If an ATS separates an existing grid-tie inverters from a new off-grid system, can the same solar panels be used with both inverters?

[Not Aerosmith]

Unfortunately, my saga continues.

I thought that I could buy (1) Schneider XW Pro 6.8 KW inverter and add batteries later. I was wrong!!! The Schneider inverter won't even start without batteries, so you need to buy 10 KW batteries to be installed with the Schneider inverter. The Schneider 6.8 KW inverter can only send 6 KW of solar production to the grid. This doesn't work for me, since I have (3) 5 KW GT inverters. I need to buy (2) Schneider XW Pro 6.8 KW hybrid inverters and another 10 KW in batteries. If not, my solar production to the grid and savings are reduced significantly.

The approximate cost for (1) Schneider hybrid inverter system is about $3500 + $1200 + $650 + $350 + $575 = $6250 for Schneider components + miscellaneous parts + installation. You also need about $4000 in batteries since they are not something that can be added later. Over $10K for only one Schneider XW Pro + miscellaneous parts + installation. Now, I need (2) Schneider hybrid inverters and when you put them in parallel there are additional Schneider components needed.

It is really important to research and to do your due diligence before buying. Otherwise, you could fall into a bottomless money pit. In my case bought (1) Schneider system, but don't work without buying batteries. Lose production with higher electric bills, because (1) only provides 6 KW to the grid, therefore need to buy another Schneider system. I would probably still have glitches with (2) Schneider, until I buy even more batteries.

My life would had been miserable, because my wife would be complaining every moment, because the system isn't working right and I keep spending more and more money to try and make it work.

 

[Ampster]

To successfully AC couple you will need some batteries as I mentioned earlier. Yes those are the details that matter.

 

[Not Aerosmith]

I just listen to an over 40 minutes presentation by Schneider and learn some things that I didn't know. For one thing the MPPT works between 195 volts to 550 volts. Below or above those voltage, there is no solar production. When I estimated the cost of the MPPT, I needed to provide (2) 80 amps 600 volts not just one, because my existing 5 KW inverters have 2 strings and the Schneider MPPT are only one string each. I also needed to add a 100 amp disconnect for the 80 amp MPPT, which can be used to connect up to (2) MPPT.

I suspect that the cost of all the components needed to add solar panels and batteries to a Schneider 6.8 KW hybrid inverter is about the same as the cost for the all-in-one Sol-Ark Limitless 15 KW hybrid inverters with both costing about $8K. The big difference for me is to connect my production to the grid, I would need (2) Schneider hybrid inverter systems. In other words going with Schneider is going to be twice as expensive and probably more. My reasoning is that the labor cost to connect about dozen Schneider components should be more expensive than connecting one Sol-Ark hybrid inverter.

I also suspect that since all the Schneider components need to interface with the gateway to communicate, programming and controlling the Schneider components that I will probably need a total of (2) hybrid inverters and (6) MPPT and replace all three of the Fronius GT inverters. If not, I'm sure that Schneider is going to blame the one remaining 5 GT Fronius inverters for any system issues.

Another issue for me is that the Schneider system is Nema 1 rated and needs to be mounted inside not outside. I estimate over 6 feet of wall space for the Schneider components that I would need to replace Fronius plus all the required batteries. My current equipment is rated for outdoors and they are installed in a secured ventilated protected area shielded from rain and direct sunlight. Excellent for equipment rated to be mounted outdoor, but not acceptable for Nema 1 indoor equipment.

I'm very disappointed, because the first few videos made me very excited about using Schneider and I was sure that I finally had the best answer for my situation. Originally, it was a little more expensive than I wanted to spend, but I figured it was worth it. Now it over double and just not in my budget.

 

[Not Aerosmith]

That should work. It will respond to frequency Watt by going off line then come back if the load is increased. Only the newer 1741SA will modulate but that is another reason to put panels on the new hybrid. DC coupled panels on a hybrid respond faster and will modulate. That will be a good balance of functionality.

I noticed that the new Sol-Ark Limitless 15 KW listed their UL certifications, which included UL1741 and UL1741SB. I was curious why it didn't list UL1741SA, so I looked it up.

UL1741SB is a newer listing than UL1741SA, which many states have adopted and there are some states still only requiring the older listing UL1741SA. To avoid confusion, equipment certified to UL1741SB meets UL1741SA requirements. However equipment certified to UL1741SA do not meet the newer standard UL1741SB.

 

[Ampster]

Good info. That is SolArk is on top of changing standards. I don't know the difference but that is more important in the grid dependant inverter. It should not affect how your Fronius respond.

 

[Not Aerosmith]

Good info. That is SolArk is on top of changing standards. I don't know the difference but that is more important in the grid dependant inverter. It should not affect how your Fronius respond.

The Sol-Ark Limitless 15 KW inverter has (3) MPPT, which means that I have the option to connect all the existing 17 KW solar panels directly to the Sol-Ark and not use the existing (3) 5 KW Fronius Primo inverters. Each of the existing GT inverter have (2) strings, but I believe from Sol-Ark data sheet that each of the (3) MPPT also have (2) strings.

The are many advantages for doing this. One is that the existing Fronius Primo are UL1741 certified, but not UL1741SA and therefore the existing GT inverters are probably unable to modulate with the load or demand. The Sol-Ark can modulate with the load, so I can go battery-less for a few months, until I buy and connect batteries. There could be issues trying to AC couple the existing (3) GT inverters and having the Sol-Ark to control them. The 500 vdc wiring size and cost to connect solar panels to the Sol-Ark should be less than the 220 vac wiring size and cost for connecting the existing (3) GT inverters. If there is a problem or an issue, Sol-Ark is not able to blame the GT inverters. The warranty on the Fronius Primo is only 5 years with less than 2 years remaining versus the Sol-Ark with a new 10 year warranty. Without the GT inverters I would have a 10 year warranty on the inverter, batteries and more on the solar panels.

 

[Ampster]

The Sol-Ark can modulate with the load, so I can go battery-less for a few months, until I buy and connect batteries. There could be issues trying to AC couple the existing (3) GT inverters and having the Sol-Ark to control them.

I am not sure I understand what the SolArk would modulate if it had no batteries or solar?. Yes, without batteries there would be no buffer for it to handle AC coupling when grid is down. When grid is up the Fronius AC would just pass through to grid.

 

[summit]

I am not sure I understand what the SolArk would modulate if it had no batteries or solar?. Yes, without batteries there would be no buffer for it to handle AC coupling when grid is down. When grid is up the Fronius AC would just pass through to grid.

I think NotAero was refering to replacing the 3x Fronius with 1x Sol-Ark 15K, then not AC-coupling at all but just load-demand modulation during outage. Finally took a look at the Sol-Ark line, it sure feels like an all grown-up hybrid in comparison to the toy version from across the big ocean.

What is the difference between UL1741 and UL1741SA ? emailed Sol-Ark to ask if the ancient M215 Enphase micros can be AC-coupled and the response was a resounding "yes", citing UL1741 compliance

 

[Ampster]

I think NotAero was refering to replacing the 3x Fronius with 1x Sol-Ark 15K, then not AC-coupling at all but just load-demand modulation during outage. Finally took a look at the Sol-Ark line, it sure feels like an all grown-up hybrid in comparison to the toy version from across the big ocean.

I reread his post andniw realize that is the latest iteration. I lost track of which iteration we were on. Thanks for enlightening me. That is an option.

What is the difference between UL1741 and UL1741SA ? emailed Sol-Ark to ask if the ancient M215 Enphase micros can be AC-coupled and the response was a resounding "yes", citing UL1741 compliance

UL1741SA includes the ability to modulate, whereas plain UL1741 means the grid dependant inverter(s) can just turn off the come back on when frequency returns to normal. There may be a firmware update that would allow older M215s that are generic UL1741 to update to UL1741SA. Enphase might know.

 

[Not Aerosmith]

I am not sure I understand what the SolArk would modulate if it had no batteries or solar?. Yes, without batteries there would be no buffer for it to handle AC coupling when grid is down. When grid is up the Fronius AC would just pass through to grid.

The intent is to connect all the solar panels from the (3) GT inverters to the (3) MPPT on the Sol-Ark inverter, so the new 15 KW hybrid inverter can modulate the production to match the consumption during an outage. The (3) 5 KW GT inverters would be disconnected from the new system. I do want to add Pytes batteries in a few months, since these are listed by Sol-Ark to work with their inverters.

There are so many posts and YouTube videos about all the issues and grief caused by Schneider, Sol-Ark and the MPP Solar clones that it was really hard for me to have much faith in the new models of these brands. One reason is that I have a deep well and I do need a reliable inverter system that can operate the well and provide at least 8 hours/day of whole house power in the event of an emergency.

My original goals was to keep the (3) GT inverters and simply add a hybrid inverter to work with batteries when their is a power outage. At first, I thought that this was an easy inexpensive solution, but I was wrong. It was a very hard decision for me to abandon the (3) Fronius Primo that has performed flawlessly for the past 3 years and gamble on a new model from a brand with a history of problems. Logically, I should wait at least another year for the new models to prove themselves in actual performance.

My gut tells me that I should prepare now, while I still can. If I wait, it may be too late to prepare especially if there are shortages, inflation, bans, sanctions, depression, pandemic, disease, heat waves, fires, floods, storms, hurricanes, tornadoes, earthquakes, volcanoes, tidal waves, crisis, terrorism, shootings, riots, gangs, sabotage, conflicts, war, etc. It is common knowledge that all these things in the news only happen to other people, so I probably really don't need to worry or prepare for a disaster. In my case, I prefer to be prepared for an emergency, if possible.

 

[wattmatters]

The intent is to connect all the solar panels from the (3) GT inverters to the (3) MPPT on the Sol-Ark inverter, so the new 15 KW hybrid inverter can modulate the production to match the consumption during an outage.

I don't know much about the Sol-Ark's abilities but I think it's asking a lot for an inverter to do this at such a high power level without the safety net of a battery.

The Gen 24 Fronius inverters (you don't have those in the USA) provide an outage outlet which provides off-grid power in an outage without a battery but is restricted to ~3 kW. The inverter manages the production to meet demand. I though Enphase were introducing a similar capability but maybe that's still promiseware.

 

[summit]

One reason is that I have a deep well and I do need a reliable inverter system that can operate the well and provide at least 8 hours/day of whole house power in the event of an emergency.

You may want to rethink having a minimum critical load panel, the smaller watt demand can be much more manageable. It's not like your well pump would run continuously for 8 hrs. Being in Panama, I would imagine a need for AC. Mini-splits can easily operate from a critical load panel. How many watts are needed for the critical loads ? One set of the 5kw panels may be sufficient during the emergency, especially at your low latitude

 

[Not Aerosmith]

You may want to rethink having a minimum critical load panel, the smaller watt demand can be much more manageable. It's not like your well pump would run continuously for 8 hrs. Being in Panama, I would imagine a need for AC. Mini-splits can easily operate from a critical load panel. How many watts are needed for the critical loads ? One set of the 5kw panels may be sufficient during the emergency, especially at your low latitude

I appreciate your thoughts and advice. You are right, I moved to Santiago, Panama from Virginia, USA in 2005. When I moved here, Panama was listed in most retirement publications as being in the top 3 places to retire and often #1. The weather here is usually between 75F to 90F and rarely below 70F or above 95F. English is the country official second language and currency is the USA dollar. We don't have hurricanes here, since they occur at 10 degrees above the equator and we are at 7 degrees above the equator. I have steel shutters on every window and door, but so far I have not needed them for any weather event.

Well pumps don't normally run, but a few minutes at a time and about 15 minutes a day. I don't have central air conditioning or heating, but I do have 15 ductless splits throughout our home. However, we have ceiling fans in nearly every room and usually run them without needing to run the air conditioning. At night in my bedroom, I have an exhaust fan that pulls in the cooler night air and exhaust it back to the outside. My televisions and lights are all LED.

Normally, people have a central electrical panel and install a critical load panel next to it and move a few circuits. Unfortunately, this doesn't work that easy for me. I have (5) electrical panels with no panel within 40 feet of another panel, which is why I have been looking for a whole house solution versus a critical load panel solution. Sol-Ark intends to release a load management panel, which I'm hoping that I can use to connect all the individual panels. I do have Alexa, so I can check and see, if there are any air conditioning running or any unnecessary loads. I have written a routine that turns off all non-essential loads by a voice command.

 

[summit]

I don't know much about the Sol-Ark's abilities but I think it's asking a lot for an inverter to do this at such a high power level without the safety net of a battery.

The Sol-Ark 15 specs look quite good. While the rated 15kw PV system is indeed quite high power, the system is 3-yrs old now so probably closer to 12-13kw. It seeems the Sol-Ark should be able to handle it, since it is not AC-coupling but a direct DC>AC conversion; and the MPPT should be able to regulate on-demand load. It's too bad that it's so pricey, but guess you-get-what-you-pay-for

 

[Not Aerosmith]

I don't know much about the Sol-Ark's abilities but I think it's asking a lot for an inverter to do this at such a high power level without the safety net of a battery.

The Gen 24 Fronius inverters (you don't have those in the USA) provide an outage outlet which provides off-grid power in an outage without a battery but is restricted to ~3 kW. The inverter manages the production to meet demand. I though Enphase were introducing a similar capability but maybe that's still promiseware.

I don't disagree with anything that you said. I would feel more comfortable with a Gen 24 hybrid inverter and the existing (3) Fronius GT inverters assuming that it would work as needed. The Gen 24 is listed as a whole house solution and as you said they also have some point of use receptables on the hybrid inverter itself. Unfortunately, the Gen 24 is not yet an option for me, until it is available in split phase 120/240 volts.

However, every time that I have tried to do a whole solution with another manufacture like Schneider or some MCC Solar clone, it limits how much solar I can send back to the grid or it is not rated for >500 volts vdc. Obviously, if I reduce my feed to the grid, I increase my electrical bill. Work around solution is to add more hybrid inverters and more batteries, which very quickly get too expensive for me.

Sol-Ark is a beast rated to accept my existing panels with a 200 amp bypass that can easily send my 15 KW maximum production to the grid. During an outage, supposedly, it can modulate my production to match my consumption without batteries. Regardless, I agree that batteries are needed and I do intend to add at least 300 to 600 AH of batteries ASAP.

Again, I do appreciate your comments.

 

[Not Aerosmith]

The Sol-Ark 15 specs look quite good. While the rated 15kw PV system is indeed quite high power, the system is 3-yrs old now so probably closer to 12-13kw. It seeems the Sol-Ark should be able to handle it, since it is not AC-coupling but a direct DC>AC conversion; and the MPPT should be able to regulate on-demand load. It's too bad that it's so pricey, but guess you-get-what-you-pay-for

Since I have been on DIY Solar Forum now for 2 weeks, I have learned to avoid some very costly mistakes. It is so easy to fall victim to the hype and the advertisements convincing you that this is exactly what you need.

Originally, I had thought that there were some inexpensive solutions to add an hybrid inverter to interface with my existing GT inverters. Now I can see that those inexpensive solutions would have been very frustrating and actually more expensive. I could had easily double my electric bill due to the new system limiting my production to the grid. The new system would probably be constantly tripping, because one system is only 40 amps, so I need to add a second, third or more hybrid inverters with more and more batteries. I would had fallen into a money pit where the spending never ends.

Hopefully, increasing my budget and buying a better hybrid inverter should actually save me money and frustration. I was lucky with the (3) GT inverters and I hope to God that this hybrid inverter provides me the same excellent performance with no issues.

 

[summit]

how often and duration are the outages ? I'm in CA with ever increasing outage frequency, fortunately usually not for very long, yet. I've been making it through with a gerry rigged set up using my EVs as the main pack. So I am going with a cheapy MPP hybrid ($800) with an old repurposing 8kwh LIFE pack. It's totally in "off-grid" mode during outage. Is your well pump 240vac ? probably your mini-splits as well right ? I'm still bench testing the MPP, don't really like the high idle drain (~>100w) and no easy way to turn-off completely. I do like the Sol-Ark spec and will keep an eye on it. My roof has both micro-inverters and a Fronius string grid-tie, so am planning tap the Fronius' PV-DC to power the MPP & critical loads

 

[Not Aerosmith]

We have frequent outages averaging overall several times a week. Duration is on the average is usually less than 30 minutes several times a week and usually for a few hours several times a month. Long outages of about 6 hours a few times a year. So far, no outages for days in the last 17 years, since there has been no disasters or severe weather events in my area. Adding batteries, so I have power for 3 hours after my neighbors lose their power is not important to me and definitely not worth thousands of dollars.

My motivation is to prepare for a major power outages lasting for weeks or longer. I just want to insure that I have power for at least a few hours every day. The fact that this will probably solve the normal power outages is a plus that I would enjoy.

We have already discussed that we want our next car to be an EV. I just want to make sure that the EV is bidirectional and can provide power to the house during an outage. If my home PV system was down, we might be able to go somewhere and recharge the car batteries to provide power for the house. Of course, being able to charge the car from solar versus buying overprice gas is also a major plus.

Yes, the well pump and ductless systems are 240 volts, so their loads can't cause unbalanced power and trip the inverter.

If you have a critical load panel, it is my understanding that it is required to be isolated from the grid. If so, the inverter feeding it must run 24/7 or you lose your critical loads. Powering the hybrid inverter off is probably not going to be an option.

 

[summit]

My motivation is to prepare for a major power outages lasting for weeks or longer. I just want to insure that I have power for at least a few hours every day.

totally doable with PV charging your battery pack

We have already discussed that we want our next car to be an EV. I just want to make sure that the EV is bidirectional and can provide power to the house during an outage.

It's coming, but the wait is so slow. The upcoming Ford Lightning truck has a 7-9kw AC plug and the more affordablee Kia/Hyndai iOniq 5 has a 3kw 120vac outlet.

If my home PV system was down, we might be able to go somewhere and recharge the car batteries to provide power for the house.

we have done exactly that a few time. The 60kwh pack in the Chevy Bolt can run our critical loads for days

If you have a critical load panel, it is my understanding that it is required to be isolated from the grid. If so, the inverter feeding it must run 24/7 or you lose your critical loads. Powering the hybrid inverter off is probably not going to be an option.

the plan is to employ an external transfer switch to island the critical load panel.

 

[Not Aerosmith]

totally doable with PV charging your battery pack

It's coming, but the wait is so slow. The upcoming Ford Lightning truck has a 7-9kw AC plug and the more affordablee Kia/Hyndai iOniq 5 has a 3kw 120vac outlet.

we have done exactly that a few time. The 60kwh pack in the Chevy Bolt can run our critical loads for days

the plan is to employ an external transfer switch to island the critical load panel

Here is a link for a 50 amp 5500 watts external automatic transfer switch to island the critical load panel per your description using a 5 KW inverter or grid power: https://www.amazon.com/MOES-Controller-Automatic-Transfer-Switch/dp/B07F12RDZ2 It is available on Amazon for $119 with free shipping for primer members, it has 4.5 stars with 763 ratings and 354 answered questions. Of course, you are the only that can decide, if this ATS will works for you or not.

I really appreciate your feedback. By the way it is a beautiful day and I just loss power for no apparent reason, but the outage was only about 5 minutes.