I am trying to identify inverters that can do the following:

I basically want to leverage excess solar power generation (when the grid is on) to power non-essentials like the geyser and some small underfloor heating (or even the oven). The Sunsynk solution uses the CT Coil to measure correctly and prevent feedback to the grid. The challenge I face, is that with my preferred installation setup, the CT coil cable length will end up being longer than the max. length specified (even when extended) and there is a space issue to get the CT clamp positioned around the incoming mains.

Is there are alternative solution or other inverter brands, that does not require a CT clamp installed as per the Sunsynk method? Which inverter offers the same functionality (passthrough and blending on non-essentials without feedback to he grid) but without a CT coil required on the incoming mains? A friend has a Victron inverter and says his works fine like this but doesn't have the CT coil installed as per Sunsynk's way...

There is installs where the CT cable has been extended to 50m and I believe even longer than that.

 

14 minutes ago, Octave said:

I am trying to identify inverters that can do the following:

I basically want to leverage excess solar power generation (when the grid is on) to power non-essentials like the geyser and some small underfloor heating (or even the oven). The Sunsynk solution uses the CT Coil to measure correctly and prevent feedback to the grid. The challenge I face, is that with my preferred installation setup, the CT coil cable length will end up being longer than the max. length specified (even when extended) and there is a space issue to get the CT clamp positioned around the incoming mains.

Is there are alternative solution or other inverter brands, that does not require a CT clamp installed as per the Sunsynk method? Which inverter offers the same functionality (passthrough and blending on non-essentials without feedback to he grid) but without a CT coil required on the incoming mains? A friend has a Victron inverter and says his works fine like this but doesn't have the CT coil installed as per Sunsynk's way...

If you still want pv to blend with grid on your non essentials, eg geyser, stove, then there is no other way but to use a CT on the incoming grid to stop inadvertant export. 

The other option is to do away with nonessentials altogether and put everything on essentials like the Axperts. Axperts by the way are grid tie too, but prevent exporting on the grid input of your machine. However the inverter and battery must then be rated for the full load of your home. 

The last option, probably the best., is to use an energy meter at main db box, and use long distance RS485 comms to the inverter (eg SunSynk).  But you must use energy meter compatible with inverter, eg certain CHINT models, and certain EASTRON models, amongst other. 

Edited May 24, 20233 yr by BritishRacingGreen

18 minutes ago, Octave said:

A friend has a Victron inverter and says his works fine like this but doesn't have the CT coil installed as per Sunsynk's way...

The Victron uses a Carlo Gavazzi ET112 instead of the CT (which takes more space than a CT)...

Edited May 24, 20233 yr by P1000

Then we also have the Solis S6 which has the CT connected to a small meter and the meter has  RS485 comms that feeds the status to  inverter. The Solis RHI uses a different smart meter via RS485. 

This gives about 3 different configurations. 

Edited May 24, 20233 yr by Scorp007

https://www.sunsynk.org/post/eastron-meters-do-you-need-one

18 minutes ago, GreenFields said:

https://www.sunsynk.org/post/eastron-meters-do-you-need-one

This is the same as used by the S6 Solis. 

1 hour ago, BritishRacingGreen said:

The other option is to do away with nonessentials altogether and put everything on essentials like the Axperts. Axperts by the way are grid tie too, but prevent exporting on the grid input of your machine. However the inverter and battery must then be rated for the full load of your home. 

Hi @BritishRacingGreen

My understanding is that whilst Voltronic/Axpert do make some Hybrid models (the Infini range I think), most of the models sold in SA are Off-Grid models (https://voltronicpower.com/en-US/Product/PV-Inverter/Off-Grid-Inverter)  i.e. they do not sync to the Eskom grid the way a grid-tied inverter does. Most of the models can be powered/charged from the grid but as they don't sync with the grid they would never be able to feedback into it. They also cannot blend power between grid & solar as the frequencies are not synced. You can power the inverter from the grid and use the inverter to power a load but this is less efficient than just running the load of the grid. If the load exceeds the capacity of the inverter, the complete load is transferred to the grid, it is not possible to transfer part of the load as again the frequencies are not synced. 

2 hours ago, GreenFields said:

https://www.sunsynk.org/post/eastron-meters-do-you-need-one

Hi @GreenFields I must add I am very impressed with EASTRON. @Steve87 has provided me with a 3 phase energy meter  kit  SDM630MCT  with split core 200A/5A CTs in order to develop a roving energy data logger for large commercial/industrial energy profiles. Firstly, very impressed with price . Secondly the user and modbus protocol documents are so not Chinese. They leave very little to the imagination. Its perfect English and very detailed,especially the modbus protocol. 9 out of 10 points, other chinese manufacturers can learn from EASTRON.

The meter conforms to accuracies and stability that conforms to billable metering specs. 

 

Edited May 24, 20233 yr by BritishRacingGreen

2 hours ago, Sc00bs said:

Hi @BritishRacingGreen

My understanding is that whilst Voltronic/Axpert do make some Hybrid models (the Infini range I think), most of the models sold in SA are Off-Grid models (https://voltronicpower.com/en-US/Product/PV-Inverter/Off-Grid-Inverter)  i.e. they do not sync to the Eskom grid the way a grid-tied inverter does. Most of the models can be powered/charged from the grid but as they don't sync with the grid they would never be able to feedback into it. They also cannot blend power between grid & solar as the frequencies are not synced. You can power the inverter from the grid and use the inverter to power a load but this is less efficient than just running the load of the grid. If the load exceeds the capacity of the inverter, the complete load is transferred to the grid, it is not possible to transfer part of the load as again the frequencies are not synced. 

Hi @Sc00bs I know where you come from in terms of the  understanding of the  legacy boilerplate offgrid designs. Yes,  they did not tie the grid to load, and therefore there was a hard bypass relay which will either provide grid full-on to load, or battery/pv full on to load.

However since the third and fourth generation of Axperts, the topology for even offgrid is pure gridtie. Gridtie is only way one can blend in the AC domain. So the inverter is fully bidirectional, with no seperate grid charger anymore.  So Voltronics employed gridtie topology to entertain blending for offgrid machines (offgrid is now a bit of misnomer, but thats what Voltronics call them). 

The main difference between SunSynk and Axpert, is Axpert blocks any exporting of power to grid. This is a software function in conjunction with energy sensing at the grid (CT coil) . The axpert does not need the latter as it only 'export' until the balance of load power is reached. However, the control loop is not perfect, and as @Coulombhas stated before, it may occur that from time to time the system will 'burp' a small amount of exported overruns onto  the grid.

 

 

Edited May 24, 20233 yr by BritishRacingGreen

1 hour ago, BritishRacingGreen said:

Hi @Sc00bshis is a software function in conjunction with energy sensing at the grid (CT coil) . The axpert does not need the latter as it only 'export' until the balance of load power is reached. However, the control loop is not perfect, and as @Coulombhas stated before, it may occur that from time to time the system will 'burp' a small amount of exported overruns onto  the grid.

 

 

Thanks for this post. For the 1st time I get the reason why 1 installer refuses to install the HV Voltronics for the whole DB. The risk then remains that this brief small blurp can trip a sensitive prepaid. 

Hi guys if I can weigh in on this subject. The infiniSolar machine is compatible with the Easton meter & it's completely Grid tied & synch ready it's just not been tested & NRS approved. However, the machine is capable with the Easton meter to be able to Grid interact, however, they did not get NRS approval done as the HV range did not sell as well as they would have wanted. Otherwise it would have been registered & tested. People don't realise that the testing & registration process is not cheap. The BME or infiniSolar machine is very well engineered, however, it's a complicated machine to full understand but if well understood it's hard value to beat. The other issue is that they paired with the Pylontech H2 Cube HV battery. Pylontech being 0.5C is not a popular choice as they would stack in rack form. FreedomWon did not get the opportunity to provide pairing & that also killed the BME machine. FreedomWon being one of the market leaders in the HV arena at the moment. 

The BME or any old generation InfiniSolar machine is a machine with its rated output divided by 3 phases. There is no phase overload sharing capabilities. It can bypass when overloaded but it's mode of operation needs to be understood. It can bypass but only in certain modes of operation. 

Unfortunately, it was ahead of its time but had these major Interfacing issues & this was the main reason in my opinion for them not really making a big success. 

Thank you for the informative post @BritishRacingGreen & @Steve87 

12 hours ago, Steve87 said:

Hi guys if I can weigh in on this subject. The infiniSolar machine is compatible with the Easton meter & it's completely Grid tied & synch ready it's just not been tested & NRS approved. However, the machine is capable with the Easton meter to be able to Grid interact, however, they did not get NRS approval done as the HV range did not sell as well as they would have wanted. Otherwise it would have been registered & tested. People don't realise that the testing & registration process is not cheap. The BME or infiniSolar machine is very well engineered, however, it's a complicated machine to full understand but if well understood it's hard value to beat. The other issue is that they paired with the Pylontech H2 Cube HV battery. Pylontech being 0.5C is not a popular choice as they would stack in rack form. FreedomWon did not get the opportunity to provide pairing & that also killed the BME machine. FreedomWon being one of the market leaders in the HV arena at the moment. 

The BME or any old generation InfiniSolar machine is a machine with its rated output divided by 3 phases. There is no phase overload sharing capabilities. It can bypass when overloaded but it's mode of operation needs to be understood. It can bypass but only in certain modes of operation. 

Unfortunately, it was ahead of its time but had these major Interfacing issues & this was the main reason in my opinion for them not really making a big success. 

Which is a pity , because I believe the newest generation of Infini is value for money. And what's more as I can see , the design topology is very similar to the Axperts, making it easier to support than the bulky old Infini design.

my take on this. 

 

get a dual output inverter. run everything through the inverter, and put the non essentials on the main AC output. as this one can be adjusted to drops off when utility drops. or when a certain SOC is reached. 

the second AC output will be for essentials.

AXPERT Twin comes to mind.

 

the other work around... and i personally prefer this idea, as the inverters are full of issues and niggles and firmware issues, unless you splash out on very expensive blue stuff. 

install an inverted capable of handling everything in your home. and put the non essentials through smart switches after the inverter.

Create a load shedding condition on your app. this way you can switch off the non essentials at night when there is no PV and utility drops, to protect the batteries. 

this way you will harvest all the PV you can, during daytime. battery will be charged full most of the time. and your battery will carry you on the essentials during night time. 

 

this is pretty much what i am doing now, exception being the oven and geyser that will not be connected.

i am installing a second 100L geyser (before the main geyser) with a 1500w element to push extra/wasted solar energy to the geyser during the day. the idea behind this is to use the 2nd geyser as a cheaper storage medium. and if i dont use it, it doesnt affect the rest of the system. (still toying with the idea to install both elements on the same geyser)