Bobbo
Wherever I park
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Voltage drop is related to wire size and amps flowing. Putting the panels in series keeps the amps low. That gives you less voltage drop. However, since the VOC is 45.29v, be sure that the MPPT controller is good to at least 100v.
If you opt for parallel, then be sure the wire is heavy enough to be capable of carrying 20 amps.
ON EDIT: corrected some numbers. I had misremembered and put numbers for 3 panels.
* This post was
edited 10/25/23 07:26am by Bobbo *
Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
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jodeb720
Denver
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My plane is to run 8 gauge wiring from the panels to tge controller and 2 or 4 gauge from tge controller to the battery. The biggest challenge is distance from the panels to the controller - I’m guessing 24’ conservatively.
We had one of the panel at a 75 degree to the sun (I’m currently in eastern San Diego county desert region. We were getting about 190 watts in the mid morning to noon sun, but tge controller was putting out about 15-18 amps to the battery bank.
It was impressive!
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StirCrazy
Kamloops, BC, Canada
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Bobbo wrote:since the VOC is 45.29v, be sure that the MPPT controller is good to at least 150v.
Um.. all you need is one rated for 100V150 v is way overkill unless your running three panels.
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Bobbo
Wherever I park
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You are right. He is only receiving 2 panels, not 3. I misremembered from the first of the thread where he said the buddy got 6 panels, but only used 4, so is giving away 2. I will edit my original post.
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Boomerweps
Hills of PA
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If you have ANY shading on your panels in series, you will lose a lot of power. The gain in series is two fold from the higher voltage. One, the panel voltage reaches the activation voltage needed by the MPPT controller earlier in the day and retains it longer in the evening. The higher voltage allows more power flow through thinner wires, I.e., less line loss.
Starting in parallel allows you to easily add more panels.
IMO, EPEver controllers are the most cost effective. Victron is likely the best consumer grade units with a matching cost.
Wattage equals volts times amps. Which unit you need comes down to that. Easier still, find likely candidate controllers, download their manuals. The ones I’ve seen all state the recommended maximum PV wattage input. For example mine states 390watts at 12vdc. So I’m planning on ending up with four 100 watt panels since PV panels rarely put out their rated output (for many reasons).
I agree that you would want a 50 Amp capable unit. The EPEver tracer series 4210AN (40 amp unit) lists max PV wattage at 520 watts.
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deltabravo
Spokane, WA
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Victron MPPT
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pianotuna
Regina, SK, Canada
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Don't buy a controller for just the two panels. You may want, some time in the future to increase the harvest.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.
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jodeb720
Denver
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this is all excellent advice -
One question though. Can I manually switch the controller from bank 1 to bank 2?
As I stated, I run my batteries through a marine switch - which feeds from bank 1 or bank 2 or both. I have them separated because of the age difference of the batteries and use. Bank 1 serves the RV House needs (water pump, fans, lights) and Bank 2 serves my Inverter. I currently have two separate chargers which I run off my generator to bounce them back to 80% or more.
If I have my solar setup, will I be able to focus all the amps on Bank1 until it reaches 80% and then switch it to bank 2?
If so, I can use a mechanical switch (as I have for the source of power in the trailer), but what impact will a mechanical switch have for designating the destination of the charging on the controller?
Will a sudden disconnect and reconnect from bank to bank cause a failure?
Do I need to disconnect the feed from the Panels first to the controller, then switch over, then reconnect the feed from the panels?
i know this would be a lot easier if I just had one battery bank of 420 amps. Hence, I'm asking the questions before I let the blue magic smoke out of charge controller prematurely! ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
Thanks so much!!
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pianotuna
Regina, SK, Canada
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jodeb720,
Manual switching is possible.
There are alternatives such as a voltage sensitive solenoid that would 'add' the second bank when voltage reaches 13.5.
* This post was
edited 10/28/23 01:02am by pianotuna *
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Boomerweps
Hills of PA
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If going to the effort of having switch to switch between battery banks, adding another between the panels and controller shouldn’t be a big deal.
Every controller manual emphasizes connecting the batteries first and disconnecting them last. They imply damage may occur but not stated clearly how. IMO, there is concern about the battery not powering the control circuitry and the panel power not being limited.
You could always shift banks at night ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/wink.gif "wink")
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