Portable (NOT permanently affixed to anything) PV System

[Scott Tenhunen]

I have been digging and trying to find some information on weather the NEC (Not the Utility company) would have an issue with the following proposed PV system being used:

Here is the scenario, you are a tenant in an apartment complex on the top floor. With the permission of the building owner/landlord you are allowed to put in place a temporary PV system on the roof.
The system consists of the following:
4X 410W panels (1640W Total)
1 grid-tied micro inverter that is equipped with rapid shutdown (anti-islanding)
A racking system that is NOT attached to the roof of the building (is resting on it via rubber Durablocks)
Most importantly it is connected to the tenants power via a 240V 20A cord and plug connection in the attic

Assuming the cord is rated for UV exposure and everything on the roof is wet location rated.
The 240V 20A receptacle in the attic is dedicated and specifically installed for this purpose by the building owner/landlord. The breaker in the units panel is marked accordingly.

I see there are similar products like what I am describing but they all seem to connect at any normal 120V outlet which could cause the circuit to be overloaded without tripping the breaker. Like the one linked below that claims to produce 3000W at 120V. Connecting that to a standard 15A outlet would allow 40A of electricity to flow before the breaker tripped.

PluggedSolar 1500/1800/3000 Watts (1.5/1.8/3.0 KW) Solar Grid Tie Kit

Product Features: PluggedSolar 1.5/1.8/3.0 KW Solar Grid Tie Kit makes the sun power within the reach of every homeowner. It's patent (pending) technology makes solar installation very easy. Anyone can add solar panel and can simply plug the system into an existing electrical outlet...

pluggedsolar.com

The system I am imagining is connected to a dedicated, and properly labeled, breaker in the panel. I don't have my code book on me as I am on vacation at the moment but had this thought. I am sure the Utility company would have issue with this type of install which is why I am excluding them from this thread. Is there any code violation here? I am not well versed in the PV side unfortunately. With this being essentially an outdoor rated cord-and-plug connected piece of equipment does the NEC even govern it? What makes the linked 3000W system above OK to be used and not the system I described?

 

[david]

I have been digging and trying to find some information on weather the NEC (Not the Utility company) would have an issue with the following proposed PV system

The link you sent states all components are ul listed, but does not state what they assembled is ul tested and certified as an assembled product.

The first thing that comes to mind is this product is making a load side connection to the distrubution panel without any consideration to where the breaker for the branch circuit is installed in the panel.

I also do not beleave your design will be ul approved unless it is submitted to ul as a whole product

The link you submitted says to please make sure it's a 20 amp circuit, there is no way ul would give approved to such passive language.

I also beleave it violates the definition of a general purpose outlet.

The Nec would have to redefine the term to be a general purpose outlet/inlet.

To answer your question it violates the NEC to assemble a product with components that have been ul tested without having yhe product tested as a whole unit and claim it is ul tedted

 

[GoldDigger]

To be both plug connected and legal, a grid-tied system would at a minimum require a unique connector configuration connected to a dedicated branch circuit with no other outlets.
The specialized receptacle (with recessed female contacts) would almost certainly have to be installed by a licensed and competent electrician.

 

[jaggedben]

I don't believe products like the one you linked to are okay to be used. I regard them as a scam, mostly because their marketing essentially lies to people about the legality of connecting systems without permits and utility permission. I do agree that the product listing standards are where they should be weeded out; the NEC doesn't exactly prohibit them, but it requires products to be listed, and I don't regard plug-and-play grid-tied solar to be really safe. I haven't spent the time to find out if their claimed UL 1741 listings are just lies or if they take advantage of gaps and loopholes in the UL standard that ought to be closed.

To me the fact that the racking is ballasted is irrelevant BTW. Some commercial systems with hundreds of panels are ballasted. It's still an installation covered by the NEC. But that's probably just my opinion.

 

[Scott Tenhunen]

To answer your question it violates the NEC to assemble a product with components that have been ul tested without having yhe product tested as a whole unit and claim it is ul tedted

If someone created such a product and got it listed and it was plugged into a dedicated receptacle that was purpose installed for the application.

The first thing that comes to mind is this product is making a load side connection to the distrubution panel without any consideration to where the breaker for the branch circuit is installed in the panel.

That is why I stated it would be a dedicated 20A 240V receptacle in the attic specifically installed for this.

I don't believe products like the one you linked to are okay to be used. I regard them as a scam, mostly because their marketing essentially lies to people about the legality of connecting systems without permits and utility permission. I do agree that the product listing standards are where they should be weeded out; the NEC doesn't exactly prohibit them, but it requires products to be listed, and I don't regard plug-and-play grid-tied solar to be really safe. I haven't spent the time to find out if their claimed UL 1741 listings are just lies or if they take advantage of gaps and loopholes in the UL standard that ought to be closed.

To me the fact that the racking is ballasted is irrelevant BTW. Some commercial systems with hundreds of panels are ballasted. It's still an installation covered by the NEC. But that's probably just my opinion.

I don't regard these general cord and plug systems to be safe either but only because they allow you to plug into any generic receptacle. This is why I stated that it would use a dedicated 20A 240V receptacle in the attic. Most homes, and especially apartments, I have ever been in do not have a 20A 240V receptacle anywhere in them. Let alone one in the attic.

To be both plug connected and legal, a grid-tied system would at a minimum require a unique connector configuration connected to a dedicated branch circuit with no other outlets.
The specialized receptacle (with recessed female contacts) would almost certainly have to be installed by a licensed and competent electrician.

Unique as in a new standard type or a uncommon standard for residential like a twist-lock?

I also beleave it violates the definition of a general purpose outlet.

The Nec would have to redefine the term to be a general purpose outlet/inlet.

This would be in a dedicated, purpose-installed receptacle with the correct labeling in the panel.

 

[david]

I have been digging and trying to find some information on weather the NEC (Not the Utility company) would have an issue with the following proposed PV system being

BTW, I realize the link was posted to show that your idea was safer than the type being marketed already.

The concept would bto be similar to a generator connection, but think about the gen manufacturing need certified/testing by UL or some lother egal certification.

This isn't something you assembled in your garage to be used on your own property. Your wanting to use this for the public.

 

[david]

If someone created such a product and got it listed and it was plugged into a dedicated receptacle that was purpose installed for the application.

That is why I stated it would be a dedicated 20A 240V receptacle in the attic specifically installed for this.

I don't regard these general cord and plug systems to be safe either but only because they allow you to plug into any generic receptacle. This is why I stated that it would use a dedicated 20A 240V receptacle in the attic. Most homes, and especially apartments, I have ever been in do not have a 20A 240V receptacle anywhere in them. Let alone one in the attic.

Unique as in a new standard type or a uncommon standard for residential like a twist-lock?

This would be in a dedicated, purpose-installed receptacle with the correct labeling in the panel.

What would limit, how many of these or the ones in your link being installed.

I like the idea of the dedicated circuit, but what about breaker location.

There are things that need to be certified, and a product standard develope for manufactures installation instructions.

How far does the supply on your dedicated circuit pass through the building before there is any kind of overcurrent protection.

Is the receptacle going to be the only disconnect for your system.

Again the product could be developed to meet ul standards but ul needs to be involved.

What about arc fault protection and things like that

 

[winnie]

Take a look at this thread, especially post 25:

Plug-in PV backfeeding a receptacle? Is this legal?

I've recently been in a discussion with some policy people about plug-in solar panels. Apparently there are a few products out there that are "plug-and-cord" PV panels, with an integrated microinverter, and some of these are marketed to be simply plugged in to a regular 120V receptacle. This...

forums.mikeholt.com

IMHO the devil will be in the details, and a system such as being described might be workable. However every thing that makes the system more workable (just plug it in with minimal permitting!) will make it more expensive and less valuable to the customer.

In a previous thread someone stated that these are generally allowed in Europe with a max 500W rating. I couldn't see allowing more than this without requiring proper design of the interconnection.

Proper design of the interconnection might be folded into installation of the dedicated receptacle.

20A 240V receptacles used to be common for large window air conditioners. Just because you haven't seen them doesn't mean they are unheard of in homes.

I think a normal female receptacle would be fine as the 'power inlet' for this sort of system, because of the line interactive nature of the inverter. Voltage won't be present on the male pins if not initially supplied from the grid.

Just my tuppence.

Jonathan

 

[jaggedben]

I really don't see the dedicated receptacle as being all that consequential. And in fact I regard the description of the PV system as 'portable' to be somewhat disingenuous. We all know that it's going to sit in one spot indefinitely. It's not safe (mechanically, it will blow off the roof, or perhaps fall through it) if not professionally installed. You still have a grid-tied system with an output that invokes article 705. I just don't really see where you can draw a line (unless it's something like 500W, as Jon alluded to) within which the NEC and all the other codes that pertain to rooftop solar systems don't matter.

 

[PaulMmn]

I'd be more concerned about the fact that the panels are only placed on the roof, and not fastened down! One good wind storm...

 

[GoldDigger]

I'd be more concerned about the fact that the panels are only placed on the roof, and not fastened down! One good wind storm...

Heavier ballast.

PS: But either way, it should have mandatory engineering analysis!

 

[Elect117]

I also wonder what an insurance company would say.

If we limit it to tenet installs on a apartment complex/ multifamily residential, you can assume that the owner might be SOL on the damages it causes when they blow off the roof or if they damage any of the roofing itself.

If someone owns the home and damages the roof, then I am sure the insurance will do everything they can to not pay out.

And why install something that will save you a couple of dollars if it might impact your insurance, quality of the roof or put other things at risk.

Like it falling on someone.