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Old 05-09-2018, 22:42   #16
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Re: A basic Solar Question

I really appreciate the info and thanks Rod for the technical ideas. I intend adjusting some of the locations and fitting the new panel (already bought) with its own mppt controller. I understand that two panels in parallel to one controller is not a big problem with shading but a third panel would be, so two controllers it is. Also bought a current and power meter that I can temporarily connect to my consumers to get a better power audit.
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Old 06-09-2018, 04:39   #17
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Re: A basic Solar Question

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Originally Posted by newhaul View Post
orentated fore and aft to minimize the likelyhood of shading. by the boom.
on parallel hooked up panels it really doesnt make a difference
Incorrect.

The boom normally shades one side of the bimini or the other.

If the panels are oriented fore/aft, there is a better chance only one is shaded, and the full output of the other will be realized.

If the panels are oriented athwartship, there is a better chance both panels will be shaded and the output will be zero.

If panels are connected in parallel, one can be shaded and the other work.

If panels are connected in series, if one panel is shaded, neither panel works (unless bypass diodes are installed.

For 200 W systems I recommend a single controller. For 400 W one controller is fine, 2 controllers offers some functionality if one controller packs it in.

In this case, the cost of one controller is already sunk, so the cost of the second smaller controller is less expensive.

There is also the potential for some benefit of improved MPPT operation on panels of different maximum power points and shading, that may overcome the additional energy consumed by a second controller.
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Old 06-09-2018, 04:47   #18
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Re: A basic Solar Question

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Originally Posted by Dranflydbl View Post
I have been reading with interest the threads on solar panel installation and recognise that there is a wealth of information in this community. Perhaps you guys might suggest a simple solution to my question. Ideas appreciated.
I currently have two 80 watt panels mounted on a frame over the stern of my 33 foot yacht. Each one is angled at about 40 degrees to the horizontal, sloping outboard, one port, one stbd. They are paralleled to a Steca PR1515 controller. For many hours only one would be getting full sun and I generally see 4.5 to 5 amps coming into the controller. That seems to keep the AGM battery bank at 99% to 100% at the mooring.
I would like to put a 200 watt flexible on top of the bimini to improve solar catch and we all know that efficiency will never be such that I get 200W/12V current from it. Nevertheless it would feasibly exceed the 15A in total.
I am considering either a quick solution and put a controller on that panel and direct to the busbar, so there are two solar feeds to the busbar, or replace the Steca with a 30A MPPT. If I do the latter should I put diodes in the circuits to stop back current and reduced efficiency if one panel is in shade, since all panels would then be wired in parallel?
What are your thoughts?
Because the panels are totally different, it is advisable to use a separate controller for the new 200W. If you must take a MPPT or if a cheap PWM controller is sufficient depends on the electric parameters of the panels (how many cells, Vmp and Imp). Because there are no more information about them in your question I cannot give you an educated hint. MPPT are in general more versatile, but also need a higher voltage to be efficient.
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Old 06-09-2018, 06:36   #19
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Re: A basic Solar Question

Yes matched panels if more than one per SC.
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Old 06-09-2018, 06:44   #20
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Re: A basic Solar Question

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Originally Posted by ramblinrod View Post
Incorrect.

The boom normally shades one side of the bimini or the other.

If the panels are oriented fore/aft, there is a better chance only one is shaded, and the full output of the other will be realized.

If the panels are oriented athwartship, there is a better chance both panels will be shaded and the output will be zero.

If panels are connected in parallel, one can be shaded and the other work.

If panels are connected in series, if one panel is shaded, neither panel works (unless bypass diodes are installed.

For 200 W systems I recommend a single controller. For 400 W one controller is fine, 2 controllers offers some functionality if one controller packs it in.

In this case, the cost of one controller is already sunk, so the cost of the second smaller controller is less expensive.

There is also the potential for some benefit of improved MPPT operation on panels of different maximum power points and shading, that may overcome the additional energy consumed by a second controller.
rod that is the same thing I said but without the long winded infomercial.
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Old 06-09-2018, 09:55   #21
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Re: A basic Solar Question

This is a pretty good test of wiring panels parallel vs. series. Maybe help...Maybe not

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Old 06-09-2018, 10:07   #22
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Re: A basic Solar Question

Quote:
Originally Posted by newhaul View Post
orentated fore and aft to minimize the likelyhood of shading. by the boom.
on parallel hooked up panels it really doesnt make a difference
Of course it makes a difference. With fore-and-aft orientation it's more likely that one panel will be shaded, and the other in the clear. Oriented side-to-side, it's more likely that both panels will be shaded and neither will deliver any power.

I have three panels on my dodger (yes, it's a bad location), one panel to port, one in the middle, and one to starboard, with a MPPT controller per panel. If I had them arranged bow-to-stern I would get very little output indeed.
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Old 06-09-2018, 10:12   #23
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Re: A basic Solar Question

Quote:
Originally Posted by Paul Elliott View Post
Of course it makes a difference. With fore-and-aft orientation it's more likely that one panel will be shaded, and the other in the clear. Oriented side-to-side, it's more likely that both panels will be shaded and neither will deliver any power.

I have three panels on my dodger (yes, it's a bad location), one panel to port, one in the middle, and one to starboard, with a MPPT controller per panel. If I had them arranged bow-to-stern I would get very little output indeed.
Paul I suppose I should have been more clear on that post my comment concerning parallel panels was directly related to a single or multiple controllers not the orientation of the panels they were and are two separate specific questions I was answering .
And not directly related . I should have been more clear that they were two distinct direct answers to two separate questions
I will be more specific in the future and stop posting before my morning coffee
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Old 07-09-2018, 08:54   #24
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Re: A basic Solar Question

Dear newhaul,

Quote:
rod that is the same thing I said but without the long winded infomercial.
Yes, but I did find rod's lengthy post clearer, and I did appreciate it, partly due to terminology about orientation. So, sometimes being a little pedantic with greater clarity, is helpful. Thank you both newhaul and rod! Good teamwork.

Best to you both. Rick
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Old 07-09-2018, 09:03   #25
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Re: A basic Solar Question

Quote:
Originally Posted by Paul Elliott View Post
Of course it makes a difference. With fore-and-aft orientation it's more likely that one panel will be shaded, and the other in the clear. Oriented side-to-side, it's more likely that both panels will be shaded and neither will deliver any power.

I have three panels on my dodger (yes, it's a bad location), one panel to port, one in the middle, and one to starboard, with a MPPT controller per panel. If I had them arranged bow-to-stern I would get very little output indeed.
Thanks Paul,
I understand from this that the most effective orientation of multiple panels on a "Fore and Aft orientation" means the long side of the PV is parallel to the centerline of the boat..

And you explain why it is most effective.

For example:
I was considering panels oriented fore and aft, separate PV Panels port and starboard, with matching panels on the deck just ahead of the dodger wired in series to increase power, but realized that that would not be effective due to shading by the dodger itself (PV not at the same plane).
It would be better to have 4 separate controllers for the 4 PV.
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