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Different types of inverters


Johannvdm
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Hi Guys new to this what different types of inverters are there I heard a lot about hybrid inverters and Off grid inverters can someone explain what these are? The quote I got from the guys in Alexander bay has 3 x Axpert king 5KW Hybrid inverters are they any good? Why do I need 3 won't just 1 or 2 work?

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There are basically 3 types of inverter, although in those broad  'types' there could be many different brands and models with slightly different functionality.

You get the PV grid-tied inverters which basically connect solar panels to the grid. i.e. They feed any available solar power into the AC grid and they don't have a battery connection, which means they rely on the presence of the grid to operate so if the grid goes down (load shedding etc.) they stop working.

Then you get hybrid inverters which work in a similar way to PV grid-tied inverters, in that the inverter operates in parallel with the grid, but these have a battery input, which means that they can continue to operate when the grid is not available. To do this, they have to be able to disconnect from the grid and still power your essential loads, so they typically have 2 AC ports, a grid port and a load port. There are many brands of hybrid inverters with subtle differences.

Then off-grid inverters are basically any inverter that doesn't run in parallel with the grid. There are LOTS of these as well, even some that have very similar functionality to hybrid inverters with only some small differences, such as they cannot supply large loads with a mix of PV and grid power, or use excess PV power to offset the power use of non-essential loads that are not connected to the inverter's load port.

I have heard that the Axpert King is actually not bad, although I haven't used them myself but I'm sure plenty of people on this forum have and will be able to advise you there.

You need 3 of them if you have 3 phase loads that you want to supply, or if you need to supply loads of up to 15kW. Without knowing more about your requirements it is difficult to give advice here.

Edited by Stanley
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Thanks for the info I think I understand better now also did some googling. I see there is a lot of talk about sunsynk inverters on the forum. Is that a good product sounds like its a kind of all in one inverter I want to build up my own system for my farm but it gets a little confusing some people say stay away from Axpert inverters. A company near me quoted me on 3 of the at almost 15K each but then I see some places sell them for 12K each are there better ones? I also saw on the power forum store they sell Victrons are those good prices? I know Victron is good.

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9 hours ago, Johannvdm said:

some people say stay away from Axpert inverters

The problem is not so much the Axpert inverters but that they are by far the most frequently bought product.  For every other type of inverter there are 10 other people buying an Axpert inverter.

Why is that significant?

Because when so many people buy their product, a significant portion of them:

1) Don't know what they are doing, at all.  You'll commonly see "problems" on the forum here that come down to not wiring correctly, not using the correct wire gauge, not using the right kind of battery, etc.  Just general incompetence.  Some of my personal favorites is someone constantly overloading the inverter on a daily basis and finally the relay gives in and somehow it is because the product is marginal 🤯 (or the typical wiring positive to negative and vice versa followed by the inverter blowing up).

2) Installers that are equally incompetent as in 1.  A lot of "electricians" want to get into this new Axpert fad.  They don't actually have the understanding/skills/intellect required to install inverters but that doesn't stop them.

3) Volume means more likelihood of failures being reported.  Some amount of people buying these inverters will actually experience a legitimate failure not due to one of the above.  Because the volume of these inverters being bought compared to others, the likelihood of it being reported is proportionally higher.

Lastly there are some other factors:

1) Axpert inverters is a budget product, it has limitations and some of the documentation does not make this obvious.  Do your research.  If you are the type of person that doesn't do research, get an installer that isn't just the lowest bidder to install it for you.

2) There are some "bugs", reportedly some of the inverters stop charging the batteries too soon, the King has a bug reported by some people of not charging from solar (solar freezes that last some minutes).  Not sure if everyone experiences, it may be something unique to their installation.

 

With this all in mind, I've installed roughly 5 of these so far and the oldest has been running since 2014.  They all run 24/7 and have never had any issues.  That said, I didn't install them in a way that would allow them to be overloaded and I know what I'm doing when it comes to installing it and the limitations.

You can spend roughly twice as much for a Victron inverter, but don't expect it to take more punishment just because it is Victron.  The reality is, most people actually buying Victron for example, are willing to shell out for competent installers, so they don't often run into a lot of the problems above.  (Just one example).

This isn't lego.  You need to do research, look at the specs, buy according to the specs (+10-20% headroom as a general engineering rule).

Edited by Gnome
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On 2020/09/25 at 7:29 AM, Stanley said:

There are basically 3 types of inverter, although in those broad  'types' there could be many different brands and models with slightly different functionality.

You get the PV grid-tied inverters which basically connect solar panels to the grid. i.e. They feed any available solar power into the AC grid and they don't have a battery connection, which means they rely on the presence of the grid to operate so if the grid goes down (load shedding etc.) they stop working.

Then you get hybrid inverters which work in a similar way to PV grid-tied inverters, in that the inverter operates in parallel with the grid, but these have a battery input, which means that they can continue to operate when the grid is not available. To do this, they have to be able to disconnect from the grid and still power your essential loads, so they typically have 2 AC ports, a grid port and a load port. There are many brands of hybrid inverters with subtle differences.

Then off-grid inverters are basically any inverter that doesn't run in parallel with the grid. There are LOTS of these as well, even some that have very similar functionality to hybrid inverters with only some small differences, such as they cannot supply large loads with a mix of PV and grid power, or use excess PV power to offset the power use of non-essential loads that are not connected to the inverter's load port.

To be pedantic, these are types of system and not types of inverter. My inverter (a Goodwe) can run in any of the three types of systems described above, and I think most modern inverters can be used in any of those scenarios. Which means that you could start off grid-tied and then add components to get to a hybrid system.

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21 hours ago, Bobster said:

To be pedantic, these are types of system and not types of inverter. My inverter (a Goodwe) can run in any of the three types of systems described above, and I think most modern inverters can be used in any of those scenarios. Which means that you could start off grid-tied and then add components to get to a hybrid system.

No, your GoodWe is a Grid-tied hybrid inverter, which, as I said before are very similar to PV grid-tied inverters. Sure, your GoodWe can operate without a battery and then lose some of it's functionality, so then you are using it as a PV grid-tied inverter but it is still a hybrid inverter which allows you to connect a battery.

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1 hour ago, Stanley said:

No, your GoodWe is a Grid-tied hybrid inverter, which, as I said before are very similar to PV grid-tied inverters. Sure, your GoodWe can operate without a battery and then lose some of it's functionality, so then you are using it as a PV grid-tied inverter but it is still a hybrid inverter which allows you to connect a battery.

Thanks for that clarification. Do we actually have grid-tie only inverters in SA?

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2 minutes ago, Bobster said:

Thanks for that clarification. Do we actually have grid-tie only inverters in SA?

Yes, one can find grid-tied string inverters and micro-inverters on sale in SA. It's not unheard of but probably not as popular among households in SA because of load-shedding, no battery backup, and because of the onerous conditions around exporting power to the grid.

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