Serial or Parallel

Started by pablo, June 05, 2016, 08:46:46 PM

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pablo

Hi all,

I have two Solar World SW 285 mono panels, a 12 volt battery system (2 Trojan LG 16 REs), and a Outback Flexmax 60 MPPT controller.  My cable run is 75 feet using 1/0 AL.  Shade is generally not an issue although with snowfall I guess it could happen or an oak leaf or something...  Temps can be around 100 degrees a few times each summer.   Specs on the panels, 285 Watts, 31.3 V, 9.2 A, 39.7 Voc, 9.84 Isc. 

Did I leave anything out?

So parallel or serial?  And could someone explain to me what "string" means!  That term just doesn't register for some reason...

thank you!
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.

Westbranch

With those panel specs and a 12 V battery your system will be most efficient in parallel..  that is 2P

a string is one or more panels connected together, you will have 2 strings of 1 panel, usually people use 'string' when they have 2 or more in series...
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
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West Chilcotin 1680+W to come

pablo

"2P"?

If I go parallel, is it true that I need to install some type of protection device for reverse current or short circuited panel?  I was hoping to avoid that. 

What makes parallel more efficient for my system?   

thank you
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.

Resthome

Quote from: pablo on June 05, 2016, 11:32:14 PM
"2P"?

If I go parallel, is it true that I need to install some type of protection device for reverse current or short circuited panel?  I was hoping to avoid that. 

What makes parallel more efficient for my system?   

thank you

2P = two panels in parallel

it keeps the PV closer to one step above your 12v batteries. The farther the PV is from the battery voltage the less efficient the system will be.
John

10 x Kyocera KC140, Classic 150 w/WBJr, Link10 Battery Monitor, 850 AH @ 12v Solar One 2v cells, Xantrex PROwatt SW2000
Off Grid on Houseboat Lake Don Pedro, CA

Westbranch

If you have plans to have more than 2 strings you need protection as per the manufacturers specs, found on the back of the PV..
at 2 strings or 2 individual panels you can combine  without CB's,

BUT it is quite beneficial to have them if you are doing any work on the system and you want to power down part of your setup for testing , rewiring etc...
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

russ_drinkwater

Because you have only two panels why not experiment as it is only one lot of connections for the panels.
See what voltage drops you get from each connection config!
Your VOC for the panels is high enough even allowing for some losses to do this.
No matter how you config your panels on a normal day they should have a high enough input voltage to keep your batteries
charged. Just try it test them wired series and then parallel.
You will soon see if there is any advantage for you either way.
Standalone. 20 Hyundai x 220 watts panels, 2 x classic 150's, Latronics 24 volt 3kw inverter, Whiz bang Jnr, 12 Rolls surrete  4KS 25P  batteries and WBJ.
Grid tie feed-in, 12.5 kw in 3 arrays generating 50 kws per day average. Solar river grid tie inverters

pablo

What a great idea!   Thanks.

I'm hoping to get back to this dang project next week.  I had to take a week off from work to give it some proper attention.  So, I'll probably be bombarding you guys with questions next week.    :o
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.