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Old 03-07-2013, 23:15   #1
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Solar Power

I have installed a couple of 68 watt flexible panels on my boat but am only getting about 3.5 amps at 13.4 volts from them on a sunny day. The charge controller is on bulk charge and I would have thought I should get a higher amperage. Any ideas?

Peter
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Old 04-07-2013, 00:39   #2
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Re: Solar Power

3.5amp. a piece or together? Are they wired in parallel or series? What size wire are you using and how long is the run? What type of charge controller?
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Old 04-07-2013, 09:48   #3
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Re: Solar Power

I find I get about 65 percent of rated amps out of my panels on board. The rated amps are under ideal conditions, bright sun, completely clear skys, panel aimed directly at the sun and 68 degrees F (20 degrees C). Like automobiles, your mileage may differ.
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Old 04-07-2013, 09:56   #4
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Re: Solar Power

Quote:
Originally Posted by spiritcat View Post
I have installed a couple of 68 watt flexible panels on my boat but am only getting about 3.5 amps at 13.4 volts from them on a sunny day. The charge controller is on bulk charge and I would have thought I should get a higher amperage. Any ideas?

Peter
Is that 3.5A for the combined output of both panels, or 3.5A each?

What panels and controller do you have?
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Old 04-07-2013, 11:52   #5
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You will almost never get the rated watts out of a solar panel (or wind generator) if you don't have it operating in optimum conditions.
That usually means having the directly facing the sun in the sky.
This means you need the panel to be mounted on a tracking mount (which can be automatic or manual).
A flexible panel is pretty much designed to be a compromise.
They mount in a way that is unobtrusive, but they're rarely going to be operating at rated capacity.
It's just the nature of the design.

I've been mulling over ways to mount a 50 watt rigid panel that I have in my basement.
I've been looking at something like this...
http://www.coastalsolarsales.com/Photo-Gallery.html

I also need to come up with a mount for a 60 watt wind generator I have.
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Old 04-07-2013, 12:08   #6
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Re: Solar Power

65 watts is really just a roof ornament. I would have expected a bit more than 3.5 amps but as others have noted a variety of variables can affect output. Orientation, wire gauge & length will have a big impact on your expected output.
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Old 04-07-2013, 14:21   #7
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Re: Solar Power

Right now I'm anchored at Clipper Cove in S.F. Bay for the day/night. At 1:00 pm. the MPPT switched to acceptance mode, so I'm 80%-95% fullNow it will creep up to 14.4 volts (maybe) and register "bulk". 300 watts total.
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Old 04-07-2013, 16:00   #8
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Re: Solar Power

Our case:

Panels: 75W, mono. Voltage before regulator: +/-17.5. Amps: +4 (each).

Two such panels will easily deliver +7 Amps, past the regulator, full sun, not angled. More when angled.

You need a pretty dead battery to see the max output of your rig. I measure to a very discharged battery, ex-regulator first. Max I ever measured was 4.4A from a 75W panel.

Flexies give less juice than monos too.

b.
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Old 04-07-2013, 16:00   #9
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Re: Solar Power

Thanks for the responses. I was getting 3.5amps from two 68 watt panels but after checking the wiring back to the panels themselves, I found a loose connection on one panel. I will check at midday today if the sun is out to see if the charge doubles now that I have fixed the connection.

Peter
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Old 04-07-2013, 16:36   #10
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Re: Solar Power

3.5 A from 2x68w is very poor as peak production, but iIt looks like you have solved the problem.

For anyone with similar problems a clamp on multimeter is a great diagnostic tool. It. Can be put over wires without disconnecting them and show in this case the output from each panel separately.
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