benefits of either setup

[northshoremb]

On my small 4 battery 12v system is it better to run my 4-100w panels (17.1v 5.8a) in series to get higher 68.4 volts with 5.8a or run 2s2p and go for 34.2v and 11.6a? I haven't bought a Controller yet so whatever way is best I will buy a MPPT controller just above the short circuit voltage.

[Sunking]

On my small 4 battery 12v system is it better to run my 4-100w panels (17.1v 5.8a) in series to get higher 68.4 volts with 5.8a or run 2s2p and go for 34.2v and 11.6a? I haven't bought a Controller yet so whatever way is best I will buy a MPPT controller just above the short circuit voltage.

Depends on Controller. Most cheap MPPT Controllers made for 12 volt systems do not have a high enough Voc Input to allow you wire many panels in series.

However at 400 watts you are looking at a 30 to 40 amp controller and most that size are 100 to 150 Voc. If you went 24 volts you are looking at a 15 to 20 amp controller. However at 20 amps you are still looking at 70 Voc input which is not high enough. With a panel Voc of 68.4 volts minimum Voc Input of Controller = 68.4 x 1.25 = 85.5 volts. So you need to shop for a Controller with at least 90 Voc to allow you to wire all 4 panels in series be it 12 or 24 volts. Slim pickens.

2S2P is fine though.

[badley]

it wont matter imo .. the simplest setup would be to parallel them all into xantrex~40 and you could add a couple panels later .. you dont gain anything on a smaller system by series'ing panels and raising voltage .. theres two things at work - voltage drop, which would be almost undetectable on a voltmeter using ~12awg wire under 100' - and panel cell efficiency .. going high voltage or series wont improve anything trust me .. if you want a real gain that would matter about 1000X more than series panels or mppt chargers add 'one' more panel .. its about that simple .. what people are really trying to overcome with series panels and fancy chargers is cell inefficiency in their panels .. their panels basically shut off when a bird poops on them so theyre trying to maximize output per day .. good cells dont do that .. and like i said, in a smaller home-sized system where distances are reasonable power loss is a non issue even in a 12v system with parallel panels ...

[northshoremb]

it wont matter imo .. the simplest setup would be to parallel them all into xantrex~40 and you could add a couple panels later .. you dont gain anything on a smaller system by series'ing panels and raising voltage .. theres two things at work - voltage drop, which would be almost undetectable on a voltmeter using ~12awg wire under 100' - and panel cell efficiency .. going high voltage or series wont improve anything trust me .. if you want a real gain that would matter about 1000X more than series panels or mppt chargers add 'one' more panel .. its about that simple .. what people are really trying to overcome with series panels and fancy chargers is cell inefficiency in their panels .. their panels basically shut off when a bird poops on them so theyre trying to maximize output per day .. good cells dont do that .. and like i said, in a smaller home-sized system where distances are reasonable power loss is a non issue even in a 12v system with parallel panels ...

From what I have been reading and using the online wire gauge calculator it says I need 1/0-2/0 wire for 4 my panels in parallel and 35 foot run. The reason I asked about series or 2s2p was to keep Amps down to be able to run smaller wire and save a lot of money. Wouldn't 28amps be to much for 10awg like you said over 35 foot run?

[northshoremb]

Depends on Controller. Most cheap MPPT Controllers made for 12 volt systems do not have a high enough Voc Input to allow you wire many panels in series.

However at 400 watts you are looking at a 30 to 40 amp controller and most that size are 100 to 150 Voc. If you went 24 volts you are looking at a 15 to 20 amp controller. However at 20 amps you are still looking at 70 Voc input which is not high enough. With a panel Voc of 68.4 volts minimum Voc Input of Controller = 68.4 x 1.25 = 85.5 volts. So you need to shop for a Controller with at least 90 Voc to allow you to wire all 4 panels in series be it 12 or 24 volts. Slim pickens.

2S2P is fine though.

What about this controller? 12/24v 20amp 100v max
I know there isn't a LCD readout but could get a cheap LCD screen to wire for input to the controller and output correct
OutBack Power SmartHarvest SCCM20-100 > Smart Harvest 20 Amp 12/24 Volt MPPT Charge Controller

http://www.outbackpower.com/outback-products/smartharvest/charge-controllers/item/sccm20-100-charge-controller-copy

[Mike90250]

it wont matter imo .. the simplest setup would be to parallel them all into xantrex~40 and you could add a couple panels later .. you dont gain anything on a smaller system by series'ing panels and raising voltage .. theres two things at work - voltage drop, which would be almost undetectable on a voltmeter using ~12awg wire under 100' - and panel cell efficiency .. going high voltage or series wont improve anything trust me .. if you want a real gain that would matter about 1000X more than series panels or mppt chargers add 'one' more panel .. its about that simple .. what people are really trying to overcome with series panels and fancy chargers is cell inefficiency in their panels .. their panels basically shut off when a bird poops on them so theyre trying to maximize output per day .. good cells dont do that .. and like i said, in a smaller home-sized system where distances are reasonable power loss is a non issue even in a 12v system with parallel panels ...

badley, not sure what your specific agenda is, but you have a couple days off to think about it, and have your next posting follow accepted engineering practice,


I will NOT let you, or anyone make broad blanket statements regarding "" voltage drop, which would be almost undetectable on a voltmeter using ~12awg wire under 100' - and panel cell efficiency .. going high voltage or series wont improve anything trust me ."" and ""in a smaller home-sized system where distances are reasonable power loss is a non issue even in a 12v system with parallel panels"" Factually incorrect, and you will NOT be allowed to promulgate incorrect information on my watch, regardless how amusing it is watching you dig yourself into a hole.

[sensij]

2s2p on an mppt controller definitely saves you money in wiring and fusing (which is required when you have more than two strings). Tracer 2210A is an entry level controller you might want to look at.

[northshoremb]

2s2p on an mppt controller definitely saves you money in wiring and fusing (which is required when you have more than two strings). Tracer 2210A is an entry level controller you might want to look at.

Thanks that's a sweet price on a MPPT with LCD readout. Seeing as it's 100v/20amp max inputs would it be better to run all my panels in series for higher volts at 5.8a or do 2s2p for 11.6a???

[northshoremb]

Depends on Controller. Most cheap MPPT Controllers made for 12 volt systems do not have a high enough Voc Input to allow you wire many panels in series.

However at 400 watts you are looking at a 30 to 40 amp controller and most that size are 100 to 150 Voc. If you went 24 volts you are looking at a 15 to 20 amp controller. However at 20 amps you are still looking at 70 Voc input which is not high enough. With a panel Voc of 68.4 volts minimum Voc Input of Controller = 68.4 x 1.25 = 85.5 volts. So you need to shop for a Controller with at least 90 Voc to allow you to wire all 4 panels in series be it 12 or 24 volts. Slim pickens.

2S2P is fine though.

So with this Controller should I do all 4 in series or 2s2p???
100v/20a max MPPT controller Tracer 2210a https://www.solargain.ca/product/epsolar-tracer-2210a/

[sensij]

Thanks that's a sweet price on a MPPT with LCD readout. Seeing as it's 100v/20amp max inputs would it be better to run all my panels in series for higher volts at 5.8a or do 2s2p for 11.6a???

You need to adjust your string Voc for temperature. For 12 V panels with a Voc of around 21.5 V, four in series is 86 Voc at 25 deg C. With a temp coefficient of Voc typically around -0.3 to -0.4%/deg C, that means you would probably stay under the 100 Voc limit for the controller down to about -20 deg C. As far north as you are, I don't think that would work for you, and 2s2p would be a better arrangement.

[Sunking]

So with this Controller should I do all 4 in series or 2s2p???
100v/20a max MPPT controller Tracer 2210a https://www.solargain.ca/product/epsolar-tracer-2210a/

Sorry for the delay, been in South Carolina the last week playing golf and flying. Like senij said with that controller and your location, 2S2P. Just make sure you size the wiring correctly between panels and controllers.