 0.6 volts.

But how would this stuff interact with the MPPT circuitry/algo that doesn't expect to see it?

Sweeping an array with filtering could lead to weird results...
 
A common issue- and why I NEVER 'crowd the edge' when designing the array- 'cloud fringe effect' has been known about for decades, and it isn't a 'fault of the controller'- its physics- the light output is actually spiking- and the controller just follows the laws of physics....

Scattered cloud (diffuse light) AND direct sunlight both hit the panel- and the voltage goes up (by 15-20% I have seen personally)- so I stay 20% UNDER the max PV voltage when designing the system- and never get OV spikes....

Personally I am not a big fan of 'cramming every microwatt' on a controller- especially by bumping up hard against the voltage limit- you can seriously shorten the life expectancy of your controller doing that...

1724356654593.png
https://www.solaranalytics.com.au/solar-performance/how-do-clouds-affect-your-solar
 
I can almost never figure out what problem is being discussed. This sounds like an over voltage to the battery, not the panel. I have experienced that numerous times when an inverter goes from a load to none. The CC then jumps to over 15V and faults the inverter. Different case, but I found when I added more batteries it stopped. I expect that the battery is near full and has some internal resistance to it. I had tried a relay which disconnected the panel for a short interval and the delay of the voltage sense was too long. A very large capacitor might help. It didn't for me. Instead you should try a shunt regulator to place a load on it. Pretty simple to build.
 
Most charge controllers overvolts alarm is monitoring the PV INPUT- not the battery voltage (some do monitor both, but only say 'overvolts' rather than specifying which is the actual issue)- if it is the PV volts that is setting off the alarm, then the array voltage is definitely the issue...

If the battery voltage is the issue, then that could still be the PV voltage being the root cause- it might be outside the programming parameters of the formula used and 'crashing' the controllers logic- it 'should' fail safe, but there plenty of bad programming out there in the wild...
 
I wonder if I need a low pass filter to filter out these annoying transients that trigger my inverter overvoltage protection alarm and shutoff when the voltage from the controller exceeds 15V. It only happens for a few milliseconds when a burst of sunshine from parting clouds hits my panels, during MPPT part of the cyle (not during float). Either the inverter or the controller should have a filter for this, but if they do, they are not working. I can make it better if I reduce the boost voltage to below 14.5V, but for my batteries I need it to be at least that high. Also, the internal resistance of the batteries is probably OK, not too high (inferred from density of electrolyte test with battery tester). I am considering getting a few inductors and capacitors and making a Butterworth filter, but maybe someone has a better idea. I already tried replacing the controller, no effect. Maybe I need to replace inverter?
Feels like the battery system impedance is too high, what's the wiring look like from the SCC to the batteries?
And what are the batteries and SCC? Pictures are always helpful.
 
I wonder if I need a low pass filter to filter out these annoying transients that trigger my inverter overvoltage protection alarm and shutoff when the voltage from the controller exceeds 15V. It only happens for a few milliseconds when a burst of sunshine from parting clouds hits my panels, during MPPT part of the cyle (not during float).

Sounds more like you have under-sized batteries compared to your solar array, and or a not so good charge controller. It would help if you could list the equipment used ( brand, model and capacity ) as well as wiring and gauge.
 
Are the batteries hitting over voltage protection?

What are the SCC charger settings?

Do you have a list of the equipment make/model you have in your system?

Can you upload a picture of the wiring between the SCC, batteries and inverter?
 
Luval, what controller are you using?

I had trouble running about 8 Victron SCCs on a BIG lead acid bank where they would push each other around. It wasn't a big deal since Victrons switch so fast. After converting that system over to LFP, the problem went away. All the controllers are very stable now and no jumping around. I suspect the lower charge resistance is able to soak up any spikes and smooth out any dips.
 
Thanks folks for your help. So I have 1 epever Trace 60A max (I forget which one, I had that info when I joined the forum, but I guess it doesn't show publicly?) SCC that has the maximum charge parameter set to 14.6V, the boost voltage set to 14.5. I have to manually change the equalization voltage once a month for a day to 15.5, otherwise it is set to 14.5. The inverter is a Kinverch pure sine wave 2000 watts. My panels are ecoworthy 200W panels connected in series. The wires connecting the solar panel to the SCC are 12 gauge cables that have the 3 wires all twisted together at both ends, about 14 feet long (yes, I like to save money). The other wires connecting the inverter and SCC to batteries are thick gauge, short (<4 feet) single wire cables that came with the inverter and SCC. The batteries are heavy duty "street cleaner" batteries, equivalent to L16s (but cheaper), 2 6V ones connected in series. I can't upload a pic right now, since I'm not there right this moment. Hopefully the words are good enough.
Sunsurfer, why would you connect several SCCs together, of course they would conflict with each other?
740GLE, no the batteries are not smart, they don't have overvoltage protection like some lithium ion banks. It's the inverter that has its overvoltage protection circuitry triggered (at 15V). I can lower the "max charge" parameter of the SCC further, and the problem goes away, but then the boost voltage has to be lowered too, which is not good for the batteries. I am a bit confused how the MPPT algorithm interfaces with the whole idea of a boost voltage. The other thing I did is reduce the boost time, so the problem doesn't keep happening for more than 20 minutes a day (it was 120 minutes of boost time before). But my batteries probably don't like it and will sulfate faster.
As far as solar panel output, it is possible that it spikes the voltage when the clouds part, exceeding the range of the SCC. I might check if I am willing to sit under the house for a bit till the problem happens, monitoring the solar panels' output. I think I would have noticed if the current or voltage was going higher than the SCC bounds. I actually took a video of the spike so I can convince epever that the problem is real, so I might look at that (I had only focused on SCC output, not input before). Epever, btw, just sent me a new SCC, and it didn't solve the problem, just wasted my time.
 
Last edited:
Sunsurfer, why would you connect several SCCs together, of course they would conflict with each other?
To get more solar capacity- my current system uses 2 MPPTs- one for the north facing array, one for the west facing array- but the final house system with have the two inbuilt 60A MPPTs in the inverter for the north facers (6kw), another 2 60A for the east facing arrays, and another 2 for the west facing arrays (18kw of solar/72 250w panels, 18kw total)

It certainly isn't unusual- one system I worked on a while back had 7 different charge controllers, some PWM, some MPPT, being fed from a mix of solar, wind and microhydro... (ranging in age from the brand new one I was installing, to some over thirty years old!!!) of varying capacities and brands....
 
I have 1 epever Trace 60A max
Sunsurfer, why would you connect several SCCs together, of course they would conflict with each other?
I was using ep-never controllers and had so many problems, I sent them back. Luckily it was in the return window for Amazon. They are crap. I went all Victron and they have been great. Fast and reliable. Bluetooth software is really good. You would love one and the prices have dropped. I would switch over to Victron.

I run multiple SCCs to keep my power level and volts low on my strings. High power means high potential;

Mulitiple SCC adds lots of backup and redundancy. When you are your own power company and your family depends on it, its nice to have backup and reliability to help keep things going.
 
  • Like
Reactions: Bop
Thanks folks for your help. So I have 1 epever Trace 60A max (I forget which one, I had that info when I joined the forum, but I guess it doesn't show publicly?) SCC that has the maximum charge parameter set to 14.6V, the boost voltage set to 14.5. I have to manually change the equalization voltage once a month for a day to 15.5, otherwise it is set to 14.5. The inverter is a Kinverch pure sine wave 2000 watts. My panels are ecoworthy 200W panels connected in series. The wires connecting the solar panel to the SCC are 12 gauge cables that have the 3 wires all twisted together at both ends, about 14 feet long (yes, I like to save money). The other wires connecting the inverter and SCC to batteries are thick gauge, short (<4 feet) single wire cables that came with the inverter and SCC. The batteries are heavy duty "street cleaner" batteries, equivalent to L16s (but cheaper), 2 6V ones connected in series. I can't upload a pic right now, since I'm not there right this moment. Hopefully the words are good enough.
Sunsurfer, why would you connect several SCCs together, of course they would conflict with each other?
740GLE, no the batteries are not smart, they don't have overvoltage protection like some lithium ion banks. It's the inverter that has its overvoltage protection circuitry triggered (at 15V). I can lower the "max charge" parameter of the SCC further, and the problem goes away, but then the boost voltage has to be lowered too, which is not good for the batteries. I am a bit confused how the MPPT algorithm interfaces with the whole idea of a boost voltage. The other thing I did is reduce the boost time, so the problem doesn't keep happening for more than 20 minutes a day (it was 120 minutes of boost time before). But my batteries probably don't like it and will sulfate faster.
As far as solar panel output, it is possible that it spikes the voltage when the clouds part, exceeding the range of the SCC. I might check if I am willing to sit under the house for a bit till the problem happens, monitoring the solar panels' output. I think I would have noticed if the current or voltage was going higher than the SCC bounds. I actually took a video of the spike so I can convince epever that the problem is real, so I might look at that (I had only focused on SCC output, not input before). Epever, btw, just sent me a new SCC, and it didn't solve the problem, just wasted my time.
update: I checked the video and neither input voltage nor input power exceeds the Tracer specs (a large safe margin), at least according to their MT50 measuring and display device. It's possible though that this device filters out quick spikes.
 
Personally, I prefer higher voltages and lower current for the solar arrays to minimise the cable costs (after all grid tie PV cable is readily available at least here in Australia, and thats UV stabilised, and rated for up to 600vdc for the older stuff, 1000vdc for the newer cabling...) although mains TPE in 2.5mm or 4mm in PVC conduit is legally acceptable for the PV DC side and a lot cheaper...
 
Last edited:
I was using ep-never controllers and had so many problems, I sent them back. Luckily it was in the return window for Amazon. They are crap. I went all Victron and they have been great. Fast and reliable. Bluetooth software is really good. You would love one and the prices have dropped. I would switch over to Victron.

I run multiple SCCs to keep my power level and volts low on my strings. High power means high potential;

Mulitiple SCC adds lots of backup and redundancy. When you are your own power company and your family depends on it, its nice to have backup and reliability to help keep things going.
OK, I am guessing this is the problem. Epever has been good about responding to my emails, though the engineer (or maybe just a customer rep) was always vague in answering precise questions, something I attributed to the nature of the Chinese language, but maybe also because it gives him plausible deniability.
 
Personally, I prefer higher voltages and lower current for the solar arrays to minimise the cable costs (after all grid tie PV cable is readily available at least here in Australia, and thats UV stabilised, and rated for up to 600vdc for the older stuff, 1000vdc for the newer cabling...) although mains TPE in 2.5mm or 4mm in PVC conduit is legally acceptable for the PV DC side and a lot cheaper...
Yes, I also have higher voltage, lower current, since my 3 solar panels are in series. I don't have to worry about cable voltage ratings unless my voltage spikes exceed 600V (nominal 60V).
 
Last edited:
One other thing: I have not been connecting any load to the charge controller. The inverter is connected directtly to the batteries. Should I connect it instead to the load terminals of the charge controller?
 
One other thing: I have not been connecting any load to the charge controller. The inverter is connected directtly to the batteries. Should I connect it instead to the load terminals of the charge controller?

No leave it .

Load is for if you use somting els if your battery is full.
Like a light or boiler .
All loads of your systeem have to by the battery its self.
Never on the load of the mppt.
It can not handel that power.

The load output is the same amps like mppt cable to the battery
So max 60a in your case.
 
No leave it .

Load is for if you use somting els if your battery is full.
Like a light or boiler .
All loads of your systeem have to by the battery its self.
Never on the load of the mppt.
It can not handel that power.

The load output is the same amps like mppt cable to the battery
So max 60a in your case.
Thanks. I'm looking into Victrons
 
OK, I am guessing this is the problem. Epever has been good about responding to my emails, though the engineer (or maybe just a customer rep) was always vague in answering precise questions, something I attributed to the nature of the Chinese language, but maybe also because it gives him plausible deniability.
Yes, running a single ep-never, I had voltage issues myself but my biggest issue was the loss of tracking and having to reset the controller mulitiple times per day. I had this problem with several of them, even when they ran by themselves.

Cut your losses and move on. I wasted lots of time trying to get it to work.
 
I'll stick with my old Sigineers 150v/60A- been running 24/7 (well I spose 'technically' 12/7 lol) for the last three years without missing a beat...
1724518577301.png
 
Regarding panels: is the 200 W You mentioned total power of 3 panels You said You have? Be aware, that 75/15 SCC at 12 V system is designed for 220 W nominal PV power.
And what are the open circuit voltage of the panels? 75 V are the hard limit to respect taking the lowest possible temperature into account.
It would be great to look at the datasheet.
 

diy solar

diy solar
Back
Top