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Help me to configure load priority setting on invertor


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Hi. Im new to this forum, seems like plenty on knowledgable peeps here. I would appreciate if someone could help me setup my invertor to run the input priority as solar then mains then batteries. I have a must pv1800 3024 vhm invertor. I only see option one Sol, Sbu and Uti, none give me the option i require. Sol and sbu can prioritise solar but only with battery as secondary and last mains. I want Solar and mains as priority in parralel and battery only when load shedding happens. Anything to tweak to get this? Or firmeare update etc? Thanks in advance

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On 2021/01/13 at 2:39 AM, Dollos1 said:

I have a must pv1800 3024 vhm invertor. I only see option one Sol, Sbu and Uti, none give me the option i require.

If it was an Axpert (Must seem to be partly Axpert clones, partly their own design), SOL would be the closest to what you want. It will run load on utility at night, but battery during the day, unless the battery is declared low. You could set the back to grid voltage or SOC quite high, so that the battery barely gets used. Most of the time, energy for the loads would come from solar anyway, bypassing the battery altogether. I don't know if Must copied this behaviour or changed it.

These inverter-chargers don't seem to be designed for strictly UPS use.

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Good morning Dollos,

 

I have the same inverter and have spent a fair amount of time setting it up to run as best as possible.

It will not do the Solar, Mains , Battery configuration that you are requesting, however as Coulomb has pointed out you can configure the back to grid voltage in order to minimize the use of the batteries once solar is no longer available.

When power is stable and the chance of faults is low I have set up my batteries to cycle to about 70% SOC daily and to recharge on solar only the next day which I have found is the sweet spot for my setup.

I should note that my inverter has about a 0.4v difference between the inverter display and the BMV that I have connected, however 2 other 5kva Must inverters that I have seen are accurate on their voltage reading. That means with mine and possibly yours the setup of the various battery parameters needs to take this variance into account to get it to work with some predictability.

Hope you get it set up to a way that works for you, shout if you need anything specific.

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HI @Coulomband @Dougiedanger

 

Thank you very much for taking out the time to reply to my query. it is very heart warming to see people who take time out for others and i wanted you guys to know that i  appreciate it most kindly.

Now to business.

@Coulomb the place i bought the invertor from www.geewiz.co.za also says in the specs Axpert type invertor, so would axpert invertor firmware be compatible with these invertors? or how could i go about ascertaining what is what?

On 2021/01/14 at 5:06 AM, Coulomb said:

You could set the back to grid voltage or SOC quite high, so that the battery barely gets used

1. This setting you are talking of, is it number [20] on page 17 of the manual i have attached to this post? and if yes what happens when the mains go out and what does the invertor do? go to battery or not go to battery when it sees the [20] setting is actually higher than setting[21], switch off or carry on discharging the battery until it reaches setting [19]? 

2. If using 72-cell panels with a 145 V max solar charge controller, always wire 2S! Never 3S!

i was actually going to add a third 72 cell 405 watt panel to my array to max out the 145v specified by the invertor. lucky i saw the footer of your post!

could you explain why? and according to you. i should connect the third panel in a parallel string to the 2 connected in series?

 

@Dougiedanger according to some google fu it seems like cycling the batteries to no matter what depth 10% used , 20% used also is not a good idea since "batteries are too expensive in any which form and size" so most are recommending to use them purely for backup. so i would like to know why cycling them down to 30% used as per your post above is a sweet spot, please elaborate?

i have 4 x 100ah 12v agm batteries connected in parralel series. i have connected each battery to an independent voltmeter between its + and - poles. how accurate will these readings be? or should i get a bmv later on ?

so your invertor is set to SOL option as well? but you are letting the battery drain to 70%SOC , then setting [20] kicks in and switches to grid, the next day the solar charges the batteries back to 100% and if solar is not available, grid charges batteries to 100%. is this correct?

 

Thanks guys for your feedback and once again thank you for your kindness....

 

420-00235-02-PV1800-HM.pdf

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Good Morning @Dollos1

This forum has helped me a great deal, a wonderful community to be part of.

35 minutes ago, Dollos1 said:

1. This setting you are talking of, is it number [20] on page 17 of the manual i have attached to this post? and if yes what happens when the mains go out and what does the invertor do? go to battery or not go to battery when it sees the [20] setting is actually higher than setting[21], switch off or carry on discharging the battery until it reaches setting [19]? 

 

Coulomb might be able to add more here but basically when the voltage is above the preset value in setting [20]the inverter will disconnect from the grid and use solar and or battery to power the loads. When the voltage drops below that set point it will reconnect to the utility supply if it is available and power loads from that. The batteries will then recharge depending on what you have selected in setting [10], ie either by solar[OSO] the next day or grid immediately [SNU or CSO]. Setting [21] then tells the inverter to go back to using the battery or solar when the battery voltage exceeds this value. 

41 minutes ago, Dollos1 said:

so i would like to know why cycling them down to 30% used as per your post above is a sweet spot, please elaborate?

I have a couple of personal reasons for this. I had purchased a set of Trojans after I killed my first set of batteries due to my lack of knowledge, Trojans are quite good batteries but expensive, however they have quite a good lifespan according to the data sheet so I have opted to use them relatively gently in order to recover so of their expense through saved power costs.

I also have extremely poor low voltage power supply in the evenings from the utility so my using the inverter I keep my power voltage constant and protect my other appliances.

My 'sweet spot' is the amount I draw out can be replaced by solar only the next day to get the batteries back to full, without having to use Utility power to achieve that. It also means that I leave about 80ah of emergency capacity to draw down  in the case of an unexpected Utility power loss, which wont take my batteries below the 50% SOC threshold (Setting 19 is configured to cut off at this point as well as my BMV)

49 minutes ago, Dollos1 said:

or should i get a bmv later on

Firstly how do the independent voltmeters compare to the inverter display voltage?

I would definitely get a BMV as well as a battery balancer. For me that was sound advice that i got from this forum. Lead acids are very sensitive to abuse and the Must inverter does little to prevent that abuse from happening. The BMV is far more accurate on monitoring the SOC and preventing you over discharging your batteries and the battery balancer will keep each battery balanced which prolongs their lifespan.

My first set of batteries barely lasted a year due to my inexperience and not having the setups on the inverter correctly configured.

55 minutes ago, Dollos1 said:

so your invertor is set to SOL option as well? but you are letting the battery drain to 70%SOC , then setting [20] kicks in and switches to grid, the next day the solar charges the batteries back to 100% and if solar is not available, grid charges batteries to 100%. is this correct?

Yes  I use the SOL option generally however I do not use the CSO setting as what happens is at night when it reconnects back to the grid, it immediately charges from the grid and therefore defeats me trying to save power use from the grid, so I keep it set on OSO and I have to be aware that when I leave the house in the morning if the weather is looking overcast then I need to reconfigure the inverter to recharge from grid. Not an ideal system but am working with the limited options the Must gives us.

Hope this helps...

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3 hours ago, Dollos1 said:

i was actually going to add a third 72 cell 405 watt panel to my array to max out the 145v specified by the invertor. lucky i saw the footer of your post!

could you explain why? and according to you.

I think my FAQ #8 needs a little work. Basically, 145 is the "never exceed" voltage; it can't generate ANY power at 145 V. It starts cutting back power at 130 V, and the specifications say that the upper end of the MPPT range is 115 V. Another thing is that users have found that higher panel voltages also cause the solar charge controller to get much hotter than it would passing the same power at a lower voltage (e.g. from 2S of panels). So even if the power isn't being restricted by voltage, it may eventually (especially in weather like we've had here recently) cut back power due to over temperature.

So all in all, it's just bad news running 3S of 72 (or more) cell panels. Obviously, 144 "half-cell" panels count as 72 "real" cells, for this purpose.

Quote

i should connect the third panel in a parallel string to the 2 connected in series?

NO! Paralleled strings of panels should always agree in voltage, with a maximum tolerance of 5% either way. So you can never parallel a single panel with other strings of 2. That means for 2S, you always need an even number of panels. So if you happen to have 3 now, you have to waste one or add another one (to end up with two strings of 2 in series, usually written as 2S2P). As soon as you go over 2P (so 3P, 4P etc), each string needs its own PV rated fuse. These are most conveniently wired as MC4 fuses.

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HI @Coulomband @Dougiedanger

 

Thank you very much for taking out the time to reply to my query. it is very heart warming to see people who take time out for others and i wanted you guys to know that i  appreciate it most kindly.

Now to business.

@Coulomb the place i bought the invertor from www.geewiz.co.za also says in the specs Axpert type invertor, so would axpert invertor firmware be compatible with these invertors? or how could i go about ascertaining what is what?

On 2021/01/14 at 5:06 AM, Coulomb said:

You could set the back to grid voltage or SOC quite high, so that the battery barely gets used

1. This setting you are talking of, is it number [20] on page 17 of the manual i have attached to this post? and if yes what happens when the mains go out and what does the invertor do? go to battery or not go to battery when it sees the [20] setting is actually higher than setting[21], switch off or carry on discharging the battery until it reaches setting [19]? 

2. If using 72-cell panels with a 145 V max solar charge controller, always wire 2S! Never 3S!

i was actually going to add a third 72 cell 405 watt panel to my array to max out the 145v specified by the invertor. lucky i saw the footer of your post!

could you explain why? and according to you. i should connect the third panel in a parallel string to the 2 connected in series?

 

@Dougiedanger according to some google fu it seems like cycling the batteries to no matter what depth 10% used , 20% used also is not a good idea since "batteries are too expensive in any which form and size" so most are recommending to use them purely for backup. so i would like to know why cycling them down to 30% used as per your post above is a sweet spot, please elaborate?

i have 4 x 100ah 12v agm batteries connected in parralel series. i have connected each battery to an independent voltmeter between its + and - poles. how accurate will these readings be? or should i get a bmv later on ?

so your invertor is set to SOL option as well? but you are letting the battery drain to 70%SOC , then setting [20] kicks in and switches to grid, the next day the solar charges the batteries back to 100% and if solar is not available, grid charges batteries to 100%. is this correct?

 

Thanks guys for your feedback and once again thank you for your kindness....

 

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Hi @Coulomb

 

Thanks for that info, really appreciate it. i havent bought the panel yet, i had space so i thought i would just fill it, but now i see that would be a folly.

Thank you

 

Hi @Dougiedanger

I would like to run on your style of setup for a few days and see how it goes. Could you give me your voltage settings please? namely [05], [14], [17], [18], [19], [20], [21].

 

and what is a good voltage to keep the battery at? 27? can it be higher like 27.5 maybe? since there is a slight variance on readings from the invertor and a bmv?

 

Thanks

 

Edited by Dollos1
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On 2021/01/16 at 7:39 AM, Dollos1 said:

Could you give me your voltage settings please? namely [05], [14], [17], [18], [19], [20], [21].

Good afternoon @Dollos1

I will post them below, however you will need to set up your own charging settings as per the data sheet for your batteries 

5  -  BLU

14. - USE

17.  - 28.4

18.  - 26.4

19.  - 22.8

20.  - 24.4

21.   - 25.3

Please bear in mind my settings are for Trojan Sagm 205ah batteries and are compensated for the inverter voltage error as well as temperature. My inverter and battery location is generally warmer than 25C.

What batteries do you have as set up needs to be specific for their requirements?

 

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Hi

Thanks for the settings

i have 4 x 100ah 12v vision 6fm100z-x batteries. 

I cannot for the life of me find the depth of discharge level for my battery anywhere on the interwebs also....

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15 hours ago, Dollos1 said:

i have 4 x 100ah 12v vision 6fm100z-x batteries. 

I cannot for the life of me find the depth of discharge level for my battery anywhere on the interwebs also...

Hi, have found this data sheet on the web. This suggests that your batteries should be set up very similar to mine, with the exception of the max charging current which is set at 30a.

What settings are you currently on for 11, 17 and 18?

Is the temperature there more or less 25C where they are installed and do your independent voltmeters differ to the Must screen battery voltage?

vision 100ah.pdf

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Hi @Dougiedanger

 

11. is set to 80A

17. is set at 28.8

18. is set at 27.0

19.is set to 24

20. is set to 26.6

21. is set to 27

i actually do not know even from the datasheet where to get these settings, they came like this from the company i bought from and recommended. only ones i have changed now to get the solar to work during the day is settings 20 and 21.

 

could you perhaps explain to me where to get settings such as max charging state and max absorb voltage etc from the datasheet please?

 

i found a ha02 balancer, so once i have completed the install, i should have the voltmeters outside of the box to view regularly also. should give an indication of what the batteries are doing exactly volt wise.

also i bought 2 dc 63A fuses for between the batteries and invertor. is that fine?

 

Thanks

Edited by Dollos1
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hi @Coulomband @Dougiedanger

 

please help me connect my ha02 correctly.

im a bit confused at one part. attached is a sketch where i have circled in a wire which is currently not there in my setup. should i create the bridged wire as per the ha02 connect schematic?

 

please help!!!

thanks

ha02.JPG

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  • 2 weeks later...

Hi guys

 

If anyone could help with the following it would be highly appreciated please.

 

should i set my invertor to UPS mode or APL mode? i notice that sometimes when the invertor switches between grid and battery one or 2 led lights flicker for a milisecond... is that cause i have it set to APL?

Thanks

 

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On 2021/02/05 at 4:04 PM, Dollos1 said:

should i set my invertor to UPS mode or APL mode? i notice that sometimes when the invertor switches between grid and battery one or 2 led lights flicker for a milisecond... is that cause i have it set to APL?

Yes. My understanding is that Axperts have a whole PCB devoted to a quick changeover of the load from battery to utility, and that this whole board is disabled in APL mode. But for whatever reason, that board can't operate at low AC-in voltages.  If you think your AC-in will never go below 170 VAC, then you may as well use UPS, but it may be difficult to use a generator when you need one. You could always change that setting when you need a generator, I guess.

With the South African grid the way it is, you may have no choice but to use APL mode. Though 170 V might be low even for SA? My understanding is that it's more than just the 170 VAC figure that changes between APL and UPS modes. Perhaps try it and see.

Even with the fastest changeover, some flickering may still be evident. It seems a fairly small price to pay, though.

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