Hi,

I'm new to the world of solar and would appreciate some clarity on the Axpert King Inverter 5kva... Can it mix solar and utility power the same way a victron easysolar can?

Thanks,

B

We discuss this subject (or very similar) in this topic: https://powerforum.co.za/topic/3559-do-axperts-support-grid-tiesharing .

The short answer is yes, the King can blend Utility (AC-in) power and solar power.

I don't know the Victron EasySolar well so I can't really compare. However, from this PDF file, it seems to achieve a similar result by combining at the AC level. The King combines at an internal DC bus level. The advantage that the King has is that it can never accidentally export any power to the utility, so you'll never have trouble with meters tripping, in situations (common in South Africa, it seems) where you're not allowed to export a single joule, and some meters can be quite sensitive about even small exports of power.

The disadvantage of the King's approach is that you have double conversion of AC power (AC to DC, then DC to AC again). This is always less efficient than zero conversion (AC-in connects directly to AC-out via a relay).

 

Edit: oops, the above is from the 1600 VA model; it's similar to the 5 kVA model except for breaker ratings etc.

Edited July 29, 20196 yr by Coulomb

3 hours ago, Coulomb said:

a similar result by combining at the AC leve

The EasySolar is a Multiplus with a charge controller and some breakers in the same box. The 5KVA model also includes a CCGX.

The Multiplus ties directly with the grid. It syncs with the grid frequency and then closes the relay on the input side, essentially tying the inverter, the input and the output all in parallel. It then adjusts inverter power and tries to keep the input at zero.

If the grid fails, it opens the "backfeed relay", and only the loads on the output stays up.

So absolutely correct, it combines at a different level. Upside to this is you get to push as much power through there as the transfer switch supports (typically 50A or more). With th Axpert King you can only put as much through there as the high voltage DC pipe supports.

Thanks for the quick feedback @Coulomb and @plonkster - really appreciate it!

 

With the price difference at play I'd like to go for the Axpert King, but what I'm hearing is that I might still miss out on using solar power if the load is more than what the "high voltage DC pipe" of the Axpert King supports.

 

How can I check what that threshold is? And typically what consumption - normal household equipment will match the same?

 

Any other "critical" reason to go for Victron Easysolar instead? (for basic household use. Want to limit utility bill and keep fridges and a few core components running when we have load shedding) 

 

Regards,

B

 

 

1 hour ago, MrB said:

Any other "critical" reason to go for Victron Easysolar instead? (

I'll give you two: Support and warranty. There are also some other threads here about that model that you should read. I usually skip them, don't have enough time to read everything 🙂

I really like the technology of the King model, it's a clever idea, but I'm convinced that on average owners of the blue inverter has a better experience in the long run.

(Edit: Let me just add a disclaimer... yes I am biased on account of a paycheck... subtract a few points if you feel it's appropriate 🙂 ).

Edited July 29, 20196 yr by plonkster

Thanks Plonkster. Appreciate the reply. I'll scout around for more info. Just tricky to go for blue with the budget available.

Yes I can definitely see mine mixing, for example I had a 2.6kw load on yesterday, and PV was supplying 1.7kw

Thanks Dex. I take it you have an Axpert King.

What is your experience with it and how long have you had it?

8 hours ago, MrB said:

I might still miss out on using solar power if the load is more than what the "high voltage DC pipe" of the Axpert King supports.

Well, you'll miss out on the ability to mix if that happens. But the inverter will simply switch to bypass mode, so it can support loads of up to the limit of the relays. In other 5 kVA Axperts, these relays are rated for 40 A AC. I assume the King 5 kVA is no different.

8 hours ago, MrB said:

How can I check what that threshold is?

It's too easy: it's the rated power of the inverter (5 kW). It will allow very short term overloads, up to 100% (up to 10 kW), per the advertising. Of course, that's more than 40 A @ 230 V, but I suppose a short term overload of the relay is permissible.

Quote

And typically what consumption - normal household equipment will match the same?

That depends on your household, of course. In the "average" house, the larger loads are often in the kitchen: oven, stove, kettle, dishwasher, toaster, microwave. Other high power items are the geyser, large air conditioner (especially if direct-on-load start (no inverter in the air conditioner)), washing machine, air compressor, hair dryer, electric vehicle charger, space heater. Things like geysers can vary a lot, but are often 2.4 to 4.8 kW.

Fridges and freezers are low power but high energy, because they run 24/7. So these are not a problem for this discussion.

As you can see, there are many potential high power loads in a typical house. So really it all depends on how many such loads are on at once. I have a single 5 kVA / 4 kW inverter, and for years with support from my family, have had little trouble avoiding the inverter bypassing most of the time (it bypassed perhaps once every few days). That was until I bought an electric car; now I'm seriously considering paralleling it with a second inverter. Of course, 4 kW models are now obsolete, and there are technical difficulties getting new and old models to parallel. If only I know someone who can patch firmware... 😉  (And if that someone had some spare time 😐).

Fortunately, Kings (like all the non-VM models) can be paralleled, so you can always start with one, and parallel it with another later if the need arises, and of course if funds permit. You will need a paralleling "kit" to safely parallel them, of course.

2 hours ago, MrB said:

Thanks Dex. I take it you have an Axpert King.

What is your experience with it and how long have you had it?

I do, it has only been in a week, I am still figuring some stuff out, but for the most part happy. For example the load through it has been ~24kwh of which 15 has come from pv. (my geyser and stove are the only items not through this circuit) - i would like to find a way to put the geyser through it logically as we are wasting a lot of potential at this point.

we had a power out on sat during the night and woke up like nothing had happened.

There is one thing I am struggling to figure out, and that is why it shows as low battery often, like I come home today when there has been no power issues and the unit is flashing low batt, but the batt shows full SOC and the inverter see's it in the range according to the parameters, still trying to figure this out.

 

edit i should probably point out, there are imo better options available on the market, but for the price point my opinion is that it hits the spot.

Edited July 29, 20196 yr by Dex_

7 hours ago, Dex_ said:

the unit is flashing low batt, but the batt shows full SOC

It's probably the battery low voltage cutoff setting, setting 29. Make it lower; you have the battery's BMS to protect the battery from low voltage. Make it 4.0 V lower than setting 27 (Float charging voltage).

2 hours ago, Coulomb said:

It's probably the battery low voltage cutoff setting, setting 29. Make it lower; you have the battery's BMS to protect the battery from low voltage. Make it 4.0 V lower than setting 27 (Float charging voltage).

currently float is low from what some people i see have set it, i might up this, float is 50.5, so that is only 3V off the cut off of 47.5. i will prob up this to around 52 (the float that is) from everything I am taking in.

I was wondering in terms of the bms reading everyone's posts here, like if you were to charge the unit at too high a voltage, say 56V vs the recommended 53.2 surely the bms would just it off? likewise with discharging?

@MrB if you are looking at this unit, i would suggest you make sure you are getting an origional, and that the model is manufactured after Jan 2019 to get the pylontech integration, like you can do without it, but if it is available i dont see why you wouldnt want it

Edited July 30, 20196 yr by Dex_

I've seen the comments on the "copy" axperts... very sad and tricky to manage. I'll try to make sure I get the real deal.

@Dex_,  do you mind elaborating on the pylontech integration? 

 

 

49 minutes ago, MrB said:

I've seen the comments on the "copy" axperts... very sad and tricky to manage. I'll try to make sure I get the real deal.

@Dex_,  do you mind elaborating on the pylontech integration? 

 

 

you can read about it here: https://powerforum.co.za/topic/2519-mpp-solar-inverters-support-pylontech-some-models/

but it actually looks like it doesnt add much benefit, but is a nice to have imo