Ugrading solar panel

Robert8068

I presently have (1) 190w Sanyo panel, Vmp 37.5, Imp 5.5.  Also a Morningstar 15amp SunSaver MPPT controller. and (6) 6volt golf-cart batteries, 12v wired to older Heart 2000w inverter charger, that also charges batteries when genset is running

I purchased (2) new Trina 240w panels Vmp 29.7, Imp 8.1 at STC.  Also a new Outback FM-60 controller.

I want to run the Trinas in series on a single 10ga wire, 24v+/-, to the Outback FM60, but keep my battery bank at 12v, which I'm told the Outback will do automatically. Can I also wire the Sanyo in series to the Trinas?  Or should I keep the Sanyo and Morningstar charging separately? Or sell the Sanyo and Morningstar charge controller and buy a third Trina panel instead?  Will 10ga wire handle the (3) 240w Trina panels in series, ok?  And I assume the Outback FM60  will sense the 12v battery bank ok?

What is the best way to go?  I appreciate your recommendations.

vtmaps

Robert8068 said:

 Will 10ga wire handle the (3) 240w Trina panels in series, ok?  And I assume the Outback FM60  will sense the 12v battery bank ok?

Welcome to the forum,

10 gauge wire can handle the current (ampacity), but there may be too much voltage drop... you didn't mention the length of the cable.

I strongly recommend against running three of those panels in series.  Even two in series is less than ideal.  For a 12 volt battery, the controller will be more efficient, run cooler and last longer if the input voltage is closer to 30 volts than 90 volts.

Also, if you are in a cold climate, the cold temp Voc of three in series can get very close or exceed the maximum input voltage of the controller.

Robert8068 said:

Can I also wire the Sanyo in series to the Trinas?  Or should I keep the Sanyo and Morningstar charging separately? 

You can keep the sanyo and morningstar as a separate array/conroller.

--vtMaps

Robert8068

My 10 Ga wire is approx. 25ft long, would that be ok for two panels in series or?

westbranch

there is a calculator here  http://forum.solar-electric.com/discussion/60/voltage-drop-calculator#latest...
it uses one way distances...

hth

vtmaps

Robert8068 said:

My 10 Ga wire is approx. 25ft long, would that be ok for two panels in series or?

The two trina panels can be connected in parallel and you will have a reasonable 2.8% voltage drop on a 25 ft cable.

If you try to increase the efficiency of the cable by putting the two panels in series, you will lose efficiency in the controller.  It is better to make waste heat in the cable than to make it in the controller.  If a 2.8% voltage drop is not acceptable to you, use a heavier cable....   8 gauge copper cable will give you a 1.75% voltage drop.

--vtMaps

Robert8068

Thanks for the help and recommendations I'm trying to get up to speed on this solar stuff but seem to find a lot of contradictions  in the things I read but I'm working on that learning curve thing.

BB.

Please ask more question, or "re-ask" those you did not understand the answer (or the answer was not really the question, etc.).

Connecting Panels to Charge Controller (MPPT/PWM) to Battery Bank--There are a lot of variables here--And depending on your local choices (specific models of panels, battery bank AH/Volt capacity, etc.), the answers will vary.

Don't worry.

-Bill