EG4 18Kpv Rapid Shutdown - No clear instructions

Watts Happening

I call it like I see it.
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I’ve purchased and am waiting to receive my 18Kpv with great anticipation. That said, I’m struggling with parts of the manual that feel, “less than adequate”. If it’s my lack of understanding the product, I accept that.

In this case I’m referring to page 56 of the manual that covers rapid shutdown, which as most know is now required at the panel level of any building mounted install in the US.

After scratching my head, I reached out to @SignatureSolarJames and was told the Tigo system is the way to go. Which seems to mimic the fact that Signature Solar sells Tigo devices.

That said, the manual sure seems to suggest that the inverter has some form of rapid shutdown transmitter that will initiate a shutdown of the panels. How it does this, I have no idea. What device exists on the other end to initiate/cut off production, no clue? What type of switch, unknown? Does the remote switch override the local switch? Does it turn off both PV and AC power?

I’d love to get some clarification from members whom have actually installed this unit and received a permit, as well as Signature Solar as I think this is a rather important aspect of installations. Rapid shutoff at the inverter is one thing, and is useful, but we’re forced to comply with NEC and thus I hope to ensure everyone understands this topic in its entirety.
 

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That said, the manual sure seems to suggest that the inverter has some form of rapid shutdown transmitter that will initiate a shutdown of the panels. How it does this, I have no idea.
The rapid shutdown transmitter follows the SunSpec protocol. It constantly generates a 'keep alive' signal that transmits over the pv lines. If the receivers don't see this signal for some short period of time they will disconnect the PV. Notice that with this set-up, *anything* that opens the PV line will trigger the receivers to go into shutdown.

What device exists on the other end to initiate/cut off production,
Signature solar caries at least 3 different Rapid shutdown receivers:
* Single panel Reciever
* Single Panel Reciever with built-in optimizer
* Dual Panel Receiver. (This is probably the most cost-effective).

Any RSD receiver that follows the SunSpec protocol should work. (The manual has a picture of an APSmart receiver. They also follow the sunspec protocol)


What type of switch,
I believe that electrically the switch that is wired to the inverter can be just about any normally closed switch. However, there may be visual and ease-of-use requirements on it that require the big red button. (The normally closed requirement is a safety feature. If the wires to the switch get disconnected for some reason, the system shuts down)

Does it turn off both PV and AC power?
I am not 100% sure, but I think if the RSD switch on the inverter opens, the inverter will shut down the AC output.

Does the remote switch override the local switch?
It would probably not work to have 2 different transmitters, but as I said before, anything that opens the PV line (Like a PV Disconnect) will trigger the receivers to initiate a rapid shutdown. However, I doubt opening the PV line will shut off DC AC (Corrected after the initial post).
Note: Since the activation switch is separate from the inverter box, it can be placed a distance away from the inverter box. I do not know how far but I imagine it is pretty far.

I’d love to get some clarification from members whom have actually installed this unit and received a permit,
I have NOT installed an 18Kpv. However, I am familiar with this type of rapid shutdown system and I have studied the 18Kpv extensively.
 
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The rapid shutdown transmitter follows the SunSpec protocol. It constantly generates a 'keep alive' signal that transmits over the pv lines. If the receivers don't see this signal for some short period of time they will disconnect the PV. Notice that with this set-up, *anything* that opens the PV line will trigger the receivers to go into shutdown.


Signature solar caries at least 3 different Rapid shutdown receivers:
* Single panel Reciever
* Single Panel Reciever with built-in optimizer
* Dual Panel Receiver. (This is probably the most cost-effective).

Any RSD receiver that follows the SunSpec protocol should work. (The manual has a picture of an APSmart receiver. They also follow the sunspec protocol)



I believe that electrically the switch that is wired to the inverter can be just about any normally closed switch. However, there may be visual and ease-of-use requirements on it that require the big red button. (The normally closed requirement is a safety feature. If the wires to the switch get disconnected for some reason, the system shuts down)


I am not 100% sure, but I think if the RSD switch on the inverter opens, the inverter will shut down the AC output.


It would probably not work to have 2 different transmitters, but as I said before, anything that opens the PV line (Like a PV Disconnect) will trigger the receivers to initiate a rapid shutdown. However, I doubt opening the PV line will shut off DC.
Note: Since the activation switch is separate from the inverter box, it can be placed a distance away from the inverter box. I do not know how far but I imagine it is pretty far.


I have NOT installed an 18Kpv. However, I am familiar with this type of rapid shutdown system and I have studied the 18Kpv extensively.
Thanks for the detailed response, I have a handful of questions but we're about to hit the road so I'll have to get back on the rest.

As for the RSD transmitter, initially I thought the same thing. Clearly it states there is a transmitter, I had no idea it was SunSpec protocol (nor do I currently even know what that is, I'll research it shortly). That said, when speaking with James, he stated that I would need a transmitter and receivers, thus I was left with the impression that either the Tigo system wasn't compatible (maybe not SunSpec etc), or the transmitter isn't actually in use currently. Whether that's planned via firmware or whatever the situation may be.

I would certainly prefer the simplicity of tossing some Tigo RSD receivers on the panels and running a cat6 out to the service entrance for the RSD button. That sounds MUCH cleaner than an additional device that I have to figure out how to power down to shut the panels down etc.

His response attached.
 

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I suspect @SignatureSolarJames meant to say "No you just need the RSD Receivers". I am 99%+ sure the 18Kpv has the transmitter needed. (I was 100% sure till I saw your screenshot :)). I have been wrong before so hopefully, he can clarify.
 
There was a similar question:

 
The 18kPV does have the SunSpec transmitter within the unit, so utilizing the RSD or PV Disconnect will open the circuit and reduce the Tigo MLPEs voltage to safe levels. If you use the Tigo Optimizer line, you'd need the TAP/CCA to make use of all the features but the Fire Safety line is plug and play with the 18kPV. That should go for any MLPE that uses SunSpec, but I've verified the various Tigo units firsthand.
 
The 18kPV does have the SunSpec transmitter within the unit, so utilizing the RSD or PV Disconnect will open the circuit and reduce the Tigo MLPEs voltage to safe levels. If you use the Tigo Optimizer line, you'd need the TAP/CCA to make use of all the features but the Fire Safety line is plug and play with the 18kPV. That should go for any MLPE that uses SunSpec, but I've verified the various Tigo units firsthand.
Thanks for the response, I think that leaves me with two questions:

Are you saying that the optimizer line simply won’t work with the 18Kpv without the tap/CCA or that you’d need those to see their fancy online dashboard?

Secondly, can you verify the behavior of the remote RSD button? When wired in, would pressing the button initiate a shutdown of both solar AND AC power output from the inverter?
 
Are you saying that the optimizer line simply won’t work with the 18Kpv without the tap/CCA or that you’d need those to see their fancy online dashboard?
I believe they will work as optimizers out of the box, but the CCA/TAP are required for monitoring and RSD function. They may work off SunSpec protocol if they don't have the CCA/TAP but I couldn't find anything about it after a quick glance on the datasheet.
Secondly, can you verify the behavior of the remote RSD button? When wired in, would pressing the button initiate a shutdown of both solar AND AC power output from the inverter?
Yes, but the PV line to the inverter would still be energized without MLPEs that would initiate RSD. It cuts off the stay on signal though, so it should initiate total system RSD if the panels have the right equipment on them.
 
The 18kPV does have the SunSpec transmitter within the unit, so utilizing the RSD or PV Disconnect will open the circuit and reduce the Tigo MLPEs voltage to safe levels. If you use the Tigo Optimizer line, you'd need the TAP/CCA to make use of all the features but the Fire Safety line is plug and play with the 18kPV. That should go for any MLPE that uses SunSpec, but I've verified the various Tigo units firsthand.
Any hope of adding that into the manual? Maybe a comment that power-line communications are built-in but wireless communications such as the Tigo optimizers require TAP/CCA?
 
Any hope of adding that into the manual? Maybe a comment that power-line communications are built-in but wireless communications such as the Tigo optimizers require TAP/CCA?
I'd have to check about adding SunSpec verbiage in since it is implied but not explicitly stated outside of just saying "built-in RSD transmitter". I don't think the 18kPV's manual is the place to add comments on how the Tigo systems are supposed to be configured though, otherwise it could easily become an issue discussing how one product communicates but not all of the other solutions that exist.
 
I'd have to check about adding SunSpec verbiage in since it is implied but not explicitly stated outside of just saying "built-in RSD transmitter". I don't think the 18kPV's manual is the place to add comments on how the Tigo systems are supposed to be configured though, otherwise it could easily become an issue discussing how one product communicates but not all of the other solutions that exist.
Then leave off "Tigo" and focus on SunSpec powerline communications.
 
Then leave off "Tigo" and focus on SunSpec powerline communications.
I have to agree, I feel I’m a rather experienced solar individual and I’ve simply never heard of SunSpec, or any spec.

I do come from a mobile/RV background with Victron components but I sincerely think it would be beneficial to buyers.
 
I’ve purchased and am waiting to receive my 18Kpv with great anticipation. That said, I’m struggling with parts of the manual that feel, “less than adequate”. If it’s my lack of understanding the product, I accept that.

In this case I’m referring to page 56 of the manual that covers rapid shutdown, which as most know is now required at the panel level of any building mounted install in the US.

After scratching my head, I reached out to @SignatureSolarJames and was told the Tigo system is the way to go. Which seems to mimic the fact that Signature Solar sells Tigo devices.

That said, the manual sure seems to suggest that the inverter has some form of rapid shutdown transmitter that will initiate a shutdown of the panels. How it does this, I have no idea. What device exists on the other end to initiate/cut off production, no clue? What type of switch, unknown? Does the remote switch override the local switch? Does it turn off both PV and AC power?

I’d love to get some clarification from members whom have actually installed this unit and received a permit, as well as Signature Solar as I think this is a rather important aspect of installations. Rapid shutoff at the inverter is one thing, and is useful, but we’re forced to comply with NEC and thus I hope to ensure everyone understands this topic in its entirety.
I purchased Tigo devices and placed them on my panels. They work great with the EG4 18KPV. Also if you want to hook up a external rapid shutdown switch see my attachment
 

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I purchased Tigo devices and placed them on my panels. They work great with the EG4 18KPV. Also if you want to hook up a external rapid shutdown switch see my attachment
I used the same guide to install a rapid shutdown switch that was routed to the exterior of the home. It works flawlessly, same as pretty much everything else with the 18kpv so far. Which Tigo devices did you use?

I believe they will work as optimizers out of the box, but the CCA/TAP are required for monitoring and RSD function. They may work off SunSpec protocol if they don't have the CCA/TAP but I couldn't find anything about it after a quick glance on the datasheet.

I was trying to understand the CCA/TAP requirement for my own install and I ran across this in the Tigo TS4-A-O installation manual (Pg. 6):

TS4-A-O MLPE used to optimize performance only and not monitoring or module level shutdown do not require a TAP or CCA.

Not sure if this helps answer Watts question from earlier.
 
I have to agree, I feel I’m a rather experienced solar individual and I’ve simply never heard of SunSpec, or any spec.
It is probably fair to say that RV systems are not the same as rooftop mounted house systems, any experienced solar engineer will know about sunspec.
 
I have to agree, I feel I’m a rather experienced solar individual and I’ve simply never heard of SunSpec, or any spec.
Sunspec is an industry consortium that is working on standards for communications around ESS systems.
One of the standards that it has published is a standard for the signal between a base station and the PV Panel RSD receivers. I could be wrong, but I believe the standard is based on the protocol Tigo first developed. (The signal is a heartbeat signal that is continuously broadcast. If it ever stops, the receivers assume it is an RSD event and disconnects the PV.)

 
Sunspec is an industry consortium that is working on standards for communications around ESS systems.
One of the standards that it has published is a standard for the signal between a base station and the PV Panel RSD receivers. I could be wrong, but I believe the standard is based on the protocol Tigo first developed. (The signal is a heartbeat signal that is continuously broadcast. If it ever stops, the receivers assume it is an RSD event and disconnects the PV.)

That’s basically what I’ve learned. My experience has been heavily off grid focused, thus this never has been a concern
 
For others watching the thread. This is from the Sunspec website and describes the way the protocol works.

1691255679594.png

From my experience, this is a common way for the over-the-power-line rapid shutdown systems to work. It seems like the industry is lining up behind the Sunspec standard for basic RSD functionality.

However, there may be some divergence on more complex systems that provide more detailed module-level PV data. As an example, some Tigo optimizers can provide the RSD functionality as well as pass detailed performance data at the PV module level. This system uses a much more complex protocol between the Optimizers and the base station (The base station is called Cloud Connect Advanced or CCA). Consequently, the simple Sunspec RSD transmitter does not work. In order to initiate an RSD with this system the CCA must be either powered off or turned off. Note that the optimizers also assume that an absence of signal is an indication to do a Rapid Shutdown)
 
Another aspect of all of this is the 'Dark Start' problem during normal operation.

One common way to set up an RSD transmitter is to power the transmitter from the AC output of the inverter. That way, if the inverter does a rapid shutdown, the transmitter turns off and the receivers initiate an RSD sequence.

This works fine but it can create a bit of a catch-22 during normal operation, particularly in a grid-down or off-grid scenario.
  1. Overnight the batteries run down to a point that the inverter shuts down and the AC to turn-off. This causes the transmitter to shut down which causes the receivers to disconnect the panels.
  2. The next morning, the sun comes up but the system will not start charging because the receivers have the panels disconnected.
Once in the dark start conundrum, it is hard to get out of without manual intervention.

To avoid this, it is best to power the transmitter from the battery system. Typically, the inverter will shut down while there is still a small reserve of energy in the batteries. Consequently, if the transmitter is powered from the batteries the darkstart issue can be avoided in all but the most extreme cases. However, most (all?) of the transmitters take a 12 or 24V input and use a power wart to power from AC. That means a system that avoids dark start must also have a way to convert from the battery voltage to the needed voltage of the transmitter.
 
Another aspect of all of this is the 'Dark Start' problem during normal operation.

One common way to set up an RSD transmitter is to power the transmitter from the AC output of the inverter. That way, if the inverter does a rapid shutdown, the transmitter turns off and the receivers initiate an RSD sequence.

This works fine but it can create a bit of a catch-22 during normal operation, particularly in a grid-down or off-grid scenario.
  1. Overnight the batteries run down to a point that the inverter shuts down and the AC to turn-off. This causes the transmitter to shut down which causes the receivers to disconnect the panels.
  2. The next morning, the sun comes up but the system will not start charging because the receivers have the panels disconnected.
Once in the dark start conundrum, it is hard to get out of without manual intervention.

To avoid this, it is best to power the transmitter from the battery system. Typically, the inverter will shut down while there is still a small reserve of energy in the batteries. Consequently, if the transmitter is powered from the batteries the darkstart issue can be avoided in all but the most extreme cases. However, most (all?) of the transmitters take a 12 or 24V input and use a power wart to power from AC. That means a system that avoids dark start must also have a way to convert from the battery voltage to the needed voltage of the transmitter.
Good points, however I think powering the transmitter from a battery bank essentially defeats the entire purpose of the rapid shutdown. Initiating a rapid shutdown of the inverter wouldn’t turn the panel production off due to the transmitter still being powered via the battery bank.

Correct me if I’m wrong?
 
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