Good day.

I am planning a grid-parallel system using a Victron Multigrid 3000VA, a 3.4 kW Pylon battery, 6x 355W solar panels, and a MPPT charger.

The plan is to put my essential loads (Fridge, lights and some plugs) on the AC output of the Multigrid. The power in the Pylon will mainly be used during power outages, therefore I plan to use the setting to use maybe 20% of battery when solar is inadequate to power the essential loads, but top-up with grid power otherwise. I don't think there is any 

Next thing for me is optimise my self consumption. The solar power produced will be more for most of the daytime hours than what the essential load will require. So after the battery are topped up to full capacity the excess solar power should be used to reduce the consumption from ESKOM on other loads that is NOT on the Victron's outputs. Whether that is a geyser, or a washing machine, does not matter. This is just so that the excess solar power is not wasted. Maybe I misunderstand something here, because I struggle to find clear answers on whether my idea is possible. This is maybe because it is common sense (to others except me) that this will happen autonomously, or because it is totally ridiculous and not possible.

It seems clear that I cannot just put all my non-essential loads  on the auxillary output of the Victron, as that load is limited to 16A and because I want to use the excess solar power wherever it is needed, I want the multi to basically feed that power back to the mains side and powerassist it there.

Is that possible using a multigrid? Does it require maybe some additional equipment? Or special settings?

The alternative I am looking at is using a grid-tie inverter (and setting it to zero feed-in back to ESKOM) and couple that across my main db-board, and then have a seperate pure backup system installed for the essential loads. Would appreciate your views on which option is best. It seems that going grid-tie there might be some conflicts between the two systems? Victron seems to only support that if using a very specific PV inverter? Should I then rather use another combination of PV-inverter and hybrid-inverter? What do you guys suggest?

Kind regards.

37 minutes ago, DAF said:

So after the battery are topped up to full capacity the excess solar power should be used to reduce the consumption from ESKOM on other loads that is NOT on the Victron's outputs.

Two possibilities. If you don't have a prepaid meter that bills/trips when reverse feeding, then simply set it up to feed the excess solar power into the grid. Otherwise you install a Carlo Gavazzi energy meter (I assume single phase, so it will be the ET112). You install this meter right after the main breaker so that it sees all power used in your home. The measurement from this meter then replaces the one taken by the Multi, and it will feed back power until the ET112 measures zero, thereby covering loads that are not connected to the output. If you run out of capacity, then the rest comes from the grid.

37 minutes ago, DAF said:

multigrid

This is supported by all the Inverter/Charger models, Multiplus (even the compact) and Quattro. The Multigrid is merely a Multiplus with extra anti-islanding hardware. You probably want the Multiplus-II though, which also has this extra anti-islanding disconnect.

37 minutes ago, DAF said:

Victron seems to only support that if using a very specific PV inverter?

The Fronius inverter is the main supported inverter and works very well. I'm not sure what you mean by very specific... it works with just about the entire range of Fronius inverters. You can also use SMA (but power-limiting does not work), and then as of about December you can also use an ABB PV-Inverter (although the power-limiting support is still being tested). Even Solar Edge works to some extent (no power limiting).

The important part of using a PV-inverter is that you want to prioritise PV for battery charging, in other words, you want to avoid charging with grid power (Edit: And you want to avoid feeding power into the grid when you could use it to charge your own batteries). If you install a grid meter as suggested above, then the system can also see power that is being exported, and because it attempts to hold the meter at zero in both directions, it will try to import all your PV power for the batteries, thereby achieving the same effect. So even if you use a non-supported PV-inverter, a Victron system can still prioritise PV for you. But generally using a PV-inverter with a grid limiter and then attempting to incorporate that with a Victron system does not work so well, so my advice would be that if you go for this combo: Go for Fronius.

Also note that the Multiplus-II has a current transformer that does the same job as the energy meter, so if you use that inverter you can save some money.

And finally... go to youtube and look for the video "ESS Webinar". That explains how it fits together.

Edited January 18, 20197 yr by plonkster

34 minutes ago, plonkster said:

Otherwise you install a Carlo Gavazzi energy meter (I assume single phase, so it will be the ET112). You install this meter right after the main breaker so that it sees all power used in your home. The measurement from this meter then replaces the one taken by the Multi, and it will feed back power until the ET112 measures zero, thereby covering loads that are not connected to the output. If you run out of capacity, then the rest comes from the grid.

Thank you. This is exactly what I wanted to know. These meters seems to cost in the order of R1 000, so not too expensive. 

Would either a CCGX or VenusGX work to complete the feedback loop?

2 minutes ago, DAF said:

Would either a CCGX or VenusGX work to complete the feedback loop?

You need a CCGX or VenusGX for ESS.

If you are like me, a picture person, then here it is very simply example.

Case sample 1: House needs 4kw
2kw comes from the panels.
1kw comes from batts up to the set point of using 20% of them - only then it draws the 1kw from Eskom
1kw comes from Eskom

Case sample 2: House load of 1.5kw
All comes from panels
Difference is put back into the batteries after Case 1 above took place.

ESS cleverly handles the inputs from the batteries, panels and balances that with what you need to draw from Eskom to ensure the max amount of savings.

I have once used the inverter to charge the batts. After that not once has the batts seen Eskom as a recharge source. ESS keeps them charged.

In my case, after the tripping was resolved, it is "plug and forget".

41 minutes ago, plonkster said:

Also note that the Multiplus-II has a current transformer that does the same job as the energy meter, so if you use that inverter you can save some money.

And finally... go to youtube and look for the video "ESS Webinar". That explains how it fits together.

I can get a second hand multigrid, with VenusGX and MPPT charger as a combo deal second hand, so planning to buy this, but if buying new in the end, I will definitely consider multiplus-II instead.

Thank you! Will definitely go watch that video tonight.

1 minute ago, DAF said:

Would either a CCGX or VenusGX work to complete the feedback loop?

Yup. These days we refer to it as a "Venus Device" because there is more than one that can do the same job. The CCGX is the original. The Venus-GX has no LCD screen, but has more CPU power and is a bit more modern (and costs less), and does the same job. So yes, either will do. Then the firmware also runs on the Raspberry Pi, for those who want to roll their own, but then you have to buy an MK3-USB cable to interface it (buying that cable is a good idea anyway, makes firmware updates and configuration so much easier). It also runs on the Nanopi. Finally there is also new hardware on the way that incorporates the nanopi and some other goodies, but that isn't here yet.

For most people I advise buying the Venus-GX.

2 hours ago, plonkster said:

Also note that the Multiplus-II has a current transformer that does the same job as the energy meter, so if you use that inverter you can save some money.

Plonkster,

If you bypass the inverter for certain loads, eg. geyser, oven etc., then you would still need the ET112 , correct?

1 hour ago, VisN said:

If you bypass the inverter for certain loads, eg. geyser, oven etc., then you would still need the ET112 , correct?

When you bypass the inverter (I assume with a manual changeover switch), then all your loads are on the input side of the Multi (nothing is connect to the output, right?), and if you want the Multi to feed power into the grid to cancel that out, then yes, you need something to measure how much power and to feed that back into the Venus-GX or CCGX. You can either use something like the ET112... or... the current transformer that comes with the MP-II does the same job.

1 hour ago, plonkster said:

When you bypass the inverter (I assume with a manual changeover switch), then all your loads are on the input side of the Multi (nothing is connect to the output, right?), and if you want the Multi to feed power into the grid to cancel that out, then yes, you need something to measure how much power and to feed that back into the Venus-GX or CCGX. You can either use something like the ET112... or... the current transformer that comes with the MP-II does the same job.

I don't mean bypassing all loads,  just the heavier ones. Eg. Lights,  plug points on the output side and geyser etc. on the input side. I think your answer still applies but I can't figure out how to use the MP-II's built in current transformer in the scenario I've just described. 

22 minutes ago, VisN said:

can't figure out how to use the MP-II's built in current transformer

Straight from the spec sheet. Your heavy loads is plugged into the blue "Loads" socket, which is on the input side of the Multi. The Current Sensor sees that current and the Multi adjusts to cover it.

This method should even be a little bit more reactive (faster to adjust) than using a modbus meter.

Edit: Just to be clear, that current transformer/sensor is optional. The Multiplus-II has one built in as well. But if you plug in the optional external CT then the signal from this CT replaces the internal signal, allowing the Multi to see loads (and also sources, such as PV inverters) on the input side... at a lower cost than a modbus meter.

Edited January 18, 20197 yr by plonkster

Excellent explanation. 

Thank you Plonkster. 

3 hours ago, plonkster said:

Straight from the spec sheet. Your heavy loads is plugged into the blue "Loads" socket, which is on the input side of the Multi. The Current Sensor sees that current and the Multi adjusts to cover it.

This method should even be a little bit more reactive (faster to adjust) than using a modbus meter.

Edit: Just to be clear, that current transformer/sensor is optional. The Multiplus-II has one built in as well. But if you plug in the optional external CT then the signal from this CT replaces the internal signal, allowing the Multi to see loads (and also sources, such as PV inverters) on the input side... at a lower cost than a modbus meter.

@plonkster, And do I understand correct that this setup is part of the Approved setup's for City of Cape Town (ie two anti-islanding devices)?

38 minutes ago, Herman said:

, And do I understand correct that this setup is part of the Approved setup's for City of Cape Town (ie two anti-islanding devices)?

You don't need a second anti-islanding device. The Multiplus-II has everything inside. Don't worry about the loads on the input side. That is what anti-islanding is about: If the grid fails, the MP-II will stop powering those loads.

@plonkster, I think I am right in saying:

This solution also offers Zero -feed-in without the cost of a Venus device, however as @Herman has already raised the possibility of an additional PV inverter.

If an additional PV inverter was installed later, a venus device would be necessary to achieve zero feed-in then.

2 hours ago, phil.g00 said:

This solution also offers Zero -feed-in without the cost of a Venus device

Unfortunately not. The algorithm still runs on the Venus device, and things like stopping on a lower SOC and so on is implemented on that side.

4 hours ago, plonkster said:

Unfortunately not.

Alrightey then.

With a E112 current sensor in place (install exactly like Hermans image above)  how quickly is the system able to react when the /grid side loads are high and Victron inverter (Quattro in my case) is supplying part  or most of the load trying to keep Eskom at 0 kwh (battries full and AC out loads not high), and grid side loads suddenly drop. 

My specific concern is the prepaid meter seeing a backfeed and tripping out. I have tried to see what my specific meter would do in this situation but little info avail - is a Itron ACE 9000 ISP.

I had thought of putting the setpoint for Eskom at about 300W to give a bit of a buffer, but not sure that will help if the grid side load drops from say 2.5 kw to 0) or am I worrying about nothing?

To add detail I am wanting to put Oven, washing machine, tumble dryer  and Heat pump on Grid side as they all big users - rest of house on down side of inverter. 

Tim 

Hi, I have been playing with power assist / grid feedback from DC coupled system etc but had to urgently install my test equipment for a client with a problem.  Waiting on the MPII to arrive to continue testing but very curious so hoping to get a quick answer from the experienced guys talking here:  System in question:

- Three 12kVA Quattros  (enough to handle all loads in the residence)

- 20kW DC coupled PV (Victron MPPTs of course)

- Generator (45kVA three phase)

- Grid power available

-  75kWh Lithium bank

 

Question:

Question:  Can I set the system up in such a way that it effectively never "switch" between grid power and inverter power like it would when used as a backup system only?  In other words it must always use energy in the this order of priority:  PV, battery, grid, generator and stay in inverter mode under all conditions.

I played around with this a little but before concluding my tests had to give up the equipment as I mentioned, so not 100% sure I tested all scenarios. It looked like it was all possible though using ESS.  It would seamlessly blend in power from the grid when the battery got too low at night and turning the AC input on and off did not rattle it at all.

Any comments will be much appreciated.

 

Edited December 3, 20196 yr by Hannes7212
typo

4 hours ago, Hannes7212 said:

stay in inverter mode under all conditions

It's a hybrid inverter, so it cannot stay in "inverter mode" if you want to use the grid (under low-SOC conditions or high power demands, if I had to guess).

But let me backtrack a little. There is an older hub-system (which is deprecated but still used) called Hub-2. This system has an option to disconnect from the grid and essentially run off-grid, but switch back to the grid (switching is < 1 second) if there is high power demand or the battery is low. Many older self-consumption systems were set up like this. Downside to this system is it is a little bit unstable, in the sense that your inverters has to be able to handle all the loads for that one second it takes to switch back to the grid, and the switching itself tends to upset the anti-islanding on the PV-inverters and they tend to disconnect and reconnect. Throttling the PV-inverters has to be done using frequency shifting, and the only way to prevent feeding into the grid is to disconnect from it (because you can't shift the grid frequency, that's a given constant).

Then there is the new one, called ESS. ESS always ties with the grid. PV-inverters are software-throttled. Very stable because the grid is a nice strong low-impedance source/sink. But because it is always tied to the grid, it tends to feed small amounts into the grid whenever your loads change, and it also draws small amounts from the grid if a large load starts up. IMHO, if you don't have a dumb prepaid meter that trips on reverse feed, the slight cost of electricity is worth it for the stability in this system.

Now... before you do anything else, go watch the ESS webinar.

 

Hi and thank you again.  I found that webinar very good - watched and rewinded a bit before I did my first ESS installation.  So I think you have answered me.  Running ESS will effectively do what I want I think - there will be no switch between pure grid and battery (like an Axpert, dare I say it) when the battery goes too low, it will just draw more from the grid.  I got my new Mulitplus II on Monday and will hook it up here at home to do some tests with.

On 2019/10/25 at 6:50 AM, Tim said:

With a E112 current sensor in place (install exactly like Hermans image above)  how quickly is the system able to react when the /grid side loads are high and Victron inverter (Quattro in my case) is supplying part  or most of the load trying to keep Eskom at 0 kwh (battries full and AC out loads not high), and grid side loads suddenly drop. 

My specific concern is the prepaid meter seeing a backfeed and tripping out. I have tried to see what my specific meter would do in this situation but little info avail - is a Itron ACE 9000 ISP.

I had thought of putting the setpoint for Eskom at about 300W to give a bit of a buffer, but not sure that will help if the grid side load drops from say 2.5 kw to 0) or am I worrying about nothing?

To add detail I am wanting to put Oven, washing machine, tumble dryer  and Heat pump on Grid side as they all big users - rest of house on down side of inverter. 

Tim 

To answer my own question - I have setpoint at 200W and no grid feedback enabled in ESS - no issues with prepaid meter going into tamper mode - waiting for my prepaid meter to be replaced by municipality with grid tied meter to start playing with more settings.... covoid-19 first world problems