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NNTP-Posting-Date: Fri, 31 May 2024 21:15:41 +0000
From: boB <boB@K7IQ.com>
Newsgroups: sci.electronics.design
Subject: Re: Solar panels
Date: Fri, 31 May 2024 14:15:40 -0700
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On Fri, 31 May 2024 13:50:41 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 5/31/2024 1:43 PM, Don Y wrote:
>> On 5/31/2024 12:56 PM, KevinJ93 wrote:
>>> On 5/30/24 10:00 PM, Don Y wrote:
>>>> But, the individual wafers (on a panel) are probably wired in a
>>>> series-parallel configuration with a nominal 48VDC output.
>>>
>>> Not usually true - I don't know of any panels where there is a 
>>> series-parallel configuration. As wafer sizes increase the panel current 
>>> increases.
>> 
>> I count ~72 wafers on a panel I have here.  How does *it* get to a 48V
>> nominal output?
>
>Ah!  Each *wafer* is a *single* PV cell?  The metalization layers led me
>to think each was *three* cells (~2V output) series connected.
>


72 cells is a common PV module (panel) configuration.

So is 60 cells.

An MPPT charger is usually a buck converter so that's how it gets
there.  A nominal 48V PV array will need to have a higher Vmp than the
battery voltage to charge that battery bank.

Sounds like Kevin knows his stuff regarding this and you aren't far
off, if at all.  

Rapid Shutdown requires the array at the string (HV) inverter or
charge controller input to be at or below 30V in 30 seconds after its
clear to go signal is removed.  At least those who are being inspected
to NEC.

boB