Solar module cell-count [RE-wrenches]

[Bill Brooks]

Joel,

Design is so routinely oversimplified that our industry seems to suggest
that someone with 2 months of experience can design PV systems. It's just
not true.

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

Ecclesiastes 11:7 Light is sweet, and it pleases the eyes to see the sun.


> -----Original Message-----
> From: Joel Davidson [mailto:joel.davidson at sbcglobal.net]
> Sent: Tuesday, May 22, 2007 7:22 AM
> To: RE-wrenches at topica.com
> Subject: Re: Solar module cell-count [RE-wrenches]
> 
> 
> > (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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