Newbie question on combining two arrays

Started by neutronspin, October 05, 2016, 07:46:10 PM

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neutronspin

Hello,

I have a 320 watt PV array with two 12 volt 160 watt panels in series.  Is it possible to add a second array and feed one Midnite Solar KID?  The new second array will consist of six 100 watt 12 volt panels.  How would be the best way of wiring both arrays together?  Can they all (8) be wired in series.  I think the KID will handle eight 12 volt panels in series? 

Also if I decide to purchase two KIDs and run each array separately can they both charge the same battery bank?  The battery bank will be 24 volt system.

Any help appreciated.

Halfcrazy

The general rule of thumb (Ok this is my rule and some may disagree with me)

Panels in a series string need to be within 10% of each other on the amperage and the voltage doesn't matter as it adds.
Strings of panels need to have there voltage within 10% of each other and the amperage doesn't matter as it adds.
Changing the way wind turbines operate one smoke filled box at a time

kauaisolarman

i have read that you need 2 separate controllers if you are using MPPT because the controller is trying to find the maximum efficiency of the panels and use that power.  if you have 2 different types of panels the controller can not use this function properly as it will get confused between the 2 panels maximum efficiency and not provide mppt.

please correct me if i'm wrong because im in the same situation.

i have a classic 150SL and it can handle way more panel power but i don't have the same kind/type of solar panels so i need to get another controller so i can run the 2 different types of panels to charge the same battery bank.

my different panels have a Vmp of virtually the same at 54 and 54.8, but since they are different brand/manufacture their efficiency is different needing another charge controller.

i would love to just parallel all panels together on 1 controller
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

Halfcrazy

As I stated above I tend not to worry about it to much, In my experience most panels behave roughly the same and if the voltage or current rules I put above are followed you should get acceptable results. The other way to look at it in your case is lets say you loose 2-3% of the Power you cold harvest, Panels are so inexpensive right now it makes no sense to buy an MPPT controller for each module vs just buying a 3rd module. The 3rd module would give you a LOT more power than a second controller and will cost less also
Changing the way wind turbines operate one smoke filled box at a time

neutronspin

Quote from: Halfcrazy on October 07, 2016, 05:55:14 AM
As I stated above I tend not to worry about it to much, In my experience most panels behave roughly the same and if the voltage or current rules I put above are followed you should get acceptable results. The other way to look at it in your case is lets say you loose 2-3% of the Power you cold harvest, Panels are so inexpensive right now it makes no sense to buy an MPPT controller for each module vs just buying a 3rd module. The 3rd module would give you a LOT more power than a second controller and will cost less also
Thanks....One more question....If I were to choose to use two KIDs for whatever reason can you parallel both their DC outputs to charge my 24 volt battery bank?  I think they can talk to each other....not sure....thanks for all your help.

kauaisolarman

yes i believe the kids can be paralleled together to 1 battery bank for a double team of action!

2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

kauaisolarman

Quote from: Halfcrazy on October 06, 2016, 09:54:46 AM
The general rule of thumb (Ok this is my rule and some may disagree with me)

Panels in a series string need to be within 10% of each other on the amperage and the voltage doesn't matter as it adds.
Strings of panels need to have there voltage within 10% of each other and the amperage doesn't matter as it adds.

so my issue is different panels with different voltages:

1st panel: 
sanyo 190 watt HIT
Vmp = 54.8
Voc = 67.5
Ipmax=3.47A

2nd panel:
eco worthy 100 watt
Vmp = 18  (x3 = 54Volts)
Voc = 21.6  (x3 = 64.8volts)
Ipmax = 5.5A

i am currently running:
5 sanyo in parallel = 54.8Vmp@17.35A
want to connect 3 eco worthy in series and run parallel to the sanyo. 
3 eco worthy in series = 54.0Vmop@5.5A

can i connect all to the same controller or am i good running all these different panels on the same controller?

thanks again for the input

2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

dgd

Quote from: kauaisolarman on October 08, 2016, 02:12:38 AM
i am currently running:
5 sanyo in parallel = 54.8Vmp@17.35A
want to connect 3 eco worthy in series and run parallel to the sanyo. 
3 eco worthy in series = 54.0Vmop@5.5A

can i connect all to the same controller or am i good running all these different panels on the same controller?

Yes, you can connect these to the same Classic
This 'mixed pv' setup is common as long as each parallel connected string has near the same woking voltage

dgd
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
West Auckland, New Zealand

kauaisolarman

Quote from: Halfcrazy on October 06, 2016, 09:54:46 AM
The general rule of thumb (Ok this is my rule and some may disagree with me)

Panels in a series string need to be within 10% of each other on the amperage and the voltage doesn't matter as it adds.
Strings of panels need to have there voltage within 10% of each other and the amperage doesn't matter as it adds.

ok so i have 2 more types of panels that are different brands what is the consensus about running them parallel together on the same controller (Classic 150SL) 

1st set: series of 3 suniva 315W solar panels
Vmp = 115.2
Voc = 139.2

2nd set: series of 2 panasonic HIT325 solar panels
Vmp = 109.5
Voc = 137.7

difference
Vmp = 5.7
Voc = 1.5

is the 5.7 Volts difference in the Vmp too much for using them together in parallel on the same controller?

thanks for the input
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

Vic

Quote from: kauaisolarman on October 27, 2016, 11:59:28 PM
Quote from: Halfcrazy on October 06, 2016, 09:54:46 AM
The general rule of thumb (Ok this is my rule and some may disagree with me)

Panels in a series string need to be within 10% of each other on the amperage and the voltage doesn't matter as it adds.
Strings of panels need to have there voltage within 10% of each other and the amperage doesn't matter as it adds.

ok so i have 2 more types of panels that are different brands what is the consensus about running them parallel together on the same controller (Classic 150SL) 

1st set: series of 3 suniva 315W solar panels
Vmp = 115.2
Voc = 139.2

2nd set: series of 2 panasonic HIT325 solar panels
Vmp = 109.5
Voc = 137.7

difference
Vmp = 5.7
Voc = 1.5

is the 5.7 Volts difference in the Vmp too much for using them together in parallel on the same controller?

thanks for the input

Hi Kauai..,

Speaking only of the difference in String voltage,  the string Vmps are within about 5.2% of each other,  so they should be fine.  My personal ideal difference,  is that strings in parallel be within 5%,  and that the maximum difference for parallel string Vmp be within 10%.   This meets this rule of thumb,  well.

So,  these PV will be for the 48 V battery?

Am sure that you have run the above PVs on the Classic String Sizer:
http://midnitesolar.com/sizingTool/displaySizing.php

For a Classic 150,  this is probably nearing a input voltage limit,  even in HI.  And there will be some reduction in CC efficiency due to this relatively high Vin,  even with a 48 V battery.

Looks like you are still thinking about just what CC to use.

FWIW,  Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

kauaisolarman

vic,

thanks for the reply.  yes this particular setup will be for a 48V battery bank.

i did use the sizing calculator and it said i was ok using 1 classic 150SL for that setup.  i do also have a classic 200SL that i can use instead, do you think i would be better off with the 200 for for this application?

the maximum Voc fr this setup should be 139.2V x 1.02 (temp compensation) = 142V (less than 150V but close).

would i get better performance with the 200 vs the 150?  i can use either 1 as i am still setting up/planning this system.

thanks again for the input
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

Vic

Quote from: kauaisolarman on October 28, 2016, 03:43:13 PM
vic,

thanks for the reply.  yes this particular setup will be for a 48V battery bank.

i did use the sizing calculator and it said i was ok using 1 classic 150SL for that setup.  i do also have a classic 200SL that i can use instead, do you think i would be better off with the 200 for for this application?

the maximum Voc fr this setup should be 139.2V x 1.02 (temp compensation) = 142V (less than 150V but close).

would i get better performance with the 200 vs the 150?  i can use either 1 as i am still setting up/planning this system.

thanks again for the input

Hello Kauai..,

IIRC,  you had said that the record low temps where you are were about 40 F.  Just wanted to make sure that you were not going to get into HyperVoc.

Think that the 150 V Classics should do fine,  and would probably be a bit more efficient than 200 V Classics ...  just my opinion.

If the temperature of the room where the Classic/s will be operating,  is cool,  this should help keep the Classics happiest.

Have not looked at the specs on the Panasonic HIT PVs,  and have not used them.  There may be a bit of a difference in the temperature compensation factor between the two candidate PVs,  or,  perhaps those two different PVs might have somewhat different voltages in lower light conditions,  etc ...   will try to look at that.

My opinions,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

kauaisolarman

yep coldest temps well see out here are about 57F and thats only possible at night.

when the sun is out more like 70F at the coldest.

thanks for the input.

so is it correct to assume that the bigger CC classic 200/250 is more efficient when running higher voltages.  for example my situation gives me a max Voc of 142V  which is still within limits for the 150, but will the 200/250 perform better with this voltage input?

thanks again
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

Vic

Hi Kauai..,

IMO,  would expect the Cl 200 & 250 to be a bit less efficient than the Cl 150 with the string Vmp noted above ...  just my guess.

It might have been said in this Thread ...  have not re-read it,  but;
On a 48 V system with Flooded batteries,  the sweet-spot for a Classic 150 (with not too-long cables from the PVs to the CC) string Vmp is about 90 volts.   This is a very convenient voltage for 60-cell PVs  --  three is series per string.  There are a ton of 60-cell modules around,  although,  72-cell modules are becoming popular again,  with output ratings above 300 W.

Since you are not on the Mainland,  perhaps the PVs you have been considering recently,   are being considered because they might be available locally.

We do run one system here with strings of three older 72-cell PVs.  STC string Vmp is 106 V.  This is about the limit of what I would be comfortable with on a Classic CC.  Our lowest cold temps are in the 22 F range,  so just barely out of HyperVoc on that record coldest day.

This string voltage is a bit of a strain on most MPPT CCs (or PWM for that matter!),  as the Vin to the CC under light loads often runs a bit above 120 V.  The Cl internal fans DO run much of the day,  even with A/C running in the power room to the greatest possible extent (in Absorb,  Float,  and EQ).

If you could find some larger 60-cell PVs,  like the SolarWorld 280 - 300 W modules,  this might be a bit better,  efficiency-wise.   But would guess that transportation is a large consideration in HI.

A bit of an efficiency loss is not the end of the world.  This would be a bit harder on the CC,  but the Classics are well-designed,  tough,  workhorses,  and should still last many years with a string Vmp of about 113 - 115 V.

All IMO,   FWIW,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!