Axpert generator charge

[PaulF007]

Hozid guys.

I am starting to prepare for the summer and one thing that I need to do is preparing the generator.

In the Axpert manual you can have a Solar and Utility (SNU on Menu 16) where by you can charge the batts with solar and utility at the sametime. So the thought is If in need to start up the genny to "top up" the geyser or supplement high loads I might as well charge the batts as well and use some of that surplus energy. So I changed the setting but when I start the genny there is no load on it to charge. But if I set the Inverter to (Menu 01 - UtL) the charger works very well but then no load from the panels.

Is there a way to charge the batts with the genny and solar and have the load to the panels?

Hope this all makes sense!

Regards

Paul 

[Guest]

There is Solar first or utility first. On my Axpert it can only do one.

If select solar first then it will use the solar till there is no pv voltage and then it will swich.

If there is still pv voltage , the only way then is to swich of the pv braker . Then it will charge from utility

Sent from my SM-G920F using Tapatalk

[PaulF007]

Ok so if I want to charge from the Genny I will need to switch to Utility first and then if the Utility is not available it will run from solar.

[Guest]

Ok so if I want to charge from the Genny I will need to switch to Utility first and then if the Utility is not available it will run from solar.

Yes. Or swich the pv braker off

Sent from my SM-G920F using Tapatalk

[PaulF007]

Cool thanks! 

[___]

1 hour ago, TinkerBoy said:

The Axpert is not a true Hybrid. You are either in DC or AC mode not both at the same time.

But hang on, the SCC is a separate board/unit inside the case, right? So there is no technical reason why you cannot have the inverter/charger in bypass while running the charger and ALSO run the PV panels? A little bit like us Blue Inverter people with the separate charge controller... you can use both (and it is in fact advised after deep discharges that you use both at least during the bulk phase).

So are you guys telling me the Axpert cannot use both? Reason? Just software?

[Coulomb]

For off-grid applications, the source priority should be Utl, so the generator will be used if it's on. Axperts should also charge from solar at the same time; if not some other setting is likely wrong. As pointed out by others, mixing DC sources is trivial, and the Axpert certainly does it.

There is a setting to do with solar balance, it never made much sense to me. But maybe it's for off-grid, where you can automatically use as little AC power as possible to satisfy the needs of the loads and charging. Otherwise, you may need to turn down the maximum utility charging current (but not the maximum combined charge current, which depends on your battery).

[Coulomb]

Setting 16, Charger Source Priority, would be the first one to check. If set to CUt for example, "solar energy will charge battery only when utility power is not available". You want CSO, "Utility will charge battery only when solar energy is not available".

I think you also want setting 31, Solar power balance, to be set to SBE (enabled), so that "Max. input solar power = Max battery charging power + Connected load power". That sounds to me to mean that solar power will be used for powering loads as well as merely battery charging.

Oops! I've just realised this. For off-grid use, setting 01 (Output source priority) should normally be be UtI, so that the generator is used if connected. But they don't seem to cater for your "pre-emptive generator use", because with UtI mode, "solar and battery energy will provide power to the loads only when utility power is not available". Neither of the other modes does what you want either. So it looks like Axperts can't do this (unless someone comes up with a custom firmware that does this). For now, it looks like you have to wait till the battery SOC is low before starting the generator. Perhaps the dry contact can help with auto starting your generator (assuming it has auto start capability).

 

Edit: actually, source priority (setting 01) = SbU  (Solar then Battery then Utility) will probably do what you want. It runs the loads off the inverter (powered by the battery) unless the battery voltage is low (setting 12), but all the solar power will be used to charge the battery (and hence support the loads). It's not clear, but I believe that utility power will be used to charge the battery if needed. So it would only use enough generator power to charge the battery, but since the battery is providing the load, it is providing the load power as well (charges hard enough to cause the required current into the battery). I think. Hopefully a colleague will be running his system soon (perhaps today even), and we can figure out how these things work by trying them out. We have the luxury of having mains available, so we may have more scope for experimentation.

Edited September 12, 2016 by Coulomb
Added last paragraph.

[viper_za]

8 hours ago, plonkster said:

So are you guys telling me the Axpert cannot use both? Reason? Just software?

Option 16 in the settings allows this.
Charger source priority:

1. CSO Solar first: Solar energy will charge battery as first priority. Utility will charge battery only when solar energy is not available.
2. CUT Utility first: Utility will charge battery as first priority. Solar energy will charge battery only when utility power is not available.
3. SNU Solar and Utility (4/5KVA models only): Solar energy and utility will charge battery at the same time.
4. OSO Only Solar: Solar energy will be the only charger source no matter utility is available or not.

Then the limitations on this
If this inverter/charger is working in Battery mode or Power saving mode, only solar energy can charge battery. Solar energy will charge battery if it's available and sufficient.

[PaulF007]

From what I could read and learned from some follow Axpert users is that: 

• You cannot have Utility and Solar working together on the Supply side , something to do with the Hz that needs to be in sync so either util or Solar for the Loads.
• You can charge the Batts with the Util and solar at the same time but you must be wary that the combined two does not overcharge

So in my case it seems like I will do the following: 

• Have the Inverter in 01 - UTL mode because the Genny does not run all the time
• 16 -  In SNU so that both could charge
• Could have the BMV Start the genny but:

I would not recommend it as the risk of something going wrong does not warrant the option. I would rather go for a SMS remote start (Working on it as we speak and will some for some Ideas).

I will also set the Charge current not to high as to put the genny under pressure but you can then also run the rest of the house from the Diesel that is already consumed ..

Once you switch the genny off you will resume one Solar/Batts (Remember no Eskom here)

[___]

22 minutes ago, PaulF007 said:

You cannot have Utility and Solar working together on the Supply side , something to do with the Hz that needs to be in sync so either util or Solar for the Loads.

Ag that is bollocks man. Quatsch. I mean, I don't deny that on this particular inverter they may not have the option to configure it that way, but it's two DC sources feeding the same bus, and apparently it is supported by the larger inverters.

Well, not to be uncharitable, I suppose there might be good reasons for such a simplification. You still want to limit the charge current into the batteries to a safe maximum, and when you have both the grid and PV online, how would you proportion that? If the grid is capable of doing all the work (which typically it is), then you can ignore solar. Conversely, you might want to use as much PV as is available and take the difference from the grid, but that would actually require an implementation in firmware to do that, which might explain why it is simply left out on some models. YAGNI (You ain't gonna need it).

22 minutes ago, PaulF007 said:

set the Charge current not to high as to put the genny under pressure

On the Multiplus there is a thing called PowerControl, where it automatically prioritises AC loads and reduces battery charge current to not overload the generator/shore breaker. Not a fair comparison of course... just saying :-)

[PaulF007]

3 minutes ago, plonkster said:

Ag that is bollocks man. Quatsch. I mean

Sorry man , lucky for me I did say "I was told / read it somewhere - 

4 minutes ago, plonkster said:

but it's two DC sources feeding the same bus, and apparently it is supported by the larger inverters.

This makes sense as the Axpert seems to be able to charge together but would it not  be inefficient to convert the AC to DC and then Back to AC gain?

But running from a genny you would like to utilise as much from the genny as possible as you are paying for that Diesel and as such it would make sense to disregard the Solar. Also the chances of running the genny when the Sun is at peak is quite slim as you should have enough power to start of with then. 

 

[___]

Just now, PaulF007 said:

This makes sense as the Axpert seems to be able to charge together but would it not  be inefficient to convert the AC to DC and then Back to AC gain?

It doesn't do this, hence my confusion. The DC comes from the PV panels, goes through a buck converter (aka MPPT) and ends up on the left-hand side of the 48V DC bus (for argument sake). On the larger units the inverter runs in reverse, on the smaller units there is a separate charger, but in both cases it steps down from 240VAC to 48VDC and that ends up on the right-hand side of the same 48V bus. That bus is directly connected to the battery bank using some thick cables.

It literally is a case of taking the current A from PV and the current B from the charger, and pushing A+B into the batteries. Of course that might be more than is safe for the batteries, which is why I think the omission might be a simplification: That way you don't have to write code that has to proportion these things. For 90% of the people buying this inverter, that is perfectly adequate. It's a guess, but likely a good one.

[Guest]

1 hour ago, PaulF007 said:

... something to do with the Hz ...

Hz - you cannot have inverter AC and Genny AC and / or Eskom AC all onto the same output.

DC side is fine as Plonk said, IF you don't overcharge the batts. 

[Chris Hobson]

Paul

Your setup is exactly how I run my setup.

Program 1 set to UTI

Program 2 set to 30A  (whatever is appropriate for your batteries).

Try run Program 3 in UPS mode if it does not like you gennie run in APL mode.

Program 11 set to 20A. Only 3kVA available from gennie.

Program 16 SNU

Program 31 SBE

Chris

 

 

 

[Coulomb]

My memory from reading the firmware disassembly months ago is that the Axpert can conrol mains and solar combined charging without overcharging the battery. There can be temporary over or under voltage for tens of seconds, but that is to be expected when one source is intermittent. But if I remember correctly it adjusts the PV and utility chargers to achieve the present voltage setpoint.

I'm hazy on how it asks the SCC (solar MPPT charger) for more current, since the panels might not be able to provide it. Maybe it just sets a maximum current, and the utility charger provides the difference if possible, or as much as it is allowed otherwise.

I'll check on this if I'm in the vacinity of that code again.

[Chris Hobson]

Yesterday we did not have enough diesel on the farm to run the generator. So we saddled up the Chinese petrol gennie. The last time I used it, the inverter made a peculiar hum. I though I would get around it by just charging the batteries and powering the load off the batteries. The inverter however cannot do this the load must be carried by the gennie for it to charge the batteries. This is not surprising but yesterday I thought maybe but the inverter is all or nothing when it comes to AC power. Interesting the inverter did not hum last night like it had done previously.