[C320-list] Solar panels and shading

[Graeme Clark]

If I have read and understood correctly the issues are that on low light days the individual cells produce well below rated voltage so a nominal 12v panel may not produce sufficient voltage to charge a battery
Conversely if wired in series to produce a higher voltage then one single cell, fully shaded, can produce enough resistance to block the current flow almost completely
As I read it an MPPT controller is the answer as this will trade volts for amps and amps for volts for optimum battery charging 
Standing by to be corrected!
Graeme

Sent from mobile: please excuse typos etc.!


> On 30 Jan 2018, at 01:24, Pat Tormey <ptormey at 4Square.net> wrote:
> 
> Yes, you are right. I was supposing that they wanted to charge 12 volt batteries. Putting 2, 12 volt rated panels in series will output 24 volts just like batteries.
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> Catalina 320’s are 12 volt systems, right?
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> Pat
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> Pat Tormey 
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> 
> From: sail-ability sail-ability [mailto:sail-ability at sympatico.ca] 
> Sent: Monday, January 29, 2018 7:30 PM
> To: Pat Tormey <ptormey at 4square.net>; c320-list <c320-list at catalina320.com>
> Subject: RE: [C320-list] Solar panels and shading
> 
> 
> 
> I'm sorry but this is incorrect, the panels can indeed be connected in Series so that they put out 24V same as connecting 12V batteries in series to produce 24V.
> 
> Regards
> 
> JohnM
> 
> 1999#574
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> 
> ---------- Original Message ---------- 
> From: Pat Tormey <ptormey at 4Square.net <mailto:ptormey at 4Square.net> > 
> Date: January 29, 2018 at 5:41 PM 
> 
> Since most Panels have reverse polarity protection you don’t want to put them in series, you can simply parallel them (in theory)
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> 
> Pat
> 
> Pat Tormey PE
> Microsoft MVP <https://mvp.microsoft.com/en-us/PublicProfile/4025688?fullName=Pat%20Tormey> 
> 
> 603.437.5726
> 
> 
> 
> From: sail-ability sail-ability [mailto:sail-ability at sympatico.ca] 
> Sent: Monday, January 29, 2018 4:47 PM
> To: ptormey <ptormey at 4square.net <mailto:ptormey at 4square.net> >; c320-list <c320-list at catalina320.com <mailto:c320-list at catalina320.com> >
> Subject: Re: [C320-list] Solar panels and shading
> 
> 
> 
> I have a single 180W panel on the davits on Luffin Life. Never had a shading issue due to location of the panel. I have learned however that if you have two panels hooked in series that the shading issue is mitigated somewhat. There's a guy in Mississauga ON (S.A.W. Technologies) who sells semiflex 100W panels which weigh in at 4lb. The issue is that you need a controller which will handle 24V; my Blue Sky controller will do that. I'm thinking of an upgrade as my single solid panel weighs in at 40lb and difficult to handle. I think those panels come in at 280 CAD each.
> 
> Cheers
> 
> JohnM
> 
> ---------- Original Message ----------
> From: ptormey at 4square.net <mailto:ptormey at 4square.net> 
> Date: January 29, 2018 at 1:13 PM
> 
> 
> Keep in mind that you can always add another panel someplace else if you
> have two smaller spaces or to keep one in the sun.
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> 
> Pat
> 
> Pat Tormey
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