Rapid shut down options

[Bluedog225]

Is anyone aware of a comparison of the various rapid shut down systems?

I’m specifically interested in the ability to shut down a rooftop array as follows:

Manual Operation
External Power Loss
Temperature Rise Trigger
And automatic shut down upon detection of various fault conditions (see below and sorry about the quality). Esp. the pv array and cable fault sections.

I see Tigo, SMA, Fronius, Outback Fire Raptor.

Many seem to have hit and miss marketing and product descriptions. I get bogged down when I try and go through each product manual. But that may be what it’s going to take.

Being lazy, I thought I’d check with you guys.

Thanks

 

[chrisski]

To me, getting one that the AHJ will approve is most important. If the AHJ is not a factor or you want to go above the bare minimum, than it's what you want.

I have an Outback Radian installed by the contractor. I did not want to spend two years of my life knowing every detail of this system.

I do have the Outback Fire Raptor with the Emergency Shutdown switch, and it does remove DC power when the switch is pressed. What I don't like about the switch is it has a red LED that I'm wonder if I will get pranked one night and someone will press the switch by the bright red LED to shut the system down. The LED and 24 VDC is part of what the switch needs to qualify as a quick disconnect.

For the way the switch works, it has a wire that goes to each charge controller and once that switch is activated, that signals the MPPT to stop producing. This is like going into an app and hitting production off, like in a Victron MPPT. Shutting the MPPT down this way is different from flipping a circuit breaker or throwing a blade switch.

EDIT: panel level shutdown with a fire raptor described in post 4.

 

[Madcodger]

For the way the switch works, it has a wire that goes to each charge controller and once that switch is activated, that signals the MPPT to stop producing.

What I don't understand about a system like that is how it qualifies as panel-level RSD, which is what I thought was required. I get that the MPPT isn't allowing power production for the overall system, but what's to prevent individual or a string of panels from continuing to produce current that could be dangerous to people (e.g., firefighters) on the roof if, say, they complete the circuit prior to the MPPT device (i.e., short it with body or equipment)? Please note, I'm not criticizing - I just don't understand how this system accomplishes the core goal of RSD (firefighter protection) and am hoping someone can explain it.

 

[chrisski]

What I don't understand about a system like that is how it qualifies as panel-level RSD, which is what I thought was required. I get that the MPPT isn't allowing power production for the overall system, but what's to prevent individual or a string of panels from continuing to produce current that could be dangerous to people (e.g., firefighters) on the roof if, say, they complete the circuit prior to the MPPT device (i.e., short it with body or equipment)? Please note, I'm not criticizing - I just don't understand how this system accomplishes the core goal of RSD (firefighter protection) and am hoping someone can explain it.

I described the switch. Panels have a fire raptor which does the rest of what you’re saying. They shut off around 200 f. Fire raptors can be installed on each panel or one string. They cost about $75 each.

I am hoping that someone who installed this protection themselves replies. I do think that not many people install on a 32 panel system, 10 string system at the additional cost of multiple fire raptors, switch, and wiring.

 

[Madcodger]

I described the switch. Panels have a fire raptor which does the rest of what you’re saying. They shut off around 200 f. Fire raptors can be installed on each panel or one string. They cost about $75 each.

I am hoping that someone who installed this protection themselves replies. I do think that not many people install on a 32 panel system, 10 string system at the additional cost of multiple fire raptors, switch, and wiring.

Thanks. But what if the temperature is nowhere near 200F at the panels (which is very common situation)? Firefighters often need to access the roof to cut a vent hole. The fire itself is inside the structure, and the panels they need to cross or go around wouldn't be anywhere near 200F. So what protects them in that situation? I just don't see how anything other than panel-level RSD accomplishes the goal. It would be much simpler if it exists, but if so I haven't wrapped my head around it.

 

[Bluedog225]

There are no code requirements in my install. I want the maximum fire protection available. Assuming I remember every time I leave, I can shut the system down manually by hitting the rapid shut down button. Greatly minimizing the chances of roof fire. I’d bring the system online when I’m in residence to run air conditioning loads

But if I’d like to keep the system alive 24/7, I want the maximum arc fault protection and fire protection available.

I’m guessing that involves some kind of fancy computer algorithm monitoring the line for irregularities associated with fault and executing an operation to shut down the panel level devices.

 

[Hedges]

IMO FRS-01 FireRaptor Rapid Shutdown Unit

Shop now for IMO FRS-01 FireRaptor Rapid Shutdown Unit.

www.stellavolta.com

"
IMO FRS-01 FireRaptor Rapid Shutdown Unit

Features

• Manual Panel Shutdown to 0V Operated from Ground Level
• Automatic Panel Shutdown to 0V at >85°C (185°F) Temperature
• Automatic Panel Shutdown to 0V on External Power Loss
• Hardwire or Mobile Communication Alarm Signalling
• Compliant with NEC 2014 & NEC 2017
• Suitable for New Installations or Retro-Fit

The IMO FireRaptor shuts down DC supply at panel level to ZERO VOLTS in case of emergency.​

Shut-down is initiated in three ways:

• Manual Operation
• External Power Loss
• Temperature Rise Trigger

"

85 degrees C is an ambient temperature typically used for testing electronics.
Parts on a board are expected to function at that temperature, heated by surrounding components. Their internal power dissipation raises junction temperature higher.
Semiconductor junction temperature might have an absolute max limit of 125C, and we want operation lower. Power devices might be 150C or 175C.

It is something we would test cell phone, office equipment, etc. PC boards to in an environmental chamber.

Seems to me this Fire Raptor device might be built from electronic components not designed for higher temperatures, and it turns itself off to avoid overheating based on a temperature sensor on the board.

I don't think that feature has anything to do with fireman safety.

 

[chrisski]

I’m guessing that involves some kind of fancy computer algorithm monitoring the line for irregularities associated with fault and executing an operation to shut down the panel level devices.

My Outback FM100 Charge Controller meets the Arc Fault requirement. Inside the MPPT, a small circuit card does arc fault.

Thanks. But what if the temperature is nowhere near 200F at the panels (which is very common situation)? Firefighters often need to access the roof to cut a vent hole. The fire itself is inside the structure, and the panels they need to cross or go around wouldn't be anywhere near 200F. So what protects them in that situation? I just don't see how anything other than panel-level RSD accomplishes the goal. It would be much simpler if it exists, but if so I haven't wrapped my head around it.

I can’t speak much to this, but there is an additional fire raptor installed in my roof. It seems this does the temperature detection on the attic.

 

[Hedges]

I can’t speak much to this, but there is an additional fire raptor installed in my roof. It seems this does the temperature detection on the attic.

I think each individual MLPE has its own temperature sensor and shuts itself off if too hot.
But doesn't tell anyone else what it is up to, so they would remain on.

 

[chrisski]

Now that I look at the FRS diagram, each individual raptor is wired together separately, so appears one would shut them all down.

 

[Hedges]

Depending on how shutdown button communicates with each of them.
If current through a loop, all could respond to loss of current, also any one could interrupt current in the case of over-temperature.
If voltage, would need to be moderately high impedance (through a resistor) so any could crowbar it.

In the absence of any documentation saying that one Fire Raptor detecting over-temperature tells the others to shut down, I would assume it doesn't.
All can be shut down by loss of keep-alive signal. Each can shut itself down for over-temperature, likely just to protect its own electronics.

I suspect marketing just took an engineering designed reliability feature and touted it to attract customers who think it provides safety.

 

[chrisski]

This is a link on a webinar of Outback Rapid Shutdown.

Also, here is better diagram of how it works

So, appears there are the six connector for the panels which appear in the pic where each module shuts down and two additional wires that don’t seem pictured, but appear in block diagrams in any of the manuals would provide common panel shutoff on loss of common 24 VDC.

 

[chrisski]

I suspect marketing just took an engineering designed reliability feature and touted it to attract customers who think it provides safety.

Could very well be. I also find Outback documentation lacking in many places.

This missing wire is one of them, but you’re right, until verified independent or in documentation, should assume it does not provide that feature.

 

[robbob2112]

Pretty much all RSD work on a fail-safe model. Either a signal is imposed on the PV lines via a loop coil they pass through or they are separately wired.

If the signal is lost or if the wire is broken they turn off the voltage from each panel. Depends on the electronics but they all accomplish the same thing... a low enough resistance to drop the voltage below 30v.

For the ones wired separately they usually have a 24v supply then the switch, then wires in a loop. The wires in a loop open relays on the MLPE that shorts the power of the panel through a load resistor, not a dead short, but low enough load to draw down the voltage. Add a thermistor and you can have it do the same based on temperature.

The ones that also include optimizers work a little different but the result is the same.

Loss of signal or open wire via switch or fire and the panels are disabled.

There are two systems for tigo, one that uses the coils to impose the signal on the PV wires and one that uses the TAP which is wired to a unit sending a signal from cloud connect. The systems are NOT compatible with each other at all.

I think there are also a few wireless systems, but haven't really deep dived anything but the Tigo brand.

Summary of the wireless system was register when setting up, then when signal is lost they short the load through a dump resistor same as the others.

Pretty much they all work and any hype saying one is better than the other is marketing. The wired ones have a limit on how many can be controlled by one tap or psu

 

[Hedges]

Depends on the electronics but they all accomplish the same thing... a low enough resistance to drop the voltage below 30v.

I don't think it is a low parallel resistance to short out panel and drop voltage.
With 0.6V or 1.0V per RSD unit, for a 10A panel that would be 6W or 10W dissipated.

I think they have a FET to open or close connection from PV panel, let's just assume PV+.
And a bypass diode, so that FET never sees more than 80V or 90V of a single panel across it.
When keep-alive signal is received that tells it to turn gate of FET on.

I would guess it has either SMPS or simple pull-up resistor to a forward-biased diode to create 0.6V output of Tigo.
SMA wants 1.0V per panel so not as many needed for its 5.0V requirement to power keep-alive. Some RSD deliver more.

30V max would be achieved with no more than 30, 1.0V RSD or larger number of 0.6V RSD in series.

 

[Bluedog225]

I guess I could use a 12 hour manual (spring) timer to turn the system on in the morning and it would fail-safe activate the rapid shutdown if I don’t reset the timer each day.

My “not in residence” general air-conditioning and dehumidification needs could be met with a ground mounted array that presents lower fire danger to the building.

 

[wpns]

What system components do you have already?

For instance the EG4 ESS can (from one NC pushbutton) disable the RSD signal to the (Tigo or other standard RSD) which shuts all the panels down (0.6V each), disables the inverters, trips the battery breakers, and shuts down the BMSes.

The 18Kpv (and, I’m sure other) inverters have GF and AF detection, and can do the same. You can hook in your own fire/smoke/heat detectors or other sensors.

Not sure I’d use the above to power off a system I was leaving for the weekend, as it’s a pain to re-enable, but all the pieces are there.

 

[Bluedog225]

I’ve got an existing Victron system with batteries and inverter out in a power shed. The system I’m contemplating will be separate. Roof mounted with an inverter inside the cabin.

 

[HarryN]

I am also looking at the fire raptor setup for similar reasons - panel level shut down to meet what appears to be the constantly changing code here.

It looks fairly easy to implement.

My understanding is that the temperature shut down spec has to do with the idea that if the roof is hot / fire is detected, it will turn off, even if the fire department has not arrived yet and flipped the switch.

Some information has been collected in this thread:

E

Thread 'IMO dc disconnect isolator switch sold by Signature Solar'

May 17, 2023

Hi
Looking at the wiring diagram it appears that this device can function as a combiner box. I want to wire 2 pv arrays into it.
Is my assumption right?
thanks
eddie

• ELT
• Replies: 7
• Forum: Wire/Connectors/Junction Boxes

 

[Nick34]

Do you install one fireraptor RSD on 2 panels? I have 415 W panels

I have a Fronius Symo 15kw 208V 3 phase inverter

 

[Capt Bill]

I described the switch. Panels have a fire raptor which does the rest of what you’re saying. They shut off around 200 f. Fire raptors can be installed on each panel or one string. They cost about $75 each.

I am hoping that someone who installed this protection themselves replies. I do think that not many people install on a 32 panel system, 10 string system at the additional cost of multiple fire raptors, switch, and wiring.

I will be studying to learn more about "fire raptors" that are maybe temp activated ??? to shut down PV or PV strings. ... Any web links for further study of such options?

 

[chrisski]

I will be studying to learn more about "fire raptors" that are maybe temp activated ??? to shut down PV or PV strings. ... Any web links for further study of such options?

Post #7 by @ hedges contains links to the data sheet and installation guide which is about all I know.