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Author Topic: How to do big AC Off grid with small Multiplus  (Read 8953 times)
freddyuk
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« Reply #15 on: July 03, 2014, 06:19:30 PM »

PV is matched to Victron so cannot overload it. You can use relay on the AC out but we don't want on/off situation but proportional control. You would need 3 x immersuns plus one for the ultimate dump protection so getting expensive that way. Have something in the pipeline I hope.
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billi
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« Reply #16 on: July 03, 2014, 08:27:59 PM »

Quote
PV is matched to Victron so cannot overload it

Cool


 Smiley


Quote
You can use relay on the AC out but we don't want on/off situation but proportional control. You would need 3 x immersuns plus one for the ultimate dump protection so getting expensive that way. Have something in the pipeline I hope.

 Roll Eyes   Dont understand your  setup  idea    or problem   then (when Victron meets  PV potential)   ,  4 immersuns  ?    for  What ?  Do you have 9-12 kw PV   ??


Quote
proportional control
   what do you intend to control ?


Just invest your money in a well sized battery and a dump load controller  or bigger Victron .... i guess





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freddyuk
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« Reply #17 on: July 03, 2014, 09:32:00 PM »

PV = 10kw. Victron = 10kw. Any more inverter is wasted.
Victron relay switches on the dump so 3kw load (immersion) will draw 3kw - but there is only 2 kw spare PV coming on so the other 1kw will come from the batteries. With proportional control only surplus PV power will be dumped based on SOC.
Immersun switches 1 x up to 3kw immersion based on surplus solar power? I need 9.5kw dump capacity measured from the battery SOC so batteries always charged first. Victron just checks SOC and then either opens relay to dump or switches off the GT inverters thus no generation. It is not a sophisticated system for diversion.
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billi
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« Reply #18 on: July 04, 2014, 10:33:15 AM »

Hi

..."morningstar relay driver"  with its 4 relays  perhaps ? http://www.morningstarcorp.com/products/relay-driver/

 So you have 5 programmable relays  with the Victron inverter  and 6 if you install a Victron battery monitor with your system  .....  to control  smaller immersions  

Sure i understand that this is all then controlled by SOC  of battery  , but does not matter too much in my opinion cause battery is always kept full  

Or as an alternative to immersun    .... the powerdog https://translate.google.ie/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.eco-data.de%2Fprodukte%2Fpowerdog-m-detail.html&edit-text=&act=url

Its unfortunately a bad google translate  , from this German product,  that  i know of  since a while

as far as i know it can  (close  to) step-less increase the output of one or more immersions , it means  if there is only 600 watt surplus it will transfer this to the immersion , if there is more surplus it will transfer  more


Just thinking

CU Billi

Edit :... on the otherhand , if you would have a grid  connection , the Victron would work without any surplus  gear  and any excess  power would just  be feed in http://www.victronenergy.com/upload/documents/Whitepaper-Self-Consumption-and-Grid-independence-with-the-Victron-Energy-Storage-Hub-EN.pdf



So probably  another idea  to have a second small grid with heating  idea , that is a   "fake grid" on the AC-in side of the Victron

But  again just thoughts ...




« Last Edit: July 04, 2014, 11:06:58 AM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
Fionn
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« Reply #19 on: July 04, 2014, 04:47:46 PM »

I came across an interesting possibility that's related to this issue recently so I'll post it here in case anyone is interested.
Basically there are very cheap sine wave inverters available that have built in battery chargers also.

This is such a model:
http://www.ebay.com.au/itm/LCD-8000W-power-inverter-LF-pure-sine-wave-DC-48V-AC-240V-charger-LCD-UPS-/321260371334?pt=AU_Boat_Parts_Accessories&hash=item4acc9c3d86

Now they have DC input from the battery bank, and AC output, as well as an AC input to charge the battery bank.

However, they can be used to sync a grid tie inverter to their output, but what's more they can also back feed any excess production from the GTI into the batteries.
This means they can behave in a very similar way to a sunny island or whatever.
Apparently they will supply up to 3kW of charging current in reverse to the battery string.

There are two caveats:
1. You now need to install a dump load controller on your battery bank to cope with situations where the bank is charged and the GTI is still providing lots of power.
2. The inverters need a very minor mod (ferrite core on input to transformer) to allow the GTI to sync and reduce idle current from 4A to 1A or so.

The full details are posted in this thread:
http://www.anotherpower.com/board/index.php/topic,902.0.html
and  this massive one - which initially is about a different (but related) inverter.
https://forums.energymatters.com.au/solar-wind-gear/topic3344.html

It seems that there are cheap chinese power and control boards which are being used in a lot of these inverters.
The PowerJack brand ones these boards in conjunction with toroidal transformers which are of very high quality and efficiency and the ones to go for it seems.

Some Australians have been using the inverters for long periods and have ditched expensive name brand models in favour of them they are so happy with their performance.

I hope that this is of help to any off grid people that haven't come across it before.

Fionn.

« Last Edit: July 04, 2014, 05:57:49 PM by Fionn » Logged

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Eccentric Anomaly
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« Reply #20 on: July 04, 2014, 05:43:27 PM »

Fionn, your two anotherpower.com URLs are rather similar.
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Fionn
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« Reply #21 on: July 04, 2014, 06:00:11 PM »

Fionn, your two anotherpower.com URLs are rather similar.
Thanks for the heads up, now rectified!
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« Reply #22 on: July 04, 2014, 10:22:31 PM »

Umm, thanks, I think - that second thread is a bit long.

Still, very interesting that these things are seem to be reasonably robust. My expectation of something like that would be that it'd work fine if used exactly as specified but would likely go phut if you go a volt or watt out of range. Inverters do seem to be remarkably expensive for what they do.
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rogeriko
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« Reply #23 on: July 04, 2014, 10:31:04 PM »

Wow they even do a marine version  hysteria hysteria


* LF inverter.jpg (79.72 KB, 1200x800 - viewed 487 times.)
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Fionn
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« Reply #24 on: July 04, 2014, 10:51:41 PM »

Umm, thanks, I think - that second thread is a bit long.

Still, very interesting that these things are seem to be reasonably robust. My expectation of something like that would be that it'd work fine if used exactly as specified but would likely go phut if you go a volt or watt out of range. Inverters do seem to be remarkably expensive for what they do.
Yes, the second thread is very long but it's not necessary to read it all.
A synopsis of it is as follows:
Guy buys W7 inverter, it works but has terrible idle current. This turns out to be due to cr*p transformers.
He gets a custom toroidal transformer wound and it vastly improves efficiency.
Adding a small inductor on the transformer primary reduces the idle current by 75% as well as producing some unknown result (noise reduction or something presumably) which improves the output sufficiently for grid tie inverters to sync to it.

User oztules then buys a "PowerJack" brand inverter and finds it has the same electronics as the W7 but also includes toroidal transformers.
All that's required is the added inductor for tip top performance.

Around the same time they discover a cheap source of toroids from non compliant grid tie inverters and start using them to upgrade the W7s.
The rest of the thread as far as I've read (page 55) is concerned with them gilding the lilly fine tuning the toroidal winds.

Also some are picking up the 2nd hand toroids and creating a whole inverter for very little outlay by just adding the replacement control and power cards that are available for AU$179.


Bottom line - the Power Jack inverters are high quality pieces of kit and with a very minor modification have very low idle power consumption (~20 watts).
They also - like many inverters of this type apparently, can sync to a grid tie inverter and soak up any available excess power (on the AC side from the GTI(s) ) up to their limit of about 3kW / 60A and use it to very efficiently charge the batteries.
They appear to extremely robust - not just reasonably robust.

For the OP on this thread you would still need AC dumping to keep the grid ties from going overvolts and disconnecting if your grid ties are capable of outputting greater than the 3kW.
You'd also need to add a dump load to your battery bank of at least 3kW capacity.
« Last Edit: July 04, 2014, 10:53:55 PM by Fionn » Logged

PV - 2.75kW East, 1.5kW South, 2.5kW West. 3 x Flat Plate Solar Thermal with side arm FPHE on 268L cylinder
billi
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« Reply #25 on: July 04, 2014, 11:57:28 PM »

Wow they even do a marine version  hysteria hysteria

 Grin  , touch wood that only the bikini breaks .....
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stephendv
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« Reply #26 on: July 05, 2014, 07:12:50 AM »

Dug up this old post about a different experience with power jack inverters: http://ludens.cl/Electron/chinverter/chinverter.html
Maybe they've changed the design since then.
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freddyuk
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« Reply #27 on: July 05, 2014, 08:39:15 AM »

Dug up this old post about a different experience with power jack inverters: http://ludens.cl/Electron/chinverter/chinverter.html
Maybe they've changed the design since then.

That's the one I remember!
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clockmanFR
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« Reply #28 on: July 05, 2014, 01:41:06 PM »

I have noticed these power jack inverters for some time and the first ones were rubbish as per stephendv's link. I actually asked the chinky firm what would a 6000w actually handle, "just about 2000w of standard stuff because they can not cope with the inrush required when capacitor starting stuff like motors".

However I have also heard good points about them and they certainly stand a bit more if they have those toroidal transformers in them.

http://www.ebay.co.uk/itm/6000W-LF-pure-power-inverter-DC48V-to-AC220-240V-100A-BTY-charger-UPS-3-5-LCD-/261519232446?pt=UK_Car_Exterior_Accessories&hash=item3ce3c2cdbe

Looks like the same girly? But the company selling them seems to have some bad negative feed back from across Europe.

 0.99p..... might even bid. But what is interesting is there terminology on a High Freq inverter and a low Freq inverter and what each can take according to them. The market price seems to be about 480 but then that's a bit much for me to play around with, but its certainly a consideration.

Note, Sorry Navitron, but these Inverters have come on, so sorry for the links. But perhaps an English company could stock a few.


* aaPSW%20warning%20label.jpg (335.41 KB, 949x730 - viewed 385 times.)
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stephendv
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« Reply #29 on: July 05, 2014, 02:25:02 PM »


Pah! you only get 1 girl with the 6000W inverter, for a bit more money you can get the 8000W and 3 girls!  http://www.ebay.co.uk/itm/8000W-LF-pure-power-inverter-DC48V-to-AC220-240V-Battery-charger-UPS-3-5-LCD/261518856325?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D23777%26meid%3D8100583807917985562%26pid%3D100005%26prg%3D10165%26rk%3D1%26rkt%3D6%26sd%3D261519232446&rt=nc
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