[Server-devel] [UKids] NUC and solar power questions

Richard Smith smithbone at gmail.com
Fri Jun 20 13:37:00 EDT 2014

On 06/20/2014 12:07 PM, George Hunt wrote:

>     2. Is the 10 amp charge controller (described on the website)
>     sufficient or would a 20 amp be better?

If you are considering other charge controllers I'll note that with the 
PV-136 a MPPT controller is basically required.


Vmp of the panel at the NOC they specify is 30.8V.  A 24V PWM only 
system would be close but a PWM only controller @ 12V will yield 
terrible PV performance.

The manual doesn't give any specifications about the max amperage for 
the load (ie the XOs).  If this is the same as the max battery current 
10A than 10 XO's at full load could exceed that.  17W peak per/XO 170W 
total @12V is 14 amps.  You would hit peak XO draw if you are both using 
the XO and charging a low battery at the same time.

If you think there's any chance of increasing the number of XO's 
serviced in the future then I's suggest you go with the 20A.

The 10A is also assuming adequate airflow across the cooling fins the 
20A controller is going to give you more headroom for sub-optimal 
airflow installations.

Richard A. Smith

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