diy solar

diy solar

Surge protection for PV panels and proper grounding.

Perhaps this is true for the all in ones. But don't think it would apply to seperate inverters and sccs.
Yes, I think that's right. I haven't thought about the separate option.

I worry more about static charge buildup than an actual strike.
Rain around here during summer can cause a surprising amount of static buildup on ungrounded wires.

For my outdoor PoE camera network, I use gas discharge tubes on all of the RJ-45s coming into the house, along with conventional MOV devices inside.
Did you built your own, or do you use commercial devices? I recently found out manufacturers of PoE SPDs are seriously overpricing their products. To the point of $100 for 4 ports for the cheapest option (only mov's, no GDTs, $150 for both).

So I'm considering DIYing it.
I’m not sure there is a universal “right” answer, but I appreciate the thought you’ve put into this, thanks.
Thanks
 
@timselectric - the expert on all things to do with ground

He would say 'There can be only one' - meaning one grounding system and everything is attached to that single grounding system.

So, in the case of the remote array when the lightning strikes near the whole system attached to the house ground raises by many thousand volts at once because they are connected to the house ground. No difference of potential so no damage. A few microseconds later the house ground is raised by many thousand volts. No difference in potential so no damage.

It is unfortunate that the array mount is grounded by virtue of being in concrete in the ground, but there isn't anything you can do about it. To avoid a difference of potential when touching metal frames of panels and the racking you MUST attach the racking to the EGC from the house.

A lightning strike has a great deal of voltage and not much current - so the EGC connecting size just needs to be the same size as is used for the PV lines.

And the recommendation stands - SPD at both ends if the distance is more than 30ft
 
Did you built your own, or do you use commercial devices? I recently found out manufacturers of PoE SPDs are seriously overpricing their products. To the point of $100 for 4 ports for the cheapest option (only mov's, no GDTs, $150 for both).

I get the devices for POE and other signaling wires that run outside from l-com - I get the ones that are 3 stage - GST (gas discharge tube), FET, TVS diode -


I've had a number of them blow up and never lost attached equipment.

For the pv power lines I will use the midnight solar SPD which appears to contain a GST among other things.
 
Did you built your own, or do you use commercial devices? I recently found out manufacturers of PoE SPDs are seriously overpricing their products. To the point of $100 for 4 ports for the cheapest option (only mov's, no GDTs, $150 for both).
I use these:
Screenshot 2024-06-10 at 11.41.10 AM.png

Though I don't know why Amazon thinks Thunder can be arrested.:)
 
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I use these:
View attachment 221061

Though I don't know why Amazon thinks Thunder can be arrested.:)


With a translation error like that I would be worried about them having anything inside the case except 8 wires going straight through. Ever look inside to see if they have a GST or any other electronics to prevent surges?
 
IMG_6739.jpg IMG_6739.jpg IMG_6740.jpg

GDT Markings: 3R90
Looking for Chinese data sheet.
These are apparently rated 90V 10 kA

No apparent Thunder attenuation though 🤪
No plastic, case is all anodized aluminum. Pretty well constructed.

Screen Shot 2024-06-10 at 3.54.02 PM.png
 
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Basically 4 x center grounded gas discharge tubes - That should be a good start -
Yes, these are outside the house in a junction box.

I have traditional MOV-based PoE power supplies inside the house.
And then the UniFi PoE++ switch has its ESD protection as well.
 
Back to the topic -

Dualing SPD the op was concerned about - they would both be trying to short over-voltage to the grounding system. So there is no dual - if either sees voltage over the rating it will go into a shorting mode. Then if the other end sees the same they would probably both going into a shorting mode. Either way they both do what they are supposed to do and you loose a few seconds of power because there is a current short across the PV and as long as you sized the wires correctly to start with there is no problem.

Having the SPD close to both ends and a EGC between to attach them to keeps you from picking up energy in the long lines between.

Now a lightning strike that burns through insulation is going to be a problem no matter what you have.
 
Depends on the class/type. Class 1 - agreed 100% these are to protect wiring insulation from breakdown. Class 2.. Mhmm they will protect induction motor windings, some robust electronic devices etc. Class 3 - these do protect electronic devices assuming the devices can withstand 2x the normal voltage for a long time and 3x momentarily.

Are there plenty of devices that die when you exceed their voltage by 20%? Probably, but saying SPDs protect mainly from fire is incorrect.


I'm not sure how that would help, or where to put it. In general the goal when talking about dissipating surges is to lower inductance as much as possible to prevent high impedance to dissipate the surge current.

I suspect you mean an opposite. Increase impedance to present a sort of barrier to surge current, but how do you know the sign of overvoltage, or which conductor it will come from? In such case lowering inductance of everything is the safest IMO.

So scenario 3. The war of SPDs... 🙄

However I now had another idea, or a realisation. Mike Holt and others alike always talk about connecting it one place. I though what they mean is bonding it to neutral which is done at one place(the main panel) . But perhaps what they mean too is connecting the grounding electrode (including auxiliary electrodes) with system ground in only one place.

So to achieve this I'd need two grounding wires at my array. One is system ground that I connect SPDs to. The other is the conductor that ties the ground mount to the main system ground.

This has an adventage of offering some protection to everything. Still local ground can go very high and system ground will reflect some middle ground(no pun intended). This is less than ideal, but doesn't leave anything unprotected.

I'm not sure. What do people that live in places with lots if lightning do?
People in North East Florida and South East Georgia (the lighting capital of the U S) have good insurance...our boat go struck 3 times there!
 
People in North East Florida and South East Georgia (the lighting capital of the U S) have good insurance...our boat go struck 3 times there!

Sadly it is not an option for me :-( I've looked into insurance. No one will insure a DIY system in my country (Poland). Not even from things like hail, or theft/vandalism. It is beyond stupid, but every Ts&Cs of every insurance provide I read has a statement "Equipment must be installed by properly certified installer". It doesn't matter there is no certification nor any qualification required in any local code/laws for off grid systems. They still have this stupid rule and they will use it to decline any claims. Even if your panels get hail damage or get stolen.


BTW, I found this article very helpful: https://www.eaton.com/content/dam/e...arthing-surge-protection-application-note.pdf

After reading this I now have another question? If a star shaped grounding is impossible is what they call a "remote outstation installation" the next best thing, far better than connecting all the local grounds with a cable and have this "serial ground" for a lack of a better term?

Just to clarify, what I call a serial ground is imagine few buildings (or 2 buildings and a solar array). Each building and the array has its own ground. All 3 grounds are connected together building 1 to building 2 to the solar array.

Star shaped ground is self explanatory. In an ideal world everyone would have it.

The "Remote outstation" is essentially a separate building(or an array) that has its own ground not connected to the main system ground and you have SPDs fitted on all connections between it and another building.
 
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