Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 06-07-2011, 05:58   #46
McG
Registered User

Join Date: Jun 2011
Location: New Zealand
Boat: Nissan 9m Motorhome
Posts: 32
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by sailingaway221 View Post
McG, I had the work done by a friend who has been working on boats electrical systems forever. I'm not on the boat to look, but from memory the panels go to individual controller for each one , then through a Xantrex Pathmaker a breaker and to the batteries. When I get back I'll see if I can see how they go from the Xantrex to the batteries, but I believe the panels are combined as they come out of the Xantrex as there is only one breaker between that and the batteries. In real time either or both panels can charge the batteries and if one panel is covered the other still provides max output.
Thanks sailingaway, but I am still confused as to what happens with thecharge coming in from the lesser producing system. If I have 2 hosepipes running water into a bucket, one at 1 l/h and the other at 5l/h, I can fill a 6litre bucket in 1 hour. Electrics are a little more complex I believe. So my question is, if one panel gives full power, say 16.5v and 5A to the controller connected to the bat which is sitting at 13v, the controller will pass roughly 6A @ 13.4V to the batt. If the other panel is generating 14.5V 3A through its controller, hooked up to the same batt, does it assist in charging or not? The controller should push 13.4v 3.5A into the batt, but does it?

Note: All figures are for purpose of the theory and not calculated to the T
__________________

__________________
McG is offline   Reply With Quote
Old 06-07-2011, 06:03   #47
Registered User

Join Date: Aug 2008
Location: St. Martin
Boat: St. Francis 43 Brisa
Posts: 333
Re: Four Solar Panels - Parallel , Series or Series-Parallel

McG I think the XAntrex Pathmaker combines the output from both solar panels. For certain the output of both panels is combined.... When I get back i'll go have a look and see if I can see how it works exactly or i'll go ask the guy that did the work... Will let you know.
__________________

__________________
sailingaway221 is offline   Reply With Quote
Old 06-07-2011, 07:53   #48
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by McG View Post
Thanks sailingaway, but I am still confused as to what happens with thecharge coming in from the lesser producing system. If I have 2 hosepipes running water into a bucket, one at 1 l/h and the other at 5l/h, I can fill a 6litre bucket in 1 hour. Electrics are a little more complex I believe. So my question is, if one panel gives full power, say 16.5v and 5A to the controller connected to the bat which is sitting at 13v, the controller will pass roughly 6A @ 13.4V to the batt. If the other panel is generating 14.5V 3A through its controller, hooked up to the same batt, does it assist in charging or not? The controller should push 13.4v 3.5A into the batt, but does it?

Note: All figures are for purpose of the theory and not calculated to the T
Yes
The input voltage (from the panel) to the controler will be the voltage that the panel produces the most watts (the MPP). This is set and adjusted by the controler as conditions change.
The output voltage of the controler has to be the battery voltage (ignoring voltage drop in the wiring)
So with 2 controlers the input voltage from the solar panels will be different, but the output voltage will be the same. The output current will be different, but both panels will contribute, providing the solar panel voltage is above the battery voltage.
__________________
noelex 77 is offline   Reply With Quote
Old 06-07-2011, 11:09   #49
Registered User

Join Date: Aug 2008
Location: St. Martin
Boat: St. Francis 43 Brisa
Posts: 333
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by noelex 77 View Post
Yes
The input voltage (from the panel) to the controler will be the voltage that the panel produces the most watts (the MPP). This is set and adjusted by the controler as conditions change.
The output voltage of the controler has to be the battery voltage (ignoring voltage drop in the wiring)
So with 2 controlers the input voltage from the solar panels will be different, but the output voltage will be the same. The output current will be different, but both panels will contribute, providing the solar panel voltage is above the battery voltage.
Yeah... like Nolex said.... thanks.
__________________
sailingaway221 is offline   Reply With Quote
Old 06-07-2011, 14:10   #50
Registered User

Join Date: May 2011
Boat: Hitchhiker, Catamaran, 40'
Posts: 354
Re: Four Solar Panels - Parallel , Series or Series-Parallel

So we've discussed parallel which I might try but need to upgrade my wires. Two controllers I won't do unless I win the lottery but what about installing bypass diodes. Anyone have any direct experience with this option and where would I get the diodes and which diodes and would I need one per panel or two? The shadow from my mast today blocked about half a panel and my amps went from 19 to 4. Is there some sort of switching device other than a diode that could bypass a shaded panel? Thanks Phil
__________________
Thumbs Up is offline   Reply With Quote
Old 06-07-2011, 14:41   #51
Registered User

Join Date: Jul 2010
Location: Seattle, Wa
Boat: Spencer 31
Posts: 62
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Thumbs, can you give us the model of the panels? I have 2 195w panels in series, each with 2 blocking diodes. When I get partial shading, I can lose as little as 1/4 of my total power if only cells on one diode are shades. This beats parallel where any shading on one panel would put that panel's output to zero.
__________________
jaredko is offline   Reply With Quote
Old 06-07-2011, 14:58   #52
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by Thumbs Up View Post
So we've discussed parallel which I might try but need to upgrade my wires. Two controllers I won't do unless I win the lottery but what about installing bypass diodes. Anyone have any direct experience with this option and where would I get the diodes and which diodes and would I need one per panel or two? The shadow from my mast today blocked about half a panel and my amps went from 19 to 4. Is there some sort of switching device other than a diode that could bypass a shaded panel? Thanks Phil
4 A ouch! That does show the problems assiociated with series connection.
I think you will get more Ahrs with a parallel arrangement despite your wiring and MPPT regulator. The power loss associated with bypass diodes is a stumbling block, but if want to try them here is a website showing the correct wiring
Blocking and By-Pass Diodes Used in Solar Panels
Schokky diodes rated for the maximum current are available from most electronic shops. They are cheap so experiment.
__________________
noelex 77 is offline   Reply With Quote
Old 06-07-2011, 15:11   #53
Registered User
 
SV Demeter's Avatar

Join Date: Dec 2009
Location: Cruising Eastern Caribbean
Boat: Wauquiez Amphitrite 43- Demeter
Posts: 1,164
Re: Four Solar Panels - Parallel , Series or Series-Parallel

I would be interested in hearing more about power loss associated with bypass diodes. The link Noelex just posted was very helpful to me in understanding hwo bypass diodes work. I am leaning towards a series-parallel installation on my boat and was considering the use of bypass diodes to help with the shading problem. Is there consensus () that the power loss associated with using bypass diodes offsets the gains?
__________________
SV Demeter is offline   Reply With Quote
Old 06-07-2011, 15:28   #54
Registered User

Join Date: Jul 2010
Location: Seattle, Wa
Boat: Spencer 31
Posts: 62
Re: Four Solar Panels - Parallel , Series or Series-Parallel

There is some power loss associated with bypass diodes. No current flows through them when there is no shade, so we are only concerned with the impact when a panel is shaded. When a panel is shaded, the current from the other panels will travel through the diode, lowering the voltage of the system by approx 0.6v.

If Thumbs Up were to add bypass diodes to his system (sounds like he is indeed missing them), his unshaded panel that puts out 10.5 amps at 18volts for 190w, would instead deliver 10.5amps at 17.4volts, for 183w. That 7w would be dissipated as heat in the diode.

Bypass diodes are most useful if there are more than 1 per panel, because it allows parts of the panels to be disabled as they are shaded, but other parts to continue to produce power. My panels have 2 diodes and my current can drop by as little as 25% in partial shading.

Thumbs up is probably best off going with parallel connections as bypass diodes do not add value when there are only 2 panels in series. That configuration would produce a result similar to parallel (partial shading disables the entire panel), but with the diode losses as well.
__________________
jaredko is offline   Reply With Quote
Old 06-07-2011, 15:46   #55
Registered User
 
SV Demeter's Avatar

Join Date: Dec 2009
Location: Cruising Eastern Caribbean
Boat: Wauquiez Amphitrite 43- Demeter
Posts: 1,164
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by jaredko View Post
There is some power loss associated with bypass diodes. No current flows through them when there is no shade, so we are only concerned with the impact when a panel is shaded. When a panel is shaded, the current from the other panels will travel through the diode, lowering the voltage of the system by approx 0.6v.

If Thumbs Up were to add bypass diodes to his system (sounds like he is indeed missing them), his unshaded panel that puts out 10.5 amps at 18volts for 190w, would instead deliver 10.5amps at 17.4volts, for 183w. That 7w would be dissipated as heat in the diode.

Bypass diodes are most useful if there are more than 1 per panel, because it allows parts of the panels to be disabled as they are shaded, but other parts to continue to produce power. My panels have 2 diodes and my current can drop by as little as 25% in partial shading.

Thumbs up is probably best off going with parallel connections as bypass diodes do not add value when there are only 2 panels in series. That configuration would produce a result similar to parallel (partial shading disables the entire panel), but with the diode losses as well.
Ok I follow that but how about a series parallel configuration of (6) total panels with (3) sets of 2 panels each? Im guessing your above comments would still hold true about paralleled being better since we are just talking about multiple sets of 2 panel setups?
__________________
SV Demeter is offline   Reply With Quote
Old 06-07-2011, 15:59   #56
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: Four Solar Panels - Parallel , Series or Series-Parallel

I find the info in this thread highly confusing and, while individual sentences or even posts are correct, the combined story here is... mostly wrong.

A lot of people here are anti series connection, it's almost like if it's politics . The arguments are like political tactics too because the negatives put forward for series connection are so old that they have become boring and most panel manufacturers have included (multiple) by-pass diodes in their panels to solve the problem a long time ago. If they didn't, you can do that cheap and quick 'n easy. Electrical loss of diodes? A little, they get warm which is loss. The voltage loss is not a problem because in series we have plenty voltage anyway and very low current too, which minimizes the loss.

Let's calculate a bit; we take the voltage over a diode at 0.7V and lets say we have 6x 110W panel in series which gives 120V (6x20V), 5.5A output (120 x 5.5 = 660W so we got pretty handsome panels :-) Each panel has a by-pass diode across it's terminals and the array is connected to a good MPPT controller, like the Outback that can take 150V or so.

Okay, here we go, 1 panel becomes completely shaded, meaning it's output drops to 0 and it's internal resistance goes to very high. The bypass diode kicks in, bypassing the output from the other 5 panels (see, problem solved). We loose 0.7V from the diode in addition to the 20V from the shaded panel, meaning we now have 5 x 20 = 100 - 0.7 = 99.3V @ 5.5A. Power from the array is reduced to 99.3 x 5.5 = 546.15W which is 113.85W less than with the full array. The panel is 110W so the loss from the diode is a whopping 3.85W (now you know you need 5W diodes).

So, when 1% of array output is 6.6W, we are talking about way less than 1% loss (0.58% to be exact) from the diode when a panel is shaded, which gets added to the 16.6% (1/6) from the loss of one panel output.

This shows that series connection is okay; it's the way almost every solar array is configured (series-strings up to 400V). I think that one of the reasons that so many are negative about series connection is that they have bought very cheap MPPT controllers (there's the multiple controllers story popping up) that can't handle the voltages from a series-array, nor the amperage from a parallel array. To defend their choice, configurations that can't be done with their kit are now considered bad The additional loss in their wiring alone is way more than from a bypass diode with series connection because most are happy with a 3% voltage drop.

Edit: and that loss in wiring is always there, while the diode loss is only relevant when a panel is shaded anyway.


Nick.
__________________
s/v Jedi is offline   Reply With Quote
Old 06-07-2011, 16:47   #57
Registered User

Join Date: Jul 2010
Location: Seattle, Wa
Boat: Spencer 31
Posts: 62
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Quote:
Originally Posted by SV Demeter View Post
Ok I follow that but how about a series parallel configuration of (6) total panels with (3) sets of 2 panels each? Im guessing your above comments would still hold true about paralleled being better since we are just talking about multiple sets of 2 panel setups?
Looking at your other post. Not sure the details of your panel layout, but if all panels will be receiving the same illumination (oriented the same way), the most power efficient setup would be all 6 in series. The Outback 60 can handle the voltage. Assuming your panels have bypass diodes (confirm with the vendor), to me it looks like they have 3 diodes in each panel, but the specs aren't 100% clear.

The parallel-series config would mean you lose both panels in a set when any part of them in shaded. With all 6 in series, you'd lose as little as third of the shaded panel.
__________________
jaredko is offline   Reply With Quote
Old 06-07-2011, 16:49   #58
Registered User

Join Date: Jul 2010
Location: Seattle, Wa
Boat: Spencer 31
Posts: 62
Re: Four Solar Panels - Parallel , Series or Series-Parallel

Nick, agree 100%. For most instances where the controller can handle the higher voltages, series is the way to go. I have 2 195w panels in series mounted on my bimini and the output is great, and is only minimally influenced by shade.
__________________
jaredko is offline   Reply With Quote
Old 07-07-2011, 00:54   #59
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Four Solar Panels - Parallel , Series or Series-Parallel

If you are contemplating a series configuration of solar panels its important to understand that bypass diodes listed in the specifications and fitted by the manufacturer will only work within the panel . If you connect panels together in series and want to bypass a fully shaded panel this will require additional external diodes. They are not expensive if you want to include them.
I would encourage anyone to try different configurations before finalizing the wiring. The solar industry is dominated by domestic installations where multiple solar panels connected together experience the same conditions. The manufacturers recommendations reflect this and their wiring suggestions are often not optimum when installed on a boat.
__________________
noelex 77 is offline   Reply With Quote
Old 07-07-2011, 09:18   #60
Registered User
 
SV Demeter's Avatar

Join Date: Dec 2009
Location: Cruising Eastern Caribbean
Boat: Wauquiez Amphitrite 43- Demeter
Posts: 1,164
Re: Four Solar Panels - Parallel , Series or Series-Parallel

I am going to end up with (6) 85 watt panels set up in 3 pairs. One pair is going on a bar that will sit atop my simpson davits and allow the pair to be angled. The other two pairs are going on articulating mounts on the side railing along the aft deck, (see photo). Im open to putting the whole system in series but given the distances between the 3 pairs of panels would not a series parallel set up be simpler to wire? Im not even sure what 6 panels all in series would even look like?
Attached Thumbnails
Click image for larger version

Name:	Demter Edit.JPG
Views:	82
Size:	148.6 KB
ID:	29373  
__________________

__________________
SV Demeter is offline   Reply With Quote
Reply

Tags
solar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
600 Watt System - Series , Parallel or Combination ? SeaKing Electrical: Batteries, Generators & Solar 2 24-05-2011 09:15
Solar Panels Wired in Series / Parallel SailFastTri Electrical: Batteries, Generators & Solar 6 04-08-2010 07:51
Connect Solar Panels in Series or Parallel? gandalf Electrical: Batteries, Generators & Solar 2 27-01-2010 20:04
Series/Parallel Wiring for 24Volt Pelagic Electrical: Batteries, Generators & Solar 17 12-09-2008 21:00
How to wire solar panelsL Series or Parallel? CSY Man Electrical: Batteries, Generators & Solar 23 18-08-2007 16:42



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:07.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.