Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: greenhouseparos on August 27, 2011, 10:16:58 AM



Title: panels to battery 40m
Post by: greenhouseparos on August 27, 2011, 10:16:58 AM
hi
i am installing 20 suntech 190+ad panels in a stand alone system. the panels have to be mounted 40m away from the batteries which is causing me some problems with cable sizing. my current idea is to use 2 morning star 60a mppt chargers with 2 10 panel strings wired for 72v (2 panels series) 5 parrele pairs. this will need 16mm cable for a 3-4% volt drop.
chargers + cable will cost about 1500euro.
if i fitted a inverter directly under the panels and run 220v to the batteries how would i charge the batteries? could i conect to the main inverter stecca 3500xtm  (which has a battery charger) or would i need a seperate charger.


Title: Re: panels to battery 40m
Post by: Justme on August 27, 2011, 10:21:30 AM
I would look at raising the array voltage by about double to quarter the cable size needed for the same losses. So look at other charge controllers / inverters that can take the higher voltages.


Title: Re: panels to battery 40m
Post by: billi on August 27, 2011, 10:39:56 AM
stecca   is same as studer-innotec i think   and they have perhaps better information  about "AC-coupling"  and as far as i know you can have a Grid tie inverter connected  , but i think your PV Panel size will exceed the  inbuilt charger capacity (of your stecca 3500xtm )

If you would have a 48 volt system you only need one  MPPT chargecontroller
Billi


Title: Re: panels to battery 40m
Post by: billi on August 27, 2011, 11:05:59 AM
Ah  ....  Perhaps a mixed idea would be elegant  

a small Grid tie inverter ( not at the panels  better close to off grid inverter ) and run the high DC Voltage  cables  to him  

this inverter adds then power to your off grid one during the day  and the rest of the panels connected to one MPPT controller to charge batteries directly  

I had a look at your Stecca inverter and they say it can handle 90 A   of AC charge  so about 2300 watt

Perhaps not much more expensive  tumble:

have a read here and click on "Partial AC-coupling in Minigrids"


 http://www.studer-innotec.com/?cat=whitepapers  


Title: Re: panels to battery 40m
Post by: greenhouseparos on August 27, 2011, 12:15:15 PM
I would look at raising the array voltage by about double to quarter the cable size needed for the same losses. So look at other charge controllers / inverters that can take the higher voltages.

using the morningstar 60a i could get the voltage up to 109v 3 strings of 3 but this uses only a total of 18 panels which would mean another controller. do you know any charger makes that can handle larger voltages?


Title: Re: panels to battery 40m
Post by: greenhouseparos on August 27, 2011, 12:17:59 PM

If you would have a 48 volt system you only need one  MPPT chargecontroller
 
saddly costs prevented a 48v system as the batteries would have doubled.


Title: Re: panels to battery 40m
Post by: Justme on August 27, 2011, 01:12:27 PM

using the morningstar 60a i could get the voltage up to 109v 3 strings of 3 but this uses only a total of 18 panels which would mean another controller. do you know any charger makes that can handle larger voltages?


Outback FM60 or 80 both do 145v. You can over size the array to controller. The extra amps just dont get captured. I have a theoretical 100amps from my array but have used an 80amp controller.


Quote

 
saddly costs prevented a 48v system as the batteries would have doubled.

Not quite true.

You still need the same total stored energy even though its a 48v bank. So the AH capacity can be 1/4 of the 12v banks.


If you use 3kWh per day & want 3 days autonomy then you need 3 kWh x 3 days x 2 (so you never go below 50%) = 18kWh

18kWh @ 12v = 1500ah or 15 x 100ah 12v bats (not that you should ever use a bank of that many bats)
18 kWh @ 48v = 375ah or 16 x 100ah 12v bats

The only way it can cost more is if you have a total need of less than 2.4kWh (so a 4.8kWh bank) so thats a usage of less than 800wh per day.


edit to add


why not have the bats near the array & have the inverted power travelling the distance?


Title: Re: panels to battery 40m
Post by: camillitech on August 27, 2011, 04:31:31 PM
In the grand scale of your considerable investment is 40m of 16mm square really that expensive  ??? http://www.tlc-direct.co.uk/Main_Index/Cable_Index/Armoured_SWA/index.html 178GBP for 16mm as opposed to 65GBP for 4mm   ??? or am I missing something. My wind turbine's 160m from my battery bank and my hydro turbine 470m, the one I'm currently installing is 1000m away  :o Think yourself lucky  ;D

Good luck, Paul


Title: Re: panels to battery 40m
Post by: Justme on August 27, 2011, 04:36:22 PM
You could also do a cost benefit analysis to see if the net gain from the bigger cable is worth the cost.


Title: Re: panels to battery 40m
Post by: greenhouseparos on August 27, 2011, 05:24:01 PM
In the grand scale of your considerable investment is 40m of 16mm square really that expensive  ??? http://www.tlc-direct.co.uk/Main_Index/Cable_Index/Armoured_SWA/index.html 178GBP for 16mm as opposed to 65GBP for 4mm   ??? or am I missing something. My wind turbine's 160m from my battery bank and my hydro turbine 470m, the one I'm currently installing is 1000m away  :o Think yourself lucky  ;D

Good luck, Paul

no considering the overall costs 200euro more on a 16000euro system is not much. Just exploring options. my wind turbine will also be over 100m from the batteries.


Title: Re: panels to battery 40m
Post by: greenhouseparos on August 27, 2011, 05:31:07 PM

using the morningstar 60a i could get the voltage up to 109v 3 strings of 3 but this uses only a total of 18 panels which would mean another controller. do you know any charger makes that can handle larger voltages?


Outback FM60 or 80 both do 145v. You can over size the array to controller. The extra amps just dont get captured. I have a theoretical 100amps from my array but have used an 80amp controller.


Quote

 
saddly costs prevented a 48v system as the batteries would have doubled.

Not quite true.

You still need the same total stored energy even though its a 48v bank. So the AH capacity can be 1/4 of the 12v banks.


If you use 3kWh per day & want 3 days autonomy then you need 3 kWh x 3 days x 2 (so you never go below 50%) = 18kWh

18kWh @ 12v = 1500ah or 15 x 100ah 12v bats (not that you should ever use a bank of that many bats)
18 kWh @ 48v = 375ah or 16 x 100ah 12v bats

The only way it can cost more is if you have a total need of less than 2.4kWh (so a 4.8kWh bank) so thats a usage of less than 800wh per day.


edit to add


why not have the bats near the array & have the inverted power travelling the distance?

i have 12 2v opz 1100ah batteries couldnt afford more. siting the batteries and inverternext next to the panels would require building some kind of weather proof construction which would eat up valuable euros.
thanks for the info   






Title: Re: panels to battery 40m
Post by: Justme on August 27, 2011, 06:14:36 PM

i have 12 2v opz 1100ah batteries couldnt afford more. siting the batteries and inverternext next to the panels would require building some kind of weather proof construction which would eat up valuable euros.
thanks for the info   



But thats the point. With a 48v system you would have only needed cells of about 550ah (I assume you are set up as 24v) . As they would be cheaper each you then have the funds for the extra cells. One way or the other you are going to have to spend extra money compared to an ideal system thats located all in the same spot. Could be on wire, a shed or even in the losses in the system due to bad planning / implementation. A large battery bank will be perfectly ok on a pallet with a cheap tarp / tin roof. Dep on the temps you get you might need some sort of insulation. Mine is outside & uninsulated. Even when its -18c the bank still works within what we need even if its not working at full capacity.

Now that its too late to change the bank V you have to live with it.

As there are not many solutions & all of them cost its now down to which cost / level of performance balance you are happy with.

In your first post you said you were going to install 20x190w panels & use 2 x 60 amp controllers.

Are you sure thats right?

I make 20 x 190w = 3800watts or 158 amps at 24v. That will need 3 x 60 amp controllers not the 2 you are planning on. It will work but you are loosing quite a bit of power / energy. 30 amps at 24v is the same as removing 720 watts of array during peak times. 2 x 80amp FM 80's would be much better & you get the 145v input too so helping on two fronts.


Title: Re: panels to battery 40m
Post by: billi on August 27, 2011, 07:56:13 PM
Quote
Just exploring options. my wind turbine will also be over 100m from the batteries.

 ::) not the easiest  to  combine wind and PV  and maintain an expensive battery
What  is your plan, how  to  connect the windturbine ?

The suggested Outback MPPT PV controller  might be helpful  with a windturbine idea

Billi





Title: Re: panels to battery 40m
Post by: stephendv on August 27, 2011, 09:34:55 PM
The midnite solar classic charge controllers can handle up to 250V: http://www.midnitesolar.com/productPhoto.php?product_ID=258&productCatName=Charge%20Controllers&productCat_ID=21

But you'd have to import it from the US, no European distributor is selling them yet, AFAIK.



Title: Re: panels to battery 40m
Post by: greenhouseparos on August 28, 2011, 01:42:57 PM
The midnite solar classic charge controllers can handle up to 250V: http://www.midnitesolar.com/productPhoto.php?product_ID=258&productCatName=Charge%20Controllers&productCat_ID=21

But you'd have to import it from the US, no European distributor is selling them yet, AFAIK.



just read your ac coupling article on your link. very interseting.
my problem has arisen for strange reasons. the initial system i planned used 18 suntech 190 pannels. i ordered 22 becuase i need 4 for a bore hole pump. when they arrived at the dealer he had 26 because he had to order a pallet. he offered the extra 4 pannels at cost price (an offer i couldn't refuse). now i am trying to fit the extra 4 into the system with out the costs rising sharply. the original 18 on 2 x 60amp morningstars worked. 18 pannels 2 sets of 9 3 parallel 3 series on the 2 chargers 109v at 15 amps over 40 m = 6 or 10 mm cable. i will use 2 of the extra pannels for water pumping and have 2 left. trying to fit them into the house array seems expensive and not cost efficient. will definatly have a use for them but not for the house array it seems.


Title: Re: panels to battery 40m
Post by: billi on August 28, 2011, 04:41:48 PM
a SMA Sunny Boy 2100TL costs ca 550 Euro  (ex vat )  and  an  additional outback FM60 MPPT controller about 480  (ex Vat )

Those both  would be my choice today  , specially with your "small" off grid Inverter  and use the outback to dump all access  power to a water heater  (including your windturbine)


Billi


Title: Re: panels to battery 40m
Post by: greenhouseparos on August 28, 2011, 05:33:15 PM
a SMA Sunny Boy 2100TL costs ca 550 Euro  (ex vat )  and  an  additional outback FM60 MPPT controller about 480  (ex Vat )

Those both  would be my choice today  , specially with your "small" off grid Inverter  and use the outback to dump all access  power to a water heater  (including your windturbine)


Billi

where do you find those prices?


Title: Re: panels to battery 40m
Post by: billi on August 28, 2011, 06:09:25 PM
secret  ;D

similar to your plan  ;)



I advice  to have a wise  thought   before  further action





Title: Re: panels to battery 40m
Post by: greenhouseparos on November 13, 2011, 11:42:59 AM
after some re-thinking i have been able to get the array to within 28m (cable run) of the batteries. my plan now is to split the 20 panel array into 2 seperate 10 panel arrays and use 2 morningstar tristar 60amp charge controllers. wiring the arrays in parrallel they will produce 36.6v and 52amps at STC. using these figures i get a volt drop index of 32.6 at 4% volt drop which requires 35mm cable.
i know that 3% volt drop is the exceptable norm but this would mean 50mm cable and a big price increase. any comments about increasing the volt drop to 4%?   


Title: Re: panels to battery 40m
Post by: Justme on November 13, 2011, 04:12:28 PM
I think you need to look at the specs & do the sums again.

10 x 190w panels is more than one 60amp controller can handle unless its at 36v or 48v battery voltage.

The controller is spec'ed at it's charge amps not its input amps. So in your case at 24v you have nearly 80 amps of charge.

Loosing 20amps per controller does seem like a lot to me.

I would also not be happy with 4% losses in the cabling. Can you not up the array voltage by wiring in series?


Title: Re: panels to battery 40m
Post by: greenhouseparos on November 13, 2011, 08:19:22 PM
yes but you can not charge a 24v battery with 24v. the float charge has to be almost 27v and an equalisation charge needs 30v.  admitidly 10 panels will probably supply more than enough amps and remember my calculations were based on STC figures. if i use NOCT figures (134w 33.1v 4.19a) i think things balance out more.

what my worries really are focused on is the volt drop. at 36.6v a 4% loss is 1.46v and at 33.1v its 1.32v.

am i right in thinking that a lower delivery voltage will deliver less amps?

i need to purchase the cable and chargers now and i want to  double check all my calcs     


Title: Re: panels to battery 40m
Post by: Justme on November 13, 2011, 09:00:25 PM
A lower delivery voltage will UP the amps for the same wattage. So increasing the losses due to the higher amps.

So less gets into the bank.



I dont think you get it.

If you bats are at a low SOC & you have a load on them then the controller will be running at 24v or even less.

Always calc using worst case. Your controllers cant do more than 60 amps x 2 & you have  162 amps available.
(at a nominal 24v)

Doing what you plan you will be loosing nearly half of your available power in charge controller under sizing cable & efficiency losses.

cable losses = 1.46v drop at 60amps x two strings is over 175 watts lost
controller losses = 42amps x 24v = 1008watts
add in the efficiency losses of the controllers & you are really taking a hit at the top end.

Even if you cant add an extra controller or fit two bigger ones why cant you up the array voltage?

A simple wiring change that will increase performance & reduce costs.











 


Title: Re: panels to battery 40m
Post by: rogeriko on November 13, 2011, 09:44:05 PM
Hold on has anyone checked the panel specifications,  http://ap.suntech-power.com/images/stories/pdf/datasheets/july2011/STP190S_24Ad+_EN_APMEA(H+S%20Connector).pdf 

These are only 5.2A panels at 36V MPP.  10 in a string will only produce 52 amps at any voltage. When connected to a 24V battery the panels will only produce 124 watts each. You can use 2 Morningstar Tristar 60A controllers and the thinner wire because the panels can produce about 12 volts more than you can use, so it dosnt matter how much you lose in the wiring. The problem is that these panels are not good for direct battery charging you should have 29V MPP panels for the job. I know of several installations with these mismatched panels and its a shame to see the power/money wasted.


Title: Re: panels to battery 40m
Post by: Justme on November 13, 2011, 10:03:24 PM
Hold on has anyone checked the panel specifications,  http://ap.suntech-power.com/images/stories/pdf/datasheets/july2011/STP190S_24Ad+_EN_APMEA(H+S%20Connector).pdf 

These are only 5.2A panels at 36V MPP.  10 in a string will only produce 52 amps at any voltage. When connected to a 24V battery the panels will only produce 124 watts each. You can use 2 Morningstar Tristar 60A controllers and the thinner wire because the panels can produce about 12 volts more than you can use, so it dosnt matter how much you lose in the wiring. The problem is that these panels are not good for direct battery charging you should have 29V MPP panels for the job. I know of several installations with these mismatched panels and its a shame to see the power/money wasted.

Till it catches fire lol

losses are losses & should be designed out not in

5.2amps at 36 = 187.2w x 10 = 1872watts per controller.

With an mppt controller thats still 78 charging amps per controller.
(controllers are rated for charging amps not input amps)

So still loosing 36amps.

On a good sunny summers day thats about 5kWh lost.


Title: Re: panels to battery 40m
Post by: rogeriko on November 13, 2011, 10:18:06 PM
He's talking about Tristar controllers not MPPT controllers, a 5.2 amp panel will probably produce 6 amps here in the Greek sunshine but thats still only 60 amps max. A Tristar will run all day at max amps no problem. As you say when the battery is under load at only 24 or even 23 volts you will still have only 60 amps flowing max. The voltage at the panels will indeed be a couple of volts higher to make up for the wiring losses, but seeing as the panels are 36V each theres plenty to "spare".


Title: Re: panels to battery 40m
Post by: rogeriko on November 14, 2011, 06:40:38 AM
Morningstar has a string calculator on their website

http://www.morningstarcorp.com/en/strings/calc.php 

Here you can enter various panels and see what works best. It seems that using 3 strings of 3 panels in series and an MPPT controller gives you best output, this way the voltage from panels to batteries will be just over 100V so wiring shouldn,t be a big issue. Using the non MPPT controller will run into the mismatch problems discussed previously.


Title: Re: panels to battery 40m
Post by: greenhouseparos on November 14, 2011, 09:48:22 AM


losses are losses & should be designed out not in


i not sure that's totally right. if i designed around the 24v 60a figures therefore having minimum losses at this voltage i would have 54a available for float charging which would have the charger working less than its rating. (50a for absorption and 46a for equalising). building in a small loss at 24v would have the charger working closer to its full potential. as it happens the 10 panels on 1 controller i have mentioned before would supply the 60 amps for all the chargers voltage range. yes i know this is a more inefficient way (i think 9 of these panels on a 60 amp controller is the most efficient) it's just that i have these panels and not to use 2 of them would be a pity. maybe in the future i could find another use for them and remove them from the array.
 
as for cost efficencies 2x 60a charge controllers + 112m 35mm cable is 770euro
                               2x 60a MPPT charge controllers + 112m 6mm cable is 1100euro

financially i am prity much forced to go with the cheaper system.

thanks for the imput Justme and Roger         


Title: Re: panels to battery 40m
Post by: billi on November 14, 2011, 10:44:41 AM
Quote
as for cost efficencies 2x 60a charge controllers + 112m 35mm cable is 770euro
                               2x 60a MPPT charge controllers + 112m 6mm cable is 1100euro

financially i am prity much forced to go with the cheaper system.

So basically you are wasting about 1000 watt of your array , when going the non MPPT route   and just save 330 Euro upfront  ::)

Still i would get half or more  connected up to Gridtie inverter (and extend your overall inverter power during the day)  and the rest to a MPPT charger    should be possible for 1100 Euro as well   

Billi


Title: Re: panels to battery 40m
Post by: greenhouseparos on November 14, 2011, 11:06:41 AM
thats 330 euro i havent got


Title: Re: panels to battery 40m
Post by: billi on November 14, 2011, 12:13:39 PM
so why not wait   and install only  2800 watt via an MPPT   80 Amp charger (like the outback )  for 620 Euro incl shipping  should  deliver similar power then the whole 3800 watt on non MPPT  and perhaps one can connect the rest later or even without any regulator in parallel to the MPPT controlled  array  and utilize the  internal relay of the Outback FM 80 controller  to control those panels ( not 100% sure this will work )  and  any overproduction of the whole ( two arrays) ,   goes to Waterheating  then

or i can tell you where to find a  4 year old Sunny Boy 2500 in good condition  for 400 Euro (or a new  one with not such a well known name for a bit  more  Navitron has one as well ) and your off grid inverter can handle  upto 2700 watt charge     and an additional  array with  MPPT chargecontroller  with the rest of the panels  and an additional 190 Euro costs

Billi


Title: Re: panels to battery 40m
Post by: greenhouseparos on November 14, 2011, 08:29:52 PM
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


Title: Re: panels to battery 40m
Post by: billi on November 14, 2011, 09:16:25 PM
Paul

I have 4000 watt PV  and two  MPPT controllers  and a 1 kw windturbine   . The windturbine has basically no controller  ;D :norfolk  ;D  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  wacko

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

Quote
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.





Title: Re: panels to battery 40m
Post by: greenhouseparos on November 15, 2011, 07:02:36 PM
So here is plan B

14 panels 2660w @ 73.2v (16mm cable  exhappy:) to an 80amp MPPT charger (more expensive than a 60amp but less expensive than 2 of them  exhappy:). 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   


Title: Re: panels to battery 40m
Post by: Justme on November 15, 2011, 08:20:00 PM
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/



Title: Re: panels to battery 40m
Post by: greenhouseparos on November 15, 2011, 08:29:46 PM
yep!
been there and looks like it gets fried.

(just an idea thermostatically controlled array disconnect)


Title: Re: panels to battery 40m
Post by: billi on November 15, 2011, 08:40:25 PM
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  whistle 

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


Title: Re: panels to battery 40m
Post by: Justme on November 15, 2011, 09:18:47 PM
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
 


Title: Re: panels to battery 40m
Post by: greenhouseparos on November 16, 2011, 06:34:40 AM
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 


Title: Re: panels to battery 40m
Post by: Justme on November 16, 2011, 09:39:40 AM
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.


Title: Re: panels to battery 40m
Post by: greenhouseparos on December 06, 2011, 07:19:26 PM
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. 


Title: Re: panels to battery 40m
Post by: billi on December 06, 2011, 07:52:10 PM
Great .....

Quote
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  whistle , 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


Title: Re: panels to battery 40m
Post by: greenhouseparos on December 07, 2011, 01:24:27 PM
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       


Title: Re: panels to battery 40m
Post by: rogeriko on December 07, 2011, 08:16:25 PM
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.


Title: Re: panels to battery 40m
Post by: Outtasight on January 08, 2012, 12:20:51 PM
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  ;D


Title: Re: panels to battery 40m
Post by: greenhouseparos on January 19, 2012, 08:09:33 PM
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