[C320-list] Solar panels and shading

[Scott Thompson]

Tim, which panels did you buy?


On 1/30/2018 2:19 PM, Timothy Woods wrote:
> Two years ago I installed two 100 watt flexible panels on my bimini and
> haven't plugged in since. I connected them in parallel with a MPPT
> controler and have no problems with shading when sailing. I'm in south
> Florida and primarily use my boat during the winter months when the sun is
> low. ( November till April.) We live full time on the boat for two to three
> months at a time. At anchor or on a mooring I tie the boom off to the side
> and get approximately 65 amp hours returned on a good day to the batteries.
> The refrigerator is the biggest draw at 35 AH per 24 hours. We also watch 2
> to 3 hours of TV and charge both cell phones.
>
> I hope this helps, Tim
>
> On Jan 30, 2018 9:22 AM, "Marek Fluder" <marekf at gmail.com> wrote:
>
>> 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
>>>
>>>
>>>
>>>
>>
>> --
>> ~~~~~~~_/)~~~~~~
>>