How are you all addressing Rapid Shutdown?

Status
Not open for further replies.
B

bbartmasse r

Member
Location
Washington State
Hello,

I am just curious how other PV business's have been addressing the Rapid Shutdown requirement. We use Sunpower ACPV whenever possible and that takes care of it, but when that is not in the customers budget what do you do?

We have been installing more Solaredge for this reason. But it is funny because we used to only install Solaredge when it was a partially shaded site. Feels wasteful installing all those optimizers in full sun.

So what is the best option for a lower budget array with FULL sun? What have you all been using? I have used the SMA rapid shutdown box a few times but found it kind of a pain to work with. Anything else?

thanks for the input.
 
bbartmasse r said:
Hello,

I am just curious how other PV business's have been addressing the Rapid Shutdown requirement. We use Sunpower ACPV whenever possible and that takes care of it, but when that is not in the customers budget what do you do?

We have been installing more Solaredge for this reason. But it is funny because we used to only install Solaredge when it was a partially shaded site. Feels wasteful installing all those optimizers in full sun.

So what is the best option for a lower budget array with FULL sun? What have you all been using? I have used the SMA rapid shutdown box a few times but found it kind of a pain to work with. Anything else?

thanks for the input.
Click to expand...
I feel your pain. For the time being on commercial jobs we sometimes put the inverters on the roof with less than 10 feet of DC in conduit outside the array, but when the 2017 NEC starts being enforced we won't be able to do that anymore. We install a lot of SPR ACPV, a bit of SolarEdge, a few Enphase, and the occasional SMA RSD box (but as you say they are a pain).
 
About 90% of our systems get SolarEdge. We've had bad experiences in the past with Enphase products and we've heard rumors about the financial stability of Enphase from residential installers we're friendly with so we avoid using them.

There are a smattering of inverter specific rapid shutdown boxes on the market like Solectria and Fronius. SolarBOS has a rapid shutdown box that is inverter agnostic. Come 2019 I betting module manufactures will begin replacing the bypass diodes with the Maxim optimizers.
 
BandGap1.1eV said:
About 90% of our systems get SolarEdge. We've had bad experiences in the past with Enphase products and we've heard rumors about the financial stability of Enphase from residential installers we're friendly with so we avoid using them.
...
Click to expand...

Funny you say that, I have found Enphase to be somewhat more reliable than SolarEdge since the latter came on the scene. (They are both very reliable.) It's true that Enphase's 2nd generation inverter had issues but that is years in the past now.

I've heard rumors about the financial stability of every single solar manufacturer there is. Well, except those who do a lot of other things, e.g. several large Korean conglomerates.
 
BandGap1.1eV said:
Come 2019 I betting module manufactures will begin replacing the bypass diodes with the Maxim optimizers.
Click to expand...

Let's hope something like this is workable. Right now, the Maxim cell string optimizers don't send or receive data, as far as I am aware. So today's versions of the cell-string-level optimizers can't do squat to help you comply with rapid shutdown. Presumably that is part of their technology roadmap, but the people I've spoken to at Maxim always seem clueless about Code issues, including rapid shutdown.
 
We are starting to use solar modules with the Tigo j-box covers that have rapid shutdown built into the module. We also use Enphase, Solaredge, and the SMA and Solectria rapid shutdown combiners. I just specified some Solarbos rapid shutdown equipment on a commercial job, but we didn't get the job. Solectria makes a rapid shutdown unit for their commercial 480V TL inverters, and the tech video on it that I watched indicated that it would work with other manufacturers' inverters as long as the DC capacitors weren't too big. I know a lot of companies do it, but I don't like the idea of installing the inverter on the roof next to the array. I am thinking that the module manufacturers will all have rapid shutdown addressed with module level electronics in a few years.
 
Pass-through contactor boxes or getting the AHJ to sign off on keeping combiner boxes/string inverters within 1' of the array.

Come 2019 I don't see an alternative to MLPE.


Sent from my iPhone using Tapatalk
 
After 20+ years it will be interesting to see if these tightening RS measures will have had any effect on the safety and reliability of installed PV systems.
 
ggunn said:
After 20+ years it will be interesting to see if these tightening RS measures will have had any effect on the safety and reliability of installed PV systems.
Click to expand...

My gut says that arc-fault protection and advanced ground-fault detection provide the most meaningful benefits in terms of safety. Arc-fault detection is really a must have safety measure; rapid shutdown is nice to have.

All of these measures—arc-fault protection, highly sensitive ground-fault protection, and rapid shutdown—have a negative impact on reliability. Nuisance trips go up; potential points of failure go up. The real question is whether the promised O&M improvements—more granular detection and identification of field failures—offset these reliability impacts. In other words, is more data a good thing or a PITA.

Over time, I bet a lot of these safety features migrate to the product safety standards, which will simplify the Code.
 
SolarPro said:
My gut says that arc-fault protection and advanced ground-fault detection provide the most meaningful benefits in terms of safety. Arc-fault detection is really a must have safety measure; rapid shutdown is nice to have.

...
Click to expand...

But wouldn't you say that the first two are for preventing fires whereas the the latter is for keeping firefighters safe if a fire has already started (quite likely from an unrelated cause)?
 
jaggedben said:
But wouldn't you say that the first two are for preventing fires whereas the the latter is for keeping firefighters safe if a fire has already started (quite likely from an unrelated cause)?
Click to expand...

Yes, absolutely. I just don't think anyone wants to fight a fire within or in close proximity to the array, regardless of whether or not it has rapid shutdown functionality. And in many cases firefighters can see where conduits with dc circuits leave the array and route across or down a building. While rapid shutdown provides an additional layer of safety, it's probably not one that firefighters can count on being 100% effective. (Are things still deenergized after fire burns through the array?) So engagement strategies probably aren't THAT different with and without rapid shutdown when things really go sideways.

I'm glad I have rapid shutdown functionality at home, but mostly because the solution gives me module-level optimization and performance data. In terms of safety, it's really arc-fault and enhanced ground-fault protection that puts my mind most at ease. Since this is a new build, we also have arc-fault protection on roughly 70% of the branch circuits. That's a high level of protection. I worry a little bit about nuisance tripping (on the branch circuits), but the benefits probably outweigh the potential inconvenience.
 
Last edited:
SolarPro said:
While rapid shutdown provides an additional layer of safety, it's probably not one that firefighters can count on being 100% effective. (Are things still deenergized after fire burns through the array?) So engagement strategies probably aren't THAT different with and without rapid shutdown when things really go sideways.
Click to expand...

I chuckle every time someone mentions "Fire fighter safety" as the reason for driving the rapid shutdown conversation. No one ever seems to mention the safety of the installer or the O&M technician who is forced to crawl back onto a roof, partially disassemble and array, and replace a failed device, or the overall reliability of the system now that you've doubled the amount of devices and quadrupled the number of connections. Why is their safety a lesser priority than the fire fighters?
 
BandGap1.1eV said:
I chuckle every time someone mentions "Fire fighter safety" as the reason for driving the rapid shutdown conversation. No one ever seems to mention the safety of the installer or the O&M technician who is forced to crawl back onto a roof, partially disassemble and array, and replace a failed device, or the overall reliability of the system now that you've doubled the amount of devices and quadrupled the number of connections. Why is their safety a lesser priority than the fire fighters?
Click to expand...

Because installers & O&M workers aren't in a critical emergency situation when they do their work, like the firefighters are.
 
Carultch said:
Because installers & O&M workers aren't in a critical emergency situation when they do their work, like the firefighters are.
Click to expand...
And they can be expected to be familiar with the layout of the system and do any necessary fact finding before going into the array, while firefighters have at absolute most very general training on solar PV and its hazards.
 
Answering original question:

(All residential installs, no commercial)

Almost all Enphase now. Reluctantly.

Solaredge if system is over at least 4 kW...... AND I can mount inverter right next to Main Service Panel.
(because it has the rapid shutdown switch on inverter)

Sucks for SMA in resi. I just don't bother any more.

I've got a nice big pile of labels from PV LABELS, they seem to have the nicest ones.
Nice = big, explanatory and colorful.:p

I label the main service panel to notify people of the fact that there IS in fact RS,
whether it is just conduit or conduit + array (2014 vs 2017 NEC)
then a label on the main disco or other switch to indicate that is the rapid shutdown switch.

I don't know what this may foreshadow.... but I constantly mistype rapid shutdown as sh##down. :dunce:
 
Last edited by a moderator:
Status
Not open for further replies.
Top