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Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 03:29am 17 Jul 2017
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Cant seem to find a reason why I cant online apart from `the rules say' but no electrical reason I can find
To start with, I got the option to get 6x 1.5 or 1.8Kw (owner isnt sure and isnt at the farm atm) grid tie inverters brand unknown- whatever was being installed most commonly in NSW about 5 years ago... for free, just gotta pick them up they were configured as 3xsingle phase at the house and shed, and another 3x singles phases at the dairy- all being replaced with two larger 5kw 3 phase units
Now I know they are designed for grid tied use, and sample the mains to get phasing etc correct, what I am wondering is if I give them such a signal (from an existing 12v 50w pure sine wave inverter I already possess- that would obviously have to have its own small battery bank/solar panel- handy for 12v lighting etc too) and basically hook up to the correct DC voltage string of batts as a replacement for the solar panels with a `normal panel/controller' system for charging those batterys
Outputs could either be run as individual circuits ie one inverter does bedrooms, another kitchen, another loungeroom etc or surely they could just be paralleled to form one `big' approx 10kw unit (as thats how they basically run in grid tied mode, your inverter hooks up to the same wires as your neighbours etc etc) and as they would all be synced by the same signal from the small standalone inverter
Possible? Or is my whole idea doomed from the start??? (if so maybe good for parts for a homebrew I spose)
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 11:07am 17 Jul 2017
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I don't know if that would work but a factor you need to consider is that you would need a battery bank voltage up around 300V.There 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: 11:51am 17 Jul 2017
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Now we know we can control the GTI very closely, then theoretically yes.
In practice no.
You really want to try to be fairly normal, and then you have some back up.... going maverick requires that you know all about what your doing, as help may never materialize.
Eg, Most grid ties are not designed to run off a low impedance source, so a battery hook up will probably shut the thing down immediately.. ie normally if to much input current is available, they will just error to over current, and thats it.
So after setting up an abnormal 300v battery, you may be no better off.
If your trying to go it cheaply, then maybe a powerjack or solinda or homebrew 8010 will do it all just fine..... then you can use the GTI off panels to run the thing, and it will work just fine. The GTI cannot be the prime inverter, as it can't support the surge currents inherent in a house situation. Both theirs and my control system is not up to instantaneous surge control.
.....oztulesEdited by oztules 2017-07-18Village idiot...or... just another hack out of his depth
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 12:02pm 17 Jul 2017
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:-(
shame as the price certainly was right- otherwise they are going on the scrapheap and burnt with the rest of the rubbish (typical farm lol)
the voltages arent an issue, used to working with those, just trying to find circuit diagrams on grid ties seems hard, and without those I have been stumbling around without really knowing even the basic details of what controls em....
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 12:16pm 17 Jul 2017
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Get them anyway... you can incorporate them into a system if you buy/build the right sort of inverter. Will be easier than your original thoughts.
Once you have a working "normal "system, you can add things to it... like a few GTI's with controllers like the ones I outlined. then your away....
........oztulesVillage idiot...or... just another hack out of his depth
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 12:46pm 17 Jul 2017
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I hadnt bothered looking at powerjacks until now- it appears that I have one already in my car?? 8Kw (yeah I know lol) that could be used to control the GTI's???- why not the little one then?
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:04pm 17 Jul 2017
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If you install the GTI with panels connected as normal and use the power jack as your grid it will back feed the excess power into your batteries. The small inverter won't do that.There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 02:12pm 17 Jul 2017
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shame, i'll probably have to buy another powerjack then as I really dont want a 10kw 12v system.... the wires would have to be- um - substantial... ;-)
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:57pm 17 Jul 2017
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I have seen the odd one come up second hand on Gumtree for around $400 for 48V units.There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 03:09pm 17 Jul 2017
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yeah, I was just hoping that I could make use of these gti's- I mean 10kw of inverters- for free, if they could have been run as a kind of `minigrid' would have been nice
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 03:25pm 17 Jul 2017
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Remember to get the LF version... the HF version won't do the back feeding.
.......oztulesVillage idiot...or... just another hack out of his depth
rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121
Posted: 04:15pm 17 Jul 2017
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I can not understand this 300 volt battery are solar panels that feed grid tie inverters 300 volt NEVER seen one ????Always Thinking
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 04:30pm 17 Jul 2017
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waves hi
yeah, looking at specs at one (ABB pvi 5000 tl outd) min dc input voltage is 150v, max is 530vdc!!!!
edit to add- thats the grid tie inverters specs, they series string the panels to get to that figure, the panels here are 36v nominalsEdited by Boppa 2017-07-19
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 08:15pm 17 Jul 2017
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As they put out 240V having the input voltage near that improves efficiency, also the high voltage means thinner cheaper wires due to low current usually >10A.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: 03:52pm 18 Jul 2017
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for on grid systems we used the highest inverter voltage (265-270 volts AC) times the square root of two gives the AC peak voltage 370 volts. we would aim to keep the DC voltage above that number if the roof space would allow the right amount of panels. I'm confused, no wait... maybe I'm not...
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 04:19pm 18 Jul 2017
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I have been wondering about over sizing the panel wattage, the 5KW GTI setup I am using ATM is 2 X 10 250W panels with 30.4 MPV. If I added another 2 panels to each string or even 4 to each string I am I at risk of harming the Zeversolar GTI?There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 05:00pm 18 Jul 2017
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Seems not everyone was getting what I was trying to do hopefully above will clarify
the 6x gti inverters arent for battery charging or anything else except acting as approx 10kw of offgrid inverters for the house/shed
if the sinewave inverter wasnt happy or the gtis werent happy with the voltages, I got a 300w variac I could put inbetween the sine wave and the gti's to boost/cut the voltages appearing to them and act as isolation between them and the little one(plus maybe a incandescent bulb on the sinewaver to keep it happy)
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 05:42pm 18 Jul 2017
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I think the first reply you got from Oztules is going to be the best answer you will get. GTI's were never designed to be stand alone inverters in most cases. But having the right off grid inverter will allow you to get some use of the GTI's.There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 06:21pm 18 Jul 2017
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I know at least some peoples will, I was talking to a friend who got his to fire up off his genny when they had a 3 day blackout after a major storm, during the day it was working off the genny and giving him full output from the panels into the house, and that was just a little 300w chinese job feeding the gti, that fed his water pump and fridge and freezer, something the genny couldnt have done by itself lol
edit to add just got an email back from him, his inverter is a SB10000TL-US-12 made by SMA apparently, so they do pass through the dc from the panels, which makes me wonder if they would from a battery bank instead
admittedly I still have no idea of what the inverters at the farm are or if they can do this, I'm gunna get him to keep them there for me to pick up next time i'm down there and then basically try it and seeEdited by Boppa 2017-07-20
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 09:19pm 18 Jul 2017
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[quote=madness]I have been wondering about over sizing the panel wattage, the 5KW GTI setup I am using ATM is 2 X 10 250W panels with 30.4 MPV. If I added another 2 panels to each string or even 4 to each string I am I at risk of harming the Zeversolar GTI?
As long as you stay within the amp and voltage specs it should be fine. the 5kw SMA was 4.6 nominal and we were allowed to take them 33% overpanelled to 6.1kw and it still complied with the CEC paperwork. I am guessing the zeversolar has roughly the same internals as the SMA inverters seeing as it is the same company.
The current fronius primo is rated at 5 kw and that can be paneled to 6.5 kw on grid legally (33% overpanel). The installers manual says they are good for 7.5kw. I am interested in this because I think there is a possibility that we will get to install the full 50% overpaneled system if it is combined with a battery bank.
sorry Boppa we got sidetracked. I kinda agree with the other guys, I have done a few 120 volt systems and there are certain components that will have to be custom made or you will need deep pockets, some of the stuff can be found from EV build suppliers but it is still a hassle. I waited for 6 months for the right spec fuses on one build. With 48 volt everything is off the shelf and reasonably affordable.
I am going to try oztules new test setup with a 2.5kw offgrid inverter and a 5 kw GTI and see if that will work for me.
I would go solar panels...oztules pwm hi volt DC regulator....1.8kw GTI inverter(1 to start with)....h bridge inverter....batteries
see if you can get that working and build up from there. I'm confused, no wait... maybe I'm not...
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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