Posted by LectronNuis on June 9, 2010, 6:15 am
>vaughn wrote:
>>>
>>> One problem could be caused by shading of one panel while the other has full
>>> sun.
>>
>> That would be much more of an issue for series panels than parallel. Panels
>> usually have blocking diodes installed internally, so a shaded panel simply
>> contributes little or no charge current, but causes no problems.
>That's an interesting scenario. I would think the shaded series panel
>would still conduct most of the current being generated by the others,
>so the total power loss would be about the same as in a parallel setup.
>That hypothesis may be completely out to lunch, so if it starts to
>really bother me, I'll get the ammeter out.
Hi Mike..
For polycrystalline cells I do believe the circuit is actually opened,
within the panel, as cells within the area of shade cease functioning.
So a series connected array would not "open circuit" as there would
always be one circuit available in a single shaded panel or shaded
area of array. Certainly I recall tests with polycrystalline panels on
pumps (circa 1991) had the effect of slowing the pump dramatically, ceased
pumping even at low percentages of "shade".
Today I only have monos and those are some distance from my
location, on property, or I would grab a meter and go check.
Shading affects a mono array output but nowhere near the effect
the same shading has on poly. Also, monos "kick in" long before a
poly array even thinks about generating.
I jump in Mike, as I pinged you in a remote group on the 1st of June.
A place you posted this comment on the 24th of May:
"Too many people confuse arrogance with wit. They see themselves as
smart, not obnoxious."
Would you kindly search out my post and consider my request?
Thanks.
LN
Posted by vaughn on June 9, 2010, 11:11 am
> That's an interesting scenario. I would think the shaded series panel
> would still conduct most of the current being generated by the others,
> so the total power loss would be about the same as in a parallel setup.
I did not say that the panel would be an open circuit, (if it does, a parallel
diode could conduct around it). I was more thinking about the dramatic
reduction in output voltage which could possibly go below your battery voltage
and not charge at all unless you have invested in a fancy MPP charge controller.
Vaughn
Posted by John B. slocomb on June 9, 2010, 11:24 am
>vaughn wrote:
>>>
>>> One problem could be caused by shading of one panel while the other has full
>>> sun.
>>
>> That would be much more of an issue for series panels than parallel. Panels
>> usually have blocking diodes installed internally, so a shaded panel simply
>> contributes little or no charge current, but causes no problems.
>That's an interesting scenario. I would think the shaded series panel
>would still conduct most of the current being generated by the others,
>so the total power loss would be about the same as in a parallel setup.
>That hypothesis may be completely out to lunch, so if it starts to
>really bother me, I'll get the ammeter out.
>mike
The multiple solar panels used on sailing yachts are nearly always
connected in parallel, for whatever that is worth.
Cheers,
John B.
(johnbslocombatgmaildotcom)
Posted by m II on June 10, 2010, 12:37 am
John B. slocomb wrote:
> The multiple solar panels used on sailing yachts are nearly always
> connected in parallel, for whatever that is worth.
Are these panels usually charging a 12 volt battery? I would think there
many similarities to automotive equipment.
mike
Posted by John B. slocomb on June 10, 2010, 1:43 am
>John B. slocomb wrote:
>> The multiple solar panels used on sailing yachts are nearly always
>> connected in parallel, for whatever that is worth.
>Are these panels usually charging a 12 volt battery? I would think there
>many similarities to automotive equipment.
>mike
Nearly always. There are boats built to run on A.C. but usually the
big ones and they generally have a gen set running contentiously.
Occasionally you come across a 24 VDC system but again that is unusual
as nearly all "boat gear" is built to run on 12 VDC so having a 24
volt system entails a step down system to run the 12 volt stuff.
Cheers,
John B.
(johnbslocombatgmaildotcom)
XML site map
>>>
>>> One problem could be caused by shading of one panel while the other has full
>>> sun.
>>
>> That would be much more of an issue for series panels than parallel. Panels
>> usually have blocking diodes installed internally, so a shaded panel simply
>> contributes little or no charge current, but causes no problems.
>That's an interesting scenario. I would think the shaded series panel
>would still conduct most of the current being generated by the others,
>so the total power loss would be about the same as in a parallel setup.
>That hypothesis may be completely out to lunch, so if it starts to
>really bother me, I'll get the ammeter out.