Pylontech - The Right Buy for Me?

[wattmatters]

Makes sense, but that still leaves the problem that the inverter will beep continuously with low battery warning which will be audible in half the house. How can I make it shut up?

There will be setting options in the inverter to turn alarms and sounds on/off. In my inverter these are settings #18 and setting #22. Check the manual for which settings apply for your inverter.

For mine I leave the alarm on (#18) but turn the beeping off (#22). When you turn the beeping off it will stop that incessant beep every time you press a button on the display. Not sure about which setting silences alarms because I've never had one! Personally I wouldn't mind if the inverter sounded for alarm states.

thanks a lot for helping out. is it a bit late for that now, since they have already been connected?

Well you'll know for next time.

I think in your case because there are only two batteries they will be OK, the batteries will self balance over time provided you change the main terminal connection point as discussed and because you only have two batteries that will do a good job of charging/discharging them evenly and they should sort themselves out. Hopefully you will get a good solar day soon to give them a good full charge.

I've not used those battery power cable connectors before but pretty sure they can just be unplugged and plugged back on. They are made to be a super simple and fast to install battery system.

First turn off your inverter (should be a switch on it somewhere, probably underneath) and then turn off the batteries before unplugging the either the positive or the negative battery cable (doesn't matter which, just choose one) and reconnecting it to the other battery's spare terminal of the same polarity (black/negative to black/negative OR red/positive to red/positive).

WARNING:
DO NOT TOUCH A BLACK CABLE TO A RED TERMINAL OR A RED CABLE TO A BLACK TERMINAL.
WEAR SOME SAFETY GLASSES (it's good practice even though this is one very simple job).

Then turn on the batteries and then the inverter. That's it, simple!

 

[Mendoza]

Looks like option 18 killed all sound.

The downside is you might not know if there is a fault. So now I've turned off the sound the ignorance of faults could cause damage, problems etc.

Also last year I was finding there would be a fault, and the beeping would draw my attention to it, and I would see the fault code displayed for a few seconds, and then the system would shut down. So I would at least have a clue as to why the system had shut down, some error code number to work with. If it was quiet I never would have realized until the system turned off, and would be then clueless as to why.

On balance I'll have it off for now at least since otherwise it will be bleeping incessantly with the low battery warning, and the constant bleeping every time you press a button is so dumb. Option 18 killed both at once.

In an ideal world, I could turn off the sound for low battery warning and leave other alarms on, but I doubt that's (easily) possible.

 

[Mendoza]

So does this look OK:
---if I disconnect the cable I have marked with a green X
---and move that same cable and reconnect to the position I've marked with a green O
---and only change position of one cable; not move any of the other cables at all (might have to move/reconnect the short black cable so it doesn't get in the way)
---not touch or move any orange cables

 

[Mendoza]

Are all four black (negative) ports functionally equivalent? i.e. doesn't matter which of any you use for both short and long cable? Any cable to any connection (as long as it's black to black and not black to red of course).

 

[Don B. Cilly]

Yes, the two ports are wired together. Both the red and the black, which one you use is irrelevant.
Just switch both batteries off, connect the cables just like in your picture, move the short one if you like, turn them back on (switch first and then little red button). Don't worry about beeps and red lights when you do, it's a self-test.
They are a bit hard to pull out. It's normal. Push them in well.
-

 

[wattmatters]

So does this look OK

Yes.

Are all four black (negative) ports functionally equivalent? i.e. doesn't matter which of any you use for both short and long cable?

Correct. Both the ports on the same battery of the same colour are connected together, it doesn't matter which you choose for connecting the short and long cables to.

 

[Mendoza]

EDIT: 13th April, 2022: I found out that there is a small button on the cables that you push in to pull the cables out rather than pull them out with force.

I contacted my friend who installed the system and he was happy with the suggested change.

I have changed the connections as stated, they click when you push them in. It now looks like this (see photo).

When I got up this morning (before I made the change) all the lights were flashing and it was beeping on the second, lower, slave battery. The manual says this is due to cell overcharge. I hope this is because of the cable connections being in the imperfect positions as discussed, and won't happen again now I've changed it.

 

[Don B. Cilly]

Well, what were you charging them with?
Any indication (like a bright, big voltmeter at your distribution panel ;·) that they were, in fact, over voltage?
The LEDs seem to indicate they are discharging, and around 70% SOC.
-

 

[Mendoza]

They were being charged up with solar at the time it went wrong. The only indication of a problem that I noticed was the alarm and lights flashing.

 

[wattmatters]

Describe and show photos of the entire system.

 

[Don B. Cilly]

No DC loads? DC distribution panel with voltmeter?
Get yourself something like this, they're really quite cheap on Amazon/eBay/local electronics shop.


Put it somewhere you can see it ;·)
-

 

[Mendoza]

Thanks a lot for your help. The manual said turn off for 15 min and turn back on which I did which seemed to work, no current alarm, things look OK.
Just to be clear there is no current problem.
We have 3.25kW panels (10 Risen) with Axpert MKS II 5kW as well as the US2000C x2. I can´t get to the photos right now as I am busy on something and then going out but can do it another day if needed.

 

[Mendoza]

Here are the photos of the system. Things are working very well so far.Changing the cables may have been a great idea (thanks!) as there was an error message on the battery on the 1 day they were connected as before and things working well in the 4 days since then. There has not been a power failure or other problem since the system was installed. There have been no error messages except the inverter advising of low battery which it does most of the time unless the battery is near full. However it can say low battery and then the battery can go on and on providing another 2-3kWH of energy for 10 hours more, with no grid electricity used, which confirms as we expect that we can ignore that. The battery is filling up to the max (or close) every day and then in the early morning it still has 2 or 3 lights on suggesting it is still half or nearly half full.

 

[AlaskanNoob]

Here are the photos of the system. Things are working very well so far.Changing the cables may have been a great idea (thanks!) as there was an error message on the battery on the 1 day they were connected as before and things working well in the 4 days since then. There has not been a power failure or other problem since the system was installed. There have been no error messages except the inverter advising of low battery which it does most of the time unless the battery is near full. However it can say low battery and then the battery can go on and on providing another 2-3kWH of energy for 10 hours more, with no grid electricity used, which confirms as we expect that we can ignore that. The battery is filling up to the max (or close) every day and then in the early morning it still has 2 or 3 lights on suggesting it is still half or nearly half full.

Sweet!

 

[Mendoza]

If the battery is never emptied, I'm guessing that is no issue, if it is rarely below say 40% full, at least at this time of year. Or is there any value to empty occasionally?

So the manual says recommended current of 25A and max current of 50-89A@60 sec.
However since I have two batteries I think that should be 50A and 100-178A.
Multiplying that by 50V should give recommended 2,500W and max 5000W-8900W.

Should I read that as "don't go above 2500W load on the battery for more than 60 seconds, ever" or perhaps more as "try not to do it excessively"? Am I Ok to run 4000W load at night? - this would mostly be for 2 to 6 minutes at a time for an average of less than once a day. Will going too high cause any damage to the battery, or will it just cut over to grid electricity or withhold power when it is under strain? I'll probably run an experiment and plug in two kettles after dark to see if the battery can handle 4000W. Let me know if this is a bad idea.

 

[wattmatters]

Here are the photos of the system.

Nice, glad to heat it's all working well. A few more suggestions if you don't mind which will help your system perform better over the longer run:

i. Solar PV array - remove the agapanthus plants from in front of the array. That little bit of shade they cast is actually quite bad for the PV array's overall performance.

ii. Inverter - it looks very dusty/dirty. Take particular note of the vents in the side panels - it's important these are kept clear to allow for air flow to ensure the inverter's cooling can operate effectively. It's not something which will kill it straight away, but heat is the enemy of electronics and so anything you can do to improve the heat dissipation/cooling of the inverter will extend its life. If there is anything you can do to reduce the amount of dust in that space it will be a good idea. I know it can be difficult in some environments. You may need to give that inverter a clean out inside every so often.

iii. Inverter - the bottom cover panel (shown sitting on top of the inverter in the photos) should be fitted for safety as you have dangerous voltages exposed and which can be accidentally touched. That panel is for the safety of all.

If the battery is never emptied, I'm guessing that is no issue, if it is rarely below say 40% full, at least at this time of year. Or is there any value to empty occasionally?

That's perfectly fine. There is no need to empty the battery, but also there is no great harm done if you do. They are designed to cope well with partial and full discharge.

So the manual says recommended current of 25A and max current of 50-89A@60 sec.
However since I have two batteries I think that should be 50A and 100-178A.
Multiplying that by 50V should give recommended 2,500W and max 5000W-8900W.

Yes however if for some reason one of the batteries was unable to supply the required share of current while under such loads, then the balance of load would need to be supplied by the other battery.

Am I Ok to run 4000W load at night? - this would mostly be for 2 to 6 minutes at a time for an average of less than once a day. Will going too high cause any damage to the battery, or will it just cut over to grid electricity or withhold power when it is under strain?

If the battery is overloaded, the battery management system (BMS) should cut power supply to the inverter. If I'm not mistaken this means your inverter will also shut down as it requires battery power operate.

Your batteries are not designed to supply high power so I suspect you will be confined to operate within your 2.5kW limit.

 

[Mendoza]

Thanks a lot for helping out.

I do keep an eye on the plants, and I shoved them under the panels a few days ago since taking that photo. I do understand how plants shading 1% of a panel can reduce the energy by >>1%. However, my solar input (as measured by the inverter) is good, consistently meeting expectations. I can get 2600W (vs 3250 peak) during the middle 3 hours of the day and if I look on days of perfect alignment (at solar noon on a day the sun is almost directly facing the panel) I can see 2800-2900W.

I don't think the area is particularly dusty, I just haven't cleaned the inverter recently, and maybe not even in the 1.6 years since it was installed (only the batteries are new, everything else is 1.6 years). I did clean the front panel yesterday after noticing how dirty it was when uploading the photos. I didn't notice the side vents though, thanks for that. I cleaned the dust on the side vents with a vacuum cleaner, but the vacuum cleaner's plastic end part had to touch the inverter to do it, but probably safe enough I guess.

When I went to fit the bottom cover panel I found that it wasn't possible to align the two little holes perfectly to fit it with a screw because of the presence of the cables going down and it was pressing on the cables and couldn't go into place. Perhaps that's why the installer didn't put it on in the first place. So I put it in place using some metal wires to creates ties to bridge the gap between the holes.

I am not sure if the inverter requires power from the battery to operate because it still worked when turned off the battery connection (when the lead batteries were at end of life in Dec/Jan they won't working well so I just had direct solar and grid only). So do you think running 4000W for 2 - 6 minutes (when there is zero solar and battery will provide all) is a bad idea then?

Also, anyone know what the relationship is between the number of lights and the battery state of charge - manual doesn't say - for example it might logically be
zero light - 0%
zero lights and one flashing 0-16%
one light and next flashing 17%-33%
two lights and next flashing 34%-49%
three lights and next flashing 50%-66%
four lights and next flashing 66%-83%
five lights and next flashing 84%-99%
six lights 100%


EDIT July 2022: The above is not accurate. I later got software and checked the battery capacity as the lights changed from one amount of lights to another. Reality (when discharging) is:
one light = 10% or less
two = 11%-30%
three = 31%-50%
four = 51%-70%
five = 71%-90%
six = 91%+
When charging the percentages are 1% lower, and you count the flashing light
For example 3 lights (two on and one charging) is 30% to 49%
No lights at all usually means the battery is idle, this will happen occassionally when the load matches the solar input very well
100% can be 6 lights (if discharging or charging) or none at all (if idle)

 

[wattmatters]

I do understand how plants shading 1% of a panel can reduce the energy by >>1%.

Even though output is good, avoiding hard shade on a cell is a good idea as it reduces stress on those cells. Individual cells can eventually burn out if subjected to hard shade too often while the rest of the array is pumping power hard. It will help extend the life of your PV array.

This is why for instance cleaning off lichen growth or really persistent large bird droppings is a good idea.

Obviously some shading is inevitable for many systems, usually it's best to confine that to the mornings and afternoons where possible. Hard shade under good solar conditions is not good for a panel's cells.

one light and next flashing 17%-33%

I don't know but perhaps the flashing means the battery is charging?

 

[Don B. Cilly]

On mine, all LEDs (the ones that indicate the SOC anyway) blinking means discharge, one fixed means charge, one blinking, basically float/trickle-charge. Percentage of SOC, I have 4, so 24% each - four meaning between 75 and 100%. Six... divide 100 by 6, it still gives you a rough idea, like all leds over 80 etc.

There is no need to discharge them "completely". In fact you shouldn't, but then the BMS should avoid that.
If you want to try it as an experiment, disconnect the panels (you do have a fuse/circuit-breaker on them, don't you? ;·) and they will discharge themselves.
-

 

[Mendoza]

Yes, there is a circuit breaker, but at some point I'll have a very cloudy day or have to charge the car a large amount in one day or overnight. I guess I can wait until then to find out if this inverter can deal with the switch to grid/utility.