1 hour ago, edmundp said:

But I might need to import from grid should the load go beyond a certain threshold, i.e. 3000VA thus taking 3000VA from inverter and "combine" that with let's say 500VA from grid to give 3500VA. This will happen very seldom, but happens occasionally due to ill-household-communication....

The Victron was one of the very first that could do this, with their PowerAssist feature that they use on boats. You're in some backwater harbour with your yacht, or you're just not willing to pay for the nice mooring spot with the big power point... so you plug into the puny little shore connection where you are, and use the inverter to smooth out the peaks. This does things backwards, it assist the grid with the battery, rather than assisting the battery with the grid. You'd think that with a bit of math you can just continually adjust the number, but it's just not that flexible, there is a lower limit on the inverter (on mine it is 3 ampere) and you cannot PowerAssist below that... so for a system like mine it means that the first 600W would come from the grid if I used it like that.

Then, with the advent of hub-1, they came up with gridassist, which does the reverse, it assist your battery side using the grid. This can be adjusted right down to a couple of watts, if I recall correctly. It works exactly like a hybrid inverter, syncing with the grid, and the difference simply comes from (or goes to) the grid, just like any other GTI. The smart stuff is in the software on the CCGX, which adjusts the amount the inverter pushes into the grid.

Anything connected to its output, is of course treated like essential loads and continue to run from battery power if the grid falls out.

There are some caveats you have to know of. The Multiplus can run either connected to the grid (and synced with it), or disconnected (but still synced frequency wise). In the second mode, there is zero possibility of feedback. If the load exceeds the programmed setpoint, it will fall back to the grid very quickly, less than a second in the 3kva model, but... for that 0.8 of a second or so, the inverter will carry the full load. The Multiplus can usually handle 200% of its nominal rating for about a second, so my advice here would be to check that the surge capability can handle your largest appliance. For example, AC compressors will have a 5KW spike. It's not a complete deal breaker, it might just mean you cannot run disconnected/synced with the grid, you'd have to run connected, and of course then you run the risk of feeding back for short periods, that gray area I'm not certain of yet.

As the software runs on an embedded linux system, the adjustment has to be in the order of hundreds of milliseconds, for it has to take into account comms from the AC sensor (RS485, so a couple of milliseconds there), and then there is your scheduling granularity on the computer side, which is usually around 10ms (or more, depending on how busy it is, it is not an RTOS), so hand wave hand wave probably at least 100ms to notice a power change in which time 5 AC cycles have happened.

In my house, I'd be perfectly fine as long as I move the AC compressors to a different circuit, or even better, install inverter units. Then the 3kva multiplus running disconnected/synced would work perfectly :-)

I have the 1600VA unit though, so I will have to run connected to the grid. Time will tell if the prepaid meter can handle that :-)

Edit: I'm confusing a lot of hub-1 and hub-4 stuff. I apologise. The connected/disconnected stuff above is hub-1, which isn't integrated with an AC sensor at all!

Best way is to install VEConfigure for yourself. On the Port Selection menu, pick "Fake target", then on the Grid tab, set Country to "Other", go to the Virtual Switch tab and say "Don't use", then go to the Assistants tab, Click "Add Assistant" and add a hub-1/hub-4 assistant alternately, and look at the settings you're prompted for. That will give you an idea as to what it is capable of.

Hub-4 cannot run grid-disconnected... sorry about the confusion.

12 minutes ago, plonkster said:

Then the 3kva multiplus running disconnected/synced would work perfectly :-)

Cool. That's the idea. No large spikes here fortunately - the inductive loads connected to my solar circuit are all sub 250W units. Spikes are actually very small.

Can the unit be moved to bypass on the fly (i.e. with the whole CCGX/RPi/Linux thing?)

Just now, edmundp said:

Can the unit be moved to bypass on the fly (i.e. with the whole CCGX/RPi/Linux thing?)

Not sure what you are asking about. It can move to bypass even without a CCGX connected, for example mine is programmed to fall back to the grid if the load exceeds 1000 watts, or if the battery voltage drops too low. It does that on the fly, with about 16ms switching time*.

You can also configure it to fall back to the grid based on analog inputs (Multiplus has one or more of those). A common use case is to wire the BMV relay to an analog input and configure the BMV to close the relay at a certain SoC, thereby sending the inverter to grid if the SoC is too low. You can also wire a manual switch to such an input (or put it in parallel with the BMV relay), so you can manually force it into bypass (this is what I do on cloudy days).

If this is going to feed the whole house (rather than just a part, as in mine), Hub-1 is likely what you're looking for, and you don't need the CCGX for that (although it helps). It will work best if you also have a Victron MPPT (ironically, the smaller units are better supported now than the big daddy), and a CCGX, but it will work on its own with any charge controller, there is a trick used in setting the float voltage on the one unit a little lower than on the other so the inverter can detect surplus power situations without talking to the MPPT. There's just so much info to explain I don't even know where to start :-)

* I have an older Multiplus Compact. The "problem" with those is it takes around 10 seconds to switch, the transfer itself is seamless (16ms), but from the time it detects that a switch is necessary until it actually does it, takes around 10 seconds. This means that on my inverter, I cannot handle a 3000 watt load. It will shut down before it's done switching. I can however handle a 2000W load, because it can handle the overload long enough to complete the switch. This is thankfully no longer a problem on the new Compact models, and it was never a problem on the larger (>=3000VA) units. Just adding that for completeness.

Perfect. That answers exactly what I needed to know.

4 hours ago, viper_za said:

The infini does not need it. It's all built in already. You just set in the software what limit you want to the grid.

Realy the price alone makes it almost impossible to look somewhere else if you look at all that you get in the infini

I don't remember seeing an anti-island option on the infini. The one advantage of using anti-islanding, is that you can push back to the grid when the grid is on (so essentially use it as a battery), but not when it grid is off - to make sure some guy on the wire doesn't get electrocuted. 

For those of you who want to go the islanding route: You need to pay a monthly premium (about R800 I think) to have a permit to do so. That's apart from the fact that your inverter needs to be certified. And, then you pay to push back, or differently put get very very little "rebate" for pushing back. I don't know the exact figure, but it's not entirely enough to make any money off the electricity you feed. Lastly, you need to use everything first, and then push back. The meters that are put in place can intelligently measure this. So, in layman's terms, if you have 5KW PV on your roof, but only use 1KW of it, you can't push back. You need to use at least 4KW of it. ( I forgot the ratio). 

 

So, yes, it's easier / cheaper / safer to completely disable grid feedback at this stage. The only people who really gain anything from it are the guys with very big installations, and with little "over flow". 

The tricky bit here really is to understand the hub systems.

Hub-1: This is essentially a makeshift GTI. Your solar power comes in on the DC bus, and the inverter will feed any excess into the grid. This went through a few versions: In the first version, it would only work if you had a CAN-bus Victron MPPT and the very expensive VEBUS->VECAN cable. In the second version, you could run it without the cable using the voltage trick. In the third version, you can also tell it not to feed back to the grid.

Hub-2: You have a second GTI inverter connected to the OUTPUT of the Multiplus, thus your PV comes in on the AC bus. Excess power flows backwards through the Multiplus to the grid. Some of it may be used to charge the battery. You can prioritise solar charging, so it only uses some of this "back flow" to charge the batteries. If the grid fails, the GTI continues to work as it ties with the Multiplus. There is no way to avoid backfeed, except with some hackery where you tell the Multiplus to disconnect from the grid under low load, forcing it into micro-grid mode. In a Microgrid, it can use GFPR to back off power from the GTI.

Hub-3: You have a second GTI connected to the INPUT of the Multiplus, thus PV comes in on the AC bus. Excess power flows backwards into the grid. With an AC sensor on the GTI line, you can prioritise solar power for battery charging (once again, never charging batteries with grid power). There is no way to avoid feedback. If the power goes out, the GTI stops working.

Hub-4: Grid Parallel. This works like an AC battery, so to speak. You can instruct the inverter to push power into the grid, or take power from it to charge the battery. You can build your own control system to do this, or use the one that comes with the CCGX. You can also run your own software on the CCGX if you want to (advanced level stuff). With an AC sensor on the input, you can avoid feedback into the grid (but I am unsure of the response times). Documentation is available on how to set the feedback levels using a mk2-usb module.

Makeshift self consumption: This is what I run at the moment, and is similar to how the Axpert works. When the battery voltage is high enough and the load is low enough, switch to inverter mode. It runs fully from solar/battery in this mode. When the load goes too high, or if the battery goes to low, switch to the grid. It runs fully from the grid in this mode. Batteries are only charged from solar, unless I manually override it.

@plonksterI have a MicroCare Grid Tied Inverter with grid tied limiter. Yes its using a RS485 communications cable to link the inverter and limiter. I've not been able to get much information about the protocol they use. When I have time I'll start playing around to figure out how it works. (Not really into M$ stuff, mostly C on Linux)

Being grid tied it switches off at night so there is very little losses at night. It only powers on when the voltage on the PV input rises above a certain value. The drawback is I draw from the grid the moment the sun sets. But it is still cheaper to buy electricity from the municipality than putting in batteries. But this does not mean I don't have batteries. The garage doors, gate motors, alarm system all have batteries. So in a sens they can already act like separate small systems. All that's needed is to replace the batteries with some deep cycle (lead crystal) ones and then switch off the AC supply to them at night. They all plug into normal wall sockets so it should be easy enough just to put them on a timer plug. (I only thought of that while reading this thread...)

I also have the option of putting in one or more bi-directional inverters with their own batteries. For example have a small one in the lounge that just runs the TV and entertainment equipment. Another maybe just running the light circuits. They would all use AC to charge the batteries (during the day) when the GTI produces power. Effectively an AC coupled system. You can couple as many bi-directional inverters/UPSs to your system as you like. One per device or one big central one or a combination.

@edmundp Since its grid tied it does not limit the amount of power I can draw in the house. If the wife switches on the microwave, kettle and washing machine the GTI will still provide what it can and the shortfall (up to 60A ac) can still be drawn from the municipal feed. Thus preventing the "emotional downward spiral" :-P

4 minutes ago, plonkster said:

The tricky bit here really is to understand the hub systems.

Hub-1: This is essentially a makeshift GTI. Your solar power comes in on the DC bus, and the inverter will feed any excess into the grid. This went through a few versions: In the first version, it would only work if you had a CAN-bus Victron MPPT and the very expensive VEBUS->VECAN cable. In the second version, you could run it without the cable using the voltage trick. In the third version, you can also tell it not to feed back to the grid.

Hub-2: You have a second GTI inverter connected to the OUTPUT of the Multiplus, thus your PV comes in on the AC bus. Excess power flows backwards through the Multiplus to the grid. Some of it may be used to charge the battery. You can prioritise solar charging, so it only uses some of this "back flow" to charge the batteries. If the grid fails, the GTI continues to work as it ties with the Multiplus. There is no way to avoid backfeed, except with some hackery where you tell the Multiplus to disconnect from the grid under low load, forcing it into micro-grid mode. In a Microgrid, it can use GFPR to back off power from the GTI.

Hub-3: You have a second GTI connected to the INPUT of the Multiplus, thus PV comes in on the AC bus. Excess power flows backwards into the grid. With an AC sensor on the GTI line, you can prioritise solar power for battery charging (once again, never charging batteries with grid power). There is no way to avoid feedback. If the power goes out, the GTI stops working.

Hub-4: Grid Parallel. This works like an AC battery, so to speak. You can instruct the inverter to push power into the grid, or take power from it to charge the battery. You can build your own control system to do this, or use the one that comes with the CCGX. You can also run your own software on the CCGX if you want to (advanced level stuff). With an AC sensor on the input, you can avoid feedback into the grid (but I am unsure of the response times). Documentation is available on how to set the feedback levels using a mk2-usb module.

Makeshift self consumption: This is what I run at the moment, and is similar to how the Axpert works. When the battery voltage is high enough and the load is low enough, switch to inverter mode. It runs fully from solar/battery in this mode. When the load goes too high, or if the battery goes to low, switch to the grid. It runs fully from the grid in this mode. Batteries are only charged from solar, unless I manually override it.

It kinda makes one think, why did you Victron have to do so much research, at the expense of their clients, to get something working which other brands have done long ago already, and at a fraction of the price. 

You need to sit down and do the math, and see if these units will pay itself back in a reasonably amount of time. Or is it just a nice to have cause it's Victron and gives you bragging rights?

 

7 minutes ago, SilverNodashi said:

The one advantage of using anti-islanding, is that you can push back to the grid when the grid is on (so essentially use it as a battery), but not when it grid is off - to make sure some guy on the wire doesn't get electrocuted. 

That's what anti-islanding is. It doesn't mean you cannot push back. It means you cannot form an electrified island in the middle of a dead grid :-)

That's what the Ziehl UFR1001e does as well. It doesn't stop your inverter from pushing back... you can still do that quite successfully. You will still trip the prepaid meter if you have such a trippable meter. What it does is ensures that there is a physical switch/contactor that opens if the grid goes down. The Multiplus already does the right thing... it just doesn't comply with local legislation that requires TWO switches one of which must be a PHYSICAL switch and not an electronic one.

10 minutes ago, SilverNodashi said:

You need to pay a monthly premium (about R800 I think) to have a permit to do so.

Probably depends on your municipality. As far as I know, in Cape Town you can fit a grid limiter and remain on the domestic tariff. You don't HAVE to switch to the Embedded Generator plan. Of course, it's up to them if they will allow you to do it. The monthly "premium" is R13 a day, so it amounts to R400 a month. Not that bad at all.

18 minutes ago, SilverNodashi said:

I don't remember seeing an anti-island option on the infini. The one advantage of using anti-islanding, is that you can push back to the grid when the grid is on (so essentially use it as a battery), but not when it grid is off - to make sure some guy on the wire doesn't get electrocuted

The infini can push and pull from the grid when it's on.

edit
It also disconnects when the grid fails as far as I understand and use the batteries making it a true hybrid.
Does this not mean anti-islanding?

4 minutes ago, SilverNodashi said:

It kinda makes one think, why did you Victron have to do so much research, at the expense of their clients, to get something working which other brands have done long ago already, and at a fraction of the price. 

Long ago? These other hybrids are all Johny-come-latelys. I will concede that these other guys might have surpassed them in this respect, you know... like the Japanese did in car manufacturing. But ONLY in the home market, and only as MFD (multi function devices) which I already dislike. Also, in industrial and commercial settings where I might want to cap peak consumption (because I pay penalties) and such, there is still nothing more flexible.

I think Ed should perhaps consider the Infini. Don't get me wrong. For me personally, though... I already have the hardware. I'm the techie who WANTS to mess with this stuff, not the average home user who just wants it to work. So for me there is the potential to get exactly what I want for about half of what the Infini costs. That... and I'm still a little uncomfortable with the lack of a track record on their side, and Mike reporting on failures a few months ago...

13 minutes ago, viper_za said:

The infini can push and pull from the grid when it's on.

edit
It also disconnects when the grid fails as far as I understand and use the batteries making it a true hybrid.
Does this not mean anti-islanding?

Yes, I know it can push back to the grid. 

 

Let me rephrase, I didn't see an option that it would cut  off the grid feedback, as soon as the grid fails. Will have to reread the manual.

2 minutes ago, SilverNodashi said:

I didn't see an option that it would cut  off the grid feedback, as soon as the grid fails.

I think that's one of those implicit things. If it is certified... it already does that :-)

1 minute ago, SilverNodashi said:

Let me rephrase, I didn't see an option that it would cut  off the grid feedback, as soon as the grid fails. Will have to reread the manual.

It is on the list as one of the approved inverters to install and feedback to the grid, don't think it will get that without being able to adhere to the anti-islanding regulations

Any comments on the Infini's MPPT?

On the Infini you select the power standard for your country, in our case NRS 097-2. This sets the power quality parameters for the grid side of the inverter - a voltage range and frequency range. If the grid power quality goes outside those parameters the Infini disconnects in less than a second. Each power standard has it's own rules but I think NRS 097 specifies disconnect within 0.5s, VDE standard is 0.2s if I remember correctly.

So in case the grid goes off the frequency will drop (as well as the voltage) and the Infini will disconnect from the grid immediately. Once the grid is back on it monitors that it remains inside the specified limits for 30 seconds before connecting to the grid again. The 30s is adjustable.

18 minutes ago, plonkster said:

Long ago? These other hybrids are all Johny-come-latelys. I will concede that these other guys might have surpassed them in this respect, you know... like the Japanese did in car manufacturing. But ONLY in the home market, and only as MFD (multi function devices) which I already dislike. Also, in industrial and commercial settings where I might want to cap peak consumption (because I pay penalties) and such, there is still nothing more flexible.

I think Ed should perhaps consider the Infini. Don't get me wrong. For me personally, though... I already have the hardware. I'm the techie who WANTS to mess with this stuff, not the average home user who just wants it to work. So for me there is the potential to get exactly what I want for about half of what the Infini costs. That... and I'm still a little uncomfortable with the lack of a track record on their side, and Mike reporting on failures a few months ago...

I'm not referring to MFD or "Hybrid" inverters, but rather true grid tie inverters. There's a bit of a difference.

26 minutes ago, plonkster said:

So for me there is the potential to get exactly what I want for about half of what the Infini costs

plonkster, the 3kW Infini can be bought for around R16k, I don't see a system of that capacity and functionality being built for R8k, I think you will be hard pressed to build it for the same amount. Let alone having a certified system.

1 minute ago, cvzyl said:

plonkster, the 3kW Infini can be bought for around R16k, I don't see a system of that capacity and functionality being built for R8k, I think you will be hard pressed to build it for the same amount.

True, but Plonkster already has all the equipment.

Edmund, I agree 100% of that. Use what you've got, no sense in disposing or replacing good quality equipment if it still operates. I was more referring to someone starting out.

Might I just say, in a grid tie inverter anti-islanding will disconnect from the grid in a power failure and switch the inverter off, it will no longer produce power. With a true hybrid it disconnects from the grid but continues supplying power to the loads as normal, no interruption. It continues with PV production if available, charges batteries or used battery storage if PV insufficient.

7 minutes ago, edmundp said:

Any comments on the Infini's MPPT?

It has dual MPPT trackers, do you could effectively have poly and mono crystal panals mixed, or west/south orientation mix if you need to. OR just have two strings of the same panels. Quite a nice feature. But it's a high voltage system - 250V - 900V, so you need minumum 11x 250W panels. 

2 minutes ago, SilverNodashi said:

It has dual MPPT trackers, do you could effectively have poly and mono crystal panals mixed, or west/south orientation mix if you need to. OR just have two strings of the same panels. Quite a nice feature. But it's a high voltage system - 250V - 900V, so you need minumum 11x 250W panels. 

Could you not just use one string of 9 x 250W panels all in series? Thus 37Voc (approx) * 9 = 333V? Or would this result in terrible MPPT usage?

@SilverNodashi I did say I am open to suggestions did I not? 

The cost of going Victron, not a chance, sorry Victron. It is not even remotely cost effective unless you already have the inverter.

@edmundp I would not spend this kind of tom on Victron if there are approved Infini's, if you want grid-tie.

@The Terrible Triplett The more you read here, the more you want to take small systems, using milk money, off-grid ne? Grid tie complication is just not your cup of tea.

13 minutes ago, SilverNodashi said:

I'm not referring to MFD or "Hybrid" inverters, but rather true grid tie inverters. There's a bit of a difference.

Aaah ok. Heritage probably. They come from a "I need power on my barge" background :-)

20 minutes ago, edmundp said:

True, but Plonkster already has all the equipment.

Exactly. And as I intimated yesterday... I value other things. The fun of playing with things, learning new skills, etc... those things are worth way more to me. Within reason of course. I'm still just an average oke who financed a lot of this through traditional and expensive credit sources :-)

In some ways I find it similar to my preference for Toyota. If I wanted best bang for buck, I'd buy a Hyundai or a Kia. I'd take the Terios (sadly no longer imported) over the Rav4 every time. I'd use a Tata on the farm and not a Hilux. That sort of thing. I bet you someone already thinks I'm wrong (how could I even mention a Telcoline and a Hilux in the same sentence, right!?), but that is kinda how I feel about the inverter subject too :-)

Edit: I'm still wondering why I let the wife buy a Suzuki. All Japenese cars share around 50% of their parts, they said. So it's half a Toyota in some ways. It's very well built, in some ways it's better quality than the Toyota. It's a pleasure to work on. It's a funky little pocket rocket. What on earth could be wrong with it? Well... finding parts for it. That sets you back a bit... because you usually end up buying them at the dealer and not at the local Midas.