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Advise needed on changeover to Blue

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Advise needed on how to move forward on my setup to improve things around  I would like to gradually move  to a 3 phase quattro setup to replace Axperts  and get rid of all my changeovers and small 7.5 KVA DG  over time 

Yearly budget is capped at  around 2500 Euro - I buy additional components every year on my wedding anniversary  as a present to ourselves

Over the last five years I have managed to make a bit of mess:) and a very complex system to run  as the expansion has been in stages  The goal was to solve the availability of power while trying to do a cheaper Hybrid Diesel solar setup using Axperts  and other components I could find  over amazon and Aliexpress and other online sites 

The family which involves myself wife two kinds plus the security , driver and two maids  .  Total consumption is around 22 KWH and avg loads of 500 watt during the day and around 1000 Watts during nigh excluding aircons . The solar is mainly to  supply load and reduce DG usage   ( power cuts are normally 8 to 14 hours in Nigeria and frequent)

The 5 KVA  was chosen for price point , charging capacity and I have peaks from vacuum cleaners, Coffee machine etc of almost 2 KW as well as starting surges of Plasma and Home AV receiver - 5 KVA Axeprt limits to 3.5 or lower   KW at 40 DEG  Ambient  and I dont want to risk it 

My setup schematic is below 

The washing machine , Dryer and 4 aircons ( invert energy efficient types) are already on the inverter ( 5KVA x 2 ) outputs but run only  During daytime on solar or when SOC is 100 % ( grid or DG running) 


1. I cannot use 8 KVA quattro on my small 7.5 KVA 3 Phase 4000 V DG ( min shore current limit of 11 amps) I have to choose 5 KVA ( 5.8.Amp limit ) -  

2. No lithium batteries or Rdflows available in Nigeria  yet - Stuck with flooded lead acid so SOC is limited to  50 % max  with round trip efficiency of 65 %- Makes a large battery bank very unattractive as my 7.5 KVA KIPOR DG cannot charge more than 60 amps at 48 V . Building D..I.Y Lithium a strict no as they dont perform very well in the long run on safety aspects (BMS is always the weak link) 

3. The 20 KVA DG although from Caterpillar is 2001 model and has very poorly designed AVR - the Axeprts continuously reject the changes in UPS mode after large load changes such as water pump coming on  but work fine in Appliance mode 

4.  20 KVA and 7.5 KVA are supplied and fuel is managed by the Employer so Have to work around them and no chance of replacing the 20 KVA Gen

5. ESS cannot be used in Nigeria with weak and non existent grid -

6. Multiple assistants will have to be loaded to Multi to make full use of Generator power 

7. House has LED bulbs and class A appliances all around  with home automation and timers and no more efficiency gains possible  ( using broad combionation of Hues, Xiaomi, Broadlink,  Smartthings , grundfos motors , Inverter AC's and washing machine )

8. No  Grid export allowed by law and even if allowed grid is missing  most of the time 


1.  Move the critical loads electronics  of the house to an inverter like Quattro which will be able to use small and big generator in UPS mode and keep the power interruptions to minimum -Should be easy 

2.  maximize the solar use - The 5 .6 KW setup is wasted during weekdays  but fully used during weekends - Already running water pumps and washing machine/dryer during the day any other creative ideas required .  except water heating - Already on direct solar heat pump

3. Find a suitable technology like Redflow which will allow long term storage of daily production  with out significant efficiency loss - the Holy Grail  :D-Too bad Aquion closed down 

4. Minimize the energy loss in inverters and monitoring , control equipment 


1. Move the critical load to 5 KVA Quatrro to start with 

2. Replace the 7. 5 KVA DG  with a 5 KW variable speed DC generator normally used in telecom applications increasing the DC efficiency 

3. Seprate battery bannks for bulk consumption and critical loads with different SOC limits 

Hopefully additional creative brains  will have more info and knowledge 










solar setupMaster Layout with connections  June 2017.jpg

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It's almost 11pm and I still have to debug a mother of an issue tonight... so I need to be quick. First, I'm not quite clear why you're unhappy with the Axpert. Is there a specific reason you want to move away from them? Or do you just want to simplify and consolidate things a bit?

At the budget you have in mind, you can pretty much buy a 5kva quattro now and have the rest of the year to plan the rest of the system :-) The 48V 5kva Quatro is almost 3k Euro. It looks like you already have a Venus GX and a BMV, as well as one MPPT, so you'll be able to make a good start. You'll need MPPTs for the other arrays (that are presently on Axperts).

There are various ways to start a generator using the multi or the ccgx/venusgx, but I am not fully familiar with them. Haven't yet had the privilege of setting one up.

Also, I'm not sure if you really need the Quattro? The use case for the Quattro is where you have grid and generator and you want to use whichever one is available, or you have loads that are not critical and can be dropped, but you want to use something like PowerAssist. The moment you have existing transfer switches -- in other words you're not using the one inside the inverter for this purpose -- I wonder if you really need it. Especially since the changeover part is 3-phase, but you'll be using a single-phase inverter. You might be able to get away with the cheaper 5kva Multi.

But, I mentioned PowerAssist. There is a Victron whitepaper on their website about reducing Diesel cost by using an inverter together with a generator. You may want to read that.

That's assuming that I understand this correctly. I'm not clear from your picture if the three Axperts are configured in a 3-phase configuration or not. You will obviously need 3 multis/quattros if you want 3-phase output.

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Thank you. Not in a hurry As I said it is planned yearly changeover - Everything works for now Just not efficiently 

The system is not three phase - two Axperts in Parallel doing 10 KVA on R Phase and one Aexpert on Y phase . The House DB is one single Giant one and if I carry a 3 phase configuration most of the loads can not be supported on any one phase - Mainly to do with time of day e.g. water pumping and heaters in the morning with lights but  TV , Water booster , Air Conditioner later part of the day - In the evening we have 3 TV's with 3 DSTV decoders going !! So Even if I have  3 phase setup I will need large battery to achieve C20 rate between 6 pm to 9/10 PM

I need Large capacity per phase as most of the house ( three properties - house , guard house , BQ) will need extensive rewiring if I have to separate critical and non critical loads on all three phases 


1, Quattro already planned - as I said limited to 5 KVA Multi or Quattro if I have to use 7.5 KVA DG with shore power option. Discussed in detail with  Johannes Boonstra- I want to make something like the Quattro DC genset  scheme shown below but Grid also being fed in one AC1 and 7.5 KVA DG on ACin 2

2. AXpert while very good at inverting are not good at high ambients at 40 DEG ambient on 3KW Load they  are heating UP - ( i  am on my 5th Axpert by the way in 5 years) Plus they have no Ac Coupling  function so when running on DG I am  limited to DG power 1.5 KW per phase  ( which limits the battery charging to 30 Amps)  and no Load possible on that Axpert ( hence no 3 phase operation ) - The current setup of 7.5 KVA DG to Battery charger losses almost 300 to 400 watt in the charger ( efficiency of 87 %) 

2. I am thinking of using the Quattro with Powerassist on ACout 2 to run  the Washing machine which sits on 200 watts most of the time but reaches 2.5 KW during water heating and high speed spinning  while ACout 1 will supply house critical loads on R phase . retaining the 10 KVA axeprts for AC's and water pumps 

3. I want to reduce the transfer switches in the long run - the power interruptions are sometimes 5-6 a day  which means the battery cycles between discharge , boost and absorb  repeatedly. Lead Acid is most inefficient at last 80 -100 % for charging and that where I am sitting most of the time . 

4. The current system is very difficult to monitor as the status of battery chargers , changeovers are not captured 

5. Using BMV 702 with Time of Day ( TOD) timer to selectively start the genset 

6. One thing I forgot to mention was the grid is still the preferred option if available as it is less than 0.1 Eu cents a day  at current tariff and paid by the Landlord 




Ps. One question Can quattro  function correctly if the same ACin 1is being fed from Grid or 20 KVA generator with No grid export selected  - I was thinking of feeding the status of changeover so Shore power limit gets applied only when connected to 20 KVA DG 

quantrro DC genset .JPG

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  • 1 month later...

Nice! I currently have a similar dilemma.

My house is split into 2 DBs, Critical Loads & Heavy Loads. I want both on solar during the day, but only the critical loads on battery at night. As you already know, the grid is non existent.

Can the Axpert be operated in this mode: "At night, Use grid if available, else shutdown." 

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