So I just had a situation where we had 900W solar and 1800W load and it switched over to using the grid even though the battery was still maybe 40% full. This likely happened because the voltage fell to 48V or below. I was looking at it a minute before it switched and it showed a voltage of 48.1.

Beats did say above "That means that under heavy load the battery voltage will reach the limits of settings 12 and 29 earlier than with little load." and this seems to have been an example of that.

I don't want that happening. I can't believe it is so much strain on the battery to have to put out 900W.

To reduce this happening in the future, I changed option 12 to 47V and option 13 to 49V just now and it switched back to solar precisely 10 minutes after the switch to grid. It looks like the inverter is programmed that once it switches to grid it must use grid for at least 10 minutes after that regardless of settings changes or loads. After 10 minutes, it will respond immediately to changes in setting 13 but before then any changes will be ignored until the 10 minutes is up. At least that seems consistent with my experience.

Should I be Ok with those settings?

Only issue I see with that is that what Coulomb posted in the other thread in January, which I referred to above (and see image below), says always have greater than or equal to 1.5V between settings 12 and setting 29 and I currently have the former at 47V and the latter at 46V. Pylontech tells me not to go below 46V, and setting 12 is only to the nearest 1V, so unfortunately my inverter won't let me select 47.5V.

 

2 hours ago, Green Power said:

Beat, my main two goals are to avoid power outages of any sort and use minimal grid. I am also interested in extending battery life, but that is a bit below the other two goals. Do you have to manually change from 49V to 50V every day or is programmed to do that in the inverter with a timer? Can settings 12 and 13 be 48V and 49V - 1V apart - or might that cause the inverter to constantly flick between solar and grid? What do you have setting 12 on when you have setting 13 at 49V?

I actually have setting 12 at 47V. However if load shedding looms I set it to 48V and 13 to 50V.

There is no way to automate that setting 13 change in my knowledge. However theoretically it could be done with software. But as a matter of fact I leave it most of the time at 49V. So fare I had no negative experience with it.

I highly suggest setting 16 to CSO. With my suggested settings for 12 and 13 it works very well and will never charge from grid as long as PV power is present. Except of course if you empty the battery during the day with heavy load that cannot be covered with the PV power.

My understanding is that LFP batteries are less affected by deep discharge than lead batteries. The data sheet of my batteries guarantees 3500 100% discharge cycles. That would last almost 10 years with one 100% cycle per day. But with above settings it never reaches 0% SOC. Design live is 20 years. Therefor I do not worry about battery live saving. As a matter of fact I lately bought a Canon picture camera. Its Lithium battery came willingly discharged. That means to me that those batteries do not suffer from being left discharged.

I have also found my Axpert clone does not always switch at the set voltage but is does not bother me a lot.

Some settings you might have to see what works for your situation.

As was said the load of 900W can drop tth value rapidly to below your setting. One must measure it and not just assume a certain load should not drop the volts by what you would like it to be.

2 hours ago, Beat said:

I actually have setting 12 at 47V. However if load shedding looms I set it to 48V and 13 to 50V.

There is no way to automate that setting 13 change in my knowledge. However theoretically it could be done with software. But as a matter of fact I leave it most of the time at 49V. So fare I had no negative experience with it.

I highly suggest setting 16 to CSO. With my suggested settings for 12 and 13 it works very well and will never charge from grid as long as PV power is present. Except of course if you empty the battery during the day with heavy load that cannot be covered with the PV power.

My understanding is that LFP batteries are less affected by deep discharge than lead batteries. The data sheet of my batteries guarantees 3500 100% discharge cycles. That would last almost 10 years with one 100% cycle per day. But with above settings it never reaches 0% SOC. Design live is 20 years. Therefore I do not worry about battery live saving. As a matter of fact I lately bought a Canon picture camera. Its Lithium battery came willingly discharged. That means to me that those batteries do not suffer from being left discharged.

I don't really understand "load shedding". I googled the phrase but I don't see exactly what this means in the context of the settings for home solar. Does "if load shedding looms" mean "If I know a high load is coming or likely to continue for a long time". Or perhaps you can ignore this for now if it's not critical for me to understand it.

If possible, I'd like to just pick one favourite set of settings and use that almost always. The only times I would want to make a manual intervention would be in winter when the battery is getting low and I want to boost it. Or on stormy/windy/rainy days when I'll want to maintain the battery above half full incase of a power cut. I'm hoping that apart from those cases I can, if it's working well, just leave it to one setting most of the time to save hassle, time, and interruption to my daily life.

I think I used CSO in 2020 with the old lead acid battery and if I recall it would just lead to continual topping up of the battery at night which is not what I want since it was just another example of pointless grid use when there was already enough battery power to get me through the night. I want to absolutely minimize the grid use. Can you explain the advantage of using CSO?

LS is a period where areas around the country do not have power as our only utility does not have enough power due to 33% of the power stations out of service.

The utility would announce the actual stage. Mostly stage 2 but we have had stage 4 as well.  Stage 2 means once or twice a day we will be without power. Luckily there are time tables for each area and an APP where one can get the hours of LS based on your address. Stage 2 then lasts for 2.5hrs. Some areas might be LS for less periods but lasting longer like 4 hours.

Normally hospitals have power on all the time. People close to them will have power all the time.

We are also experiencing longer power failures due to lack of maintenance and fires are a common problem after switching on after LS.

We normally have stage 1 or 2. This is what the schedule looks like. We have been spared LS for the last 23 days. These times are when power will be off and times change every day.

Edited March 3, 20224 yr by Scorp007
Added schedule

6 hours ago, Green Power said:

"That means that under heavy load the battery voltage will reach the limits of settings 12 and 29 earlier than with little load." and this seems to have been an example of that.

I don't want that happening. I can't believe it is so much strain on the battery to have to put out 900W.

That all depends on the capacity of your battery. The more Ah you have the less a heavy load would pull down the battery voltage. And you are right, the inverter waits around 10 minutes before switching back.

By the way, Coulomb has a patch to some of Axpert firmware that among other improvements eliminates the kettle effect. Tell him what firmware version you have.

1 hour ago, Green Power said:

Can you explain the advantage of using CSO?

The manual explains: Solar energy will charge battery as first priority. Utility will charge battery only when solar energy is not available.

That means i.e. that if you reach limit 12 during the day due to a heavy load, the inverter will switch to utility bypass for the load but will recharge the battery only from the PV panels. During the night in that situation however it will recharge  from utility.

OK, thanks for that. I can guess I can ignore the references to load shedding then since I live in Chile so it´s not really relevant.

That´s going to make it pretty hard for anyone in South Africa to make the argument that coal plants need to be shut down for climate change and pollution reasons. I had a quick check and I see South Africa isn´t rated as highly on corruption as it is on freedom and democracy. Perhaps corruption, or at least poor government, has had a role here. Seems a bizarre situation.

Do the load shedding problems greatly boost the solar market? Or is just generators for the rich, and no power for the poor I imagine? We have a lot of power outages in my area and most people just get noisy polluting generators.

I remember being in Tanzania in 2004 and there were some places (budget hotels) where there was no electricity at all except 7pm-11pm, no mains connection, and just a generator in those hours. If I was reading a book I would have to stop reading it from 6pm to 7pm when it was dusky. They didn´t turn the electricity on until it was almost completely dark.

I had a journalist contact me a few months back and ask me some questions about South Africa. I didn´t realize she was then going to publish everything I said. The result can be seen here: https://www.autotrader.co.za/commercial/news-and-advice/transportation-news/chile-is-going-all-electric-can-south-africa-do-the-same/9693 Hopefully it wasn´t too bad.

Edited March 3, 20224 yr by Green Power

I am new in this world. Just installed  one pylon 2.4 kw/50A , on a no-name inverter - actually he calls himself as MPS-V PLUS 5.5KW. Got 10 panels 350W. Evrything made in ...china. The inverter has no comm port (CAN,RS458), so the pylon cannot communicate. I hope that BMS it's on duty. I made the voltage settings ( back to utility, back to battery, bulk charging, low dc cutoff, float ). Then i was killing the grid power. (the inverter is hybrid). The primary source was SOL.  It was dark outside, so no sun, meaning inverter was functioning in "bypass mode". The test succeeded - inverter switches on battery instantly, when i killed the power.

I re-connected grid power, I switched inverter on SBU as primary, instead SOL. Looks okay also. But not for long ! As i saw also here, the problem occurred when the big consumer ( boiler, water-heater, geyser) started. He draws like crazy from battery. He needs 1.6 kw. Way too much for my little pylon. The battery voltage drops instantly. The inverter goes in alert mode, displaying 4 = voltage too low on battery. He switched back to grid. In seconds, he changes again to battery - i presume the voltage on it has raised at point back to battery. But, having the big consumer, he falls again instantly in alert - low voltage. It was an infinite loop, he goes back and forth from grid to battery. Kind of idiotic behavior - i mean i would expect it to be more clever. Meanwhile, pylon seems happy and - all greens lights , SOC near to max. Another stupid thing - how to display all green and same time low voltage ? Clearly, there is no way to deal with a load bigger than pylon it's able to. Piper / Coulomb warned me about, but at that time i was more idiot than today to understand.

The inverter option "switch on grid on overload" is useless. Because event was set, the idiot keeps the loop, despite the overload. I managed situation by raising the voltage for come-back-battery, and exit from that loop. 

So - at least my no-name inverter , in such case, was going in an infinite loop. Maybe inverters which are communicating with pylon don't do that.

I am still trying to guess the combination in such manner to avoid the loop, and have the inverter to act logic - IF load it's too much for battery, go back on grid, and STAY there, don't switch back-forth every second.

Ok, i am aware that the geyser wants too much from pylon. It would be nice if i could find a way to deal with through settings. If not.. my plan to stay on SBU at night falls down. Because of the geyser. Hm. Okay, i have a stupid solution... barbarian but looks workable. I could kill the power for geyser at night. With a timer outlet - case closed - he will sleep. No power from sun-set till dawn to  geyser. This is less expensive than another pylon, to increase capacity.

What i would like to have...but it seems impossible - at least with my inverter - would be the ability to change AUTOMATICALLY, on a time-schedule, the "primary source". it would be nice if i could program SOLAR from dawn to sun-set (i.e. 7 a.m to 7 p.m) and SBU for night. My inverter does not look like to be able for that. Neither to let me have a combination alike SOL+SBU. Theoretically, what i want it's what does inverter on SBU. But - what do you know... as i said above, i got a beautiful endless loop.

 

3 hours ago, SolarNoobish said:

I am new in this world. Just installed  one pylon 2.4 kw/50A , on a no-name inverter - actually he calls himself as MPS-V PLUS 5.5KW. Got 10 panels 350W. Evrything made in ...china. The inverter has no comm port (CAN,RS458), so the pylon cannot communicate. I hope that BMS it's on duty. I made the voltage settings ( back to utility, back to battery, bulk charging, low dc cutoff, float ). Then i was killing the grid power. (the inverter is hybrid). The primary source was SOL.  It was dark outside, so no sun, meaning inverter was functioning in "bypass mode". The test succeeded - inverter switches on battery instantly, when i killed the power.

I re-connected grid power, I switched inverter on SBU as primary, instead SOL. Looks okay also. But not for long ! As i saw also here, the problem occurred when the big consumer ( boiler, water-heater, geyser) started. He draws like crazy from battery. He needs 1.6 kw. Way too much for my little pylon. The battery voltage drops instantly. The inverter goes in alert mode, displaying 4 = voltage too low on battery. He switched back to grid. In seconds, he changes again to battery - i presume the voltage on it has raised at point back to battery. But, having the big consumer, he falls again instantly in alert - low voltage. It was an infinite loop, he goes back and forth from grid to battery. Kind of idiotic behavior - i mean i would expect it to be more clever. Meanwhile, pylon seems happy and - all greens lights , SOC near to max. Another stupid thing - how to display all green and same time low voltage ? Clearly, there is no way to deal with a load bigger than pylon it's able to. Piper / Coulomb warned me about, but at that time i was more idiot than today to understand.

The inverter option "switch on grid on overload" is useless. Because event was set, the idiot keeps the loop

 

 

OK just a few points. You choose the way the inverter should operate.

1. Such high loads are only for guys with deep pockets to install perhaps 10-20kwh of battery power to prevent your loop.

2. Your current SBU setting is not what I would even consider with water heaters on the inverter.

3. If inverter is used to have power when the grid is not available your inverter would do what it is designed for. Ma y people fall in the trap of trying to save by working in battery mode charges by PV.

4. If it was a proper hybrid like the Sunsynk you would have had timers to set and control if and when grid is used for the battery. Also what max loads can be powered at different times.

5. Your inverter core is a UPS to power loads when the grid is off.  Use the UTIL setting and once battery is full it will be on bypass and provide power directly from the grid instead of going in the spinning loop you mention.

6. It all boils down to connecting only sensible loads like those essential loads that don't use too much power. This will then work fine when there is no grid.

Sorry being a bearer of the limitations when trying to run the whole house on battery power.

Say you have a 10kwh load from dusk to dawn you can never expect the 2.4kwh battery to supply this power without using the grid.

Edited March 4, 20224 yr by Scorp007

@SolarNoobish Your Pylon battery is 0.5c. Which means, even if the battery is 2.4kwh, you are not able to draw more than 1.2kw of power continuously from it. That is the maximum, you can use on the load when utilising the battery. 

Edited March 4, 20224 yr by PowerUser

6 hours ago, SolarNoobish said:

What i would like to have...but it seems impossible - at least with my inverter - would be the ability to change AUTOMATICALLY, on a time-schedule, the "primary source". it would be nice if i could program SOLAR from dawn to sun-set (i.e. 7 a.m to 7 p.m) and SBU for night. My inverter does not look like to be able for that. Neither to let me have a combination alike SOL+SBU. Theoretically, what i want it's what does inverter on SBU. But - what do you know... as i said above, i got a beautiful endless loop.

With such a small battery capacity I highly suggest you split your DB in essential and non essential consumers. Connect all heavy loads like geyser, cooking, air conditioners and the like to non essential directly fed from grid. Connect inverter output to essential loads only. I suppose that you can live without those non essentials during power blackout.

15 hours ago, Green Power said:

We have a lot of power outages in my area and most people just get noisy polluting generators.

Well, then the "Load shedding looming" argument becomes permanent for you. Set the 12 and 13 limits accordingly in order to always have sufficient energy spare in the battery.

Thank you @Scorp007, @Beat

My inverter it's a piece of junk, i am aware of. I discovered, after hours of playing with and going from loop to loop, that  it pretends to control voltage in 0.1V steps, in reality it is working with math round... only INTEGERS. Sounds crazy but experiments are talking.

Of course, there is no such reference in "manual". Therefore i am trying to find the best way to set the junk in order to avoid looping and stuff.

Looping was triggering EXACTLY because of this issue - real he's working with integers, even you put in it decimal values. Ok, i got it, lesson learned. Till i'll got money to buy a real inverter i have to survive with the junk. There is a gain , this way i have to learn more, to understand more. I made settings after settings, looks like i found a combination which does not go looping. I checked manually, on inverter's screen what happens, voltage , bla-bla-bla. I have these settings now :

With these, the gap between go-to-grid and go on batt it's large enough, no looping.

I tested, playing with loads - usual loads, no geyser. I cut-off power on geyser. But water pump it's mandatory...

 

These are readings from the inverter's screen. The "peaks" 1.4Kw = testing what's happening on flush water ( he he he...i need to do that even on black-outs...) and rest are usual consumers. What it's a kind of weird for me is that when a big load ends, the voltage reported by inverter raises. Hm. Meanwhile, the battery lights are displaying the same SOC - 5 green lights shining, no matter what the web-interface of inverter says... 

Do you think that these values i use in settings can harm pylontech ? From experience i mean... To me they are looking in the limits.

I am a little bit worried by the 35Amps drawn by water-pump... Pylon says MAX 50A... I think it's ok for couple minutes...

Struggling to understand what am i doing here, i really don't get it, how the inverter / web interface calculates the capacity of battery...

He is giving some figures... i don't believe them, since the pylon shines on 5 lights... Clearly the invertor uses inside some algorithm, NOT for litium, so, he makes some wrong calculation and displays these figures.

My hope is that BMS it's on duty. 

These are Data from inverter-web. 

Ok, this is correct, same values i've read directly.

Now comes the madness.

Well, well, well... what do you now ! My battery grows it's capacity from air, from nothing, without charging ! I am cool, huh ?  

same proof of my perpetuum mobile, free energy fro data-sheet :

 

I am putting these here just in case someone like me will encounter same issues. Bottom line  - i don't believe nothing from what inverter says, excepting Voltage. 

This is the big "advantage" using cheap inverters, no communication, they allow to charge batt from nothing...

Just to answer one question. One cannot go against the laws of physics. Just like us after we worked hard and we rest we recover energy.  The same after you had a high load on the battery the voltage would recover as you have indicated in your tables. The same you will see that you get more Wh out of the same battery if you discharge at a lower rate. At a 25A load you will get more than 2 times the power than at 50A.

For the price you pay for your inverter to have an inverter, AC charger and MPPT you cannot expert it to be a Rolls Royce.

Normally one would use a lower setting for float than bulk. Then the inverter knows what you expect of it. Also I would use 44V for cut out to allow if the inverter over reads. Disclaimer: I don't have any Pylontec batteries but other lithiums.

Your observation is spot on that using voltage alone without looking at your actual load gives you a false indication of SOC. Perhaps using the volts at  no load will be more accurate. Also spot on why comms is much more accurate than voltage.

My suggestion is learn how best to use it for now. 35A for your battery might also be higher than the specs.

Edited March 5, 20224 yr by Scorp007

You' re right, @Scorp007

For sure  i need to change the AC circuits, eliminating geyser from them - i mean from back-up part through battery. As you pointed out - in case of emergncy / blackout, ino one needs to take shower. It will remain only water pump as the big consumer, but at night, no one will use it, except flushing water  - this takes 1 minute of load or less. True, i am scarred because the current drawn - 35A it's too much, but i don't have a solution yet. A less power-pump cannot push water , it's a zug-zwang, a loose-loose situation. But... one of the goals to do what i trying to do it's exactly this - case no grid, i need water pump working.   Last night all house was on battery - geyser off. There was little loads - 2-300 watts when the refrigerator goes on, in rest 100-150 w. At morning, the pylon shows 2 green led on SOC. So - in normal and low loads she can manage it successfully. 

I am trying to USE the battery because i've read that she goes out when no cycling for 3 days. Kind of block, pain in the b... They say that no usage means less life, they like to be charged/discharged at least once per day.

2 hours ago, Scorp007 said:

For the price you pay for your inverter to have an inverter, AC charger and MPPT you cannot expert it to be a Rolls Royce.

Even with a Rolls Royce you cannot do a transport job that requires a lorry. I suspect his Voltronic clone is working quit good. For what he wants to do he requires much more battery capacity. Or he reduces the loads to essentials.

44 minutes ago, SolarNoobish said:

I am trying to USE the battery because i've read that she goes out when no cycling for 3 days. Kind of block, pain in the b... They say that no usage means less life, they like to be charged/discharged at least once per day.

Never read such n..........e . The datasheet of my LEOCH LFP battery states: "Low self discharge rate of 2 years before recharge required". That suggests that not use or cycle the battery does no harm. In contrary, it guarantees 3500 cycles at 100% DOD. That suggests that less cycling would extend its life time.

One more thing: If you use a LFP battery you must set 05 to USE, not AGM. Otherwise your limit settings will not work correctly.

Edited March 5, 20224 yr by Beat

@SolarNoobish

Please take note of the 2 points from @Beat

Lithium need not be cycled but best to be store at 20 to 80% SOC. My one lithium is not cycled and yes some would say it is a waste but it is for LS. Now and again I would cycle iit after 4 weeks the lithium still shows 53.4V so it discharges real slow. The only load on them is my voltmeter.

I have some ex laptop lithiums although a slightly different chemistry that are 12 years old and at times they are not used for months.

Second point is the AGM profile is close enough for lithium but the USER setting is better if you can adjust the settings as you can. For other chargers without this feature one can use AGM.

AFAIK the AGM profile will equalize and you never want to do this on a lithium. Make sure you have it off when you do the USER settings.

I don't k ow what is your head on the pump but using over 1.5kW is a mean pump. May be get a smaller pump just for the toilet as the rate of flow can be low. Lower power for longer would be another plus point. You even get 12V 80W pumps although noisy that can pump at a 70m head = 7-8bar. Also an accumulator would reduce the starts of the pump if you don't already have one fitted. The start current of the pump is a killer on battery systems.

13 hours ago, SolarNoobish said:

Well, well, well... what do you now ! My battery grows it's capacity from air, from nothing, without charging ! I am cool, huh ? 

You and the inverter cannot determine battery SOC from the voltage because the inverter firmware does not have another SOC/voltage characteristic than AGM. Only the BMS can inform you correctly. What you see in your graph at approx 17:.. is probably the on switching of a heavy load (geyser) that pulls the battery voltage down (kettle effect). As soon as it switches off the battery voltage recovers and falsely suggests higher SOC.

@SolarNoobish

Just another thought. Currently when that pump of yours starts you will be exceeding even the maximum current you are allowed to draw short term for your Pylontec 2.4 battery.

5 hours ago, Scorp007 said:

Currently when that pump of yours starts you will be exceeding even the maximum current you are allowed to draw short term for your Pylontec 2.4 battery.

They allow a short term overload, I assume for exactly this sort of thing (starting motors and pumps). Edit: oops, I haven't checked the sizes; the allowed overload on the Pylontechs is only 2x from memory; typical motor startup surges are 7x continuous power.

Edited March 6, 20224 yr by Coulomb

6 hours ago, Coulomb said:

They allow a short term overload, I assume for exactly this sort of thing (starting motors and pumps). Edit: oops, I haven't checked the sizes; the allowed overload on the Pylontechs is only 2x from memory; typical motor startup surges are 7x continuous power.

Yes to get into the nitty gritty. The US2000 states 25A and peak of 95A. Thus the pump running at about 35A would exceed even the 95A rating given for 15 sec. Luckily it is only for a second but I don't think the battery would handle it for many years.

It would be interesting to know?

18 hours ago, Scorp007 said:

Yes to get into the nitty gritty. The US2000 states 25A and peak of 95A. Thus the pump running at about 35A would exceed even the 95A rating given for 15 sec. Luckily it is only for a second but I don't think the battery would handle it for many years.

It all boils down to that you need additional battery capacity. That would also attenuate the stress on the battery, thus extend live time.

For the inverter it's not that much of a problem. The starting current of an induction motor at rated voltage is around 5x to 7x rated current. That does not translate to 5x to 7x power rating, only to apparent power rating (kVA). The Voltronic 5kW rated inverters have 10kVA capability for 1.5 seconds (short circuit power). As this is not active, only reactive power, it does not translate into corresponding current from the battery. The capacitors inside the inverter provide the reactive current. It's actually a current that oscillates between the inductive load (motor) and the capacitors.

Edited March 7, 20224 yr by Beat

@Beat

Thanks for a great explanation on current vs power. I can just mention I have measured 10 times the running current on a fridge during starting. The fridge used 14A from a 12V battery when running. During starting I recorded a video of the clamp meter and the peak was 140A although for a very short period. Measuring on the DC side is just easier without having to deal with power vs VA.

My post was based on the pump being a 1.5kW. Thus the running amps at a 0.7 PF is 9. 3A. Using a lower 5 times current means 46.6A for a short period. I would be reluctant to subject a 5kW Axpert to this type of current each time the pump starts when a tap is opened. 

Even with a larger battery I would rather use a smaller pump for topping up the toilet.

We are now hijacking the post of @Green Power

BIG TIME