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Author Topic: panels to battery 40m  (Read 8071 times)
billi
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« Reply #15 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
« Last Edit: August 28, 2011, 04:49:39 PM 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
greenhouseparos
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« Reply #16 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?
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2660wp array, 1000amp 24v Ops battery bank, 3500XTM Struder24v, 80amp Outback, 750w Wind Turbine, Solar powered water supply
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« Reply #17 on: August 28, 2011, 06:09:25 PM »

secret  Grin

similar to your plan  Wink



I advice  to have a wise  thought   before  further action



« Last Edit: August 29, 2011, 12:15:51 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
greenhouseparos
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« Reply #18 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%?   
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Justme
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« Reply #19 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?
« Last Edit: November 13, 2011, 04:15:12 PM by Justme » Logged

Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
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6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
greenhouseparos
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« Reply #20 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     
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Justme
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« Reply #21 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.











 
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
rogeriko
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« Reply #22 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.
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Justme
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« Reply #23 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.
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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
6kva genny
6 x 2v cells 1550amp/h 5C
24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
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« Reply #24 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".
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rogeriko
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« Reply #25 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.
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greenhouseparos
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« Reply #26 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         
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2660wp array, 1000amp 24v Ops battery bank, 3500XTM Struder24v, 80amp Outback, 750w Wind Turbine, Solar powered water supply
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« Reply #27 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  Roll Eyes

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
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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
greenhouseparos
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« Reply #28 on: November 14, 2011, 11:06:41 AM »

thats 330 euro i havent got
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« Reply #29 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
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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
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