Hi all. 

I have a Mecer SOL-I-AX-5KP which everyone tells me is a Axpert MKII inverter. 

So my setup is as follows:

The inverter- Mecer SOL-I-AX-5KP

4x 550 JA solar panels

2x 2.25 kw Pylon tech US2000c batteries

Solar assistant running on a pi

And I also have Home Assistant running on a old macbook.

Now my question is what should the settings be for me to use solar to First charge my batteries and then secondly power my loads?

I stay in Cape Town, the guy that did the install was a fly by night guy hence me ending up here.

This is my current settings. So what happens is that somedays I pull 1.3kwh at 11:30, then i get days when I pull 600 watts. I dont know what is wrong , is there settings that I need to change or is this the limitation of the inverter? 

Maybe the firmware needs to be updated. I am planning on getting a pylontech USB cable from solar assistance site this week maybe that will help. I am really out of ideas and options. The solar can't be this inconsistent, can it?

 

If inverter is the same as sol-i-ax-5nb

Setting 01 is the output source priority

To use solar 1st put to sol

If sol is insufficient or battery voltage drops it goes to utility but when no solar present switch to utility

Sbu is solar: solar then battery and then only utility

Some newer inverters have SUB which is solar utility then battery

Setting 16 is charge priority

CSO = Solar First Utility only if no solar available

CUT = Utility first Solar if no Utility

SnU = Both can charge

OsO = only solar

So in your case during day you want setting 1 to be SOL

16 also needs to be either SnU or OsO

But not having coms between inverter and your lithium batteries you may have cut out because inverter thinks battery is flat when its not.

When you say you pull 600w or 1.3kw is that your solar input or is that your load output.

What is your average load vs your average solar input

It is possible that inverter may need firmware update for lithium, did see a few posts during my search for firmware of my unit that spoke of two separate firmwares for the diffirent battery chemistries.

Just some thoughts, not a solution.

3 hours ago, techbw said:

If inverter is the same as sol-i-ax-5nb

The sol-i-ax-5nb from what I can see, is Mecer's version of the MKS II, and that one looks like the type of inverter that doesn't blend power.

4 hours ago, Marantz2245 said:

I have a Mecer SOL-I-AX-5KP which everyone tells me is a Axpert MKII inverter.

The OP is referring to the SOL-I-AX-5KP, which looks more like Mecer's Version of the Axpert King, which ties up with the description in the specification above.

ie. something like this: https://www.gntc.co.za/collections/solar-inverters/products/mecer-king-5kw-off-grid-inverter-ii-charger-4000w-mppt-220v-48v-dc 

 

For starters, I'd read through this thread to see if there's anything that sounds familiar in the behaviour of the inverter: 

 

Beyond that, this inverter is supposed to be able to blend power between sources, but you've got a maximum of 2.2kW of solar connected, and a 0.5C battery pack that should typically discharge and discharge at just 2.4kW. The balance would be blended from grid as needed. Perhaps more knowledgable folks can suggest how this blending is supposed to be co-ordinated.

5 hours ago, Marantz2245 said:

The solar can't be this inconsistent, can it?

Depending on the weather and several other issues, yes, it can.

17 hours ago, Marantz2245 said:

I have a Mecer SOL-I-AX-5KP which everyone tells me is a Axpert MKII inverter. 

No, it's equivalent to an Axpert King 5K-58, and NOT an Axpert King II, or an MKS II.

17 hours ago, Marantz2245 said:

4x 550 JA solar panels

Do you know if these are wired 4S (i.e. all four panels in series), or 2S2P (i.e. two strings of two panels, both strings in parallel)?

One way to guess this is to check the typical panel voltage. If it's up near or over 115 V, then that can cause the Solar Charge Controller to throttle back the solar charge current (and hence power). Assuming that the JA 550 W panels have 72-cells (or 144 half-cells, then you'd expect around 72 V when operating in good sun, or around 86 V when not producing much power, if they are wired as they should be in 2S2P.

But 4S would usually be over 144 V, which would never produce essentially any power at all.

17 hours ago, Marantz2245 said:

Maybe the firmware needs to be updated.

Indeed, 71.92 is a bit old, and there were problems around 71.92 with PV "dips" and "freezes". That doesn't sound exactly like your problem, but it's probably best to update to the latest firmware, which at present is version 72.04:

Yes, 72.xx is a different major version number than 71.xx, but they ran out of numbers in the 71.xx range, and allowed the numbers to overflow into 72.xx territory.

@Coulomb Its wired as 2S2P. Like today I only make about 580 watts. Will it help if I take each parallel string to the inverter with its own cable so two pairs of cables. There is a 2x1 combiner in line currently. I assume I can use the firmware you provided above. Can I use watchpower app to update the firmware?

What do I need to use to update the firmware for the inverter? 

Is there anyone who can maybe assist me with setting up the inverter to work optimally with solar assistant?

 

2 hours ago, Marantz2245 said:

Will it help if I take each parallel string to the inverter with its own cable so two pairs of cables.

I find it convenient to be able to switch in strings independently; I have 8 breakers for 14 strings, so still some strings are paralleled before the breakers.

But it won't give better performance unless the wiring is too thin.

2 hours ago, Marantz2245 said:

Can I use watchpower app to update the firmware?

No, you need the special reflash tool that is inside the firmware update zip/7z/rar file. If Watchpower is talking to the inverter via the USB port, then you have to get a different cable as well; see below.

2 hours ago, Marantz2245 said:

What do I need to use to update the firmware for the inverter?

See firmware upload instructions.

@Coulomb I keep getting u03 error when I try and upgrade the firmware. This is the firmware I try to use.

 

dsp_original_71.97.hex

So the inverter is in SBU mode now but these values don't make sens to me can someone please explain it to me.

 

1 hour ago, Marantz2245 said:

So the inverter is in SBU mode now but these values don't make sens to me can someone please explain it to me.
 

Something looks strange. PV could power the load but then not sure why the battery is charging at 313W as there will be a shortfall. 

If load is running from grid then there is 300W from PV missing? 

2 hours ago, Marantz2245 said:

So the inverter is in SBU mode now but these values don't make sens to me can someone please explain it to me.

 

The above does not make sense. In SBU- Solar-Battery- Utility mode you have solar input and battery capacity at 68% so Grid should not be enabled. You have ample solar(618w) to cover your loads(420w) and charge the battery@ around 198w. Attached screenshot of SBU on SA see grid at 0W. 517w(solar) -(299w(load)+190w(batt))=489w 28w convertion loss.

 

 

Edited March 28, 20242 yr by TaliaB

On 2024/03/27 at 11:03 PM, Marantz2245 said:

I keep getting u03 error when I try and upgrade the firmware. This is the firmware I try to use.

I know nothing about updating main firmware via USB, other than the obvious stuff like make sure the hex file is named exactly dsp.hex and is in the root directory of the USB stick. 

Some others seem to succeed with it, though I don't know if that includes any King users.

I would update via RS-232. Also, use the latest firmware (version 72.04), as 71.97 is now quite old and there have been firmware issues.

Edited March 30, 20242 yr by Coulomb

Ok so I got my PV to push more power. (It was a faulty join on the roof) Now I am wondering why am I getting only like 300 watts for the battery to load if I produce 1180 watts solar and use 730watts load.

 

Am I missing a setting?

8 hours ago, Marantz2245 said:

Ok so I got my PV to push more power. (It was a faulty join on the roof) Now I am wondering why am I getting only like 300 watts for the battery to load if I produce 1180 watts solar and use 730watts load.

 

Am I missing a setting?

This looks right. PV produces 1153W. 269W goes towards charging the battery and 743W is powering your load. The rest of the PV is powering the inverter. The readings on inverters are not alway very accurate. 

Edited March 29, 20242 yr by Scorp007

6 hours ago, Scorp007 said:

The rest of the PV is powering the inverter.

Yes, a combination of idle power consumption (some  50 W if the DC-AC converter is in use, perhaps more for a King as it also has the AC-DC converter (dual conversion)), plus some I²R losses. The I²R losses increase rapidly with higher loads.

6 hours ago, Scorp007 said:

The readings on inverters are not alway very accurate. 

True; some of them aren't measured directly, and so have to be inferred using guesses for efficiency etc. Plus, these values often fluctuate, and the monitoring software sometimes can't get all the values at the same time, so you may not get a "matched set" of readings.

I can't seem to be able to charge my battery more than 200 watt from solar but grid pushes it till 1900 + watts. Why would that be?

3 hours ago, Marantz2245 said:

I can't seem to be able to charge my battery more than 200 watt from solar but grid pushes it till 1900 + watts. Why would that be?

For the graphs above the energy balance makes sense, as explained by @Scorp007. If as in your example you are generating around 1153W from solar, the first 743W is prioritised towards running your loads first, then 269W goes into charging your battery. The remaining balance of 141W is attributable to a combination of self-consumption of the inverter, efficiency losses, etc.

The grid can raise the energy to the maximum that the charger and/or batteries can handle, and in this case it's the batterie that are the bottleneck with around 2kW-2.4kW depending on the charging stage. The solar charging is constrained to the leftover surplus of energy from the sun after the loads are supplied.

That begs the question, what is actually the peak power that your system currently generates around 12-1pm on a clear day? If you turn off all your household plugs and lights at the DB board, and ONLY charge the battery, what is the charge rate from solar you can achieve? Is there anything in the orientation of panels that is affecting your peak power generation?

7 hours ago, Marantz2245 said:

I can't seem to be able to charge my battery more than 200 watt from solar but grid pushes it till 1900 + watts. Why would that be?

Good suggestion from @GreenFields

With 4x550W one would expert to see about 1800W produced from PV say during the peak period on a clear sunshine day. Area specific. This value for Gauteng.