[RE-wrenches] Fwd: Grounding on a glacier, SunPower modules

[Larry Crutcher, Starlight Solar]

boB,

I usually put only two in series and use MPPT to down convert to 12  
volts. Some RV customers have 6~8 modules, series/parallel. I promote  
the use of battery monitors in all systems so if there was a  
performance issue, I would have seen or heard of it by now. RV  
customers have nothing better to do than to stare at the monitors.  
Really though, most RV full-timers are a dedicated group of "off- 
gridders" conserving energy and water resources.

Now that you and Dan mention it, I did hear that the polarization  
effect did not occur at low string voltages. I have never installed  
any high voltage strings with SP.

Larry

On Jul 23, 2009, at 7:56 PM, boB Gudgel wrote:

> Larry Crutcher, Starlight Solar wrote:
>> I meant to type ...NO noticeable loss of power.
>
> Hi Larry....   But how do you ~really~ know you weren't losing power  
> because of their lower efficiency unless there was
> a comparison made ?  :)     I'm not sure that I believe it's all  
> that much of a problem, either.
>
> But seriously, I think that  what Sunpower ~really~ means is that  
> they have a problem with their lower efficiency on high voltage  
> strings.
> I don't imagine that an RV installation would be that high of  
> voltage ?
> I would just like Sunpower to explain this all a bit better.
>
> boB
>
>
>
>
>>
>>
>> On Jul 23, 2009, at 7:27 PM, Larry Crutcher, Starlight Solar wrote:
>>
>>> I have installed tons of SunPower 90's without any ground  
>>> connection on RV's with noticeable loss of power. I believe the  
>>> problem only occurs when you have a path to ground from the frame.
>>>
>>> Larry
>>>
>>> On Jul 23, 2009, at 12:58 PM, boB Gudgel wrote:
>>>
>>>> Larry Crutcher, Starlight Solar wrote:
>>>>> Hi Jay,
>>>>>
>>>>> An interesting quandary indeed.
>>>>
>>>> This is another good example of an application that I was trying  
>>>> to grill Sunpower about --- as far as grounding their modules  
>>>> that need to be positive grounded
>>>> in order to take advantage of their higher efficiencies.   They  
>>>> couldn't answer this simple question.  How would you use one in  
>>>> an airplanefor instance ?
>>>> There are solar powered airplanes (sort  of)   Is a large faraday  
>>>> shield enough ?   Sort of like the ground radials that Larry has  
>>>> mentioned.  I would
>>>> imagine that if you get large enough radials that it ~might~  
>>>> approach being a virtual ground. Works for antennas though.
>>>>
>>>> I like questions like this one.  Sure makes one think a bit.
>>>>
>>>> boB
>>>>
>>>>
>>>>
>>>>
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