panels to battery 40m

[greenhouseparos]

nice ideas there billi.

seem to have gotten myself into chicken against the fence mode. now been able to take a step back.

the second inverter and MPPT together seems to offer good flexibility while giving good efficency.
i have actually got 22 of these panels so this approach could be very useful.

reading the outback manual dosen't suggest that there is a problem with using the aux contacts to control a second array although if the bats need charging i think i get the same wastes as before. maybe more? for money saving though it's  good.

Paul

[billi]

Paul

I have 4000 watt PV  and two  MPPT controllers  and a 1 kw windturbine   . The windturbine has basically no controller      anymore ( disconnected the dump for a reason)  , cause the outback MPPT   slows down in amps   , when Wind picks up , so they basically think  those Amps from the turbine are theirs 

Surely , if you have 1000 watt connected directly to your battery   , while the rest  about 2800 watt is regulated and decreases to 0  AMP charge  while battery gets stuffed , 1000 watt  is still too much  for a float charge  , so  some sort of  regulator or dump would be ideal  ( like the internal relay in the outback) or just a voltage sense relay that kicks in at say 30 volt and dumps  say 300-500 watt

But read your Inverter manual   ,  cause they(Studer ) have something as well

All the Best
Billi

7.5 AUXILIARY CONTACTS
The XTH, XTM and XTS, with TCM-01 and ARM-02 module, have two dry reversing contacts that are potential-free. The status of the contacts in deactivated mode is indicated by the annotations, N.C. = normally closed and N.O. = normally open. When the contact is activated
Maximum contact loads: 230 Vac / 24 Vdc: 16 A or: max. 50Vdc/ 3A
These dry contacts are programmed by default for the following functions:
Contact no. 1 (AUX 1): The contact has a function of automatic start of generator (two wires). The contact will be activated when the battery voltage is below a value, during a given time fixed by parameters {1247/48}/{1250/51}/{1253/54} The contact will be deactivated or when the charge cycle has reached floating {1516}, or when the "Aux. 1 deactivation voltage" {1255} is reached during a predetermined time {1256}
The voltage of the battery is automatically compensated according to the instantaneous battery current the same way as it is done for compensation of LVD (see sect. 7.3 – p.26) if parameter {1191} is activated.
Contact no. 2 (AUX2) : alarm contact by default. It is deactivated when the inverter is out of service or is working at reduced performance, either because of manual control or if there is an operational fault such as overload, under-voltage of the battery, over-temperature, etc.
If the operator or installer requires different behaviour for the auxiliary contacts, they are both freely and individually programmable depending on the battery voltage, the output power, the inverter status, the internal clock and the Battery state of charge (if BSP module is present) . These setting can be done with the the RCC-02/-03 (remote control unit)
The intelligent programming of the auxiliary contacts allows many applications to be considered such as:
 Automatic startup of the generator (two or three wires)
 Automatic load shedding of lower priority loads of the inverter (2 sequences)
 Global or individual alarm
 Automatic disconnection (load shedding) of the source
For more information on the auxiliary contacts nr 1 and 2 programming, do refer to our application notes available on Studer web site www.studer-innotec.com. Like:
AN003: Anti-blackout system for grid connected application (Solsafe)
AN005: Automatic management of 2 different energy sources
"AN007 Automatic start of a generator" available on our website www.

[greenhouseparos]

So here is plan B

14 panels 2660w @ 73.2v (16mm cable  ) to an 80amp MPPT charger (more expensive than a 60amp but less expensive than 2 of them  ). This will get my system up and running within the funds available and without to much losses. Then i have another 8 panels to play with. As it has been pointed out my inverter does indeed have some interesting features which could help utilising these as does the charge controller.

any comments??

one question i have is with the array voltage. the panels have a Voc of 45.2v and the charge controller spec recomends for 0c low temp (Greek islands don't normally freeze) to multiyply Voc by 1.1. This makes  49.72v. Max v input to charger is 150v. Is (49.72 x 3) 149.16 cutting it a bit fine?
 
thanks Paul   

[Justme]

That looks a bit to fine to me.

Remember that the magic smoke gets released when you go over the volt limit.

There is a string / array calc on the Outback forum that you can put all the specs & local temps into & it will give you the results

http://www.outbackpower.com/resources/string_sizing_tool/

[greenhouseparos]

yep!
been there and looks like it gets fried.

(just an idea thermostatically controlled array disconnect)

[billi]

Paul

73.2v VOC   or 2 panels in series  is    good   , what i would consider   is to use 16 or 18 panels  on the one  controller   

AMPS are just  clamped to  80 Amps  ,  so do not see why this should harm the controller

But  Justme   knows more about this , i think

[Justme]

Yeh the FX80 will clamp the charge amps at 80 (it will actually let more through but not for very long).

I have 1200watts connected to a FX80 & a 12v bank. So thats like you having 2400watts @ 24v. It does not run at max amps for long either due to the lack of sun or that the bank is to full to take the charge. I would not worry about the 2660watts you are planning on fitting unless you have long periods of high sun & low bats.

I run mine at up to 115v in normal weather, cant go over 130v even at -20c. Coldest we have ever had is -15c
 

[greenhouseparos]

couple of questions:

what exactly does "clamp the charge amps at 80amp" mean?

reading the manual i understood that any extra power over 2500w (24v) is simply lost. am i reading it wrong and what are the adverse effects of extra power from the array?

paul 

[Justme]

couple of questions:

what exactly does "clamp the charge amps at 80amp" mean?

reading the manual i understood that any extra power over 2500w (24v) is simply lost.

Thats exactly what it means. Any power over 80amps out is simply not collected.

[greenhouseparos]

a small update
to get the system up and running i have now committed to the MPPT outback 80amp charger with 14 panels wired to give 73v 2660w. seems like you get a lot of options to use this charger in varying ways and the Aux rely looks very useful. maybe able to control the remaining 8 panels(thanks for the idea Billi) will post some pictures of the install soon. should be happening within the next week depending on delivery. 

[billi]

Great .....

maybe able to control the remaining 8 panels(thanks for the idea Billi)

.... Maybe  it will work to connect them directly to the battery with the aux relay in the Outback or your Inverter relays) shifting excess  power away  ,  but i forgot the 40 meters  run  the last time   , but will have a think... about it


But i would say there are better options if you have more money spare later  ( second controller or small Grid tie inverter)

Billi

[greenhouseparos]

some more advice needed.
what if any protection should i be considering between array and controller and controller and batteries? i have been in touch with Hager about using one of their MCBs and they have advised a triple pole 40a with 2 poles wired in seires for the array to controller which would give isolation and protection.
the outback 80 manual advises an 80amp breaker. anybody else using these standard MCBs or are there other options?

Paul       

[rogeriko]

You cannot use regular breakers on DC circuits because the contacts do not open far enough apart and they spark inside like a small arc welder. I use these cylindrical fuses on my panel installations they open far enough not to arc. I would not put a fuse between the controller and batteries because if someone opens it by mistake the controller will probably be damaged by overvoltage. Just put one of these on the wire coming in from the panels and you can use it as a disconnect too. About 14 euro.

[Outtasight]

AC MCBs are fine for lower voltage with a single pole gap.  Mine work just fine at 24V, happily breaking 35 to 40 Amps without burning.

As the supplier mentioned to Paul, you can use MCBs at higher DC voltages if you put poles in series to increase the DC breaking capacity (puts double the gap in the switched path).  You can then use them just fine for a 48V DC system.  Up to 100V you can try using a 3 phase breaker with all three poles connected in series.

Only for grid tied PV where you get DC voltage of 200-400V do you need special DC breakers.

You should still use a appropriate fuse on the controller to the battery.  A 80A controller should use a 100A fuse.  I use ANL DC fuses that bolt down for a good contact.

Not fusing the controller is dangerous.

If the fuse blows the controller will only be exposed to the Voc of the solar panels so will not be damaged from over voltage (if it`s designed well).  The Morningstar MPPT60 has no problem with being disconnected from the battery at full power.  I accidentally shorted my PV bus bar on the wall outside and the battery supply fuse blew without harming the controller.  Just nearly blew me off the platform with the copper plasma blast from the vaporised test meter leads - the meter was set by mistake to current rather than volts reading  

[greenhouseparos]

a big thanks to all the advise thats been given so far.
finally got my system up and running. now charging 12 opz 1000ah batteries (24v) with a 2660 array using an outback fx80 charger. although i have the batteries conected to an inveter xtender 24v 3500w i havent had any loads conected until today.
the charger displays min and max voltages for the day with 25.2v being the normal min low voltage which i believe means that the batteries are charged (no soc metering yet). tonight i run 4 low energy 15w lights for about 2 hours and when i finished and turnned of the inverter i notice that the min bat voltage had dropped to 24.7v which is a 75 - 80% soc voltage. whats happening?
this seems like a very big drop in the soc voltage or am i not understanding things correctly
paul