Solar module cell-count [RE-wrenches]

[Joel Davidson]

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> (Topica has been flaky lately so I'll try sending this a 4th time.)
>
>> Bill,
>>
>> Thanks for your input. 6-inch polycrystalline cell 36, 54 and 60-cell
>> modules are available. Bob-O (thanks) says different cell configurations
>> can
>> be used for battery based PV systems thanks to MPPT controllers. Andy
>> Riegler (thanks) says Xantrex inverters with 300 to 600 VDC input have an
>> MPPT sweet spot around 30% above 300 volts (for example 21 each Kyocera
>> KC130 modules which is 756 cells). The SMA Central also likes 21 each 6"
>> cell 36-cell modules. Although PV modules have no moving parts, there 
>> sure
>> are a lot of PV system design "moving parts."
>>
>> Happy designing.
>> Joel Davidson
>>
>>
>> ----- Original Message ----- 
>> From: "Bill Brooks" <bill at brooksolar.com>
>> To: <RE-wrenches at topica.com>
>> Sent: Thursday, May 17, 2007 4:46 PM
>> Subject: RE: Solar module cell-count [RE-wrenches]
>>
>>
>>>
>>> Joel,
>>>
>>> A key to better system design is not directly cell count. Higher cell =
>>> counts make it more difficult to maximize dc voltage into an inverter
>>> since
>>> = each module step is so large. Lower cell counts necessitate larger
>>> cells
>>> so = that wiring costs are reduced. For larger scale projects, it would
>>> be
>>> nice to have 6" to 8" cells so that each string has the highest possible
>>> current = and voltage therefore getting the most power per labor dollar.
>>>
>>> Smaller rooftops necessitate smaller cells so that the designer can get 
>>> =
>>> more voltage per smaller area. Therefore, big systems need big cells and
>>> =
>>> small residential systems need smaller cells.
>>>
>>> Everyone seems to talk about module power and cell count, but they =
>>> rarely
>>> discuss the issue of cell size and current. That's my story, and I'm
>>> sticking to it.
>>>
>>> Bill.
>>>
>>> Bill Brooks, PE
>>> Brooks Engineering
>>> 873 Kells Circle
>>> Vacaville, CA 95688
>>> office and mobile phone: 707-332-0761
>>> fax:707-451-7739
>>> email: billbrooks7 at yahoo.com
>>> web: www.brooksolar.com
> 


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