Why are panels rated in 12 Volt units?

[Alaska Man]

So if I add another panel, I make the one array into two Arrays wired in series I get.

Where does the parallel come into play and what what am I losing over all?

[vtmaps]

So if I add another panel, I make the one array into two Arrays wired in series I get.

Where does the parallel come into play and what what am I losing over all?

You put two panels in series (called a 'string' of panels) and connect it to a breaker in your combiner.  You take the other two panels and also put them in series and connect them to a different breaker.  You now have two strings of panels (two panels per string) that are in parallel (the parallel connection is made by the combiner).

Your classic will work more efficiently with the lower input voltage of only two panels in series (rather than three panels in series which you currently have).

--vtMaps

[Vic]

A M,

As vtmaps has said twice;

You CAN add an additional 230 watt PV,  identical or very similar in specs to what you now have.

ALL that you need to do is to run two 230 W PVs in each string.  There will be two of these strings of two 230 W PVs,  four in total.

You will need to add an additional pair of wires from this new string to your Combiner or Charge Controller,  and make sure that the added current from this new PV will not overload the cables from your Combiner to the CC.

The Classic should be able to accept this additional power,  and convert it to added current to your batteries.

This new configuration to TWO Strings of two PVs each,  will allow the Classic to run cooler,  and therefore will be more efficient (will waste less power).

You will not really need separate breakers in the Combiner with only two strings,  but might be handy.

BUT,  the MAXIMUM breaker or fuse size is 15 Amps.  Think that there is only one 15 A breaker in that mockup of the Combiner.   You may have additional 15 A breakers available.

You appear to be off to a good start on the Combiner -- just needs some more cable connections.   But with one or two strings of these PVs that you speced,   a Combiner is not absolutely required.

Just make certain that all of the circuit breakers are not too large for the wire that connects to them,  as breakers and fuses are really there to protect the wiring from overheating,  and causing a FIRE risk.

Good Luck,     Vic

[Alaska Man]

I replied don't know where that one went. I'll try again.


I get the two arrays and I can do this no problem.

Please forgive my ignorance, but if two arrays are feeding one controller isn't that the same thing. I would still be pushing 73.4VOC from number one array and 73.4VOC from array number two. All of which are combined (146.8VOC) and then fed through the top mounted bus bar on top of the breakers and into the controller? 

I realize I must be missing something here.

[Westbranch]

Nope, when the voltage and amperage goes into the combiner in parallel, the voltage does not add as in series, BUT the amperage does add in the combiner...

[Alaska Man]

I went over to the string sizing tool and according to it, I can do 3 strings of (2 Panels in series) and still use the 150.

Now we're talking.......... Wire is cheaper than another controller by a long shot.

[Alaska Man]

Thanks the light just went on............  I get it now.

[dgd]

AM,

Just looking at the house pic you posted, I see you have space for another panel that would, as you say, balance the look. If you had the battery bank at 24v then you could probably get another two of those panels installed to make six in total - 3 strings of two.  You certainly have enough breakers and connections in the breaker box for 3 strings.

There seems to be enough space to have 3 panels each side of the windows mounted horizontally instead of vertical as you now have them.
Perhaps two beside each other with a third on top of one nearest window. Looks like they would still fit below that shadow line your roof overhang is casting

dgd

[Alaska Man]

Thanks again everyone for the schooling.

The house faces due South on that end and with one more panel it will be just about right for my 880Ah battery bank. Right now the three panels can keep up in full sun, but a bit more juice would be nice.

However, the sun shines on the western side (side to left of pic) for even longer. The panels on the west side would get sunlight from 5:00 pm until well after midnight. Although the sun is not as bright during the night,  I'm thinking the next (2) strings would go on that side. The Black on Black panels that are designed for lower light situations would be ideal, I think?

In the winter the sun hits that left corner so that low winter sun would get a crack at the front and the side. Granted it's only for about 3 hours, but still every bit helps during late Dec-early Feb. If I had the sense god gave geese I would spend those months in Kauai. Which, truth be told is the eventual plan.