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Hi Guys,

Let me start by saying this looks like an awesome forum. Tons of information here. Also the community looks like a bunch of epic people.

 

Now let me also start by saying what system I have installed and how its currently running:

 

330W X15 solar panels.

RCT - Inverter 5kva MK2

Polytech 2000 battery

BMS box - Has not been setup.

 

I want to system to run as follows:

During the day it must run on solar and at night I want it to run on eskom. I only want to battery to be used/run off when we have load shedding.

 

Currently its using the battery and solar during the day and thats fine with me as long as the battery does not go below 60%.

I have yet to setup the BMS box as I have no clue on how to do this.

 

Would any of you mind the recommend settings for my inverter giving the above scenario.

Currently my house uses about 2000w constantly during the day and at night time 1300w. There is the odd jump to 4000w when we turn on the kettle or vacuum machine.

I did order a pi from icc with the software.

 

Anyway any help would be awesome.,

 

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Welcome @OneillZA

Let's see if we can help you a bit

7 hours ago, OneillZA said:

RCT - Inverter 5kva MK2

Could you please post a picture of the label from the side of the inverter? I have to admit that I am not as versed as other resident members here in the differences between the various models - so that label will help me understand better which model exactly you have

7 hours ago, OneillZA said:

I did order a pi from icc with the software

Great stuff. I am a big fan of ICC as it makes managing your system a whole lot easier

Have you also ordered the Pylontech cable to connect the Pylon to the Pi?

7 hours ago, OneillZA said:

BMS box - Has not been setup

Can you please help me understand what you mean by this? Your Pylon has a built-in BMS

7 hours ago, OneillZA said:

I want to system to run as follows:

During the day it must run on solar and at night I want it to run on eskom. I only want to battery to be used/run off when we have load shedding.

Once ICC has arrived, we can set it up that way based on your actual Pylon SOC and also time-based if desired. In the meantime we can set it up to something that is close to that (based on voltages). Let me try to explain:

Based on your screenshot, at the moment your system ('Output Source Priority') is set to SBU - which means Solar -> Battery -> Utility. This means that your system will run on PV during the day. Any PV amount above your load will be used to charge your batteries. If PV drops below your load (clouds or towards the end of the day), the system will draw the shortfall from your Pylon. Once your PV is down to 0, it will draw your full load from the Pylons. Once your Pylon voltage drops to your 'Back to Grid voltage for SBU priority' setpoint (47.0V as per your screenshot), it will switch over to Utility. It will run on Utility until your Pylon has been recharged back to the 'Back to Discharge Voltage' setpoint (54.0V as per your screenshot - way too high - see below). Then it will run on PV/Battery again until your Pylon voltage drops to your 'Back to Grid voltage for SBU priority' setpoint - and so on...

This I believe is not how you want to run your system.

You have 2 options:

  1. Change your 'Output Source Priority' to SOL - which means that it will run on PV until PV drops down to 0 (shortfall supplied by battery until then) and switch to Utility at that point
  2. Increase your 'Back to Grid voltage for SBU priority' setpoint to a higher value to have the system change earlier to Utility (e.g. increase from 47V to 50V)

A few further settings that you should change immediately:

  1. Your charging parameters are way too high for the Pylon. Recommended settings here are Bulk 52.5V and Float 51.8V
  2. Your 'Back to Discharge Voltage' is also set too high - which means that at the moment your system will only switch back from you to PV once your Pylon is fully recharged. This obviously needs to be somewhere in between your Float voltages above and your 'Back to Grid voltage for SBU priority'. Remember that your inverter will keep constantly drawing just over 40W from your Pylon even if it running on Utility - which means that your Pylon in the morning will be at a lower SOC than it was in the evening even if you have been running on Utility the whole night

I would also recommend changing the following other settings:

  1. 'Output Mode' is currently set to Parallel. If I am not mistaken, this should be set to Single as you are running only a single Axpert and can cause sometimes problems
  2. I would set 'Max charging current' and 'Max AC charging current' both to the same value. Recommended value for your Pylon is 25A. As I don't think that the Axpert supports 5A steps, I would recommend 20A for both settings
  3. Your 'Charger Source Priority' is currently set to Solar First, which means the Axpert will use whatever PV is available to charge the battery. If no PV is available, it will charge from Utility. If with the settings made above you are not significantly drawing down on your Pylon in the eve, then I would change this to Solar Only. Then your Pylon will only be charged by excess PV that you have and not by Utility. You need to decide for yourself how often and long your loadshedding is and if you believe that you will get by with only charging your batteries during the day (e.g. you would have problems if you have loadshedding from 18h00-20h00 and then again from 06h00-08h00 as your batteries will not have recharged in the meantime due to lack of PV). Maybe in the meantime leave the setting like this. With ICC it is easy to change this setting whenever required (that's what I do)
8 hours ago, OneillZA said:

Currently my house uses about 2000w constantly during the day and at night time 1300w. There is the odd jump to 4000w when we turn on the kettle or vacuum machine.

That is quite a high load. For that load I would say that your single Pylon is not enough. You need to keep 2 things in mind:

  1. Your Pylon does not like to be discharged by more than 25A for an extended period of time. This equals roughly 1250W - which means that your nigh time load of 1300W is already borderline. Turning on the kettle or vacuum cleaner while only running on Battery your Pylon will not appreciate
  2. Your Pylon has 1.9kWh of usable capacity at 80% DOD. That means that it will not be sufficient to power your 1300W night time load for the loadshedding period of 2h (=2.6kWh). For your 2000W load it would only be sufficient for about 1h - but as per above you should not power your 2000W purely from the Pylon
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On 2020/07/23 at 9:11 AM, OneillZA said:

As for the ICC this is the one I got:

Cool - and yes, that is the cable to connect your Pylon to the Pi. Then you are all set

On 2020/07/23 at 9:11 AM, OneillZA said:

So we saying I will need at least one more poly?

Yes, I would say (at least) 1 more Pylon. 2 Pylons in total will cover your night-time loads for 2h of loadshedding. During (most of) the day your PV will be sufficient to carry your 2kW load. You will, however, run into problems in 2 scenarios with 2 total Pylons and your 2kW load for 2h of loadshedding:

  1. If you have a cloud cover and your PV drops close to 0W.
  2. The late afternoon / early evening hours where PV drops to 0W but you are still running your 2kW of day-time loads (I do not know when in the day your change from 2kW to 1.3kW loads occurs)

2 Pylons will be ok to carry your 2kW loads for longer periods without complaining (2x 25A = 50A = 2500W) - however, they will not have the capacity to run your 2kW loads for 2h of loadshedding by itself (2kW for 2h = 4kWh vs usable Pylon capacity of 2x 1.9kWh = 3.8kWh - and you still need to account for conversion losses)

And even with 2 Pylons please keep in mind that they will still be the limiting factor on how much power your inverter can provide while purely running on battery. Even though your inverter is capable of delivering 5kW, with 2 Pylons you should not draw more than 2.5kW - otherwise your Pylons will complain

On 2020/07/23 at 3:58 PM, OneillZA said:

Here is the pic of my inverter

Thanks. I wanted to check how much your Max PV Array Power is (4500W in your case but other/older models only support 4000W) as I thought your 15x 330W (4950W) of panels was quite a lot. You have oversized your PV array by 10%, which to my understanding is still within 'limits'. But maybe @Coulomb can provide better assistance if this is still ok or if he would deem this as potentially harmful

If you need assistance with fine-tuning your system once you have ICC up and running, give another shout here and we will see what we can do

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21 hours ago, wolfandy said:

I wanted to check how much your Max PV Array Power is (4500W in your case but other/older models only support 4000W) as I thought your 15x 330W (4950W) of panels was quite a lot. You have oversized your PV array by 10%, which to my understanding is still within 'limits'.

Actually, Voltronic are a bit fast and loose with the specifications of this inverter-charger. The sticker says that the maximum PV array power is 4500 W. It doesn't say that it can use all of that power to charge the battery. In the manual, it seems a little more specific; in the solar charging section of the specifications it says "Rated power 4500 W". Pretty clear, right? Not really, because this section is headed "Solar input". So again, it could be interpreted as the maximum nominal power of the PV connected to the solar input.

The clincher is setting 02, maximum total charge current. The highest value the 5 kW model allows for this setting is 80 A. All the other models rate their solar charge controllers at a battery voltage of 50.0 V. So that's 50 x 80 = 4000 W, just like all the other 5 kVA models since late 2015. If your battery voltage is actually 56.3 V, then you might get 4500 W from PV, but I suspect that the firmware won't allow the inverter to work in reverse at greater than 4000 W.

So I think that this is really a 4000 W rated solar charge controller, and they are telling you not to connect more than 112.5% of rated power (i.e. 4500 W) of panels. To then say that 4950 is only a little over rated power is then not correct.

In summary, I don't know for sure. But keep this image of a burned Axpert MKS II solar charge controller in mind (from this post). He had 12 x 440 W = 5280 W, 7% more than 4950 W:

file.php?id=2565

 

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Ok hectic. Would you guys then recommend I remove 1 panel per pack of 5? @Coulomb. The other thing is I only get max 3400W of solar power in the day. It might be because its winter or I dont know.

Have stress tested this with a kettle and the max the pv goes to is 3400

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8 minutes ago, OneillZA said:

Would you guys then recommend I remove 1 panel per pack of 5? @Coulomb.

I assume you presently have 5S3P. That's a bit short (too few in series) and fat (too many in parallel). So definitely don't go down to 4S3P. They seem to make a big deal about the input current not exceeding 18 A. Your panels would be capable of some 8 A, so three strings would bring that to 24 A, quite a lot more than the 18 A max. I think you'd be better off reconfiguring for 7S2P (14 panels). 14 panels is then 4620 W, which is only 3% higher than the specifications. More importantly perhaps, the maximum PV current would be more like 16 A, under their 18 A figure.

8 minutes ago, OneillZA said:

The other thing is I only get max 3400W of solar power in the day. It might be because its winter or I dont know.

It could well be because the SCC won't use more than 18 A of current (as it says on the sticker and in the specifications). Let's guess the Vmp of your panels at 41 V each; 5S would give a total of 205 V, times 18 A is 3690 W, a little more than what you see in winter. With one fewer panel and 7S2P, you could expect very roughly 80% of rated power in summer, 75% in winter, so that's 75% x 330 x 14 = 3465. A possible improvement with one less panel in use. In summer you'd see the extra 5% (really 80/75-1 = 6.7%), whereas with 5S3P you'd still be limited to 18 A of panel current and possibly see less than 3400 W max due to the higher temperature (and hence lower panel voltage).

 

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Posted (edited)

Here is a pic for my panel.

At the moment we have 3 packs connected with a 3-1 way male and female connector. How would you then change this connection? @Coulomb

each pack has 5 panels connected to each other and then the ends goes to the 3-1 connector

Thank you for the help so far

WhatsApp Image 2020-07-25 at 16.04.29.jpeg

Edited by OneillZA
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2 hours ago, Coulomb said:

I assume you presently have 5S3P. That's a bit short (too few in series) and fat (too many in parallel). So definitely don't go down to 4S3P. They seem to make a big deal about the input current not exceeding 18 A. Your panels would be capable of some 8 A, so three strings would bring that to 24 A, quite a lot more than the 18 A max. I think you'd be better off reconfiguring for 7S2P (14 panels). 14 panels is then 4620 W, which is only 3% higher than the specifications. More importantly perhaps, the maximum PV current would be more like 16 A, under their 18 A figure.

It could well be because the SCC won't use more than 18 A of current (as it says on the sticker and in the specifications). Let's guess the Vmp of your panels at 41 V each; 5S would give a total of 205 V, times 18 A is 3690 W, a little more than what you see in winter. With one fewer panel and 7S2P, you could expect very roughly 80% of rated power in summer, 75% in winter, so that's 75% x 330 x 14 = 3465. A possible improvement with one less panel in use. In summer you'd see the extra 5% (really 80/75-1 = 6.7%), whereas with 5S3P you'd still be limited to 18 A of panel current and possibly see less than 3400 W max due to the higher temperature (and hence lower panel voltage).

 

I have change the cabling to have 2 packs of 7 panels. 

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11 hours ago, OneillZA said:

Please note I have received my Pi and its plugged and ready to go.

Cool - that will make changing settings on your inverter a lot easier as well allow you better / more accurate control of your system

Am I correct to assume that both the inverter as well as your Pylon are being recognized correctly? And that you have VNC up and running so that you can make changes remotely?

You can now have ICC switch your inverter between PV/Battery and Utility based on SOC or a specific time of day rather than on the voltage guesstimate of the inverter.

To do that you need to first change the following settings on the Settings/Inverter tab to make sure that the inverter does not change based on voltage settings:

  • Change the 'Back to Discharge Voltage' as high as possible (mine is set to 58V)
  • Lower the 'Back to Grid Voltage' to a value that is lower than your Pylon at the lowest SOC that you want to discharge it to (I discharge mine down to just over 20% and have my voltage set to 47V)

On the Settings/Battery tab you can then set when you want ICC to change the inverter between PV/Battery and Utility:

  • First you need to make sure that 'Use Pylontech Battery Values' is switched on (you  need to click the 'Stop' button in the top left to be able to change that setting; afterwards press 'Start' again for ICC to reconnect to your inverter)
  • If you enable 'Use SOC for Control' you can set the SOC values (based on the reading from the Pylon BMS) to change to Grid and back to SBU
  • Alternatively you can enable 'Use Time for Control' to choose between Utility/Solar-Utility-Battery/Solar-Battery-Utility for each hour of the day

You now need to figure out which works best in your circumstances/environment. It will probably involve some playing around with the settings and testing to see what works for you.

What I like about ICC very much is that it easily and quickly allows me to make changes. I live in an area where we have virtually no unscheduled outages and have a set of settings that works best for me in normal day-to-day use (e.g. running my batteries down to just over 20% every night and only charging from Solar). If loadshedding is announced for my area for late night or early morning hours, I simply raise the 'Back to Grid' SOC value to ensure that I change back to Grid earlier in the eve/night and still have sufficient capacity left in my batteries to get me through loadshedding. Only if I am looking at 2x loadshedding in short sequence (and no PV) or during extended periods of time of low PV do I change the inverter to also charge from Utility

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10 hours ago, OneillZA said:

I have change the cabling to have 2 packs of 7 panels. 

Wow. That was a quick implementation of my suggestion. Well done. It will be interesting to see how it performs today.

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  • 3 weeks later...
2 hours ago, OneillZA said:

Hi Guys, I want to add another 3.5 poly 300 to my system that currently has the poly 200.

How should I go about wiring this?

pol 300 as main or keep 200?

I do not have any experience in running Pylons of different capacities together

I have always added the newest Pylon as Master to my stack

And please remember to connect + to the first and - to the last battery in your stack

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  • 1 month later...
On 2020/09/14 at 3:34 AM, OneillZA said:

So my solar panels are still only getting max 3840 a day!

I assume you mean that you only see a maximum of 3840 W of PV power even at the best time of day. That's actually not bad for a single Axpert 5 kVA model. You are allowed to connect up to 4500 W of nominal panel power, but the solar charge controller will only push 80 A into the battery at most. Even with the maximum of 4500 W nominal PV power, you generally only see about 80% of that for various reasons, so that's 4500 x 0.8 = 3600 W.

If you mean you only generate 3840 Wh of evergy over a whole day, that's quite different, and certainly less than you'd expect.

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On 2020/09/13 at 7:34 PM, OneillZA said:

I assume its because of the 18 amps max input

It could also be because of overheating of the SCC PWM.

On my inverters (Kings) there is a control that reduces PV power when the SCC PWM temperature (as reported by the Q1 command) reaches 87C.  Interestingly this only happened when I ran my panels in 3S - since I changes to 2S the SCC PWM temperature never gets near 87C.

Not sure if the high voltage models would muse the same logic, but it might be worth checking (if you have the ability to run terminal commands)

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