working space soleredge inverters

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Dustinecs

New member
Location
Gainesville Fl.
Our sole edge inverter is not readily accessible so we installed readily accessible ac and dc disconnects all within eyesight, less then 50', and properly labeled. Would we still need the 3' of working space in front of the inverter for maintenance, I believe the system would not be energized with disconnect cover off.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Our sole edge inverter is not readily accessible so we installed readily accessible ac and dc disconnects all within eyesight, less then 50', and properly labeled. Would we still need the 3' of working space in front of the inverter for maintenance, I believe the system would not be energized with disconnect cover off.
I'm pretty sure that the working space requirement holds irrespective of the system connectivity.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I'm pretty sure that the working space requirement holds irrespective of the system connectivity.

On the other hand, any troubleshooting or servicing done on a microinverter (other than measuring input voltage and current) is going to be done with the unit removed from the array and sitting on a shop bench where the work space is less limited.
Otherwise you could argue that the NEC prohibits mounting the micro on the back of a panel.
 

Carultch

Senior Member
Location
Massachusetts
Our sole edge inverter is not readily accessible so we installed readily accessible ac and dc disconnects all within eyesight, less then 50', and properly labeled. Would we still need the 3' of working space in front of the inverter for maintenance, I believe the system would not be energized with disconnect cover off.

Work space specifically discusses equipment that is likely to be serviced while energized. Conservatively, it is best to apply it to all equipment.

On the DC side, you might have up to 30 Volts DC, in the event that you shut off the system and allow the optimizers to generate their open circuit output voltage. There is a part of 110.26, which talks about where special permission is granted, low voltage equipment can have less workspace. Special permission means that you receive it in writing from the inspector/AHJ. And it is unrealistic to rely upon the inspector knowingly allowing you to have less than 36" in an application such as this.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Our sole edge inverter is not readily accessible so we installed readily accessible ac and dc disconnects all within eyesight, less then 50', and properly labeled. Would we still need the 3' of working space in front of the inverter for maintenance, I believe the system would not be energized with disconnect cover off.

The Solaredge disconnect does not shut down AC power to the inverter, so it could well be energized. Also, depending on how long it's been shut down and whether Rapid Shutdown has been installed, the DC voltage may also still be high. I sort of get that it seems like overkill, but I can't imagine how I would change an inspector's mind on this.

On the other hand, any troubleshooting or servicing done on a microinverter (other than measuring input voltage and current) is going to be done with the unit removed from the array and sitting on a shop bench where the work space is less limited.
Otherwise you could argue that the NEC prohibits mounting the micro on the back of a panel.

I'd argue that a microinverter doesn't fit under "likely to require examination, adjustment, servicing, or maintenance while energized." A key difference is no openings or serviceable parts. "Examination" is maybe the most borderline, I guess, but what's to examine? Also, you'd kinda be violating 110.3(B) if you didn't install the microinverter on the racking.
 

Carultch

Senior Member
Location
Massachusetts
Also, depending on how long it's been shut down and whether Rapid Shutdown has been installed, the DC voltage may also still be high. I sort of get that it seems like overkill, but I can't imagine how I would change an inspector's mind on this.

To me, SolarEdge's "Rapid Shutdown kit" seems to be a solution to a non-problem. In otherwords, money you spend to solve a problem the NEC doesn't require you to solve.

The rapid shutdown requirement doesn't require you to de-energize circuits within a piece of manufactured equipment. It's main intent is to require you to de-energize field-installed circuits.

And even without this rapid shutdown kit, if you open the DC disconnect, you already disconnect the field-installed circuits from the capacitors in the inverter. The optimizers then default to 1 volt per unit, and the circuit is brought down to safe levels of DC voltage meeting the NEC.

In the event that you have numerous inverters, the only way to initiate rapid shutdown within the time limit is to turn the DC disconnect off on each one of them. Given much more then ten inverters, this obviously cannot happen within ten seconds. What really would be useful, is to have a single action initiation of rapid shutdown. A master AC disconnect almost does this, except that it doesn't guarantee meeting the ten second time limit.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
To me, SolarEdge's "Rapid Shutdown kit" seems to be a solution to a non-problem. In otherwords, money you spend to solve a problem the NEC doesn't require you to solve.

The rapid shutdown requirement doesn't require you to de-energize circuits within a piece of manufactured equipment. It's main intent is to require you to de-energize field-installed circuits.

And even without this rapid shutdown kit, if you open the DC disconnect, you already disconnect the field-installed circuits from the capacitors in the inverter. The optimizers then default to 1 volt per unit, and the circuit is brought down to safe levels of DC voltage meeting the NEC.

In the event that you have numerous inverters, the only way to initiate rapid shutdown within the time limit is to turn the DC disconnect off on each one of them. Given much more then ten inverters, this obviously cannot happen within ten seconds. What really would be useful, is to have a single action initiation of rapid shutdown. A master AC disconnect almost does this, except that it doesn't guarantee meeting the ten second time limit.
Solar Edge's rapid shutdown kit is merely a set of high resistance jumpers between the DC positive and negative conductors which bleed off the capacitors in the inverter upon shutdown so that the DC voltage falls quickly enough to satisfy the requirements in the NEC. Newer Solar Edge inverters don't need it because these resistors are now incorporated into the inverter design. One kit retrofits three or four inverters.
 

SolarPro

Senior Member
Location
Austin, TX
To me, SolarEdge's "Rapid Shutdown kit" seems to be a solution to a non-problem. In otherwords, money you spend to solve a problem the NEC doesn't require you to solve.

The rapid shutdown requirement doesn't require you to de-energize circuits within a piece of manufactured equipment. It's main intent is to require you to de-energize field-installed circuits.

And even without this rapid shutdown kit, if you open the DC disconnect, you already disconnect the field-installed circuits from the capacitors in the inverter. The optimizers then default to 1 volt per unit, and the circuit is brought down to safe levels of DC voltage meeting the NEC.

In the event that you have numerous inverters, the only way to initiate rapid shutdown within the time limit is to turn the DC disconnect off on each one of them. Given much more then ten inverters, this obviously cannot happen within ten seconds. What really would be useful, is to have a single action initiation of rapid shutdown. A master AC disconnect almost does this, except that it doesn't guarantee meeting the ten second time limit.

You might want to read Bill Brook's article on Rapid Shutdown for PV Systems. The SolarEdge retrofit kit solves a real problem. Namely, an inverter's capacitor bank can energize field-installed circuits.

Many PV systems are still dangerous even after you open a rooftop disconnect because there are typically power sources on both sides of the switch. On the one hand, the PV power source energizes the conductors on the PV array side of the switch during daylight hours, typically at voltages greater than 300 Vdc and up to 1,000 Vdc in nonresidential applications. On the other hand, the PV output side of the switch is often connected to the dc input bus of an inverter, which is another potential source of power. This side of the switch remains energized as long as PV output circuits are connected in parallel at a subarray or inverter-input combiner. For example, in a scenario where 15 dc disconnects are installed on a commercial rooftop—one at the location of each source-circuit combiner box—if an emergency response team leaves only one of these 15 in the on position, that could leave all array wiring fully energized and potentially lethal. Even where there are no parallel-connected PV power circuits, large dc input capacitors at the inverter may keep this side of the switch energized long after responders open the rooftop disconnect. [emphasis added]

As ggunn notes newer SolarEdge inverters will have this feature pre-integrated. I suspect this will be true of all inverters before too long.
 
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ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I didn't know that. How do you tell if an inverter has the feature built in?
By the serial number and an inquiry to Solar Edge would be my guess. I went to a Solar Edge installation class a couple of weeks ago and the instructor told us that all Solar Edge inverters being shipped now incorporate the resistors but there is still new old stock without them out there. The resistors may or may not be visually verifiable when you open the interconnection compartment.
 

SolarPro

Senior Member
Location
Austin, TX
The retrofit kit isn't intended for inverters that accomplish this as shipped from the factory. (Redundant capacitor bleed down circuits would be a solution in search of a problem.)
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
By the serial number and an inquiry to Solar Edge would be my guess. I went to a Solar Edge installation class a couple of weeks ago and the instructor told us that all Solar Edge inverters being shipped now incorporate the resistors but there is still new old stock without them out there. The resistors may or may not be visually verifiable when you open the interconnection compartment.

Thanks.

Even if the capacitor bank is disconnected from the field-installed circuits, as it is in this example?

My understanding was that the optimizers, not the inverter, are what take a few minutes to bleed down without the rapid shutdown kit.
 

SolarPro

Senior Member
Location
Austin, TX
That's interesting. I haven't been to a SolarEdge training since the NABCEP conference in 2014. They officially launched their 690.12 solution a couple weeks later. So the training I sat in on was more conceptual than concrete.

Thinking through a rapid shutdown scenario: Vendors like SolarEdge don't want to rely on opening the inverter-integrated dc disconnect as the initiation device, because that isn't scalable for systems with multiple inverters. So they need to develop a solution that is initiated by loss of ac power. If rapid shutdown is initiated upon loss of ac power, the inverter-integrated disconnect remains closed after rapid shutdown is initiated. In some cases like this, you need a capacitor bleed down circuit in order to meet 690.12.

In the case of the SolarEdge system, I suppose this resistor could bleed down voltage from either the capacitors or the optimizers. And it may be that the optimizers are the sticky wicket. After all, some transformerless string inverters can meet the 30-volt and 10-second limits in 690.12 without any other mitigation, provided you can isolate the PV array on the roof.

In any case, we know that the SolarEdge could not comply w/ 690.12 without adding this resistor. Going forward, system will have this capability as a default. And you can retrofit old system to comply with 690.12 if desirable.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
In the case of the SolarEdge system, I suppose this resistor could bleed down voltage from either the capacitors or the optimizers. And it may be that the optimizers are the sticky wicket.

All I know is that the resistors are installed on the array side of the integrated disconnect. Also there are instructions in the manuals that say (IIRC) to wait three minutes before working on the DC wiring after you turn off the switch. If the danger is on the inverter side then that shouldn't be the case.

I suppose the location of the resistor means that you could tell if the inverter comes with it installed just by looking for it in the disconnect enclosure.
 

Carultch

Senior Member
Location
Massachusetts
I suppose the location of the resistor means that you could tell if the inverter comes with it installed just by looking for it in the disconnect enclosure.

I think it is more important to know these kind of things BEFORE you specify or order products, rather than needing to wait for material to arrive on a site (that you might not even visit until it is too late).
There really ought to be an updated part number, as products begin to come standard with new features, that previously had to be ordered separately.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I think it is more important to know these kind of things BEFORE you specify or order products, rather than needing to wait for material to arrive on a site (that you might not even visit until it is too late).
There really ought to be an updated part number, as products begin to come standard with new features, that previously had to be ordered separately.
FWIW, Solar Edge recommends that you just buy a couple of kits to have on hand should you encounter an inverter without the resistors if you are somewhere that is enforcing rapid shutdown. Apparently the kits are cheap and will retrofit 3 or 4 inverters.

Don't shoot the messenger. :D
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
FWIW, Solar Edge recommends that you just buy a couple of kits to have on hand should you encounter an inverter without the resistors if you are somewhere that is enforcing rapid shutdown. Apparently the kits are cheap and will retrofit 3 or 4 inverters.

Don't shoot the messenger. :D

Actually I find this annoying. We bought a kit, only had to use one set of jumpers with resistor so far, and now have a hundred dollars worth of other jumpers we don't need. And a bit of wire and a resistor should not cost that much.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Actually I find this annoying. We bought a kit, only had to use one set of jumpers with resistor so far, and now have a hundred dollars worth of other jumpers we don't need. And a bit of wire and a resistor should not cost that much.
Ebay?
 
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