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nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458
Posted: 09:40am 29 Dec 2022
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WoW, 49$ each pff... That's why I buy in bulk, prices will always go up more in comparison with what I earn at work.
But I'm not always looking for the best ROI if it's hobby related I must say, emotions van take the upper hand.
Not An option anymore for you since you bought allready another inverter but it might be for others. This type of inverters could be quite handy and universal:
I have one since may 2018, it did 6300kWh since then. Not one of the Quality brands but it's doing it's job. It's working great on my microgrid.
poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418
Posted: 02:19am 30 Dec 2022
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I was wondering if I could make a dangerous self sustaining arc from the output of one of my arrays after seeing some posts above showing bad things that happen with solar array wiring.
I chose the North facing array, since it was about 12pm so it will be able to produce full power.
3000W nominal, 12 panels, 4 strings in parallel, each string 3 in series. about 98V open circuit, and about 32 Amps shorted.
I took a pair of "4 Amp" solar twin core cable out from the isolator/CB, ran the twin core down a bit of timber and bared 1cm at the ends of each. I wanted these ends to remain close so as to help maintain the arc.
I ran wires from the isolator separated over a foot from each other to prevent ANY self sustaining arc running up to it.
Video here https://youtu.be/0dOjZ4TIce4
As you can see, it was difficult for me to start an arc.
I think that in my case here, the arc might be able to be made but I would have to be skilled in keeping the wires within 1mm or so once the arc begins. I was not going to do this by hand, I used a chicken stick but I think I gave it a fair enough chance to arc up.
a view of the fail (or reassuring success, maybe)
wronger than a phone book full of wrong phone numbers
pd-- Senior Member Joined: 11/12/2020 Location: AustraliaPosts: 122
Posted: 04:43am 30 Dec 2022
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I wonder at what voltage it would become self sustaining.
Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 648
Posted: 07:36am 30 Dec 2022
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Poida, If I was trying to do that I would solder the wire ends to an old switch.
Do that with the other wire end unplugged/ disconnected .
Connect, flick that switch to ON and run
Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 648
Posted: 07:38am 30 Dec 2022
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I saw articles of people doing emergency bush welding with two 12V batteries in series. Welding requires a sustained arc.
Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024
Posted: 07:58am 30 Dec 2022
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Yes welding needs a sustained arc, but if you knock the flux off the rod it will not hold an arc at 12volt, some of the older welders would be 100v open circuit until striking an arc, and we used to hold on to the metal handle with out a glove at times. I had 3 x 75v volt panels in series and the could hold an arc but very small, anyone tested the amperage used when the arc is going, I expect it to be somewhat less than the short that started it.Cheers Aaron Off The Grid
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 04:08am 31 Dec 2022
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Peter, that is a sorry tale of trying to make an arc and I can only suggest that another 30V would have yielded much better results. Most of my high power DC work involved 125V @ 2,000A rectifiers. Exide used around 10 of these monster rectifiers and ~ 1,000 20A 96V nominal chargers for forming plates and charging 6 x 12V lead acid batteries in series.
On the bench and with various attempts at relay switching the 125V DC and switching with a 415V rated switch. If the switch was turned off the 20A still flowed until you clobbered the PWM drive (and then throw the switch away). If you turned off the series relay the 20A still flowed whilst it was emitting a bright green glow internally & rapidly changing colour externally.
So in the video clip of the guy with 4 panels I am assuming around 36V x 4 = 144V, and if you look closely at the video he had a space between the ends of the wires of ~ 15mm that was supporting the arc. The way he bought the wires together horizontally was probably easier to control the arc so it is difficult to say how his test would have performed with just 3 panels and your setup of the wires tied to the board.
If you end up adding another panel it may get more exciting ? Edited 2023-01-01 10:30 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
andymc70 Regular Member Joined: 30/06/2019 Location: AustraliaPosts: 43
Posted: 03:16am 01 Jan 2023
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I am not sure if this item is something that what you are looking for: https://www.solarquotes.com.au/blog/goodwe-bp/
If it is I am sure there are enough smart people in this forum to build something similar.
I agree with Mark, with regard to the grid, but I don't know how you can do it here in Melbourne, especially during winter and family needs (I know my wife and kids won't have it). I think if I can only pay the connect fee for the year, then it's like insurance if anything ever happens.
I am wondering how long before Victoria goes the same way as QLD. https://onestepoffthegrid.com.au/industry-slams-antiquated-brutal-rooftop-solar-switch-off-plan-for-sunshine-state/
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 05:57am 01 Jan 2023
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Hi Andrew, thanks for pointing out that unit, it is excellent for single phase use and essentially the topology I am proposing to adopt, I was not aware of it.
is ~ 250 quid and $445 AUD. However elsewhere it appears to be sold in Australia for ~ $1,300 - still not too unreasonable if you already have batteries and a modest solar array.
The main point of difference is that I have a 3 phase Fronius 10kW inverter. The DC input from the PV panels is shared internally and fed equally to the 3 phases. That is why I was going to include a separate grid feed inverter to just the one phase, and my lower voltage 200-400VDC I am more comfortable to play with.
Again my situation is a bit one off, I got my 3.6kWH storage unit for zero cost, the 4kW grid feed inverter for $400 and I hope to fill in the missing DC/DC & control bits for quite a few hours work and maybe 1 or 2 hundred dollars of additional purchases.
I think if I had a single phase 5kW Fronius or similar with two MPPT inputs I would do what this Growatt does and install a DC/DC converter & controller as Nicks suggested with a diode OR to merge the Solar PV & DC/DC inputs to one MPPT input and essentially create what this Growatt appears to do.If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458
Posted: 09:19pm 01 Jan 2023
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Mike, that IC is a nice piece of device, it will take a while to fully understand and implement that device.
I did a quick google search and You might find this useful, or maybe you find it already: https://github.com/engkan2kit/ADE7758
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 10:57am 03 Jan 2023
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Thanks Nick I was not aware of the github link, I intend to download the files to check them out more thoroughly shortly.If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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