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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:44pm 13 Jun 2013
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I recently bought a solar grid tie system for the panels. It came with a Latronics grid tie inverter. Is it of any use with off grid? If not I will sell it and put the money towards a MPPT charge controller.There are only 10 types of people in the world: those who understand binary, and those who don't.
MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819
Posted: 10:02pm 13 Jun 2013
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I don't know much about Latronics but I have a SMA Sunny Boy GTI connected to a RAPS Sunny Island with its bank of batteries. I use the RAPS as the "grid" and all works quite well. I can't see why the Latronics can't be used in much the same way except that the GTI would have to be told in some way to switch off when the batteries are full if the RAPS unit also doubles as a battery charger as the SMA unit does.
David M.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 01:08am 14 Jun 2013
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My understanding of grid tie inverters is that have a maximum voltage output. This is to prevent the grid voltage getting too high especially with a lot of households feeding in from one area.
The off grid inverter I have is also a battery charger but it can not charge and be an inverter at the same time.
There are only 10 types of people in the world: those who understand binary, and those who don't.
I know SMA as mentioned and Selectronic both support hybrid AC coupled systems consisting of a standard offgrid inverter/charger and a normal grid inverter.
The off grid inverter provides the AC sync the grid inverter requires. It also draws excess power if available to charge batteries.
While I have not looked into it in detail I would assume any grid inverter that is capable of controlling its output to a maintain a specific grid voltage would be compatible. Some don't and just shutdown for x time if the limit is reached.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:09am 14 Jun 2013
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I think I will just get rid of it and use 2 mppt chargers that work together.There are only 10 types of people in the world: those who understand binary, and those who don't.
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 04:31am 14 Jun 2013
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If the Latronics inverter is a transformer based inverter, which i think it is then it can back feed as a charger, as the H bridge works both ways.
It is only a matter of having a 240 VAC signal to activate the inverter to get it out of anti island mode, ( it thinks its connected to the grid,) then if the DC input is greater than the AC demand it will back feed to the batteries at a converted amps / power input ratio.
All you then need is some form of charge control circuit to disconnect the input when the batteries reach full charge, because the back feed system has no charge control built in, unlike Mobie's SMA inverter/charger which i have the same unit with built in charge (back feed) control.
Personally i would not dispose of the inverter as its one of the top brand names and can be used, its all a matter of how skilled you are or how deep your pockets are, my pockets are shallow and i make the best from what is free with little outside cost
Its a not common known fact that few have tried but backfeed works well, as a old long term member here (OZ) found out recently from a visit from another long term member (Gordon) who done the R&D for a back feed system for transformer based inverters.
Just to be clear im not the guru here (i wish i was) on this system it is Gordon, who is presently band from the forum to comment, although i am one of few who know Gordon and get to see his work and developments, which is far advanced to what most forum members do on the cutting edge.
Pete
Sometimes it just works
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 01:04pm 14 Jun 2013
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Tell me about the shallow pocket issue.
The panels I have are are grid connect type Sharp NU-SOE3E which have maximum power at 23.7 volts open circuit is 30. At present I have a 24 volt battery bank that I charge from a generator and use a inverter charger. I have 16 of these panels now, 5 came with the inverter and I have since purchased another 11. My plan is to use 2 MPPT chargers with a string of 8 panels on each charger. The chargers are like a master and slave with one controlling he other. I have not bought them yet but will in the next few weeks.
The inverter is a PVEdge 2500 which can operate of solar panels or a 48 volt battery bank by changing a switch. If I had a 48 volt battery bank would there be any advantage running this inverter parallel with the off grid inverter?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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