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gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 02:54pm 29 Jan 2017
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Hi all,
With the finish of the 60c rebate that ended on the 31st December 2016, I now have a 2 kw system sitting on the roof that producing plenty of power but only getting a measly 6c kw/h. Hardly worth it really. It dosent even pay for half of the daily connection fee, let alone using their expensive power. Since I am heading towards an off grid scenario, I am planning on using the 12 panels, reconfiguring to to a 24v system and connect to my battery bank. This will include additional heavy wiring thru conduit of approx 15 metres plus a controller and ancillary items plus me crawling up in the roof in the middle of summer. (Man, it gets so hot up there. Don't quite know how sparkies handle that ) I can go down this path, OR, is it possible of using the available setup thru the GTI to feed my system as Clockman suggests at the beginning of this thread.
So I assume this is quite a doable thing, as I remember reading it elsewhere in the "Back Shed", but unable to find again. So how hard is it to do and what are the pitfalls. What are the necessary connections and where are they to be made? Do I need additional dump loads to shed of excess power as there will be plenty of times where I will have that senario? I'm in the dark with this, but it may just be an easy solution of utilising the 2kw already wired up! Any help would be appreciated.
Marcus if it aint broke dont fix it!!
Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429
Posted: 11:06pm 29 Jan 2017
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Hi Marcus, I will try and keep this understandable, as my Mrs says, "you start talking, folks eyes start to glaze over".
The GTI's, used or old stock, under 3kW, here in Europe are as cheap as chips.
I have a normal GTI pushing into the OzInverter created Mini Grid. It works, and I believe 'Oztules' has the same.
So how hard is it to do and what are the pitfalls.
Firstly, the OzInverter is a simple, robust and cost effective H Bridge 48vdc to 230vac, (settable) 50HZ, (settable) Pure Sine Wave Inverter.
Give it 48vdc and it starts the 230vac 50HZ Mini Grid, The Normal domestic PV roof LF GTI's will start up and feed into this Mini Grid as though they were feeding in to the Countries Utilities Grid, and like the Utilities Grid if the GTI's 230vac Output rises above a set criteria then the GTI shuts down.
We use this 230vac output rise to shut down the GTI's when we are not needing the power on our Mini Grid.
Our OzInverter, with the H Bridge arrangement, takes the GTI's output and if the 230vac power is not being used, the OzInverter reverse's and changes the 230vac into 48vdc to 60vdc, (this top end DC voltage is set when winding the toroid), and feeds the dc into the batteries and charges the batteries.
However, when the batteries start to push back as they reach finishing a bulk charge, the OzInverter has slight resistance and starts to raise the 230vac voltage, this then trips out the GTI's. (I have codes for my GTI's so I have set them sequentially).
I like things simple, so raising the AC voltage slightly is far far better than raising the HZ frequency. At 54HZ modern and old synchronous stuff stops working correctly. I had a big unpleasant Experience with a very well known Inverter manufacture, (to get my money back I have a gagging clause on me). There whole answer to there industry standard frequency rise, was to install masses of very expensive auxiliary equipment to control the battery charging regime when there is a mix of DC and AC renewable energy coming in, yep it was a costly toy.
I finish charging and float on my batteries using 5kW of DC with a Midnite Classic 200. I use its Aux relay function when it reaches float, as a safety trip out system with my GTI's. I have never seen this work as the GTI's just trip out nicely with the Ac voltage rise.
What are the necessary connections and where are they to be made?
I think the above explains this?
Do I need additional dump loads to shed of excess power as there will be plenty of times where I will have that senario?
As I have said the AC voltage will rise and your GTI's will shut down. However, a Arduino system that sees Battery voltage at float and excess 230vac voltage rise may be configured to load shed..... ie a dedicated heating circuit etc.
I have 4 dump loads, 8kW, because I have 3off WILD Hugh Piggott design 3.7m 48vdc Wind turbines, these are controlled by Morningstar Tristar PWM controllers that are set for Load Diversion on the battery bank.
I'm in the dark with this, but it may just be an easy solution of utilising the 2kw already wired up!
48vdc battery bank is a must for a normal domestic off grid situation. I think for a On Utilities Grid, to Off Grid use, and Big Change Over switching, the BOOK is still being written.!
For me its keeping things as simple as possible, with robust gear, but very very importantly keeping it all cost effective.
Just seems nonsensical to me, watching folk spending vast sums on complicated control equipment for there renewable Energy creation system.
I trust this helps?.
Edited by Clockmanfr 2017-01-31Everything is possible, just give me time.
3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v.
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 12:05am 01 Feb 2017
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Thanks Clockman,
And thanks for your speedy reply. Sorry I didnt get back earlier to you.
I get the gist of all that. Connections therefore are fairly simple but Im basically going to have to upgrade my system to 48 v before I can utilise the installed GTI! That is different to how I thought it would work. I assumed that the GTI would detect the grid/my grid voltage and synchronize with it then start charging to my system. Just proves how little I know bout these things.
Is it worth a shot to see if it does work?
I was originally going to go 48v but was held back by my initial battery purchase that I could afford at the time. Found out later there are cheaper and better battery alternatives.
Looks like I will have to go back to the original idea of feeding directly to my battery bank with heavier cables.
Thanks for you help.
Marcusif it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 01:05am 01 Feb 2017
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It does not matter what voltage your battery bank is, however 48V = less current and therefore is better for higher power applications.
The GTI back feeds through your DC to AC Inverter and converts AC to DC. That is providing you have an Inverter of a suitable H-Bridge type.
PS You're not wrong about the heat we are getting cooked here in SE QLD as is so many other places.Edited by Madness 2017-02-02There are only 10 types of people in the world: those who understand binary, and those who don't.
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 11:16pm 01 Feb 2017
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Thanks Madness, So maybe it is worth a go...that is if my inverter is a H bridge type. Its based around a 8kw PJ main and control board, so Im not sure if they are compatible for the application. Any way of knowing if they are?
Marcus
ps Were in northern NSW. Today was a killer! Couldnt wait to get home and jump in the pool...even that was warm..! Cool breeze now!
if it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 12:49am 02 Feb 2017
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I am not up on the Chinese Inverters but if you post some pictures someone else may be able to confirm if you have the right type.
I am very happy I installed AC late last year, it runs off 100% solar, there is at least another week of this heat to deal with.There are only 10 types of people in the world: those who understand binary, and those who don't.
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 02:54pm 02 Feb 2017
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The powerjack inverter is a H bridge design. It is what was used as a starting point/template for all of this DIY tinkering.
God has it been 5 years I'm confused, no wait... maybe I'm not...
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 11:06pm 03 Feb 2017
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Hi Madness and Yahoo,
I have included a pic of the PJ boards. I just wanted to confirm before doing any changes to my system. If its not up to scratch then Im sure I could use the original 3kw power star inverter as I know for sure they are also work as a battery charger. Presently its just sitting there collecting dust
Having Air condition running on solar is impressive to say the least. Just shows that even with a large power demands it can work on house hold applications.
Yep ! 5 years goes fast! So much has been accomplished, learnt AND burnt in that time with this new DIY inverter technology.
Marcus if it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 01:46am 04 Feb 2017
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Yes that is the right type Marcus.
I now have 2 AC's running off my inverter, the one for the house and another to cool the shipping container where my solar power station and batteries live. 6 KW for a few hours is no problem at all, I will add another 5 KW of panels soon and the AC can run all day then.There are only 10 types of people in the world: those who understand binary, and those who don't.
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 01:06pm 05 Feb 2017
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So just to clarify this...
By removing the AC output connections from my GTI and reconnecting to the AC output to my home made inverter with PJ boards it will 1) sync waveforms , 2)feed AC thru the H bridge inverter arrangement, be consumed as AC if needed, and if any left over, converted to DC, then charge my batteries. 3) When the batteries are charged the GTI will shut down until a time it is required again.
If it does all this I'm impressed. ....or... have I got it all wrong.
4)So this is the part that scares me a bit. Do I need a dedicated dump load as backup for too much power or can I rely on the fact that it will shut down. Could it be a connect and watch scenario, then shut down if the voltages (AC,DC) rise too much?? The last thing I want to happen is to fry my inverter.
Any help here would be greatly appreciated.
Madness, that sounds a great setup you have there knowing you have more than enough power the feed your house and run the air too! Think I recall reading a post some time ago bout your air an how you wanted to run it whenever you want. Are they inverter type units? I hear they consume substantially less power than the older models. Marcus if it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:00pm 05 Feb 2017
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Hi Marcus,
Oztules has a circuit somewhere for a PVstopa I think he called it if you need to limit charge but I thnk he has said it tends to self-regulate anyway.
Yes Inverter AC's is the way to go less power, more efficient and more consistent load. Old school AC's just cycle the compressor on and off to regulate the temperature so they work flat out then nothing and keep repeating that. Inverter AC's use the Inverter to vary the compressor speed to regulate themselves and as they slow down from full load I think they run more efficiently.
Another way to reduce power consumption is to change to a Hydrocarbon Refrigerant, power consumption is reduced by 25% or better with the same cooling effect. I have a 10 KW cooling AC that draws 3KW and a 3 KW cooling AC that now draws a maximum of 670W with Hydrocarbon Refrigerant gas. It's rated power consumption is 980W, that is with the original R410 gas.There are only 10 types of people in the world: those who understand binary, and those who don't.
Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429
Posted: 10:15pm 05 Feb 2017
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Hi Marcus,
1, ... Your GTI needs to see a Wave Form and the specified voltage.
2, ... Yes. Remember that this back charging voltage will be raw/ bulk.
3, ... The battery fills and pushes back and the AC voltage will rise, and should push the GTI into shut down mode. (The GTI has set voltage parameters) CONSIDERATIONS.....However a good battery bank with a suitable amp hour capacity is required, depends on your source and GTI output. If the batteries capacity is small then the GTI will be shutting down real quick, and your batteries will be hammered. Some form of float charging your batteries will be required.
4, ... Dump loads are not required, but you could use the Excess GTI output for heating etc. Hence me mentioning the Arduino or the Morningstar Tristar PWM controller set for Diversion. Its directly on your battery bank and is a good battery monitor controller, and excess voltage it sends to heaters.
I also have a fail safe, that interrupts the AC connection on the GTI's if the battery voltage rises more than the battery needs, but as I have said, I have not seen this work as the GTI's just disconnect themselves.
Its my batteries I am always worried about. I have been looking at making my own on another forum. My OzInverters are no problem.Everything is possible, just give me time.
3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v.
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 11:11pm 05 Feb 2017
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Today I went out to an outer island, and installed two 3kw aerosharps onto an ozinverter.
The inverter and battery is a long way from the wool sheds, where the new salt water desal unit is built. It uses 1.4kw or more. So we put 2kw of panels on the wool shed roof, and hooked them into one of the aero sharps. It delivered 1.5kw of power into the house grid, and when the RO unit was off, drove that into the battery over 100 yards away at the house. This is where this sort of hook up shines.
The second aerosharp was modified with bridge rectifiers and capacitors, so that it is driven by a 3kw honda 240v 50hz generator. This will be used next winter should we get three days of sea fog.... otherwise it will not be required..... but once again, it shows that the grid tie reverse charging is a very useful thing. In this case, the generator will be a long way from the house, so if it is needed to supplement the house, and fill the battery, it is so far away, that it will not be heard.
Marcus 1.yes the GTI output goes straight to the inverter outputs.
2.yes... and hopefully Waro will tell us how it does this. I think it is the H bridge acting like a synchronous boost converter.
3.yes it will, but it is not an exact science. A dedicated voltage switch will be better. preferably an arduino so you can shut down, but monitor whats going on so your in a better position to decide to reconnect.
4.no.A dedicated voltage switch will solve your worries. Particularly if you ar a programmer, but an analog one works well too. ( I did do one on the net somewhere )
.........oztules
Village idiot...or... just another hack out of his depth
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 11:42pm 06 Feb 2017
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Firstly, thanks guys for you detailed responses....much appreciated.
OK...so the first 2 answers to my questions, I am happy about. The third is a concern as I checked my output voltage today..234V. Which is really close to the magical 230v cutout you guys are taking about. At this rate could it be possible to develop some sort of hysteresis as the GTI syncs, raises the voltage then then cuts out. You were saying Clockman that my batteries might cop a hammering. My battery bank is not that big, just 24v 550AH, but im planning on increasing that soonish. Should my voltage be higher, or is this a normal reading for the PJ boards, OR are my transformer winding not quite up to scratch?
As an idea, I could disconnect 2 x 1kw arrays, leaving the third connected to power the inverter, which would make the GTI sync and work harder and perhaps to its limit so there is less chance of too much power going in and causing a catastrophie! As a test of course!
Answer 4 sounds like it could be fixed by voltage switch. Im not a programmer so analogue I like Are these an ebay item that can be purchased on line?
Madness, you sound like the Air Conditioning king. You had much to do in the industry? The one thing that I regretted being an Auto Sparkie , was that I never got into Air!
Marcusif it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 01:14am 07 Feb 2017
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Marcus the Internet is a wonderful resource especially forums and youtube. About 25 years ago I went into a computer shop to buy a modem, the owner of the shop asked if I wanted it for the Internet, I told him yes and he proceeded to tell me that it was a waste of time and money. So I went to another shop and bought one, that shop closed a year or 2 after that. That is where my knowledge has come from, 10 years prior to that I did study Electrical Engineering but never completed it. The most valuable thing I got from that was on day one when they said they would not teach us much information but teach us how to ask the right questions and find the right answers.
Can I persuade you to have a closer look at the Arduino, they quite easy to work with and designed to be easy for novices to work with. They are actually much easier and simpler to work with than analogue but infinitely more flexible. For example it could turn on a relay to your hot water system when the battery voltage is close to the maximum, then if that does not keep it under control then turn another relay off to disconnect the GTI. If you need some help to set one up to control some relays I can help you get started. Doing that is really quite simple once you get over the initial small learning curve.
Edited by Madness 2017-02-08There are only 10 types of people in the world: those who understand binary, and those who don't.
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 01:15am 07 Feb 2017
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The best you can do is plug it in ( use a small fuse in series until you prove your GTI will work ... if it is not galvanically isolated like the aerosharps, inspires etc, I don't have experience, but it will make a difference on your active and neutral connections I suspect), and watch what happens to get a feel for what is going on... and all will be revealed.
ie... plug gti into your output power points, and watch the gauges and you will get a feel for how it works, what happens as the voltage rises etc.
You may also have already, a voltage switch connected to your battery bank if you use a number of commercial controllers that switch in and out loads at certain voltages, or a dump load controller would do fine as well.
Ebay will throw up all kinds of sensing circuits I have no doubt.
..........oztulesVillage idiot...or... just another hack out of his depth
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 02:09pm 08 Feb 2017
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HI guys, thanks for you advice.
I got home yesterday and decided to give it a go. Unhook 2 wires in the back of the meter board and reconnect 2 wires. Simples! As there was a storm around, cloud cover lowered the output considerably, but did make a difference to to battery voltage. I knew it synced and was working
The next morn(today)the whether was similar but when the sun came out the battery voltage very quickly rose to 28v then the GTI cut out. I watched it do this for a while cycling on and off.. going thur the start up process which takes bout a minute then when the watts are displayed the batt voltage climbs. If there is little usage, the GTI soon shuts down again. As you said Clockman it is raw power and goes flat out trying to dump all it has. With a few power consuming appliances (toaster, kettle) it brings it back down to earth again, but once they are turned off the process repeats and shuts down. I also noticed if I was using an appliance with say 2kw and the GTI was suppling 1.6kw, my inverter watt meter was only 400w. So it seems to draw off the GTI first and the inverter last! Having another possible 2kw on tap is awesome. I can almost have full power at first light in the morning.
I am so impressed by all this
So the solution is
1) Bigger battery capacity. This is overdue, as I was planning this anyway, and will partially or fully( depending on batt size ) help alleviate the GTI cycling, and hopefully keep me off grid powered thru the night as well. A Bonus!
2) Being able to dump excess power to other appliances would completely fix the problem. I dont think its good if the GTI cuts in and out constantly.
SO....I think its time I came out of my analogue closet and start to learn more about the Arduino system....Madness, Im all ears.. where do I start?
Marcusif it aint broke dont fix it!!
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 02:32pm 08 Feb 2017
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See if you can find out the specs for your GTI Marcus?
it is handy to know what the high grid voltage disconnect is.
and the reconnect voltage and if there is a wait time set
for example it might be disconnect @ 270V wait 3 minutes reconnect if below 255V, that sort of thing. Then you have a rough idea of what to expect
some inverters can be tweaked a little using an installers code, some just have fixed settings for each country. I spent a couple of years hoping to crack this and customize the settings for a couple of brands. the conclusion I come to is that it doesn't matter how smart we think we are and what we can do using the original equipment it is usually a waste of effort to reverse engineer code when we can simply over-ride it externally.
edit sorry, your last post has slipped in before mine, looks like it works, I am surprised the battery voltage didnt go higher than that. You should be able to measure the AC and work out the gti settings. cycling every minute will fritz the relay eventually, looks like you need that external control.
Edited by yahoo2 2017-02-10 I'm confused, no wait... maybe I'm not...
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 04:15pm 08 Feb 2017
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A check with Mr Google and soon found out about my GTI. Mines the WR2300. This is all that I could find in the 85 page online catalogue about input/output specs.
Not sure if this page tells all. Seems the voltages are set. There is more info about fault codes which is important too plus more pages of reading bout instillation. Im not going to even think about trying to tweek it in any way...I aint that smart and would just end up stuffing things up! It is working right now, but just noticed that the battery voltage just climbed above 28.5. Thats not over the top but I dont normally see it there.
This is really a test to see if it works or not.... and it does, which is great. So it has satisfied my curiosity for now with the help of you guys, and I do appreciate that. Until I work a few things out, I can just turn it on first thing in the morning, off around 10am , then back on in the arvo around 4pm. That will give me more flexability of power for now until additional battery storage/ power diversions can be organised.
Just noticed 29.3v... just shut it down.
Marcusif it aint broke dont fix it!!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 06:07pm 08 Feb 2017
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Hi Marcus,
Perhaps increasing your Inverter output voltage a bit might stop it charging so high.
I will start a new thread for the Arduino voltage control later today. There are only 10 types of people in the world: those who understand binary, and those who don't.
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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) I can go down this path, OR, is it possible of using the available setup thru the GTI to feed my system as Clockman suggests at the beginning of this thread.
Is it worth a shot to see if it does work?
Just shows that even with a large power demands it can work on house hold applications. 
....or... have I got it all wrong. 
Are these an ebay item that can be purchased on line? 
