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Noob - Baby steps to solar


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Howzit peeps, thank you for accepting me.

So I'm a complete noob but read quite a bit so I did a fair amount of homework before the time.

I installed my own system over the weekend, I'm not an electrician but can help myself to some extent, 5kVA 5000W The Sun Pays Inverter (Axpert) and 4x 100Ah Natlon Batteries. Current settings is what I got from The Sun Pays website.  I did this because I just got so fed-up with starting a generator every time it is load shedding, replacing alarm/electric fence and garage motor batteries and also remembering to shut down the mini server we are running in the house.

01 - SBU but I changed it to UtI because I don't have panels yet.

02 - 25Amp because my max charge current on the spec sheet for the batteries is 30A

12 - 49V not really applicable to my setup

13 - 54V also not applicable

16 - CSO also not really applicable

26 - 56.4V

27 - 55.2V

29 - 48V

Due to not having load shedding (I'm not complaining) I created my own load shedding yesterday by switching utility off just after 16:00. First thing I noticed is that once you switch off utility there is quite a voltage drop to +/- 51V where it stabilises.  Stuff running at that point incl. both Fridges, mini HP Server, Router, CCTV, Mac, work laptop and external screen and maybe a few other things, the inverter showed +/- 500W and if I remember correctly about 5A.

I pushed the limits, I had to do the test for when I'm not around to monitor everything, and used the air fryer for about 20min and microwave for about 5min, later on we switched some lights on, TV, Home Theater, Apple TV and then the kids used a hair dryer for about 3min.  At 21:00 we decided to switch utility back on with the inverter showing 48.6V under load.

This is a back up system for load shedding so it will be a stupid move to do what I did as part of my testing outside load shedding, I understand.  What I would like to know, based on the below info on my batteries should I change some of the setting I'm currently running?

Battery Specs;

Cycle Use: Initial Charge Current less than 30.0A, Voltage 14.4V - 15.0V (I've got no idea what they mean with initial charge current)

Standby Use: No limit on Initial Charging Current, Voltage 13.5V - 13.8V (Same here, with no limit it would opviously not be a good idea to charge at 60A)

26 - 56.4V seems low for the cycle use voltage but on the top bracket for standby use voltage.

29 - 48V is this to low as this is basically 12V per battery, it is obviously under load so should recover a bit.

 

Your advice would be much appreciated.

Thx Ricco Noob

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3 hours ago, RiccoS said:

I installed my own system over the weekend, I'm not an electrician but can help myself to some extent, 5kVA 5000W The Sun Pays Inverter (Axpert) and 4x 100Ah Natlon Batteries.

Are those flooded or sealed batteries? AGM or not? A quick web search could not find them.

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02 - 25Amp because my max charge current on the spec sheet for the batteries is 30A

I assume that should read 20 A, because 5 kVA Axpert models only allow multiples of 10 A.

Quote

 

26 - 56.4V

27 - 55.2V

 

These are 14.1 V and 13.8 V per 12 V module. See more below.

Quote

29 - 48V

Is it possible to set that value higher? That would allow for longer life of the lead acid battery.

Quote

Due to not having load shedding (I'm not complaining) I created my own load shedding yesterday by switching utility off just after 16:00. First thing I noticed is that once you switch off utility there is quite a voltage drop to +/- 51V where it stabilises.

Yes, that's because they're no longer being float charged. 51 V is an average of 12.75 V per 12 V module, which is approximately 100% SOC with no to light loads.

Quote

Stuff running at that point incl. both Fridges, mini HP Server, Router, CCTV, Mac, work laptop and external screen and maybe a few other things, the inverter showed +/- 500W and if I remember correctly about 5A.

It would have to be over 10 A; 10 A x 50 V = 500 W, plus an extra amp or two for losses. In this forum, we obey the law of conservation of energy 😀

Quote

 

Battery Specs;

Cycle Use: Initial Charge Current less than 30.0A, Voltage 14.4V - 15.0V (I've got no idea what they mean with initial charge current)

Standby Use: No limit on Initial Charging Current, Voltage 13.5V - 13.8V (Same here, with no limit it would opviously not be a good idea to charge at 60A)

 

Those sound like AGM figures. In summer, you should aim for the lower end of the voltage range, perhaps 14.5 V. 14.5 x 4 = 58.0 V (setting 26). Similarly 13.6 x 4 = 54.4 V (setting 27).

Quote

26 - 56.4V seems low for the cycle use voltage but on the top bracket for standby use voltage.

Again, it's 14.1 V per 12 V module. Too low for AGM bulk/absorb as you say, but way too high for float.

Quote

29 - 48V is this to low as this is basically 12V per battery, it is obviously under load so should recover a bit.

Yes, voltage sag is your friend here. Depending on your exact interter model (you didn't say; there are many 5 kVA models), you might or might not be allowed to increase setting 29 past 48.0 V. If you can, set it to about 49.0 V (12.25 V per 12 V module); this will increase battery life, at the expense of run time. But the exact SOC will depend on temperature and load, so you may have to fiddle with it a bit. You can use the rested average battery module voltage as a crude estimator of battery SOC (find a SOC table on-line, preferably one specifically for AGMs, if that's what you have).

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36 minutes ago, Coulomb said:

Are those flooded or sealed batteries? AGM or not? A quick web search could not find them.

AGM some Leoch and Natlon Partnership battery.

36 minutes ago, Coulomb said:

I assume that should read 20 A, because 5 kVA Axpert models only allow multiples of 10 A.

Setting 02 Max Charge Current Combined Solar + Utility allows 10A all the way to 140A if I remember correctly but I definitely set it to 25A 

Setting 11 only allow 2A, 10A, 20A, 30A, 40A, 50A and 60A

There is a note on setting 11 in the manual to say setting 02 will overide this setting if 02 is set lower than 11.

36 minutes ago, Coulomb said:

These are 14.1 V and 13.8 V per 12 V module. See more below.

Is it possible to set that value higher? That would allow for longer life of the lead acid battery.

48V is the max

36 minutes ago, Coulomb said:

Yes, that's because they're no longer being float charged. 51 V is an average of 12.75 V per 12 V module, which is approximately 100% SOC with no to light loads.

Great news

36 minutes ago, Coulomb said:

It would have to be over 10 A; 10 A x 50 V = 500 W, plus an extra amp or two for losses. In this forum, we obey the law of conservation of energy 😀

Those sound like AGM figures. In summer, you should aim for the lower end of the voltage range, perhaps 14.5 V. 14.5 x 4 = 58.0 V (setting 26). Similarly 13.6 x 4 = 54.4 V (setting 27).

Again, it's 14.1 V per 12 V module. Too low for AGM bulk/absorb as you say, but way too high for float.

I will up setting 26 then to 58V instead of the current 56.4V.

36 minutes ago, Coulomb said:

Yes, voltage sag is your friend here. Depending on your exact interter model (you didn't say; there are many 5 kVA models), you might or might not be allowed to increase setting 29 past 48.0 V. If you can, set it to about 49.0 V (12.25 V per 12 V module); this will increase battery life, at the expense of run time. But the exact SOC will depend on temperature and load, so you may have to fiddle with it a bit. You can use the rested average battery module voltage as a crude estimator of battery SOC (find a SOC table on-line, preferably one specifically for AGMs, if that's what you have).

Unfortunately I cannot go higher than 48V but the alarm kicks in ruffly 1.5V-2V above the 48V so I will know. 

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