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Old 23-06-2022, 09:27   #136
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Four questions about solar

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Originally Posted by Adelie View Post
Yeah, and NEC Section 110.9



I also found: BS EN7671 Sec 712

https://s3.amazonaws.com/ecodirect_d...Protection.pdf



https://iaeimagazine.org/columns/pho...how-and-where/



Hereís a really good discussion: https://www.eaton.com/content/dam/ea...ar-systems.pdf



While the NEC and other codes are aimed at shoreside installation, they are probably good practice afloat too.


No they are not. They are designed for specific use cases and boats arenít one of them. Both standards mentioned are for houses/land based installations typically very high voltage and large numbers of big panels. Itís a huge error to mis apply standards.
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Old 23-06-2022, 09:28   #137
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Re: Four questions about solar

I'll jump in to say that parallel connected modules, when there are three or more of them, may benefit from some module-side OCP. That is a design decision around a faulted module sucking power out of good ones. Since modules are current-limited sources, any OCP you put in two modules in this scenario will never trip, because it has to be able to handle the maximum current the unfaulted panel can produce during normal operation, and that is the same current that could flow to a faulted module. When you get to three or more modules in parallel then you can start to have a conversation about whether OCP is beneficial at each module - in which case two (or more) modules feeding into a faulted module would trip the OCP on the faulted module (they would not trip their own OCP because they are still singly only running at or below their current limit).

Codes are wonderful, but these kind of questions really take an actual design and a specific case to answer properly. One or two modules, generally no OCP even useful, much less needed. Modules with each to its own controller, no OCP useful or needed. Three or more modules in parallel, design consideration.

Now, if you want a disconnecting means on the module side, and it happens to provide OCP
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Old 23-06-2022, 10:29   #138
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Re: Four questions about solar

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Originally Posted by Adelie View Post
So you think itís in Standard 3000 but donít know where?
Have you read 3000 yourself?
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Originally Posted by Baronkrak View Post
You should find normally at the start of the document under Scope a mention about ensuring safety from fire and shock.
Sorry no cut and paste the document is Copyright
Yes I read it just to write the above post.
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Old 23-06-2022, 10:54   #139
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Re: Four questions about solar

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Yes I read it just to write the above post.
The "Fair Use" doctrine allows for the copying of a "limited portion" of a copyrighted document. (at least in the USA). Why don't you show us enough of the Standard text to demonstrate your point?
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Old 23-06-2022, 13:52   #140
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Re: Four questions about solar

Parallel protection fuses in a parallel panel situation are rated above any current a single panel can produce and these fuses are fitted to each panel not the panel feed to the controller. They are there not to protect the panels per se , but to protect the wiring. A full panel short is not at all common.
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Old 23-06-2022, 15:15   #141
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Re: Four questions about solar

A couple of final comments on this thread, after which I will not be responding to a certain poster.


Making statements of facts you incorrectly believed to be true is excusable.

Constantly repeating these assertions without providing any actual supporting evidence for your beliefs when they have clearly been shown to be false is not acceptable



Deliberate falsehoods are also not acceptable.
Some recent posts clearly appear to be in this category.
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Old 23-06-2022, 15:46   #142
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Re: Four questions about solar

Well, if we want to reference AS/NZ 3000:2018 and 5033:2021...

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What considerations need apply to the unprotected PV array consumers mains(dc array cable)?
The PV (DC) array cable between the arrays and inverter are deemed to be electrically unprotected consumers mains. Unprotected consumers mains would normally be installed fully enclosed in heavy duty conduit. As a PV array is a current limited generator the Australian Standards EL 042 committee ruled that the DC cable can be installed with mechanical protection,this can be achieved by the cable location or additional protection by installation within a wiring enclosure.
Consumers mains not provided with short-circuit protection on the supply side, shall—
a)be constructed in such a manner as to reduce the risk of short-circuit to a minimum; and
b)be installed in accordance with the relevant additional requirements of the electricity distributor. The following wiring systems are deemed to reduce the risk of short-circuits to a minimum:
i. Insulated and sheathed cables enclosed in heavy-duty insulating conduit to AS/NZS 2053.
ii. Insulated and sheathed cables installed in underground wiring enclosures.
Reference –AS/NZS 3000:2007 Clause 3.9.7.1.2
Quote:
If there are a number of PV array strings, which could result in a potential fault current in any one string greater than the reverse current of an individual module, is appropriate string protection provided? (e.g. protected with fuses or nonpolarised circuit breakers)
Reference - AS/NZS 5033 Cl 3.3.4 and 3.3.5
AS 3000 and its companion standards clearly do not require OCP on the DC side of an array. Similarly to other standards there are conditions, the overall gist of which is that paralleling 3 or more modules/strings may require the installation of OCP at the module/string level.

Furthermore, the limit for Extra Low Voltage within these standards is 50V AC or 120V DC (ripple free), below the Extra Low Voltage limit even fewer sections of the code apply.
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Old 24-06-2022, 00:20   #143
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Re: Four questions about solar

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AS 3000 and its companion standards clearly do not require OCP on the DC side of an array. Similarly to other standards there are conditions, the overall gist of which is that paralleling 3 or more modules/strings may require the installation of OCP at the module/string level.
The take home message for our marine systems from this non marine standard is that if you have three panels in parallel you need to do some calculations to determine if circuit protection (fuses or circuit breakers) are needed on the panel side of the controller in addition to the circuit protection that is always required on the battery side of the controller.

The calculations are explained in simple language here:

https://www.cedgreentech.com/article...-when-not-fuse


If you have trouble understanding these calculations and have three panels in parallel you should fit circuit protection.

The same applies with four or more panels, but in this case circuit protection on the panel side of the controller is almost always needed so the calculations are superfluous.

Sorry to labour this point, but there is a widespread, wrong and dangerous belief among sailboat owners that fusing on the panel side of the controller is always unnecessary.

Note the circuit protection on the panel side of the controller requires protection for each solar panel.
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Old 26-06-2022, 01:45   #144
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Re: Four questions about solar

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Originally Posted by StuM View Post
Ö
The current would have been the rated Isc ("short circuit current)
It doesn't cause any problems because there is no voltage across the terminals.
Ö
Of course, the terminals are short-circuited. It does not mean there is no voltage in the circuit.
A current cannot be created without voltage.
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