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Axpert 5000Kva


Energy-Jason
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Just some further info - Max PV in is 3000W per Axpert (it won't downgrade input, and DOES shut down DC input if higher), so for SA type sunlight, stick to a 2800W PV max per Axpert. Decent Solar Panels will output more than 2800 when getting awesome sun, many here have seen 105%+ from panels like Renesolar on good days.

You know my rant with the Axpert - Batteries, Batteries, Batteries! It is effectively an invertor with Solar switchover (basically either Utility or Solar to Load, Solar will only help recharge the batteries when on Utility, the rest is wasted)! A bad configuration can cause the system to cycle the batteries between 4 and 58 (my worst count) per day. But to decide the batteries you need to know the load and how much time you want to stay on Batteries without Sun to back you up.

Axperts also have a very bad calculation of the available power on higher loads (anything over 400W), they work on Voltage to decide when to switch over back to Utility... Don't get me wrong, for a <R10k system they are brilliant, but it does mean that you can almost never use a proper % actual calculation for battery discharge. My average (using the Victron 702 for reference) is 25% discharge on a 48V 200Ah bank. The great part about an Axpert is that when you are on Utility you can really push loads through it MUCH higher than rated (up to 130% easily and up to 8000W for 30s or less) without detriment (it beeps a lot though :D)

This is how an extremely rough calc can go:
My load is between 500-700W constantly, which I always round to 1kW for easy calcs and losses, and I would like to stay up for 20 hours without Sun/Utility (huge ask, but what I want), :
1000W/hr x 20hrs = 20000W! If every bank of 48V batteries is made up of 260Ah units -> 1 bank is (25% of 260A) x 48V = 3120W!
20000/3120 = at least 6 Banks of 4 batteries (260Ah)!!!! Not possible or feasible with single Axpert, don't even think can recharge in time or even properly with the Axpert's max 30A charge... Not to mention the cost of 24 x 260Ah batteries (over R120k)! Yes, not the perfect way to work with an Axpert, defeats the point.

One day when I am rich again, definately will choose an online setup with batteries only there for power failures. I came into the game thinking solare panels and invertors where the most expensive items - Boy was I wrong!
 

Edited by KLEVA
clarification of solar charging (bold)
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1 hour ago, KLEVA said:

Solar will only help recharge the batteries when on Utility

Seriously? That sounds rather poor... even for an Axpert :-P As I recall, it's just an MPPT+inverter+transfer switch in the same case, if you have more solar than what is being used, the rest should be used for charging. Otherwise... how are the off-grid guys coping? :-)

1 hour ago, KLEVA said:

I came into the game thinking solare panels and invertors where the most expensive items - Boy was I wrong!

Yup. I'm with you there.

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Apologies guys, that was poor wording and not what my train of thought was. It does Solar charges either way, what I should have said was along the lines of: Solar is wasted while on Utility. All the solar power that could be generated is not going anywhere if the batteries are charged and unit is in Utility mode. Does that read better?

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Apologies guys, that was poor wording and not what my train of thought was. It does Solar charges either way, what I should have said was along the lines of: Solar is wasted while on Utility. All the solar power that could be generated is not going anywhere if the batteries are charged and unit is in Utility mode. Does that read better?


I've also noticed that. When battery is full and bypass mode is active the mppt only uses what's necessary. Even when in battery mode, if the batteries are full and i'm only using eg. 400 watts, the mppt will only produce say 480 watts to keep a floating charge and the rest to cover the loads. Thats why i run my swimming pool pump when the wife finished with the dishwasher, washing machine, etc and there's no other loads. At least my pool is clean, very clean![emoji4]

Sent from my S60 using Tapatalk

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11 hours ago, KLEVA said:

Solar is wasted while on Utility.

Aaaah, that makes complete sense. Had the same with the Multiplus before I went ESS. Now I pump all the extra energy into my other appliances, which due to my relatively small array size means at this present moment none of it is being wasted. I do 5kwh out of a 900wp array almost every day now, while before between 3.5 and 4 was more common.

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13 hours ago, Czauto said:

 


I've also noticed that. When battery is full and bypass mode is active the mppt only uses what's necessary. Even when in battery mode, if the batteries are full and i'm only using eg. 400 watts, the mppt will only produce say 480 watts to keep a floating charge and the rest to cover the loads. Thats why i run my swimming pool pump when the wife finished with the dishwasher, washing machine, etc and there's no other loads. At least my pool is clean, very clean!emoji4.png

Sent from my S60 using Tapatalk
 

 

Well, anything that draw electricity will operate this way ;) Start up a 20KW generator and hookup a 2KW kettle to it, it will only use 2Kw (+ some?) electricity from it. Now it's just more apparent since you can see how much electricity is used / generated VS how much could potentially be generated. 

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That's correct. But run a 20Kw generator WITHOUT any load and it will still use fuel. With a 1500W PV array sitting there, with a FREE generating potential of , say for arguments sake 1300W, but only generating 200W because that's the only load, is just sad. I guess all of you have the same problem as me then, getting the Missus to use high electricity consumers during the peak of the day!! If you don't have solar you won't understand the frustrations of finding your relatively small battery bank drained because the dishwasher was switched on 8 o' clock at night!!! Aaaargh anyway.......you know what I mean!!  

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1 hour ago, Czauto said:

I guess all of you have the same problem as me then, getting the Missus to use high electricity consumers during the peak of the day!!

The ESS setup I have now does allow some of that to be bridged. You would in fact make the PV array slightly smaller so that the dishwasher (for example) ends up using all the PV plus a little bit from the battery, but as soon as the dishwasher finishes (and you're back to using only 200W) the surplus goes back into the battery. But this really works best with Lithium batteries... so the struggle is no less real.

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1 hour ago, Czauto said:

That's correct. But run a 20Kw generator WITHOUT any load and it will still use fuel. With a 1500W PV array sitting there, with a FREE generating potential of , say for arguments sake 1300W, but only generating 200W because that's the only load, is just sad. I guess all of you have the same problem as me then, getting the Missus to use high electricity consumers during the peak of the day!! If you don't have solar you won't understand the frustrations of finding your relatively small battery bank drained because the dishwasher was switched on 8 o' clock at night!!! Aaaargh anyway.......you know what I mean!!  

Ok, so I used a generator as example, unwisely. But it was a practical example.  Solar panels, on the other hand use the sun, so by that analogy, the sun goes wasted. I hear what you're saying, but as you say, you need to adapt your lifestyle so that just about every runs during the day, off solar power ;)

The only time we use Eskom, unwillingly, is like this week when it's raining and the 3KW PV array I have is too little for the load we put on. Clothes don't dry very well outside so we use the tumble dryer a lot more. Would you believe that it's actually stored, on a shelve, in the store room most of the time? I was too lazy to take it off so we're drying clothes, on the shelve in the store room this week ;) 

My general rule of thumb: Don't wash clothes or dished before 8am in summer, and before 10am in winter. The pool pump switches on at 13:00 for 4 hours. I don't weld, drill, grind, etc after 16:00. Nor do I mow the lawn after 16:00. 

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Luckily my lawn is only about 120squares so I just run through it with the mower. 

Speaking of which. Do anybody know is the BMV-700 Relay can be activated when amperage being drawn from the batteries goes above a specified amount? I'm thinking of installing a relay that can switch to Grid power as soon as the load being drawn from my batteries exceeds eg. 40Amps for more than 30secs. I don't know what the Axpert 5Kva uses to determine the switching from grid to solar but it seems to be very irregular. I need more control over that.

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1 hour ago, Czauto said:

Do anybody know is the BMV-700 Relay can be activated when amperage being drawn from the batteries goes above a specified amount?

I think I looked into that some months ago when the same requirement came up and found that the answer is unfortunately "no".

I looked again, just to be sure, and going through the "VRegs" document, which documents the canbus/nmea2000 registers (although in my experience they tend to mirror the register numbers onto their vedirect hex protocol) allows the relay to switch on voltage (main or starter battery), state of charge, temperature, mid-point deviation, or under manual control. That's in the protocol, it's possible that all features aren't supported by all hardware either.

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That's a shame. It would really be nice if one could have a proper controlled "overload bypass". The Axpert's work fine but you don't seem to have any control on when the circuit is switched from solar to grid and back from grid to solar. Not sure if mine is just not set up properly but I've tried any settings and just cannot get it to work like I want..........

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5 hours ago, Czauto said:

Luckily my lawn is only about 120squares so I just run through it with the mower. 

Speaking of which. Do anybody know is the BMV-700 Relay can be activated when amperage being drawn from the batteries goes above a specified amount? I'm thinking of installing a relay that can switch to Grid power as soon as the load being drawn from my batteries exceeds eg. 40Amps for more than 30secs. I don't know what the Axpert 5Kva uses to determine the switching from grid to solar but it seems to be very irregular. I need more control over that.

I have similar thinking with some differences, We are three families living in the house . My solar system is enough to supply all of us when skies are clear. Unfortunately this summer we had lot of cloudy days and every time the clouds cover the sun my batteries are suffering heavy draw (+100A). In two occasions when I was not at home to divert the load from inverters, by changeover switch, to Eskom my battery fuse burned. So, my idea is to automat the diversion of the  loads in four steps until the battery draw become acceptable (40-60A). My search for proper devices was unsuccessful as I don't have enough knowledge in electrics.

I am looking for device that can (at certain conditions) trigger a solenoid changeover switch in order to divert the load from inverters to Eskom and switch it back to solar when power become available.

Any suggestion  will be appreciated .

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Just now, ibiza said:

I have similar thinking with some differences, We are three families living in the house . My solar system is enough to supply all of us when skies are clear. Unfortunately this summer we had lot of cloudy days and every time the clouds cover the sun my batteries are suffering heavy draw (+100A). In two occasions when I was not at home to divert the load from inverters, by changeover switch, to Eskom my battery fuse burned. So, my idea is to automat the diversion of the  loads in four steps until the battery draw become acceptable (40-60A). My search for proper devices was unsuccessful as I don't have enough knowledge in electrics.

I am looking for device that can (at certain conditions) trigger a solenoid changeover switch in order to divert the load from inverters to Eskom and switch it back to solar when power become available.

Any suggestion  will be appreciated .

You can do this with something like ICCPi or SolWeb - in both cases the software could instruct the inverters to use eskom as source and charge batteries from solar

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Thanks for your quick respond Rudi. I don't want to switch off all "consumers" as there is enough power for at least one family. Problem is when the load is 7-8kw and suddenly clouds cover the son and production drops to 2kw.Axperts take the rest of energy from the batteries (5-6kw). In such situation I want to reduce some of the loads, not all of them as there is still available power for some of us to use.

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Just now, ibiza said:

Thanks for your quick respond Rudi. I don't want to switch off all "consumers" as there is enough power for at least one family. Problem is when the load is 7-8kw and suddenly clouds cover the son and production drops to 2kw.Axperts take the rest of energy from the batteries (5-6kw). In such situation I want to reduce some of the loads, not all of them as there is still available power for some of us to use.

I guess you could use a contactor to switch some of the loads / circuits over, but you would still need something to monitor the load VS solar production to know when to switch it over. Either @Manie or @The Terrible Triplett need to give some input here and say if their software can do something like this. 

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1 hour ago, ibiza said:

Unfortunately this summer we had lot of cloudy days and every time the clouds cover the sun my batteries are suffering heavy draw (+100A). In two occasions when I was not at home to divert the load from inverters, by changeover switch, to Eskom my battery fuse burned.

@ibiza, when you have a high load on your batteries, the voltage would drop a lot faster than in normal use. Once the high load subside, the battery voltage would recover without charging. Have a look at your setting 12 (Back to Grid Voltage) on the Axpert. Set that to say 49 or 50 volts. If you are not home and you have a sudden high load, the batteries would reach that voltage relatively fast and switch to grid.

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Just now, Don said:

@ibiza, when you have a high load on your batteries, the voltage would drop a lot faster than in normal use. Once the high load subside, the battery voltage would recover without charging. Have a look at your setting 12 on the Axpert. Set that to say 49 or 50 volts. If you are not home and you have a sudden high load, the batteries would reach that voltage relatively fast and switch to grid.

that's still not good for the batteries... I think in his case, it's a gradual drop as the clouds move in and that's not good either. 

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