navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: 1 [2] 3 4   Go Down
  Print  
Author Topic: Off gird battery voltage  (Read 7489 times)
jonesy
Hero Member
*****
Offline Offline

Posts: 839



« Reply #15 on: August 14, 2015, 02:24:51 PM »

no. I'm talking about solar inverters. Or wind. The SMA stuff actually, but I suppose anything.
Unless I'm missing the key to the puzzle, they would be just as happy converting 300Vdc into 230Vac as they would from a solar panel.
If I understand you correctly, then you are missing the key.
A solar inverter/grid tie inverter GTI will not work with a battery.  Well, it will, but you will kill the battery.  The GTI will take the power out of the battery to the limit of the GTI. So if you have a 1kva GTI, it will take 1kva out of the battery until the battery is completely flat. It's technically possible to manage the (newer) GTI, like the sunny island does, using frequency control, but that would be a interesting personal project.
The 2nd problem is that the GTI won't island, unless you know how to over-ride the built in anti islanding.  Some of the non-G83 may island, but IIRC the non-G83 was because there were not 2 means of anti-islanding, so you had to install a 2nd one to meet G83.
I do agree with you that theoretically they would make a nice inverter.
Logged

1.1kWp PV & SB1700. 7kW log burner.
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11908


An unpaid Navitron volunteer who lives off-grid.


« Reply #16 on: August 14, 2015, 03:33:59 PM »

Then of course,
                 If you are just talking about solar powered inverters, you can work without a controller and just a voltage relay to dump the excess,letting the battery itself provide the resistance. This would entail a bit of trial and error but a 330watt array dumping straight into a 850ah x 24v forklift pack during the height of summer would need a slight little top up every 14 days if you had no divert to dump and no load. You could hard wire any inverter you like to the pack with a sensible inline fuse. I used to think that putting the fuse next to the battery pole (which was originally advised) was a good idea but then common sense dictated that it be as far away as possible from the bubbling gas.
  A rated 330watt array can provide a steady 450 watt+ at noon, just think of the extra profit that the energy supply guys were making before the advent of immerSun.
 The whole renewable energy idea boils down to a question of balance. Balancing what you need, with what you can get by with,and what you can afford to supply.
  As time goes on, betters idea will surface as they already have and we would be sensible to adopt them and make the best of them.
                                                                     Biff
                                                   
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
nominous
Full Member
***
Offline Offline

Posts: 136


« Reply #17 on: August 14, 2015, 04:43:46 PM »

A solar inverter/grid tie inverter GTI will not work with a battery.  Well, it will, but you will kill the battery.  The GTI will take the power out of the battery to the limit of the GTI.
Assuming you are islanded, then will it only take out of the battery to satisfy the demand of the devices connected to the island ?
Because it cannot supply more than is demanded upon it. But in a grid tie situation the grid is "demanding" whatever the inverter can manage to output.
Else where does the excess power go ?
Same operation as a non-grid tie inverter.

Quote
The 2nd problem is that the GTI won't island, unless you know how to over-ride the built in anti islanding.
I may suck here again from poor terminology, but reading the manual for the older transformer sunnyboys, you can set them up to operate without syncing to a grid.
Apparently.

Quote
I do agree with you that theoretically they would make a nice inverter.
OK, so I'm not totally off the right track Smiley
Logged
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11908


An unpaid Navitron volunteer who lives off-grid.


« Reply #18 on: August 14, 2015, 04:52:59 PM »

               "Same operation as a non grid tied inverter" Grin
             Errrrrr Not quite,
                        If only it were that simple,
                                Could be big bang, lots of black smoke,,great variations of explainations and big hole in pocket.
                                                                           Biff
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
skyewright
Hero Member
*****
Offline Offline

Posts: 1763


« Reply #19 on: August 14, 2015, 06:00:06 PM »

Assuming you are islanded, then will it only take out of the battery to satisfy the demand of the devices connected to the island ?
What's missing with a GTI is (among other things) something to handle putting charge into the battery. That's why things like the SMA Sunny Island & Victron MultiPlus/Quattro are described as Inverter/Chargers, i.e. they are dual role.

Logged

Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
Tiff
Hero Member
*****
Offline Offline

Posts: 934


« Reply #20 on: August 14, 2015, 06:51:41 PM »

Assuming you are islanded, then will it only take out of the battery to satisfy the demand of the devices connected to the island ?
What's missing with a GTI is (among other things) something to handle putting charge into the battery. That's why things like the SMA Sunny Island & Victron MultiPlus/Quattro are described as Inverter/Chargers, i.e. they are dual role.



You can always charge from seperate charger or solar charge controller.
Logged
skyewright
Hero Member
*****
Offline Offline

Posts: 1763


« Reply #21 on: August 14, 2015, 07:00:20 PM »

You can always charge from seperate charger or solar charge controller.
Indeed, and using a separate charger/controller brings us back to the (currently) more 'normal' 12V/24V/48V battery choices, which nominous felt a GTI might get away from because if its high DC voltage spec (unless I'm misunderstanding).
Logged

Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
woodi
Full Member
***
Offline Offline

Posts: 119



WWW
« Reply #22 on: August 17, 2015, 11:01:40 PM »

We are 24v here, with 1000ah, and a couple of Victron Multi 3000 inverters in parallel. We've an Aurora 3600 GTI ac coupled to the output of the multis. It needs 50v to wake it up, but works great with the Multis. 4kw solar and 3kw wind runs our place with a 'normal' set of appliances, and we've just moved over to a series of storage and immersion dumps to reduce our woodfuel consumption. We'd probably go with 48v if doing it again, but the setup we have just crept up on us. I sold a couple of Sunnyboy GTI's to pay for some of this kit as I was worried about the whole AC coupling idea, but it has turned out well with the Aurora to manage the wind generation.
Logged

8kw PV - 40x80w; 8x100w;13x300w Victron 150/70, 100/50, 100/30 MPPT; 3x Victron Multiplus 24/3000/70; Color Control GX Monitoring; 1000ah@24v traction batteries - 50 tube solar thermal - 3kw Bornay Inclin grid tie/ac coupled wind turbine - wood fuel cooking & heating.
jonesy
Hero Member
*****
Offline Offline

Posts: 839



« Reply #23 on: August 18, 2015, 09:38:58 AM »

A bit more info, nominous
http://www.anotherpower.com/board/index.php/topic,1044.msg10320.html#msg10320
TBH you need to read the entire thread to understand the post I've linked to. What the guy has done is take a 6kW bidirectional charger/inverter and add a (large) choke.  The choke allows his GTIs to connect to the inverter without blowing it up, and then the inverter will charge the batteries.  However, if the batteries don't take enough load, or load isnt taken on the AC side, the GTIs trip out on over voltage.
The rest of the link describes a second mod he did to replace the enormous transformers they came with, which gave a high quiescent power of around 150W.  After making a large toroid replacement he got the quiescent down to around 30W, which rivals the big brand devices for a fraction of the cost, if you have the time and patience. If you aren't worried about the quiescent, then the same trick of adding a choke might even work on any transformer based inverter/charger.
GTIs are just 'all or nothing' inverters.
Logged

1.1kWp PV & SB1700. 7kW log burner.
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11908


An unpaid Navitron volunteer who lives off-grid.


« Reply #24 on: August 18, 2015, 09:58:46 AM »

                          "GTI are all or nothing inverter"
       That is a pretty good description of a GTI Jonsey,  fingers crossed!
                                                  Biff
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
camillitech
Hero Member
*****
Offline Offline

Posts: 5403



WWW
« Reply #25 on: August 18, 2015, 09:16:13 PM »

The choke allows his GTIs to connect to the inverter without blowing it up, and then the inverter will charge the batteries. 

I tried reading the whole thread Jonesy but it was way over my head. Unless I'm missing something, I have been doing this for years without a choke and charging my batteries. Trace 4548e, SMA Windy Boy 1200, Powerspout hydro turbine. You can do it with any Bi directional inverter with a transformer so long as you do not exceed the charging capacity of the inverter. Of course you need some form of 'diversion load control' but in my book that's essential with any kind of turbine and preferable to 'throttling' solar anyway.

https://lifeattheendoftheroad.wordpress.com/2012/05/15/commissioning-the-powerspout/

My new system is a mixture of both AC and DC coupled sources, the AC side of things being handled by 'cheap as chips' GTI's. One of the advantages being that you can upgrade to a higher battery voltage without affecting anything coupled via the AC side. Of course it's got disadvantages too, but Woodi, Heather Hopper and I have got grid tied wind turbines 'for buttons' and successfully integrated them into 'off grid' systems.

Cheers, Paul

Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11908


An unpaid Navitron volunteer who lives off-grid.


« Reply #26 on: August 18, 2015, 10:45:30 PM »

So lets say,
            You had 3.8kw of pv going into your bank,and you happen to have some spare PV left over, enough Panels to produce 210volts @ 970watt.
 and you have a grid tied inverter as well. It is a 2.5kw jobbie with a voltage range of 195v to 500volts.
  The specs say that the Inverter is Bi-directional,
  So I just wire the inverter into the house, wire the PV into the inverter and sit back and enjoy life,?
  The extra power that is not going to be consumed goes back to the bank and goes out again into the dc immersion dumps,? or I can add another controller2kw to the bank to take care of the excess.
  Could that possibly work,?
                               Biff
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8926



WWW
« Reply #27 on: August 19, 2015, 12:11:24 AM »

can you  provide a link or a name of those inverters ? are you talking about battery-inverters ?

no. I'm talking about solar inverters. Or wind. The SMA stuff actually, but I suppose anything.
Unless I'm missing the key to the puzzle, they would be just as happy converting 300Vdc into 230Vac as they would from a solar panel.
But they wont do anything to manage your battery bank. You'll be doing that with something else.

The new old stock stuff which is not G83 and sells for buttons on ebay. Still worthy for off grid.
Cheap enough to have a spare or two lying around.

a link would help ,    a quality  5000  watt MPPT charge  controler is under 500     a  decent offgrid inverter including a  pv chargecontroller is only similar money  ....



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
camillitech
Hero Member
*****
Offline Offline

Posts: 5403



WWW
« Reply #28 on: August 19, 2015, 06:16:25 AM »

So lets say,
            You had 3.8kw of pv going into your bank,and you happen to have some spare PV left over, enough Panels to produce 210volts @ 970watt.
 and you have a grid tied inverter as well. It is a 2.5kw jobbie with a voltage range of 195v to 500volts.
  The specs say that the Inverter is Bi-directional,
  So I just wire the inverter into the house, wire the PV into the inverter and sit back and enjoy life,?
  The extra power that is not going to be consumed goes back to the bank and goes out again into the dc immersion dumps,? or I can add another controller2kw to the bank to take care of the excess.
  Could that possibly work,?
                               Biff
Aye Biff,

and this is exactly when AC coupling starts becoming useful, when you've run out of roof space and  want to put panels a long way from your battery bank.

You will need a total diversion capacity of around 5kW and an 'off grid' inverter with enough charging capacity to cover the 970 Watt of PV, so at least 20 Amps @ 48V or 40 @ 24V. You can have as many controllers as you like, I have 4 and you can either set them all at the same voltage or at slightly different voltages to bring immersions on sequentially. I've done both and it works well.

Cheers, Paul
« Last Edit: August 19, 2015, 06:33:05 AM by camillitech » Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
billi
Global Moderator
Hero Member
*****
Offline Offline

Posts: 8926



WWW
« Reply #29 on: August 19, 2015, 08:31:48 AM »

.... one can run  quite long distances  between PV  and battery with an Mppt chargecontroler  ..... a 500 meter roll  6mm2 solarcable is about 200

-as an example- that would cover about 6000 watt of PV  50 meters away from the battery and charge controllers  @ 120 volt (PV)
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
Pages: 1 [2] 3 4   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!