Axpert invertors

[desiganp]

You also do know there's a good chance that some of the hardware you're using to post these messages might also be from China?

You guys do know that these Axpert inverters are Chinese Chinese ? meaning the low quality Chinese inverters.

There is a need to differentiate between low frequency and high frequency inverters. The Axpert I believe is a high frequency inverter (makes use of MOSFETs and other components - 2 x surge usually) . High Frequency inverters have a life span of < 5 years but also more affordable.

Low frequency inverters make use of transformers (3-5 x surge) which have a life span of 8 years +. More reliable but more expensive.

It's not about "Chinese" quality. Majority of electronics in the world are produced in China e.g. LG Fridges, dishwashers etc.

The difference between good and poor quality is whether strict Global standards are applied or not. The lower life span of some inverters has nothing to do with "chinese" as high life span has not much to do with "european". It's comes down to the design i.e. low frequency inverter (long life) vs high frequency inverter (shorter life).

Ultimately its about value for money. For most people, high frequency inverters will fit this category.

 

[savage]

At the end of the day I think the Axpert is a good buy, just don't run it near full load for any length of time.

Which can pretty much be said of any UPS/Inverter. You don't want to go (at most) more than 80% load. I'm not talking about spikes / surges, I'm talking about average, constant load...

Even large ass 80KVA+ UPS / Generators... It's never, ever, recommended to push more than 80% constant load... Some prefer to even go as low as 60%...

 

[Chris Hobson]

9:45am -Time for a cup of coffee. So I put the kettle on and it is a good time to see what the panels are doing.

P = V x I (91.8V x 36A) = 3304.8 W. But I only have 3kW of panels and it is the middle of winter (OK today's temperature could be making the panels more efficient).

The power being consumed is only 2415W so where is the unaccounted for 800 odd Watts (plus we are drawing 600 odd Watts from the battery - even worse - now we are looking for 1400W).

Does anyone have a reasonable explanation?

I do not think the figures on the Axpert are accurate and will do the same experiment once I have my battery monitor set up.

 

[scottwday]

Which can pretty much be said of any UPS/Inverter. You don't want to go (at most) more than 80% load. I'm not talking about spikes / surges, I'm talking about average, constant load...

Even large ass 80KVA+ UPS / Generators... It's never, ever, recommended to push more than 80% constant load... Some prefer to even go as low as 60%...

Difference is that if you run your Victron at 99% for 4.5 years and it conks out, they'll fix it for you.

My feeling is that even 60% average load is pushing it on the Axpert.

 

[savage]

Does anyone have a reasonable explanation?

The Axpert doesn't monitor itself real time (there is a bit of a delay)

It's not 100%, real-time, accurate. It's a well known fact. Even panel/DB Amp/Volt meters update's only once per second (at best). Even cheaper multi-meters, aren't 100% accurate either You get what you pay for. If you want accurate meters, prepare to spend large amounts of $$$

 

[Chris Hobson]

A few tricks I have picked up (and believe me I have been around the block on the setup):


Big tip - if you want the battery % to be accurate - set your final battery voltage to 42V as suggested in the AGM setting. I know this is too low, but I will never be able to run down my bank to that given my setup. This causes the inverter and charger to successfully detect when the batteries are actually low and full correctly. Many people set that to something like 46V, but in my case it made everything go awry - batteries would charge endlessly and frequent cutouts back to grid, etc.

Thanks! That was a revelation! I am waiting for a Victron monitor as I don't like the way the Axpert makes no sense at times.

Do you have a blog of your experiences?

 

[scottwday]

I think I also need to give my HO:
Big tip - if you want the battery % to be accurate - set your final battery voltage to 42V as suggested in the AGM setting. I know this is too low, but I will never be able to run down my bank to that given my setup. This causes the inverter and charger to successfully detect when the batteries are actually low and full correctly. Many people set that to something like 46V, but in my case it made everything go awry - batteries would charge endlessly and frequent cutouts back to grid, etc.

Don't you mean 52V?

 

[edmundp]

No - the Battery Cut-Off Voltage = 42V

Back to Grid Voltage = 49V (in my case at least - represents 70% DOD)

Back to Discharge = 57V as the Inverter seems to struggle to determine exactly when the batteries are actually full if on the FULL setting.

 

[scottwday]

No - the Battery Cut-Off Voltage = 42V

Back to Grid Voltage = 49V (in my case at least - represents 70% DOD)

Back to Discharge = 57V as the Inverter seems to struggle to determine exactly when the batteries are actually full if on the FULL setting.

Ok right that makes sense, I thought by 'final' you meant the fully charged voltage.

 

[edmundp]

Thanks! That was a revelation! I am waiting for a Victron monitor as I don't like the way the Axpert makes no sense at times.

Do you have a blog of your experiences?

No I do not. Not much of a "communicator"... but you are more than welcome to ask me by PM or what ever.

What I can say though that in comparison to the Victron the Inverter shunt seems to be off by about 2 amps in both ways for the worst, i.e. shows 20A charge is actually 18.5 and 20A discharge is actually 21.5A.

You also need to remember that in the case of the actual I and V solar readouts it might no be so accurate partly due to assumed factors and the MPPT coming in to play. Best is to look at the actual KW solar reading on the inverter itself - I find that pretty accurate.

 

[Chris Hobson]

Don't you mean 52V?

No the Battery cut off voltage (range 40-48V default 42V). With that set to 42V My SOC is correct (or nearly so).

P.S. Nice Youtube videos BTW

 

[edmundp]

Anyone wanting to ask questions to me on the actual settings of the Axpert are more than welcome. As said - been around the block and still fidling daily to optimize results and benefit.

What I also did is to setup Teamviewer on the connected laptop so that I can monitor things remotely on my Android.

 

[Gnome]

Quality is NOT determined by where it was built, it is determined by how well it was designed and how high quality the components are.
99% of all electronic are built in China because the largest factories in the world are there.
They build the best quality electronics by far because that is the heart of electronics manufacturing in the world.

Are they using well known capacitors (Nippon Chemi Con) or some unknown Chinese brand.
Even if they are using an unknown Chinese brand it can still be good quality, it would just depend on the designer to pick the right kind (very localized knowledge required)
How well are the components spec'd
What kind of quality is the soldering work, surface mount or hand soldered?

This is usually markers other than the design that indicate quality or lack thereof.
It has absolutely nothing to do with where it was built.

In fact if what you buy wasn't built in China or Taiwan you almost certainly overpaid for lower quality.

 

[Gnome]

There is a need to differentiate between low frequency and high frequency inverters. The Axpert I believe is a high frequency inverter (makes use of MOSFETs and other components - 2 x surge usually) . High Frequency inverters have a life span of < 5 years but also more affordable.

Low frequency inverters make use of transformers (3-5 x surge) which have a life span of 8 years +. More reliable but more expensive.

100% absolutely untrue.

Low frequency is an old design.

You take your battery voltage, you invert it then send it through a massive transformer.
Because of core losses and massive copper losses (because of the high current you need to deal with) you get a very inefficient design.

Low frequency is simpler to design and any product sold with a low frequency inverter is an old design.

High frequency uses mosfets to push current at high frequency through a transformer by switching on and off very quickly.
Because transformer cores can be smaller at higher frequencies you get a lower core losses.
You can also parallel the transformers which doesn't work with a low frequency design.

This part is called the boost stage and it is the very same design used in a switch mode power supply (which does the same but for a buck stage)
A very reliable and efficient design.

After that you have high voltage DC which you invert.

Neither topology has high surge ratings or VA ratings just because they are low frequency or high frequency.
The VA rating on the low frequency design is simply the last leg transformer and that rating isn't worth the paper it was written on.

Nor is the surge rating provided by inverters because they are lying 99% of the time.

 

[desiganp]

100% absolutely untrue.

Low frequency is an old design.

Neither topology has high surge ratings or VA ratings just because they are low frequency or high frequency.
The VA rating on the low frequency design is simply the last leg transformer and that rating isn't worth the paper it was written on.

Nor is the surge rating provided by inverters because they are lying 99% of the time.

I have to respectfully disagree with you.

How can it be "100% absolutely untrue" ? It is scientifically accepted that transformer-based inverter designs are more reliable (for obvious reasons) than non-transformer based designs and that transformer-based inverters have surge capability far superior (3x) to non-transformer based inverters. They are less prone to damage when starting difficult loads when compared to non-transformer inverters.

Low frequency may be an "old design" but it is by no means outdated technology and certainly has it's uses.

High frequency is more efficient yes, but only marginally, this is hardly enough to convince someone to go for HF simply based on efficiency alone, without comparing other other factors like life span/reliability/ability to withstand high loads.

It is scientifically accepted that low frequency inverters have a much longer lifespan than high frequency inverters.

 

[Gnome]

I have to respectfully disagree with you.

Same for me, but I must say at my young old age I've given up on forum arguments

I'd rather continue in the spirit of the thread.

I am very curious about the Axpert inverters (my current Cotek is super reliable but not as feature rich).
I like the features but this notion of errors popping up does make me worry a bit.

 

[The_Traveller]

Don't know why some of you getting the knicker twist effect , I'm just stating my opinion based on thorough research.
Top brands that have their products made in China have very strict QC and QA Standards. That's what sets them apart from the rest. But I'll stop here because I'm not here to convince anyone , just giving a 'heads up' about these inverters.

Lastly, low frequency inverters are meant to power up components with motors that draw and spike at high current. High frequency (being transformerless) inverters cannot handle these kind of motor loads so (again imo ) , anyone loading their Axpert with motors, be ready to replace them sooner.

And yes desiganp, low frequency inverters have a minimum lifespan of 8 years. I know the Sako brand claims 15.

Peace,out !

 

[Gnome]

Lastly, low frequency inverters are meant to power up components with motors that draw and spike at high current. High frequency (being transformerless) inverters cannot handle these kind of motor loads so (again imo ) , anyone loading their Axpert with motors, be ready to replace them sooner.

And yes desiganp, low frequency inverters have a minimum lifespan of 8 years. I know the Sako brand claims 15.

High frequency transformerless? Do you just read this stuff off of a brochure?

All I will say is, this guy shows the low frequency topology and one variant of the high frequency topology:
https://www.youtube.com/watch?v=iMHBw93W-XM

Notice the lack of the sales pitch BS.

 

[Jackie.P]

ADVICE ON SIZING PV PANELS TO AXPERT INVERTER

Hi all

I am a total newbie to this forum and have literally spend hours reading through all the threads and comments over the past few months. I am now in the final stages of acquiring components for my systems to power my house off solar during the day, and off batteries during the night, but I need advice please, as I am getting very different responses to some issues.

1. I have already bought one Axpert 5kva inverter(48v) and this will be wired into my DB Board. I will add-on another 5kva unit and run it in parallel as to be able to increase my total PV input to the maximum of 6kw.

2. I've already bought 4 12v 260ah Omnipower solar batteries and this will provide me with battery backup during loadshedding for now, and maybe enough to carry me through the night (30% DoD), as I've calculated my average nightly use to be in the region of 600w-700w. If I add the other Axpert it will also have the same battery bank as above

3. My DB board will be split into various sections, as I am planning to remove my garage from running from the inverter fulltime. I have lots of woodworking machinery, grinders and cutters as well as welding equipment which I do not think would be wise to run through the inverter. I am however considering (if possible) having my garage on a manual changeover switch which would enable me to run normal lights and plugs through the inverter during light use, and manually switch back to Eskom should I start working with my machinery over weekends. Any ideas or recommendations if this would be a viable idea?

4. My scullery's plugs running serving the dishwasher, auto washing machine and tumble dryer I am also planning to still run from Eskom power. I am unsure if these machines can be run effectively through the inverter setup, but if it will be mostly run during the day, so it would be nice to run this while my PV is supplying the power. Anyone having some comment on this?

Lastly, and this is where I really need advice, as I am now in the final process of going ahead and buying the solar panels.

I am looking at the ReneSola Solar Panels as they are priced well, but I am having some issues sizing my panels to correctly function with the Axpert. The Axpert is limited to 3000W maximum PV input, and a maximum PV of 145vdc, with a MPPT operating voltage of between 60vdc and 115vdc. These panels will be installed on my Garage's roof, which is facing north, and I have space for at least 21 panels for now. I am in Centurion and my garage is getting full sun during the day

I am however confused on whether to use the STC values of the panels for working out string and panel combinations, or rather using the NOC values.

I am considering the 250W panels, providing Voc(STC) of 37.4v, and max power of 8.31amps (STC). If these are the values to be used instead of NOCT values, I can effectively have 12panels to each inverter, set up in 4 strings of 3 panels each. This will give me a max of 3000w(STC) with 112vdc which is within limits of the Axpert, with maximum 33.24amps. Am I correct in my calcs?

However, if I look at the NOCT values of the same panels, using the same string combinations as above, max Watts drop to 2220 (185w per panel), with 105vdc(35v per panel) at only 26,28Amps (6.57a per panel)

So can someone please comment on whether this would be sufficient, or can I maybe look at adding one more panel to each string as the NOC values are more realistic and would still maybe leave me within the limits of the Axpert.

I would really appreciate some feedback and any other comments to my planned system as I want to be sure that my system is configured to the maximum efficiency.

Thanks in advance

 

[Getafixx]

Measure DOD

Hi All,

How can I accurately determine my DOD? From the Axpert side it gives me battery voltage, the battery current and the 4 level battery indicator (how accurate is that anyway)?.

I have done some research and it sounds like measuring DOD using volts while the batteries are under load is not accurate. But obviously it is not practical to disconnect my batteries the moment that load shedding stops.

What do you guys do?