[C320-list] Solar panels and shading

[Marek Fluder]

Last summer our docks were rebuilt so we had no power for quite some time.
I played with a fixed 100W panel/controller that friend had sitting unused.
I wanted to check the feasibility of sustaining the fridge running.
In full sun with the panel fully perpendicular to sun rays and unobstructed
it was able to "pump" 6.5A at 12.7V, so roughly delivering 82W.
With the panel just sitting at a convenient and most optimal location on
the foredeck it was producing 5.5-6.0A - about 70W.
Any partial shade on the panel would drop the current substantially - I do
not remember to what level, but it was dramatic.
This setup was able to sustain the fridge running for a few days, but the
battery voltage was dropping slowly so I have determined it is not
sustainable in the longer run.
I ran this test in second half of June which has the longest days.
I hope this shed some practical light on this topic.

Marek
#1028
Hamilton, ON



On Tue, Jan 30, 2018 at 8:58 AM, <ptormey at 4square.net> wrote:

> Well, I think you really do need to check with the manufacturer. They'll
> have guidelines.
>
> Internal to a panel the cells are wired both parallel and in series to
> achieve the voltage and amperage required (Power=Volts X AMPS). This also
> protects failed cells from blocking the output.
> In the old days it was common for some cells to be dead at manufacturer
> and still perform within spec.
>
> My own unit (Suaoki 100W 18V 12V Solar Panel Charge) is 12-18 volts with
> an XCSOURCE 30A 12V/24V Solar Charge Controller Solar Panel Battery
> Intelligent Regulator LD296
> Works fine on cloudy days and great on sunny days I keep it on the
> 'flexed' over the Dodger which is, of course, under the boom.   It doesn't
> do any heavy lifting like refrigeration but keeps the batteries fresh.
> IF I wanted more power I'd parallel another 12-18 volt panel and let the
> regulator do its job.
>
> It's hard to express the affect of shade without a constant load, but your
> supplier should be able to put some parameters on it.
>
> Here is a good (simple ) article on the subject
> http://www.mpptsolar.com/en/solar-panels-in-parallel.html
>
>
>
> Pat
>
>
>
>


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