EG4 FlexBoss + GridBoss + Tigo CCA

[downeycl]

I am about to install a new system with Flexboss + Gridboss. My AHJ requires a lockable RSD separate from the one on the Gridboss. I will also have a Tigo CCA with Tigo TS4 optimizers. The designer has created the below one line diagram, but I am not sure how to wire in the RSS and CCA. Any guidance is welcome!

 

[mciholas]

If your image had enough resolution to read it, you might get better help.

The NEC does not requires RSD to be lockable. The AHJ is exceeding their authority on that. Get them to show you the code that requires a lock.

Mike C.

 

[CaySol]

I am about to install a new system with Flexboss + Gridboss. My AHJ requires a lockable RSD separate from the one on the Gridboss. I will also have a Tigo CCA with Tigo TS4 optimizers. The designer has created the below one line diagram, but I am not sure how to wire in the RSS and CCA. Any guidance is welcome! View attachment 261910

Edit: not sure either.

 

[Quattrohead]

You just need one of those inexpensive RSD twist switches that has the little useless holes to put a tiny useless padlock in.
Amazon device

 

[downeycl]

Thank you all!

 

[kscessnadriver]

If your image had enough resolution to read it, you might get better help.

The NEC does not requires RSD to be lockable. The AHJ is exceeding their authority on that. Get them to show you the code that requires a lock.

Mike C.

NEC is minimum code to be enforced. They could have a local or state code in addition to the NEC...

 

[Quattrohead]

And of course your electric company can demand whatever the frig they want.

 

[mciholas]

NEC is minimum code to be enforced. They could have a local or state code in addition to the NEC...

Then that should be written down and approved by local ordnance or other official process.

You can't just have requirements they make up out of thin air.

I've had many authorities say something is a requirement and my most effective strategy to deal with that is simply to ask "where is that requirement written down?". You'd be surprised how often that leads to that requirement suddenly becoming not so required or the wording giving you more options once you know what it is.

I would be extremely surprised if the AHJ has a written policy that requires lockable RSD buttons.

Mike C.

 

[blackstart]

Edit: I have my equipment now, I can fix all my wrong posts.

The GridBOSS manual says to connect the mushroom button line this:

• SW->SW
• 12V-> Mushroom -> 12V

And this works correctly because the GridBoss just acts as a NC switch on its RSD port; it does not output any voltage. If someone rotates that rotary 'off' switch on the right side it just breaks the connection between the RSD terminals. This acts just like the external mushroom button and breaks the circuit.

Now Tigo has a good page on how to use their CCA's AUX port with the mushroom button; it's just a simple NO contact. I see you have that already drawn up and it looks good to me. We just need clarity on the EG4 side.

 

[blackstart]

Keep in mind breaking the RSD loop (and thus triggering an RSD) shuts down the backup outputs of the GridBoss by design. So your whole house goes dark.

If you just want to halt the PV to do some roof work safely, here's a hot tip: in the web-based monitor portal, go to 'maintenance' and look for RSD under "protection settings". Set it to Disable and then mash the mushroom button. Now only the Tigo will go into rapid shutdown.

 

[downeycl]

After studying the FlexBOSS user manual's RSD section, and then comparing it with the tips from their 18KPV manual:

https://eg4electronics.com/wp-content/uploads/2024/04/EG4%C2%AE-18kPV-Version-1-External-RSD-Initiator-Install-Instructions.pdf

I have come to the conclusion that EG4 just made a mistake in the GridBOSS manual. It really is as simple as breaking the 12V from the SW input to cause RSD. This implies we should connect the +12V output from either BOSS unit to a NC contact on the mushroom, then running *2* wires from the other NC contact to the 2 "SW" inputs.

Now, there are two ways to cause the CCA to go into RSD: (a) remove its 24V power, or (b) short the two AUX pins. If you want logging to continue working, use option (b). That's what I plan on doing with the NO contacts of the mushroom.

So yes, that means we'll need the NO and the NC contacts of a single mushroom button (good thing they generally provide both). The NC is used for the BOSS units, and the NO is used for the CCA's AUX pins.

BTW, the FlexBOSS has a 24V output on the RSD wire block that can used to keep power on the CCA at all times. I plan to use that rather than an external 24V wall wart.

This is so helpful! Thank you very much!

 

[BackyardBandit]

After studying the FlexBOSS user manual's RSD section, and then comparing it with the tips from their 18KPV manual:

https://eg4electronics.com/wp-content/uploads/2024/04/EG4%C2%AE-18kPV-Version-1-External-RSD-Initiator-Install-Instructions.pdf

I have come to the conclusion that EG4 just made a mistake in the GridBOSS manual. It really is as simple as breaking the 12V from the SW input to cause RSD. This implies we should connect the +12V output from either BOSS unit to a NC contact on the mushroom, then running *2* wires from the other NC contact to the 2 "SW" inputs.

Now, there are two ways to cause the CCA to go into RSD: (a) remove its 24V power, or (b) short the two AUX pins. If you want logging to continue working, use option (b). That's what I plan on doing with the NO contacts of the mushroom.

So yes, that means we'll need the NO and the NC contacts of a single mushroom button (good thing they generally provide both). The NC is used for the BOSS units, and the NO is used for the CCA's AUX pins.

BTW, the FlexBOSS has a 24V output on the RSD wire block that can used to keep power on the CCA at all times. I plan to use that rather than an external 24V wall wart.

Do you know which two pins (on the Gridboss) gives the 24VDC power for the CCA? And would that interfere with wiring in the external RSD switch?

 

[zgtd01]

I am about to install a new system with Flexboss + Gridboss. My AHJ requires a lockable RSD separate from the one on the Gridboss. I will also have a Tigo CCA with Tigo TS4 optimizers. The designer has created the below one line diagram, but I am not sure how to wire in the RSS and CCA. Any guidance is welcome! View attachment 261910

 

[zgtd01]

May I ask what you used for your 200 amp fused disconnect?
Thanks,
Gordy

 

[blackstart]

May I ask what you used for your 200 amp fused disconnect?

Those tend to be very large, so to save wall space I spec'd the 200A breaker recommended by EG4. It's the QOM2E2200NRB from Square D (only 8.7" wide).

My plans were approved so this saved a lot of wall space for me successfully.

 

[blackstart]

Do you know which two pins (on the Gridboss) gives the 24VDC power for the CCA? And would that interfere with wiring in the external RSD switch?

I don't see a 24VDC output in the GridBoss manual. I'm planning on using the 24VDC output of the FlexBoss as shown in its manual:

Using this voltage output will have no effect on the RSD switch or its wiring. This +24 just provides constant power to the CCA.

And yes I found it was still live during RSD, and the fans were spinning at full speed. My guess is they do that to try and discharge the internal capacitors as quickly as possible.

 

[zgtd01]

Those tend to be very large, so to save wall space I spec'd the 200A breaker recommended by EG4. It's the QOM2E2200NRB from Square D (only 8.7" wide).

My plans are still in review with the utility though so hopefully it flies.

Good luck, my poco requires visible break,

 

[kscessnadriver]

Good luck, my poco requires visible break,

Siemens GF224NR seems to be the standard fused option

 

[TacoMeat]

Post some pictures here once you get it setup! I'm in the same boat as you so looking for ideas

 

[lkdiaz]

This is as far as I've gotten with this system as well. FlexBoss21 + GridBoss + EG4 Indoor batteries + Tigo Optimizers with TAP and CCA. If anyone sees anything wrong with it please let me know.

 

[blackstart]

If anyone sees anything wrong with it please let me know. I believe the +12 and +24 outputs remain active even during RSD. The whole inverter doesn't shutdown when RSD is triggered; this prevents your house from going dark. Grid power continues to pass through, and basic monitoring features continue to function.

Edit: I now have all my equipment set up and have tried some experiments so I can answer better now.

I use the "AUX" port of the CCA to trigger RSD. Most mushroom buttons have a set of NO contacts as well as the NC contacts. Use the NO for the CCA's AUX port.

The FlexBoss is the opposite: it sends out 12v and wants to see it come back into the SW input to stay alive. It will shutdown if the circuit gets broken. So you wants the NC contacts for the flexboss.

 

[TacoMeat]

Talked with SS Tech support today and they said the External RSD +24 / Ground for CCA power. So it’ll be interesting to see what real world does when you get your gear.

 

[lkdiaz]

According to EG4 Tech Support, terminals Po and G provide 24V that are de-energized when RSD is activated. This would eliminate need for an NO contact to short AUX on CCA board.

I have revised drawing to reflect accordingly. In theory, if I was guided correctly this should be accurate.

Please post if you hear otherwise. Wouldn't surprise to have different techs provide different response.

 

[ejh]

I just talked with SS tech support and they told me External RSD +24 / Ground for CCA.

My installers are working it now and should finish Friday. I have the GridBoss, FlexBoss and two indoor wallmount EG4 batteries.

Seems to be conflicting word. Jess at Signature Solar, this might be something to get an official answer on.

 

[lkdiaz]

I just talked with SS tech support and they told me External RSD +24 / Ground for CCA.

My installers are working it now and should finish Friday. I have the GridBoss, FlexBoss and two indoor wallmount EG4 batteries.

Seems to be conflicting word. Jess at Signature Solar, this might be something to get an official answer on.

That's my exact setup that I'll be installing once equipment arrives.

My understanding is that, yes you can use the +24/Ground for CCA and it will power up the CCA as required without needing to use an external 24V power supply such as the one sold in the CCA Kit. However, it appears that this 24V source is constantly on as long as there is battery power. This requires another way to trip the CCA so that it shuts down the PV optimizers. As posted in previous threads, this could be done by shorting the AUX input in the CCA via a Normally Open (NO) contact in the emergency stop. Or, if I was told correctly by EG4, we can use the Po and G terminals which do shut down when the RSD is activated. So the sequence would be, activate emergency stop button. This will trigger the RSD in the FlexBOSS and the GridBOSS. Because the RSD in FlexBOSS was triggered, it will power down terminals Po and G which will turn off the CCA which in turn will power down the optimizers.