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Fooling a grid tie inverter?

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studio45 View Drop Down
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    Posted: 23 June 2020 at 2:13pm
Not strictly speaker related - mods feel free to delet this....but I feel like there are people with relevant knowledge here.

I've been given a huge Aurora 6kW grid-tie solar inverter with a small fault, that I think I can fix. However, I've got no solar panels, nor any real intention of getting any. However, I like the idea of having a powerful pure sine inverter that can accept a wide range of input voltages.

CAN I....use a function generator to make a 50Hz sine wave and use this to fool the thing into thinking it is connected to the grid, and thus enable power output? I'm thinking to find the point in the circuitry where the 50Hz grid voltage has been stepped down to a logic-level signal, and inject there.

Anyway is this likely to work, or just result in smoke?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2020 at 3:07pm
I can't help I'm afraid but I'm interested - could you not connect to the grid by plugging it into a wall socket? Or is the issue that you want to use it off grid and it needs 240v 50hz to work at all? If so could a low power sine inverter be used just for providing the 'grid'?
Keep pushing on, things are gonna get better.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2020 at 3:42pm
Yes the idea would be to use it out in a field, probably as the 240v power source for band's backline on a small live stage with a 12v PA, maybe to power the mixing desk too. So no grid present. 

I thought about using a small inverter, but then what happens if the big boy goes offline suddenly when everyone's hammering away? The little one will be faced with a sudden huge load and probably won't survive...I wouldn't trust fuses to blow fast enough. The signal generator idea seems a bit safer, if I can find the right place to put the signal in.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2020 at 12:21am
Funnily enough I ended up with 2 x 5kw grid tie inverter a while ago. Gave it to my very techie friend who was going to " fool" it into thinking it was on the grid to run some extra panels and inverter in his shed. I'll see how he's getting on !

Again like panels here in Aus, old grid tie inverters are being given away for nothing. The new CE regs plus everyone wanting battery back up capability has made them virtually worthless.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2020 at 1:59pm
Brilliant thanks Phil! Yes this one sprouted from a lamp post outside my mate's bike shop. Presumably left out for the scrap men. I actually haven't powered it up at all so not even sure if it works already! But quick Googling of the model number revealed there is a common fault involving some capacitors on the board, that stops them working after a while. So running on the assumption that'll be why it was discarded.
If I could get panels for AU$40 (£22!) as you mentioned in another thread, I might be tempted. But never really been alongside the idea of storing/carting about a large number of relatively fragile, heavy bits of glass in order to do music in a field. I'd much rather have a wind turbine or generator bikes like Reaction.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 25 June 2020 at 1:33am
Panels are way better than Wind or bike generators for a mobile application. If you read my thread about our system down here we tried a mobile wind genny and it just can't compete with modern panels in output. You need a decent, high, uninterrupted wind supply and most places we went to were surrounded by trees or buildings. And bike generators...you need many fit humans!

And we have never broken a panel yet. We made some covers for the side panels on the last desert adventure to protect against stone chips on the dirt roads ...



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Mostly harmless.... except if catering is shut.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 25 June 2020 at 1:27pm
There are solar soundsystems in the UK, but frankly it's a struggle. The sun just does not shine reliably enough. (Today being an exception!)
 
The serious rigs I've seen have 5x more panels than you have there, and normally turn up on site with an already charged, dedicated battery truck of several thousand AH, on the assumption that they might not get any significant recharge for the 3 days of the festy.

All of which is out of the question for me and my mate, with the bike rigs, and the geodome, travelling to site in his one normal sized LWB van. 

Whereas I feel like a homebrewed VAWT (no problem with wind direction) could be successfully stowed in the available van space, and erected on the roof, to provide us with decent power. Whether or not the sun is shining, there's normally a good breeze. Then if we can get several collaborators to bring their batteries to make up a really big bank on site, that will get us through. 

Reaction's bike power system works amazingly well - their high efficiency rig means just one person pedalling can keep the DJ gear going and allow for a "danceable" volume, and three or four people pedalling allows them to get the rig to full power continuously. An average, sustainable amount of effort from an adult rider will give 100 watts or so! not too shabby!

I've asked them how they do it, but they're not telling...which is entirely fair enough, and suggests quite a lot of effort has gone into making it work. I'm trying to climb the same tech ladder, one rung at a time ;)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2020 at 6:33am
Many many years ago I saw what I presumed was the early incarnation of Rinky Dink sound system at the Kingston green fair ( 1989/90 ?? ) . They had rows of modified excercise bikes at the back of a tent with those powering the stage & PA. Kinda always stuck in my head how much fun it was to tell everyone " Pedal HARDER! If you want the DJ to play another tune !!"

If you look at the last page on my TH & Unity thread here you'll see we did a show with bike generators recently. They were running constantly all day to charge a 1100amh battery bank to power a projector. That was a lot of school girl kilojoules !! They had 4 systems running for about 8 hours...



And as for a VAWT, we thought about that as well but the difference in wind speeds at ground level versus building tops / hillsides is the reason there aren't any urban systems available... just not enough reliable, clean wind under roughly 10m ....
I was always hopeful our wind system would crank for 24hrs so make up for it's low power output, but 6 newer 250w panels would make way more in just a couple of hours. They are also a pain in the butt to setup correctly and you have to watch out for vibration and that it's not going to fall over !

.p.
Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans..http://diyhifi.biz/
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