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Old 24-07-2015, 12:14   #1
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Yet another solar wiring question

I am about to add four solar panels to the fly-bridge roof of my Leopard 47PC to go “off the grid”. I am a solar “newbie” and would appreciate any comments before I mess this up.

The four panels are Apolloflex 145W and the manufacturers spec sheet indicates a “short circuit current” of 8.69A and open circuit voltage of 22.57V (rated current and voltage 8.08A and 19.01V respectively). The battery bank will be 4 in parallel of 210 Ah AGMs, set up for a 12 volt system.

I plan to wire the 4 solar panels series / parallel producing an assumed 45.14 Volts @ 17.38 Amps to be fed into a Morningstar Tristar MPPT 45A controller. The controller specs claim a maximum current of 45 Amps and 600 Watts of power at a nominal maximum input of 12V. Max open circuit voltage of 150V.

My questions are: Any problems going series / parallel on the panels? Do you think that the controller is within spec for this set-up? Finally, 4 AWG gauge wire OK for controller to battery and 14 or 15 AWG gauge wire OK to wire up the solar panels?
Ed
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Old 24-07-2015, 12:53   #2
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Re: Yet another solar wiring question

I think you will hear, way upsize your wire at least to the controller and to go with parallel as opposed to any series.
Lets see
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Old 24-07-2015, 13:33   #3
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Re: Yet another solar wiring question

I think your setup sounds reasonable given the numbers and series/parallel you've decided on, so if it's what you're set on, no worries.

I ran some numbers, and if it were me, I'd run independent charge controllers per panel for efficiency gains with regard to shading and equipment redundancy. The only slight downside here is mounting a few more charge controllers and a slightly different wiring job. I had originally posted some Genasun GV-10's, but I noticed the rated maximum wattage for those is at 140W, which is just a bit under the 145W panels you've shown. They would probably work, but you don't want to cut it that close. I don't know of any other real reputable charge controllers within the ~12.5A range that are cheap enough to really be suitable here, but maybe others could comment on one. The GV-10's are just $109 each, but again without downsizing the panels just slightly I'd be sort of uncomfortable cutting it so close.

So I guess it's back to either your original proposed setup, or maybe 2 30amp controllers for redundancy/efficiency, with each controller hooked up to a pair of paralleled panels.

1 TriStar TS-MPPT-45 at $459.49, or 2x TriStar TS-MPPT-30's for $720 total.

My thoughts for being self-reliant is with multiple controllers if something goes wrong with 1 controller or panel, you only lose a portion of the system. I imagine that comparing the two setups you will have slightly better numbers with the multiple controller setup in shade or partial shading scenarios.
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Old 24-07-2015, 15:03   #4
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Re: Yet another solar wiring question

Thank you both for the feedback. The solar panel manufacturer recommended 5 m of 1.5 mm**2 and that translates as 15AWG. Seems skinny though.
Ed
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Old 24-07-2015, 19:02   #5
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Re: Yet another solar wiring question

Quote:
Originally Posted by FatChance View Post
I think your setup sounds reasonable given the numbers and series/parallel you've decided on, so if it's what you're set on, no worries.

I ran some numbers, and if it were me, I'd run independent charge controllers per panel for efficiency gains with regard to shading and equipment redundancy. The only slight downside here is mounting a few more charge controllers and a slightly different wiring job. I had originally posted some Genasun GV-10's, but I noticed the rated maximum wattage for those is at 140W, which is just a bit under the 145W panels you've shown. They would probably work, but you don't want to cut it that close. I don't know of any other real reputable charge controllers within the ~12.5A range that are cheap enough to really be suitable here, but maybe others could comment on one. The GV-10's are just $109 each, but again without downsizing the panels just slightly I'd be sort of uncomfortable cutting it so close.

So I guess it's back to either your original proposed setup, or maybe 2 30amp controllers for redundancy/efficiency, with each controller hooked up to a pair of paralleled panels.

1 TriStar TS-MPPT-45 at $459.49, or 2x TriStar TS-MPPT-30's for $720 total.

My thoughts for being self-reliant is with multiple controllers if something goes wrong with 1 controller or panel, you only lose a portion of the system. I imagine that comparing the two setups you will have slightly better numbers with the multiple controller setup in shade or partial shading scenarios.
There is actually a little bit of headroom in the Genasun GV10 specs...they should be fine with those panels.
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Old 25-07-2015, 00:06   #6
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Re: Yet another solar wiring question

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There is actually a little bit of headroom in the Genasun GV10 specs...they should be fine with those panels.
Interesting, do you have a source or numbers on that you could provide? I have been really happy with the GV-10.
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Old 25-07-2015, 01:20   #7
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Re: Yet another solar wiring question

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Interesting, do you have a source or numbers on that you could provide? I have been really happy with the GV-10.
"Officially" the rating is 140W. However we have gotten approval to use the GV10 with the Solbian CP144 and SXP145 panels where they have been working fine.

In the coming weeks we (OPE) are planning some more head to head small controller testing. We already have been trying some shading configurations to learn answers to questions we've had, it has been fun. Hope to get info up online eventually.
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Old 25-07-2015, 08:19   #8
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Re: Yet another solar wiring question

Quote:
Originally Posted by edmundsteele View Post
I am about to add four solar panels to the fly-bridge roof of my Leopard 47PC to go “off the grid”. I am a solar “newbie” and would appreciate any comments before I mess this up.

The four panels are Apolloflex 145W and the manufacturers spec sheet indicates a “short circuit current” of 8.69A and open circuit voltage of 22.57V (rated current and voltage 8.08A and 19.01V respectively). The battery bank will be 4 in parallel of 210 Ah AGMs, set up for a 12 volt system.

I plan to wire the 4 solar panels series / parallel producing an assumed 45.14 Volts @ 17.38 Amps to be fed into a Morningstar Tristar MPPT 45A controller. The controller specs claim a maximum current of 45 Amps and 600 Watts of power at a nominal maximum input of 12V. Max open circuit voltage of 150V.

My questions are: Any problems going series / parallel on the panels? Do you think that the controller is within spec for this set-up? Finally, 4 AWG gauge wire OK for controller to battery and 14 or 15 AWG gauge wire OK to wire up the solar panels?
Ed

your solar panels and MPPT controller are well matched, both in terms of Voc and Impp.

I'd like to point out that if you get any shading at all on the panels, you'd be better off with all 4 panels in parallel for the least amount of losses. If you have them in series/parallel, the one panel that gets shaded will affect the other panel in series with it. In a worse case scenario, 2 panels get shaded, and the other 2 panels are affected for a loss in power from all 4 panels.

In all 4 parallel, only the shaded panels are affected, and there really isn't much advantage to series connections other than providing higher voltage and allowing one size smaller cabling. I always recommend the largest cabling practical for the lowest losses possible, just for good measure.

Another possible way to go is 2 Eco-worthy 20 amp controllers. If you're set on 2 series sets of panels, then go with a pair of panels into each of these 20 amp controllers at only $102 (ea.) delivered.

Or, if you want max. harvest and one controller per panel, get 4 of the Eco-worthy controllers and connect one panel to each. This would give a max. possible current of 75-78 amps if you chose to add 4 more panels. Total cost for 4 controllers is only $408.

Now as for cable size: 15 ga is much too thin. If I were running 4 panels into 4 controllers, I'd use 8awg. If running 4 panels into 2 controllers, I'd use 6 awg. If running 4 panels into one controller, then I'd use MC4 combiners to combine pairs of panels into 6awg, then join the 2 6awg sets into a 4 awg run to the controller.

If the controller is going to be close to the batteries, then I'd use 4 awg between controller and batteries, if longer, then 2 awg would be recommended. These numbers are off the top of my head, use an amperage chart for proper sizing, and don't be afraid to go one size larger for less loss. Also, make sure all connections are waterproof to minimize corrosion, you'll lose a lot of power from poor connections!
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Old 25-07-2015, 09:42   #9
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Re: Yet another solar wiring question

Saw this post and since it was similar I thought I would add to it.

Ok, I have two separate solar systems on board (two controllers). One forward with a 100w panel and one aft with 2-100w panels. I am using Renogy panels and their MPPT 20A controllers, one for each location.

Now here's the question: They both feed into the house bank. Do the separate controllers see the increased system voltage of the other and say...hmmm looks like the system is up and I don't need to do anything? So does one of the systems shut down now? Or output substantially less since it thinks the system is up?

I have read that some people use seperate controllers for each panel. don't they get confused? Something like me?
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Old 25-07-2015, 09:59   #10
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Re: Yet another solar wiring question

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Originally Posted by socaldmax View Post
your solar panels and MPPT controller are well matched, both in terms of Voc and Impp.

I'd like to point out that if you get any shading at all on the panels, you'd be better off with all 4 panels in parallel for the least amount of losses. If you have them in series/parallel, the one panel that gets shaded will affect the other panel in series with it. In a worse case scenario, 2 panels get shaded, and the other 2 panels are affected for a loss in power from all 4 panels.

In all 4 parallel, only the shaded panels are affected, and there really isn't much advantage to series connections other than providing higher voltage and allowing one size smaller cabling. I always recommend the largest cabling practical for the lowest losses possible, just for good measure.

Another possible way to go is 2 Eco-worthy 20 amp controllers. If you're set on 2 series sets of panels, then go with a pair of panels into each of these 20 amp controllers at only $102 (ea.) delivered.

Or, if you want max. harvest and one controller per panel, get 4 of the Eco-worthy controllers and connect one panel to each. This would give a max. possible current of 75-78 amps if you chose to add 4 more panels. Total cost for 4 controllers is only $408.

Now as for cable size: 15 ga is much too thin. If I were running 4 panels into 4 controllers, I'd use 8awg. If running 4 panels into 2 controllers, I'd use 6 awg. If running 4 panels into one controller, then I'd use MC4 combiners to combine pairs of panels into 6awg, then join the 2 6awg sets into a 4 awg run to the controller.

If the controller is going to be close to the batteries, then I'd use 4 awg between controller and batteries, if longer, then 2 awg would be recommended. These numbers are off the top of my head, use an amperage chart for proper sizing, and don't be afraid to go one size larger for less loss. Also, make sure all connections are waterproof to minimize corrosion, you'll lose a lot of power from poor connections!
Agree with cable size. Much better to go larger than smaller, and allow cable to vibrate. The following is from experience: I had a 00 cable, 6" long connected from the 120 amp alternator to a connector on the bulkhead. After two years, the cable covering burnt off !! Someone on this forum told me that if cable is restricted and has a high number of amps going through it it will heat up. Never learnt that in Physics class !! I made a 14" loop of 00 cable to connect the two 6" apart points. Now it vibrates a bit, but stays cool. I use an infrared thermometer to measure cable temps of inaccessible cables. Something to think about.
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Old 25-07-2015, 10:42   #11
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Re: Yet another solar wiring question

Quote:
Originally Posted by edmundsteele View Post
My questions are: Any problems going series / parallel on the panels? Do you think that the controller is within spec for this set-up? Finally, 4 AWG gauge wire OK for controller to battery and 14 or 15 AWG gauge wire OK to wire up the solar panels?
Ed
The controller specs look fine.

There is a lot of debate about whether series or parallel connections are best. Series/parallel means you keep both camps happy . Personally, while I would like to see more evidence, I think a pure parallel connection is best if there is room for the correct wire size.

In terms of wire size the distance is important and without this information it is impossible to calculate the minimium diameter.

I would encourage you to measure the actual distance with a string led through where the wire will run. A rough estimate often underestimates the true distance as the wire needs to snake around to get through the various apertures. You will need a reasonably accurate length measurement to purchase the cable anyway.
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Old 25-07-2015, 17:53   #12
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Re: Yet another solar wiring question

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I think you will hear, way upsize your wire at least to the controller and to go with parallel as opposed to any series.
Lets see
TOTALLY agree


I suggest you run nothing less than #6 AWG & parallel on all four.
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Old 25-07-2015, 19:29   #13
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Re: Yet another solar wiring question

I also favour multiple controllers for the same reasons others have suggested. I have 2 Morningstar and one older Solarex controller.
The Morningstar controllers are connected to the house bank with their own panels.


The Solarex and one other panel is dedicated to the start battery while the boat is moored unused.


When we are away cruising I use a jack plug by a quaterberth in a box on the cable between the panel for the start battery and its controller to plug that panel instead into another cable connected to a controller connected to the house bank. As the alternator is keeping the start battery charged while cruising solar is then unnecessary on the start battery. That provides additional solar capacity for the house bank.


When running more than one panel to a single controller I think it's best to take separate cables from each panel to a junction box before the the controller. Then from there one short cable to the controller. Otherwise it's almost impossible to attach multiple wires to the small controller terminals. Doing that also keeps joins inside the boat. Don't skimp on cable size.


The controllers should be as close as practical to the batteries so there is minimal cable voltage drop in the regulated voltage. The inevitable voltage drop in the longer cables from the panels doesn't matter so much as its unregulated. Also having more than one controller means separate cables from the panels to controllers which means less loss in those long cables, as well as the advantages mentioned by others.



You can have multiple methods charging one battery / bank at the same time; i.e. solar controllers, engine alternator, and a shore power mains charger. Just make sure the relevant cables are suitable size.
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Old 26-07-2015, 01:01   #14
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Re: Yet another solar wiring question

Concerning panel output, one factor often neglected is that in fixed horizontal mount you never get more then 70% of nominal output. Unless you are cruising in the tropics of course.


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Old 26-07-2015, 03:57   #15
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Re: Yet another solar wiring question

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Concerning panel output, one factor often neglected is that in fixed horizontal mount you never get more then 70% of nominal output. Unless you are cruising in the tropics of course.


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If they are fixed panels for say street lighting they should of course point due north or south and be at the same angle above horizontal as your geographic latitude.
But boats move around and for me the best average on a boat is horizontal.
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