Apollo T-80 Alert [RE-wrenches]

[Mick Abraham]

Hi, Wrenches~

The Apollo T-80 requires PV strings with more than 36 cells for every 12 
volts of battery. I learned this while replacing a Trace C-40 control on 
a 24 volt battery with "classic" array wiring (72 cells in each PV 
string). (The array is 20 feet in the air and there were no funds to pay 
for an array re-configuration.) 

The Apollo unit would not work in this situation, and it took awhile to 
figure out why. I finally installed a Xantrex XW-MPPT controller, and it 
does work. Apollo's instruction book calls for at least 32 volts peak 
power in order to charge a 24 volt battery. In additional  testing at my 
own la-bor-a-tree, however, an array providing 35 to 38 volts peak power 
(in the cool morning) still couldn't drive normal operation with a 24 
volt battery. The "35 to 38" volt number came off the XW controller 
display, which again tested fine after the T-80 balked.

I have suggested to Apollo that the spec in their instruction book may 
need revision, and I've also asked for better disclosure of this 
characteristic on all Apollo sales information. Weeks later, I'm still 
waiting for a response. Apollo did upgrade the hardware on this early 
vintage controller at no charge and they updated the firmware, but then 
they stopped answering my emails.

The T-80 may be a fine controller, but it is unsuitable for retrofit 
unless the array can be rewired with higher voltage strings. Apollo 
seems to find this unimportant; one of their techs even said that all 
MPPT type controllers have the same issue. 

Let's see: Outback, Blue Sky, BZ Products, and now Morningstar MPPT and 
Phocos...all have peak tracking type controllers which can directly 
replace a C-40 without changing the array...isn't that right? Apollo 
needs to disclose this factor more fully, and ignore emails from a 
concerned installer less fully.

Mick Abraham, Proprietor
www.abrahamsolar.com

P.S. If any of you would like to buy this demo controller, send me an 
offer off list. I don't have the carton and the left side knockout has 
been hammered out, but other than that it's in mint condition with a 
blank warranty card.


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