Existing GT Inverters to Sol-Ark Hybrid Inverter Diagram

[Not Aerosmith]

I have been trying to figure how to convert existing GT inverters system into a hybrid system. When I think that I have found a solution there always seems to be issues with the manufacturer recommended installation. They also provide little help in connecting existing GT inverters to a Hybrid Inverters. Manufacturer's focus is for you to use their equipment and buy more of their equipment to make it work. I finally decided that if I DIY my own diagram for installation most of the issues can be solved.

Attached is a proposed one-line diagram for the installation of existing (3) 5 KW GT inverters to a new Sol-Ark 15 KW:


With this installation, you only need to buy one major component the new hybrid inverter. New solar panels and new batteries are not needed, but can be added in the future. Production can be increased from 15 KW to 20 KW to 25 KW to 30 KW simply by adding additional solar panels. There are no issues about trying to AC coupling existing inverters to a new Hybrid inverter and being able to control them or if they are UL1741 or UL1741SA certified. We are connecting the solar panels not the inverters to the Sol-Ark.

Since Sol-Ark can operate without batteries, you can add batteries in the future as desired. If you want Sol-Ark UPS mode, batteries are needed for UPS to work without adequate sunlight.

The manufacturer suggests connecting your existing GT inverters to the generator connection. I believe during an outage that Sol-Ark can best match production with consumption, if the existing solar panels were connected to the Sol-Ark instead of the GT inverters. Furthermore, if you use the generator connection for the GT inverters, you lose your other choices of using it for a generator, dump load, well pump, etc. If you connect the existing GT inverters to the generator connection, I don't believe the Sol-Ark will work without adding batteries or solar panels.

This is an inexpensive way to provide backup power to an existing GT system by adding a hybrid inverter without needing to add solar panels or batteries. If the Sol-Ark has problems, I can immediately switch the solar panels manually from Sol-Ark back to Fronius. I believe the Sol-Ark is suppose to fail in the 200 amp bypass mode. If so, my system would revert back to its operation prior to adding the Sol-Ark inverter.

There are concerns about the selector switch rating and needing to be switch not under load to prevent flash or arcs that can damaged the contacts. A work around solution is not to use a selector switch, but connect the Fronius or Sol-Ark to the existing solar panels with MC4 connectors.

This is a one line diagram proposed for my existing GT inverters, which could easily be modified for other existing GT systems with different capacities. If there was a problem with the Sol-Ark, it is an easy changeover from Sol-Ark inverter to a Fronius inverters. It is also an easy changeover from Sol-Ark to existing inverters to free the Sol-Ark's MPPTs for adding new solar panels.

 

[Not Aerosmith]

I also investigated the MPP Solar LVX6048WP and SunGoldPower IP6048. These models are only rated for 6 KW and require a 40 amp breaker between the hybrid inverter and the grid power per installation instructions. They also recommend to connect existing GT inverters to the hybrid inverter using the generator connection. Since the grid and the inverter are separated with a 40 amp breaker, you should only connect 40x80%x240 or 7680 watts to the grid thru one hybrid inverter.

The manufacturer solution is to parallel more of their units and add (2) 5 KW batteries for each inverter. Using only (2) inverters $4K and (4) batteries $8K, the cost is $12K >> Sol Ark $8K. If your budget permits, $12K, then I would recommend buying the Sol-Ark with (2) 5 KW batteries.

Which is better? One Sol-Ark can pass thru 200 amp of grid power to your house panel. Two MPP Solar or SunGoldPower can pass thru 80 amps of grid power to your house. The average or larger home would want more grid power than 80 amps. If you use (3) or (4) hybrid inverters with batteries, you would have 120 amps for $18K or 180 amps for $24K. This is based on installing the inverters per owner manual and the cost listed excludes miscellaneous components, shipping and installation cost.

 

[Mattb4]

A concern I have is whether the transfer switches pictured are rated for DC.

 

[Not Aerosmith]

A concern I have is whether the transfer switches pictured are rated for DC.

Really all I need is a manual changeover or selector switch not an ATS. I will investigate and try to verify that the switch has the proper DC ratings and afterwards change the drawing.

Excellent input, I appreciate your comment. Thank you

 

[Hedges]

Once you have batteries, you should be able to AC couple (some of) the GT PV inverters. Maybe on the "load" port, otherwise on the "gen" port.

My idea for PV string transfer switch is use DC rated knife switch to open the string (and unlock door), MC3 connectors inside to unplug from one inverter, plug in to another, close door, close switch.

I've been doing that with a different combiner box, not the interlocked switch/lid, as I experiment with one of my new inverters.

 

[Not Aerosmith]

Really all I need is a manual rotary switch not an ATS. This switch is from Amazon for $44, so I will modify the drawing with this switch:
View attachment 113708
Excellent input, I appreciate your comment. Thank you

Really all I need is a manual rotary switch not an ATS. This switch is from Amazon for $44, so I will modify the drawing with this switch:

Excellent input, I appreciate your comment. Thank you

After I commented, I thought more about your concern. I remembered that DC switches can flash, arc and even physically weld themselves close. Some switches have warnings not to close under load to prevent wear or damage to the contactors. The Fronius have an existing DC disconnect and the Sol-Ark has an internal DC disconnect, so it is possible to operate the selector switch without load. It is also possible to simply manually switch the units only using the disconnects, but I like knowing that the solar panels can only provide power to Fronius or Sol-Ark.

This switch is really only a changeover or selector switch to connect the solar panels to either the existing Fronius inverter or the new Sol-Ark inverter. Once set it would normally not be changed. It is available in case the Sol-Ark has problems or we want to add solar panels.

 

[Not Aerosmith]

Once you have batteries, you should be able to AC couple (some of) the GT PV inverters. Maybe on the "load" port, otherwise on the "gen" port.

My idea for PV string transfer switch is use DC rated knife switch to open the string (and unlock door), MC3 connectors inside to unplug from one inverter, plug in to another, close door, close switch.

I've been doing that with a different combiner box, not the interlocked switch/lid, as I experiment with one of my new inverters.

View attachment 113710

It is an excellent idea. No access to the MC3 connectors without shutting off the disconnect and opening the encloser. Without a load, there is no concerns about DC flash or arc. Therefore, no damaged or welded contactors. This method also insures that only one inverter is connected to the solar panels, which was the reason that I wanted a switch.

I have read that the newer MC4 connectors lock and are less likely to become loose than the MC3 connectors. My solar panels are 3 years old and were not DIY, so I don't know which connectors were used with my solar panels.

Thanks again for the excellent input.

 

[Mattb4]

Had a thought that it might just be simpler to go with two DC breakers as a form of switching from your solar panels. You turn one off and the other on.

Doing some searching on Alie I find that there is a simple DC rated interlock that might handle the task. https://www.aliexpress.us/item/2255...00001113747164!sea&curPageLogUid=Y9cEwPEdimHZ

 

[Hedges]

MC3 was older. Your panels will have MC4.
You might use extension cables from panels and inverters into the switch box, cutting ends to make pigtails as needed.
If you cut the locks off MC4 they will be easier to use as manual disconnects. Inside the box, not subject to getting tugged on inadvertently.

You will have an assortment of connectors that could mate in various directions, including shorting out the PV string. If you bundle pairs together "PV" "inverter A" "inverter B" that would reduce such mixups.

I did do a mix-up, mating one 450Voc inverter capacitor input (still had another PV string connected) to another inverter input (zero volts) with reverse polarity. When I closed the switch, fuses in my combiner box blew as one capacitor bank started to discharge into the other. You may not have fuses, and equalizing charge across capacitors by charging one up reverse-polarity would not be a good thing. Having the two pairs of inverter wires bundled side by side so they can't mate to each other might be the thing to do.

 

[Not Aerosmith]

MC3 was older. Your panels will have MC4.
You might use extension cables from panels and inverters into the switch box, cutting ends to make pigtails as needed.
If you cut the locks off MC4 they will be easier to use as manual disconnects. Inside the box, not subject to getting tugged on inadvertently.

You will have an assortment of connectors that could mate in various directions, including shorting out the PV string. If you bundle pairs together "PV" "inverter A" "inverter B" that would reduce such mixups.

I did do a mix-up, mating one 450Voc inverter capacitor input (still had another PV string connected) to another inverter input (zero volts) with reverse polarity. When I closed the switch, fuses in my combiner box blew as one capacitor bank started to discharge into the other. You may not have fuses, and equalizing charge across capacitors by charging one up reverse-polarity would not be a good thing. Having the two pairs of inverter wires bundled side by side so they can't mate to each other might be the thing to do.

I appreciate you sharing your experience. It sounds like something that I might do. Sorta of reinforce my desire for a selector switch, so once wired correctly, there should never be a problem.

If the Sol-Ark works like the Fronius, I should have over 3 years and still counting with no problems. Considering all the past problems of Sol-Ark previous models and the fact that this is a new design, I have fairly low expectations of this new hybrid inverter. I only installing Sol-Ark because I can't find a better solution and I have looked extensively.

I'm concern about a major event where we may lose power for an extended period of time. Basically, something is better than nothing.

 

[Not Aerosmith]

I appreciate the input and advice. I have decided to proceed with the one-line diagram. I have already sent the diagram to the original installer for the GT inverters and solar panels.

Unfortunately, things move very slowly in Panama. If a contractors doesn't come as promised, he will never call to reschedule. In Panama, you need to call him and reschedule another appointment yourself. If he schedule an appointment for more than a few days, you need to call and remind him or he is more likely not going to show up.

A quote will take a month even though he is only installing one new Sol-Ark 15 all-in-one inverter and relocating solar panels connections from (3) existing Fronius 5KW GT inverters to a new Sol-Ark 15 KW inverter locating with 12 feet of each other. The new Sol-Ark 15 KW has (3) MPPT connections, so it is a simple transfer.

After almost a week, I did get a response that he can modify per my one-line diagram. However, in the same short email, it was apparent that he new nothing about the new Sol-Ark 15 and listed the limitations of a Sol-Ark 12. On the same day, I responded with an email again explaining that the new Sol-Ark 15 is a whole house bypass system, rated for my existing solar panels and I'm not using the existing GT inverters, and the Sol-Ark is able to work without a battery as a hybrid. I also clarify that the modification is to my existing system that the Sol-Ark 15 is a standard installation with no modifications. I suspect that I will need to repeat myself a few more times, before he understand the difference between a Sol-Ark 12 and Sol-Ark 15.

It is a very simple installation and probably my electrician could do it. However, I bought a generator for the well and it has been over 2 months and it is still not connected. Life in Panama is great, but not all the time.

 

[summit]

As drawn, it's not automated right ? without battery nor additional panels

 

[Not Aerosmith]

It as automatic as a standard Sol-Ark 15K installation without batteries. I'm just extending some 10 AWG wiring from my existing 18 KW of solar panels to the (3) MPPT connections on the Sol-Ark. I'm not using the existing (3) Fronius Primo inverters. The only modification is that I providing a switch at the existing inverters, so that I can disconnect the solar panels from the Sol-Ark and reconnect to the Fronius GT inverters. My reasoning is that Sol-Ark is a new design and prone to unexpected issues and problems. If the Sol-Ark needs repair, I can still use the GT inverters. If I want to add additional solar panels, I can switch back 6KW, 12KW or 18KW to the Fronius inverters depending on how many new solar panels that I want to add to Sol-Ark.

My original assumption was that Sol-Ark would perform best as a hybrid in matching the production with consumption during a power outage from solar panels connected to the (3) MPPT connections vs. (3) inverters connected to a single generator connection. Otherwise, I want to maximize the solar panel production to the grid.

My installer said that he can install it as drawn. He told me that Fronius don't use MC4 connectors, so he will be installing the selector switch at each inverter. He also said that he needs to delete one solar panel from each of the (3) Sol-Ark MPPT to not exceed Sol-Ark limitation of 425 DCV MPPT operating voltage.

A couple of days ago, I emailed Sol-Ark. I asked, if I connected the existing UL1741 15 KW inverters to the generator connection can Sol-Ark modulate the existing inverters to match production with consumption during a power outage without solar panels connected to the MPPT connections nor batteries? It only need to modulate during a power outage, otherwise I want to maximize production. If so, I wouldn't need to delete (3) solar panels. No reply from Sol-Ark.

If I get a reply, I expect Sol-Ark to advise me that 500A of batteries would be required to operate Sol-Ark as a UPS during a power outage with the scenario of no solar panels connected. If so, my least inexpensive solution is probably to connect existing 12KW of solar panels to Sol-Ark with maximum 425 volts. Connect all of the remaining solar panels to one 5KW Fronius Primo inverter and connect it to the generator connection.

However, there are many DIY posts making me aware of other newly released options besides Sol-Ark.

 

[summit]

but at the instance of loosing grid power, the Sol-Ark as shown doesn't have a 2nd/backup power, until you flip that PV switch from one of the GTs to power the Sol-Ark, and that's only when the sun is shining.

 

[Not Aerosmith]

but at the instance of loosing grid power, the Sol-Ark as shown doesn't have a 2nd/backup power, until you flip that PV switch from one of the GTs to power the Sol-Ark, and that's only when the sun is shining.

No, the manual switches for the solar panels are normally set to Sol-Ark 15K not the GT inverters.

All the solar panels are normally connected only to the Sol-Ark 15K as in a normal Sol-Ark installation. The existing GT inverters are manually disconnected from the solar panels and not used. The Sol-Ark 15K should automatically disconnect from the grid during a power outage and use the solar panels without sending any power to the grid during a power outage. When there is no power outage, it should send maximum production to the grid.

The manual switches are only for when the Sol-Ark needs repair. I can manually disconnect the solar panels from Sol-Ark, until I get support to update the firmware or whatever fix it needs. When I manually disconnect from the Sol-Ark, I only have a GT system again, until Sol-Ark can be fixed, so I can switch back to a hybrid system.

I don't recommend using ATS switches between the solar panels and the GT inverters and the hybrid inverter. From what I have already read there are reported issues of Sol-Ark disconnecting itself, having faults and etc., but it is usually only a momentarily issue and it is back online quickly. I recommend a manual changeover when the issues or problems are too much of a nuisance and an aggravation that it is better to disconnect the hybrid system and just use the existing GT inverters, until Sol-Ark support can fix it.

Sol-Ark 15K is a new design, so there are going to be growing pains and unexpected issues and problems not foreseen in the design.

I have over 3 years with the GT inverters and there has been no issues, no faults, no tripping or other problems. I have a normal electrical service and the only way that I know the GT inverters are working is because my electric bill is reduced by 90%. However, when there are numerous power outages, I would like a hybrid system to automatically let me have some electricity from the solar panels when there is sunshine. Once I have a hybrid inverter, then I would want to add batteries to have power when there is no sunshine. I'm also concern that there could be a natural or man-made event that could cause extended power outage for a long time and I would like to prepare for it, if possible.

 

[summit]

No, the manual switches for the solar panels are normally set to Sol-Ark 15K not the GT inverters.

that's clever, I missed that subtlety. So essentially the Sol-Ark will be the main inverter and the 3x Fronius GTs are unused. The Sol-Ark serves as the ATS, sitting between AC-grid and main box. The Sol-Ark, being the main inverter, would modulate the PV production to meet demand so there's no need for AC-coupling/load-dump etc....

So why do you need a contractor/electrician ? seems like a DIY do-able.

BTWay, what is the Sol-Ark idle consumption ? though probably less than the 3x Fronius

 

[Not Aerosmith]

that's clever, I missed that subtlety. So essentially the Sol-Ark will be the main inverter and the 3x Fronius GTs are unused. The Sol-Ark serves as the ATS, sitting between AC-grid and main box. The Sol-Ark, being the main inverter, would modulate the PV production to meet demand so there's no need for AC-coupling/load-dump etc....

So why do you need a contractor/electrician ? seems like a DIY do-able.

BTWay, what is the Sol-Ark idle consumption ? though probably less than the 3x Fronius

All (3) existing Fronius when not connected to the solar panels will be switched off at their 30A breaker. According to the Fronius Primo data sheet, the night time consumption is <1 watt, so 3 inverters is <3 watts.



Sol-Ark 15K idle consumption is 90 watts or 30 times more than Fronius

DIY Solar Forum is buzzing about a new GSL-H-12KLV-US all-in-one hybrid inverter for only $3200 versus Sol-Ark 15K for $8250. A couple of people have ordered one and the total cost with taxes and shipping is $3900. For the price of a Sol-Ark 15K, I could buy the GSL inverter with 10KWH 200A batteries. I have been waiting for them to receive their shipments and see their posts about their first impression before I order one. I have never ordered anything directly from China, so I need to learn from their experience.