SPD 2P DC Lightning Surge Protector Protective Low-voltage Arrester Device Solar 500/800/1000VDC?

Fabian

I want to purchase a SPD 2P DC Lightning Surge Protector Protective Low-voltage Arrester Device for my solar system but i am unsure as to which one to pick.

I have (2) solar system. One system is using a mppt charge controller that can handle a max input of 500vdc running a 48v system and i am currently sending little bit over 200volts dc to its input from the panels and the other system is using a mppt that can handle max input of 150volt dc to it running a 24v system and i am currently sending around 70volts to it and in the future i might increase the input going to it to about 100 plus if i upgrade it to 48v.

If i am to buy a SPD 2P DC Lightning Surge Protector Protective Low-voltage Arrester Device for each solar system which size should i buy for each. They have them in DC 500/800/1000 Volts as u can see in the link below:

https://www.aliexpress.com/item/4000144841221.html?spm=a2g0o.detail.1000060.1.4cfb6e5frnXx9X&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=44294d85-6120-4174-a0c9-b98e2732f863&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:44294d85-6120-4174-a0c9-b98e2732f863,tpp_buckets:668#2846#8113#1998&&pdp_ext_f={"sceneId":"3339","sku_id":"10000000440037615"}

I am thinking a 500VDC one would be ok for each of the system that i mention above?

boB

For SPD/Lightning protection, the SPD protect voltage must be lower than the product's insulation voltage or "HiPot" voltage rating that the manufacturer tests to.   It doesn't really have anything to do with the input voltages that the controller or inverter operate at....    Except that the higher the operating voltage, the higher the insulation and hipot voltage ratings, typically.

So, the SPD does not connect across the battery or PV terminals directly.  For PV input, you would connect one SPD section to the positive and the other SPD section to the negative PV wires and the common SPD wire connects to grouns.

The only way that they are connected across the PV +/- input voltage is taken as the SPD's two sections as connected in series.  That would typically be much higher clamping voltage than they woudl see across the +/- lines...

This train of thought protects the insides of the product from arcing over to its chassis or GND connection when lightning strikes which is very short time.

FYI, trying to protect the input voltage itself would normally just blow up the SPD or cause it to protect itself by opening, if the SPD is protected.

boB

Fabian

I forgot to mention that i am putting the SPD in the combiner box where all of the panels meet  just like how i see some other combiner boxes on the internet have them installed,

Below is a link on ebay with a PV Combiner Box with one of the SPD install and it is a 1000vdc one. Can i install one in my combiner box just like how it is install in the photo? and using the 1000vdc for both systems would be ok?

My panels are rated at 24v 320watt and 24v 455watt

https://www.ebay.com/itm/203477975158?hash=item2f603b8076:g:FuwAAOSw0QdhPX0z

BB.

Working backwards... I have doubts that the EARU (brand?) surge suppressors are going to (reliably) do what you want.

boB's company designs and builds SPDs, as well as solar charge controllers and other equipment. He knows much more about the subject than I... But my 2 cents worth of comments.

First, there are a lot of counterfeit and fake components being imported... Here is an example of counterfeit Circuit breaker:

https://www.youtube.com/watch?v=2TJEzdqtXlQ

For $7 (part) and $7 shipping from overseas, you are not going to get a sophisticated SPD.

The "simple" SPDs (Delta is one I recall, I think--Name brand) are just a couple of wire ends spaced with an insulator--And covered with sand. I guess they sort of work with higher voltages... But many of the circuit we run in Solar are much less than 500 Vpeak.... So a simple "spark gap" is not going to do much for your protection.

Midnite (again boB's company) makes some very nice surge suppressors that use MOVs (metal oxide varistor--I think) that allow much lower "suppress" voltages and can manage higher amounts of surge energy. Here are his products that are sold by our host NAWS (northern Arizona Wind & Sun).

https://www.solar-electric.com/search/?q=midnite+mnspd

They cover from ~100 volts up to something like 470 volts (AC ratings are different than DC ratings)

MNSPD Specifications

So you might put the low voltage on on your DC bus. And the higher voltage DC on on your solar array (if you have higher voltage MPPT type charge controllers) and one rated for your AC 120/240 VAC power (these are in pairs--DC is +/- lines to ground, AC is L1/L2 to ground).

Some documents from Midnite:

http://www.midnitesolar.com/doc_prod_list.php?menuItem=products&productCat_ID=23&productCatName=Surge Protection Devices

More information:

http://www.midnitesolar.com/videoDisplay.php

SPD (Surge Protection Devices)

• SPD E-Panel Install
• SPD Comparison
• SPD Install - Hawaii
• SPD Flush Mount Installation
• Introduction to SPDs
• MidNite Surge Protection Device and Delta Comparison

Our forum founder (now retired) mentioned years ago, that the most common failures from nearby lightning strikes seemed to be the AC output of AC inverters... So placing SPD on your AC output (main breaker panel), as well as on solar array wiring as it enters the home/shed are common places to start with.

Note, all SPDs are eventually consumable devices... The can suppress surges from "near by" strikes... But any direct strike is going to smoke the SPD (what they are designed for), and very likely to smoke other electrical devices in your off grid installation.

https://www.howtogeek.com/212375/why-and-when-you-need-to-replace-your-surge-protector/

As I understand, Midnite SPDs do have internal fuses that are there to reduce the chances of the SPD from catching fire if there is "too much" surge energy...

From the video links above, here is one (SPD comparisons) that covers the design and testing/certifications.

http://www.midnitesolar.com/video/videoPlay.php?video_ID=9&videoCat_ID=8

-Bill

boB

Thanks Bill !

Fabian, I cannot see where the ground connects in your picture.  Where does that connect ?  

Might be not shown but should be at the bottom of the SPDs in that box ?

boB

BB.

You are very welcome boB.

If I got anything wrong--Please feel free to correct. Just my observations.

The lightning/SPD ground connection is at the far bottom right (the last two are the "SPD" set (I think)). One ground screw for the set (from what I can tell). Attach the lightning/green wire ground there.

-Bill

Fabian

so guys which one u suggest i buy for my system the 500vdc one or the 1000vdc one?

BB.

What is the working voltage of your battery bank, solar array, and your AC power?

Most common battery bank voltages are 12/24/48 VDC. So a 500 Volt or less is fine.

Solar array working voltages run from 18 volts to 150 Volts for common PWM and MPPT type systems. So 500 Volt or less is fine. There are MPPT controllers (most Grid Tied solar arrays, and some high end MPPT controllers, have working voltage of upwards of 600 volts (or higher)--So 1,000 volt SPD.

For 120 VAC AC inverter outputs, 500 Volt is fine. For 240 VAC, 1,000 volt. The reality of AC systems, they are usually high pot tested in the factory (devcies, 600 volt AC wiring insulation, etc.) are tested at 1,800 Volts AC or 2,500 VDC (3x rated voltage)--So 1,000 Volt SPD.

-Bill

Vic

Hi Fabian,

With just a quick read of the e-bay listing for the eco worthy Combiner,  did not see any indication Safety Agency testing of the combiner or SPD.

Most of these types of products from reputable companies would bear a Mark from such an agency (UL,  ETL,  etc,  for example)

These safety testing agencies,  in North America are referred to,  as Nationally Recognized Testing Labrotories (NRTLs).  This testing and Listing,   Recognition (etc) of products,  gives customers confidence in the safe operation of products that have been tested,  AND,  these tests and listings help protect manufacturers from Liability exposure (ie lawsuits).

Personally,  I would answer your question about choosing which of the two SPD Combiners that you asked,   as,  "neither of them"

Why not buy MidNite ( ETL Listed) SPDs,  and Combiners?   They are the real-deal,  IMO.

The eco products may be Listed,  but  normally such a Listing would be noted on the product,  and in sale listings of auction sites.   Also,  using circuit breakers in Combiners is often more convenient than using fuses.  Although for high voltage PV strings,  fuses are often used,  as they are generally,  more compact than breakers.

All,  just my opinion,  YMMV,  etc,  Vic

Fabian

BB. said:

What is the working voltage of your battery bank, solar array, and your AC power?

Most common battery bank voltages are 12/24/48 VDC. So a 500 Volt or less is fine.

Solar array working voltages run from 18 volts to 150 Volts for common PWM and MPPT type systems. So 500 Volt or less is fine. There are MPPT controllers (most Grid Tied solar arrays, and some high end MPPT controllers, have working voltage of upwards of 600 volts (or higher)--So 1,000 volt SPD.

For 120 VAC AC inverter outputs, 500 Volt is fine. For 240 VAC, 1,000 volt. The reality of AC systems, they are usually high pot tested in the factory (devcies, 600 volt AC wiring insulation, etc.) are tested at 1,800 Volts AC or 2,500 VDC (3x rated voltage)--So 1,000 Volt SPD.

-Bill

 I have 2 systems. One is a 48v system with little over 200vdc coming from the panels to the mppt and the other is a 24v system with about 70volts coming from the panels to the the mppt, So using the 500volt SPD would be ok?

In the near future i will upgrade to the midnite or another top brand when i can afford them. But in the meantime i will have to settle for some of the cheaper type. I was researching online and i have not found a bad review on this cheap one so i guess i can use it in the meantime.

BB.

The part is cheap enough... Order an extra SPD and take it apart... See what is inside.

Run the lightning ground on the outside of the building straight to a ground rod at the base of the SPD with, I suggest, 6 awg minimum cable.

If they are spsrk gap type.... They are not going to do much on most non-direct strike situations.

If you live in a lightning prone area, some folks will use an outdoor rated cord and plug for the last 10 feet from array to building. Disconnect and move cord at least 10 feet from building until lightning threat has left the area.

Bill

Dave Angelini

The only way you will get a good review is if it works and that is hard to find or to test for on Ebay. Do it right or just pray alot. Probably used 1000+ of the Midnight SPDs and the few that got hit protected the devices downstream. You should have one for each solar array, one for the DC buss, and one for your inverter AC out to your home panel. That is minimum if you do this right. 

Not alot of confidence in your link to "PUFA"  How do you even know if it is working? I did not see an LED on the link to indicate operation.

For now, save your money and do a shutdown and disconnect of anything coming in from outdoors during near strikes. Use a 10$ battery powered AM radio to detect when flash to sound is 5 to 10 seconds apart for disco.

Good Luck!

Fabian

It has a colour code on it. Green shows that it's working and red shows when its not working..I am thinking like how it's a cheap brand would it be best to go with the 500 volt option? 

Surfpath

Dave Angelini said:

You should have one for each solar array, one for the DC buss, and one for your inverter AC out to your home panel. 

——
Hi Dave,

I use midnight SPD products. I currently have an SPD at my combiner box (between the panels and my charge controller). When you say that you ideally need another one between the inverter AC and the homr panel, is this to protect your inverter or is this to protect your house from any surges coming from the inverter?

BB.

Generally, the 120/240 VAC wiring "goes everywhere" inside the home and sometimes outside too (security lights, shed/workshop, etc.).

The experience from the founder (now retired) of this forum said, in his experience, that the largest percentage of lightning failures was to the the AC inverter's output stage.

Having surge suppressors on your main breaker panel/AC output of inverter seems to be good investment for lightning mitigation (and help reduce chances of damage to the rest of your AC appliances.

And just to be clear--SPDs are helpful for nearby strikes--Direct strikes will not protect your equipment. At this point, good wiring/code practices and possibly lightning rods/grounding system would be a next step (direct lightning strikes away from your home/electrical system).

-Bill