Inverter mains and batteries

[Clivevan]

I am new - hallo all.

A few simple questions but I cannot get an answer anywhere. 

Intended load shedding setup: Mains plus 5000 watt axpert inverter and 4x200 AH Vision AGM batteries (a few panels maybe later).

What happens if I should EXCEED 5000 watt usage? Does the inverter simply trip out?

What is the effect on the batteries (while mains is switched on) if I consistently run close to 5 000 watts? Ie does the current simply pass through leaving the batteries alone as if they are being trickle charged just to preserve them for long term storage? 

Or does that current have a life shortening effect on the batteries? If so, then surely the inverter should have some kind of automatic bypass system so as to preserve your batteries while you running mains? Or do you have to have a manual bypass installed in order to bypass the batteries during times of no (or rare) load shedding in order to keep your batteries out the loop and give them maximum long term life?

 

Regards

[Coulomb]

2 hours ago, Clivevan said:

I am new - hallo all.

Welcome. So many newbies lately; I wonder why? 

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What happens if I should EXCEED 5000 watt usage? Does the inverter simply trip out?

If you're in battery mode, yes. But the battery might lose some life as well; AGMs prefer a maximum of about 0.2C discharge, which is about 40 A, or about 2000 W. Short periods of up to 5000 W should be OK, I think.

[ Edit: In line/bypass mode, you can in theory be running up to about 9 kW, and the battery won't be stressed. ]

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What is the effect on the batteries (while mains is switched on) if I consistently run close to 5 000 watts? Ie does the current simply pass through leaving the batteries alone as if they are being trickle charged just to preserve them for long term storage? 

If you are in line (bypass) mode, then 5000 W is some 22 A (AC), and it just flows through the relays, not involving the battery at all. But if you're wanting to power some of the load from the PV panels, then you'll have to be in battery mode, which will have the 5000 W limit and will be hard on a 200 Ah lead-acid battery. The battery will only be trickle charged from PV, not mains. [ Edit: actually, you can set utility charging to 2 A maximum, that's a pretty reasonable trickle charge. ]

It sounds like you don't want to power much from PV, at least initially, so that's fine.

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Or does that current have a life shortening effect on the batteries?

In the battery mode scenario, certainly. If your load averages close to 5000 W, then a 5000 W Axpert is too small, at least with a lead acid battery.

You don't need to connect all your loads to the inverter, but of course splitting your loads will involve more electrician work.

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If so, then surely the inverter should have some kind of automatic bypass system so as to preserve your batteries while you running mains?

Yes, when the battery voltage sags to a low enough level (settable), the inverter will switch to bypass mode if possible (i.e. there is AC in present).

Quote

Or do you have to have a manual bypass installed in order to bypass the batteries during times of no (or rare) load shedding in order to keep your batteries out the loop and give them maximum long term life?

If load shedding / blackouts are rare where you are, then you could run pretty much your whole house through the inverter, and arrange for it only to use battery when there is no mains. But as soon as you lose power, you'd want to be careful about total power usage. You might not notice the power going out, until 15 minutes later there is a beep from the inverter, indicating low battery.

 

Edited March 27, 2019 by Coulomb

[Clivevan]

Coulomb, Sir - you made my day. Thank you millions.

 

The key to the problem is your answer here:

If you are in line (bypass) mode,  . . .    it just flows through the relays, not involving the battery at all. But if you're wanting to power some of the load from the PV panels, then you'll have to be in battery mode, which will have the 5000 W limit and will be hard on a 200 Ah lead-acid battery.  . . .    you can set utility charging to 2 A maximum, that's a pretty reasonable trickle charge. ]

So that means basically while I have mains available the circuit will perform as normal with the batteries lurking in the background? 

What a clever thing a modern inverter is! Actually a misnomer - it is an intelligent power management and control system not?

 

BTW I do not intend for it to reach a situation of even closely reaching 5 KW load but I need to prepare and plan because I cannot control the other household ignorami and before you know someone has stuck an iron or electric heater or both into my loadshed circuit.

 

Thanks again

Now to pay and instruct an installer.

[___]

2 hours ago, Clivevan said:

What a clever thing a modern inverter is! Actually a misnomer - it is an intelligent power management and control system not?

You should experience a real hybrid inverter if you really want to be amazed, one that can actually combine power from battery, PV and the grid, provide backup, do peak shaving, etc

[Clivevan]

Is that the difference between my cheap (but reasonably competent) Axpert and a Victron?  Does this explain the price difference?

 

regards

[Guest]

8 minutes ago, Clivevan said:

Is that the difference between my cheap (but reasonably competent) Axpert and a Victron?  Does this explain the price difference?

Jip. One is off-grid (Axpert), the Victron is a hybrid grid tied / off-grid all in one with "papers" to back it.  

[___]

21 minutes ago, Clivevan said:

Is that the difference between my cheap (but reasonably competent) Axpert and a Victron?  Does this explain the price difference?

Oh, there are a lot of reasons and differences.

1. The main one is that the Axpert is made in China/Taiwan and their main market is UPSes, so they have the advantage of BULK which means lower prices.

2. Their (Voltronic's) R & D department would have a completely different focus as well, they don't have to interoperate with other systems (PV inverters, canbus batteries, etc) to same extent, so much less development cost for them. They essentially only have to build a cheap inverter and not much beyond that.

3. It looks like they spend little effort on firmware. Some bugs have been in there for years.

4. The Axpert has absolutely no paperwork or certification, required if you want to connect it to the grid. Certification costs a lot of money.

5. Voltronic doesn't train installers in their products (though technically, they don't really have to, see points 2 and 6).

6. Voltronic is an OEM manufacturer, so warranty and service is often the job of someone else (In South Africa, Mecer would be an example).

7. The Voltronic inverters are actually fairly decently constructed, but they are definitely built to a lower price than the Victron inverters.

8. Victron inverters are a bit old-school. They still have heavy transformers and a low-frequency design. Doing some of that fancy hybrid work with a modern high-frequency design would be way harder than the price-tag of an Axpert can justify. In other words, it is actually easier to build a hybrid inverter if you make it old-school :-)

Edited March 27, 2019 by plonkster

[Clivevan]

The Voltronic inverters are actually fairly decently constructed

Well thank God for that.

At least my unit should do the basic things I want it to do - really just look after the batteries from time to time When I use them. Perhaps accomodate a few panels later just for extra charge capacity should Eskom fold completely. 

[Guest]

7 minutes ago, Clivevan said:

The Voltronic inverters are actually fairly decently constructed

Well thank God for that.

At least my unit should do the basic things I want it to do - really just look after the batteries from time to time When I use them. Perhaps accommodate a few panels later just for extra charge capacity should Eskom fold completely. 

I think we can all agree that there is no dispute about the "value vs price" for an Axpert. It has been proven over and over on this and the Australian forum.

What struck me recently is that we are comparing apples with pears, since day one.

One the one side we have the Axpert ranges, a Off-grid setup.
On the other side we have the Victron, specifically the Multiplus II, a Hybrid Grid-tied setup.

The question that SHOULD be asked: Do you want off-grid or hybrid grid tied solution?

[___]

29 minutes ago, The Terrible Triplett said:

One the one side we have the Axpert ranges, a Off-grid setup.
On the other side we have the Victron, specifically the Multiplus II, a Hybrid Grid-tied setup. 

I have repeatedly said in the past that the Multi's natural competitor is the Infini, not the Axpert. The Infini was also cheaper than the Multi (and comes with MPPTs)... bit it is priced a lot closer to everything else in the market. Which is sort of what you'd expect, right?

The Infini is a hybrid. It has paperwork. It's apparently a slightly upgraded/further-developed version of an earlier Imeon... or that is what I heard.

Edited March 27, 2019 by plonkster

[Guest]

1 minute ago, plonkster said:

I have repeatedly said in the past that the Multi's natural competitor is the Infini, not the Axpert.

Yes you did. But we forgot.  

[TheoG]

If I may bug in here...

I'm looking at the Multiplus II or a Quattro.

1. I would like it to supply power to the house via the PV Panels when available (free power and quicker re-payment term),
2. I would like it to serve as battery backup in case of load shedding
3. I do not need it to provide feedback to the grid

2 x Multiplus II's wil provide 4800w @ R29k or 1 x Quattro 48/5000 will provide 4000w R28.5k (I would like to end up around 10,000w so 4 x Multiplus II's will take up double the real estate of the quattro)

I like the redundancy of the two Multiplus II's plus i can buy one now, and battery mon, color gx etc with the money saved from the quattro, and add another Multiplus II later.

My question is whether either will provide PV power, supplemented by eskom/battery during day time. i know they will provide backup power from batteries during load shedding.

If not, what would be suggested in terms of inverters?

Thanks!

[Guest]

7 minutes ago, TheoG said:

My question is whether either will provide PV power, supplemented by eskom/battery during day time. i know they will provide backup power from batteries during load shedding.

Yes they will, when using ESS.

Multiplus II being on the "list", Quattro not.

[TheoG]

1 minute ago, The Terrible Triplett said:

Yes they will, when using ESS.

Multiplus II being on the "list", Quattro not.

Awesome thanks. Is the "list" enforced everywhere or only in metros where grid feedback is accepted?

[Guest]

5 minutes ago, TheoG said:

Awesome thanks. Is the "list" enforced everywhere or only in metros where grid feedback is accepted?

From what I have looked at, all metro's have regulations in place, CoCT the first to enforce it, NERSA pushing it, coupled with a "list".

So the thinking is to play it safe, use the CoCT regs, that they could become the norm nationally.

[The Bulldog]

Multiplus II 5KVA version is available now I believe. I was quoted around 22K. Lower price compared to the old Multiplus 5KVA.

Not on the list yet but should be with the next update.