Axpert invertors

[Chris Hobson]

Hi Jackie

One should be using VOC + temperature co-efficient for your Max voltage and Isc for max current (A). These are the maximum possible figures you could see. You design you system round this in terms of cable size, fusing and inverter input (safety). You are unlikely to get anywhere near VOC except on a very cold morning but you don't want to pop your inverter because you did not take PV variation into account. I am a newbie with less than 1 month of PV monitoring under my belt and my 3 panel 4 string array start the morning at about 109V which is well within spec, and at midday I have been within 2 amps of the maximum predicted. My cabling and fuses were over speced by 1.25% so I built in some leeway. Your MPPT is going to try and operate near PMax (NOCT). You are only going to get your rate capacity at a 1000W/m2 anyway. On occasion you may if there is cloud edge effect exceed your 250W but this is rare and a bonus. The axpert's PV input is designed for 10mm2 but with a bit of coaxing I managed to get 16mm2 cable into the terminals.

If you add 4 panels per string you will definitely go over the 115V DC MPPT max. What happens between 115V and 145V nobody has told me in spite of asking.

 

[Chris Hobson]

What do you guys do?

I have bought a Victron battery monitor. Spend the extra money and get a 702 and monitor the mid-point voltage of your battery bank. The Axpert unfortunately is like driving a vehicle with faulty fuel gauge. It is at some point going to let you down.

Edmundp in this thread posted that if you set you battery cut-off to the default 42V or 21V your SOC become accurate. I have done so and now I am more inclined to believe the figures given. In the WatchPower software the PV input voltage is read before the MPPT and the PV input current is measured after the MPPT (i.e. after the MPPT has already modified it). Thus input power is PV input current x battery voltage and not PV voltage.

 

[Getafixx]

What is your DOD after a 2 hour load shedding with everything running?

OK, so tonight we had load shedding in the 6-8 slot. The kids got fed, bathed and put to bed, the TV was on pretty much all the time and my wife was busy on the computer with two screens from 7 onwards. This is of course while using the lights as needed, which is quite a bit. We even heated a plate of food for me and milk for the youngest in the microwave. Oh and the fridge motor came on at some point. It was simply wonderful!

Anyway, as Chris mentioned above my cut-off is at 21V (factory default). I took a reading just before the power came back on. The battery indicator said 3 out of 4 and the voltage at the time (under load) was 23.5V. My 2 x 100Ah batteries have a hydrometer each that indicates SOC - green is good, black means it must be charged, white means its busted. After the 2 hours they were still green (probably not accurate but a good sign nonetheless).

But I completely forgot about the WatchPower software. I just installed it now and it does show battery percentage, for what it's worth. Will hook it up next time.

 

[Getafixx]

I have bought a Victron battery monitor.

Where did you buy it from and if I may ask, what did you pay?

 

[Chris Hobson]

Where did you buy it from and if I may ask, what did you pay?

I bought it from the Victron supplier in PE Telecom Techniques I think they call themselves. I bought the 702 (more expensive model) since I was keen to be able to measure mid-point voltage on a 48V battery bank. I paid R2622.00 vat incl This compared favourably with other quotes and the price on e-Bay. I think ExSolar is the Victron agent in your neck of the woods.

 

[Marie1]

Good day
I am a lady that doesn't know much about electric stuff so please bare with me. We have bought a Axpert 5kva inverter, 8 300 w solar panels and 4 105 A batteries. I would like to ask how do you set the whole system up to use solar during day and batteries for load shedding only? Does the inverter do it automatically or should I buy a separate swich or controller? We had an electrician here yesterday and he said he is going to connect everything on the solar exept the stove, heatpump and pool pump. I am wondering what will happen if the load is to much, let say I use my tumble dryer? Do we have to seperate the high usage appliances and also run them from Eskom? According to the efergy meter we use between 400w up to 1.8kw during the day. It sometimes goes up to 4kw depending on usage of the kettle and tumbel dryer. We use about 30 units of electricity in 24hours. For loadshedding we just want to use the lights, tv and dstv. Can someone please give me advice on how to use our system and which is the right way to go to benifit the most.

 

[scottwday]

Good day
I am a lady that doesn't know much about electric stuff so please bare with me. We have bought a Axpert 5kva inverter, 8 300 w solar panels and 4 105 A batteries. I would like to ask how do you set the whole system up to use solar during day and batteries for load shedding only? Does the inverter do it automatically or should I buy a separate switch or controller? We had an electrician here yesterday and he said he is going to connect everything on the solar except the stove, heatpump and pool pump. I am wondering what will happen if the load is to much, let say I use my tumble dryer? Do we have to separate the high usage appliances and also run them from Eskom? According to the energy meter we use between 400w up to 1.8kw during the day. It sometimes goes up to 4kw depending on usage of the kettle and tumble dryer. We use about 30 units of electricity in 24hours. For loadshedding we just want to use the lights, tv and dstv. Can someone please give me advice on how to use our system and which is the right way to go to benefit the most.

If you're normally running at 500w or so excluding the tumble dryer then it should be okay to run the dryer off the inverter if you're careful about when you use it. Obviously that way you can use the free (well, 'prepaid') solar power. It's not a good idea to run the inverter at full load for long periods of time though, so don't run the dryer and dishwasher etc at the same time.

The electrician could put in a separate plug (+breaker +EL) that runs off Eskom power for the tumble dryer/washing machine etc that you can use if there's too much other stuff running off the inverter. Depends on the house on how practical/expensive this would be, but if it's near the DB board then it should only be a few hundred bucks.

The inverter has an overload bypass mode which you could enable (#23) which switches over to Eskom power when you exceed 5kva, but switching over creates surges which could damage your appliances so its not a feature you'd want to make use of regularly.

 

[Krugeran51]

Hi I have basically same setup and yes it takes a bit getting use to changing usage not to overload Invertor. I see Marie1 mention they have a efergy meter if its version 2 one can set the alarm to 5Kwatt to help not to overload the Invertor. With the Efergy hub the user can connect 5 units so you be able to have to graphs example eskom, solar( Invertor)

 

[Marie1]

Thanks for your reply, I will check usage with the Efergy meter and set the alarm to go off when the kw goes to high. How do I swich over to batteries when loadshedding start? Does the inverter does it by itself? My husband works away a lot and I have to educate myself on how these things work. How many kw is 5kva, or what is the max kw that I can use ? I am not sure if Kw and kva is the same. The inverter is 5kva, but the watts are 4000w? Do I have to use what the panels supply daily or can I set a limit on 3500w on my Efergy meter? I have a list on what energy the appliances in my house use, so I will just manage it carefully.

 

[Marie1]

I can check the Eskom graphs on my phone or pc, how do I add the solar on Efergy, do I have to buy something additional to take those readings? I would love to have the solar usage graphs included.

 

[Marie1]

If I use the batteries for loadshedding, do I have to switch all the things of by the db box and just keep the lights and the plugs on? Must that be done manually everytime?

 

[Getafixx]

@Marie1, the inverter will do the switching to batteries and back automatically. And if wired correctly you should not have to throw any switches. Basically the circuits (breakers for plugs / lights) connected to the output of your inverter will always have power (if you stay within 5kVA). The rest will simply be dead until Eskom power comes back on.

 

[theghid]

Hi Everyone.

I just received my Axpert 5KVa and 8x Deltec BD-54-105Ah batteries a couple of weeks ago and had the electrician come through to install it.

My house has a 3 phase setup and 2 DB's, one upstairs and the main one downstairs. After a 3 full days of work we isolated all the plugs and lights we wanted to back up using the inverter and moved both the upstairs and downstairs circuits onto a single phase.

The inverter works fine and switches perfectly to battery when you trip the main breaker, however when Eskom cuts the power during load shedding its just displays error 58 and shuts off. You can manually restart the inverter and it will work but only with the main breaker in the off position.

It also shows an AC input of ~230V even when the utility power is switched off and the batteries are providing power to the DB. My guess is there is an error in the wiring and the inverter is being confused and detecting its own power source as the utility.

My house wiring is very complex and was a nightmare to isolate circuits, so let me know if you would like some pics of setup.

Any ideas of what could be wrong would be much appreciated.

 

[agentrfr]

Hi Everyone.

I just received my Axpert 5KVa and 8x Deltec BD-54-105Ah batteries a couple of weeks ago and had the electrician come through to install it.

My house has a 3 phase setup and 2 DB's, one upstairs and the main one downstairs. After a 3 full days of work we isolated all the plugs and lights we wanted to back up using the inverter and moved both the upstairs and downstairs circuits onto a single phase.

The inverter works fine and switches perfectly to battery when you trip the main breaker, however when Eskom cuts the power during load shedding its just displays error 58 and shuts off. You can manually restart the inverter and it will work but only with the main breaker in the off position.

It also shows an AC input of ~230V even when the utility power is switched off and the batteries are providing power to the DB. My guess is there is an error in the wiring and the inverter is being confused and detecting its own power source as the utility.

My house wiring is very complex and was a nightmare to isolate circuits, so let me know if you would like some pics of setup.

Any ideas of what could be wrong would be much appreciated.

If you don't isolate yourself from the gird, you'll be powering your neighbours too...

 

[theghid]

If you don't isolate yourself from the gird, you'll be powering your neighbours too...

Okay that makes sense, but how can I go about doing this as the electrician is not sure what to do at this point.

thanks

 

[Getafixx]

Okay that makes sense, but how can I go about doing this as the electrician is not sure what to do at this point.

thanks

I'd try a process of elimination. Do you have a main breaker outside the house at the meter? So you can simulate a power cut? Then I would disconnect all the loads from the inverter and first see if you still get the error when the power is cut. If you do then obviously it's got nothing to do with the load. If it works fine then start by switching on one breaker at a time, test and repeat. Perhaps you can isolate the problem to a specific breaker and its load. Then you take it from there.

 

[theghid]

I'd try a process of elimination. Do you have a main breaker outside the house at the meter? So you can simulate a power cut? Then I would disconnect all the loads from the inverter and first see if you still get the error when the power is cut. If you do then obviously it's got nothing to do with the load. If it works fine then start by switching on one breaker at a time, test and repeat. Perhaps you can isolate the problem to a specific breaker and its load. Then you take it from there.

I do have a breaker at the front of my property, however it has only 3 wires, so we tried that and the inverter will work perfectly just as if we tripped the main breaker on the DB board. That outside main breaker is not simulating loadshedding.

 

[Getafixx]

I do have a breaker at the front of my property, however it has only 3 wires, so we tried that and the inverter will work perfectly just as if we tripped the main breaker on the DB board. That outside main breaker is not simulating loadshedding.

Do you have an EL breaker between the output of your inverter and the emergency load breakers?

 

[The_Traveller]

Theghid, where you based? If in Cape then contact Savage to help you out. You definitely used an idiot of an electrician who doesn't know his elbow from his @ss concerning inverter set ups

 

[theghid]

Theghid, where you based? If in Cape then contact Savage to help you out. You definitely used an idiot of an electrician who doesn't know his elbow from his @ss concerning inverter set ups

Nope, in Ballito, KZN. Can anyone recommend a competent electrician here?