Drake,
I have seen this often. The operating voltage drops as panels age.
MPPT depends on a higher input voltage compared to the battery
voltage. When you account for module temperature and age, the panel
may not produce enough differential voltage for the controller to
convert into power. If no boost takes place, the controller will act
like a conventual PWM controller. Good news is that if the controller
will handle the Voc, you can put the old modules in series and do a
little better job of reaching the acceptance voltage.
Yes I have sold hundreds of Blue Sky products. The IPN Pro battery
monitor is the best I have ever installed. Highly recommended.
Larry Crutcher
On Mar 20, 2009, at 9:25 AM, Drake Chamberlin wrote:
At 09:46 AM 3/20/2009, you wrote:
The CTI-90, rated at 5.15 amps, will reach 7 amps here in Yuma with
the Blue Sky 3024i.
Do you use the Blue Sky metering, or have you checked the MPPT
output with independent metering? I retrofitted a 12 V Blue Sky
charger on an old cabin system. The CC had no on-board metering. My
measured result showed almost the same output and input on a cool,
sunny day. The modules were ancient Arco units, but I still
expected some improvement.
Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648
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