Optimal Solar Array Wiring

[Keegan]

I am planning to install four Kyocera 130 panels on hard bimini. the boat is a cruising cat so I have the space. I am considering the Outback 60 charge controller. I have heard two conflicting thoughts on wiring the panels for optimal efficiency. The first was to wire all four panels in a Series for the best output. The 2nd was dont wire in a series because if one of the panels has some shading from the boom then it will effect the other panels output and overall you will lose the advantage of wiring in a series in the first place.

Does partial and sporadic shading offset the improved output of wiring all four panels in a series?

I could also consider wiring each pair of panels in a series instead of all four in a series and that way when one side of the boat is shaded then then the other two would still be wired well.

Or does it really make that bid of a difference, should I just wire in parallel?

Keegan

[schoonerdog]

I am doing the exact same thing (4 sharp 175s going to an outback 60) and I'm wiring them two in series and two in parallel, but I didn't consider shading. The panels are 24 volts and I didn't want more than 48 volts DC flowing down for safety reasons (I think this is the max voltage really that would only shock you but not do anything more). It also works where one side or the other would be shaded and not reduce the output of the entire array. Finally a lot of panels are shade tolerant in they have blocking diodes on groups of the cells so they can withstand shading far better internally to the panel. I absolutely didn't want to wire them all in parallel, because the output of the panels is so high that at low DC voltage of 12 or 24 volts would mean I'd need to use huge gauge wire because of the long cable path (consult your voltage drop tables). 48 volts was high enough that I could get by without to huge an expense in the wiring but not high enough to cause harm.

[hellosailor]

OutBack Power Systems User Forum :: View topic - Partially-shaded Panels: a Newbie Question

See the comment from "sparkyinak" it seems that Kyocera panels will have a problem with shade, so your idea of splitting them series/parallel, or totally in parallel, might be the best idea. Probably worth posting the q on the Outback forum directly.

[Keegan]

Thanks for the replys!

Keegan

[sv_makai]

Makai has carried 4 Kyrocea 120's @ 12v into a 680amp house bank for the last 3 years. We use the SB50 MPPT controller. I orginally wired mine parrallel and mounted the panels length wise to the centerline. the area of wiring I went several sizes over the recommended sizes. I had planned on adding more panels in the future and to reduce the current drop due to the extended length of the cabling. This setup work superably, but i believe it can be improved.

Shading wasn't much of an issue. Usually at anchor I would just move the boom to reduce the shading on the panels. We are an electrically intensive users and found that we would have the bank fully charged by 10ish in the morning. For the most part shading was only an issue under sail, but would usually have half of the panels completed unshaded.

Planned changes. Replace the panels with the latest and greatest output for the space when getting ready to head out again. Mount the panels lengthwise parrallel with the centerline. Move 2 of the 120's to the anchor/sail locker hatches (plenty of room on the hatch) with a goal of 1000 watts or more.

I really recommend with max'ing the amount of solar and using oversized cabling. We found that if we had more we would use it and it just made life more pleasurable when out there.

[olepedersen]

I installed a radararch.and I have room for 2 approx 25" x 60" solar panels, they would have a rating of 200 watts and 26 volts each, I would also get a MPPT controller. would that give a good system??and would it be possible to add a wind generator later I have been reading your threads, and hope I am on the right track. Looking forward to your opinions Ole Pedersen,"Southern Toy"

[schoonerdog]

Ole

A wind generator would help you with your nighttime power usage and stormy days which don't have much sunlight. I know the Airmarine has a built in regulator, so if the solar panels were charging and the battery voltage read 13.5 volts, the wind generator would not be charging. If the load was greater than the power produced by the solar panels (a cloudy day or night), the voltage on the battery would drop to a more realistic 12.5 volts (depending on how depleted the batteries were) and the wind generator would kick in and charge in conjunction with the solar panels. So yes, wind and solar work well together.

[hellosailor]

Something that is confusing me here, is that all of the solar/wind regulators and charge controllers seem to be set up the same way as the obsolete "one wire" alternator systems. That is, "one wire" is used both to sense the battery voltage, and the carry the charge to the battery.

It is long accepted in the world of automotive alternators that a one-wire system is inefficient and obsolete, and that using a separate sensing wire and charging cable allows better control of the charge state, since the alternator can tell the difference between "what the battery is" and "what I am feeding it".

Isn't there an equivalent system, where someone's controller can feed both wind and solar power at the same time, without disabling the one just because the other is also active?