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Old 18-04-2016, 07:56   #1
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Solar panel help

I'm a pretty good gear-head, but admittedly lost on solar stuff.
I have built 2 hardtops for our Morgan 512. Now I want to put an bunch of solar power in place.
The space I have is 2@ 55x30 and 2 more at 60x30.
At present I can't find panels above 12 volt to fill those spaces and the ones I do find seem to be way more expensive/watt than I've been told to expect.
Can somebody help me with the right panels for the job and where to go for them.
I've been told that I want "diode"? panels as they will be angled 10-15 deg away from each pair.
I really need to be "led" thru this --thanx
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Old 18-04-2016, 08:34   #2
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Re: Solar panel help

Charge controllers usually have a diode in them nowadays.
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Old 18-04-2016, 09:28   #3
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Re: Solar panel help

Don't understand what you're saying about the voltage. Most panels have blocking diodes. If not, it's an easy add on.


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Old 21-04-2016, 06:03   #4
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Re: Solar panel help

If some panels might be trying to provide higher voltage than others (better sun angle) then you want (at least) a diode on the + lead of each solar panel to prevent reverse current.

Its not expensive to get a "Schotkey" (low voltage drop) diode for each panel. (not a bad idea to just put those in anyway in case of a panel failure)


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I'm a little out of date on what panels to get... I built a solar system for an odd use, on top of a 12 ftX 5 ft cargo trailer using the Harbor Freight panels. Its been doing well (for my purpose) for 7 years.
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Old 21-04-2016, 06:57   #5
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Re: Solar panel help

OK the biggest questions to answer first are
First. House bank size and type
Second what is expected daily power usage.
Third estimated budget for the whole project.
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Old 21-04-2016, 07:03   #6
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Re: Solar panel help

Quote:
Originally Posted by MarkJ View Post
Charge controllers usually have a diode in them nowadays.
Mark every panel I have worked with in the past few years have blocking diodes in them however they call them bypass diodes. Both do the same job and yep the controllers I have installed also have blocking diodes in them.
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Old 21-04-2016, 07:16   #7
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Re: Solar panel help

Price per watt varies by construction, efficiency, and quality. Expect to pay much more for back wired SunPower brand panels or cells made with them. Chinese panels are much cheaper, and, to date, you get what you pay for. Add all you can, if possible use a dedicated MPPT controller for each panel, and off you go. If you aren't comfortable with this hire a pro with marine experience (there are many). Good luck...
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Old 21-04-2016, 11:06   #8
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Re: Solar panel help

Quote:
Originally Posted by newhaul View Post
Mark every panel I have worked with in the past few years have blocking diodes in them however they call them bypass diodes. Both do the same job and yep the controllers I have installed also have blocking diodes in them.
A blocking diode is not the same as a bypass diode.

I don't know the configuration of the panels you have been working with, but a blocking diode is connected in series with the panel, and a bypass diode is connected in parallel. Bypass diodes are used when you have multiple panels connected in series (for higher-voltage operation). Blocking diodes are for panels connected in parallel, and to prevent a dark panel from draining your battery.
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Old 21-04-2016, 11:19   #9
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Re: Solar panel help

Paul the actual diode is the same its more where they are installed that makes the difference in what it does
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Old 21-04-2016, 13:49   #10
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Re: Solar panel help

OK, the diode will probably be the same (similar current and voltage requirements), but you definitely need to connect it appropriately. My old panels came with diodes in the terminal box already wired in the blocking configuration. Had I needed to perhaps I could have reconnected the diodes for bypass.

My point is that these are two completely different configurations.
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Old 22-04-2016, 09:37   #11
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Re: Solar panel help

I've found this to be one of the easiest How To solar sites:

https://handybobsolar.wordpress.com/

There are many other vendor's websites that will also help.

Good luck.
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Old 22-04-2016, 11:42   #12
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Re: Solar panel help

2, may be 3, years ago I got 4 110W 43"x27" panels at $90 each from Sunelec in Miami, FL. Not light but I couldn't afford flex panels at the time.

Same wattage today is probably less than 50c a watt for hard panels.
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