xantrex C40 charge controller whats the highest PV voltage they can take?

[xboxman]

Hi

am thinking about a xantrex c40 charge controller and was wondering what the highest voltage they can take from my PV ( i have 2  240 w helios solar panels the out put voltage seems to be around 30 volts  and someone told me that the xantrex c40  was mostly good for 12 volt systems ?
i am new at working with any thing over 12 volts so if you all need more info from my panels let me know

thanks

[SparWeb]

Please don't be offended, but rather than spoonfeed answers, this is easy to look up from Xantrex yourself - you just need the installation manual.  It's a free download from the website.  Finding it on the Xantrex/Schneider website might be a chore, but well worth it, if you are comparing different models.

I wouldn't be so prickly about it, but this forum is about "do it yourself" projects.

The answer is your panels are okay, by the way.

[RandomJoe]

When do you measure this 30V?  Open circuit / nothing connected?  If that's the case it's likely a standard "12V" panel anyway, or perhaps slightly higher.  I did a quick search on Helios 240W and found some that show Vmp 20V which is...  Odd...  Most "12V" panels will have a Vmp around 17-17.5V, and a "24V" panel would have to have a Vmp up around 35V. 

With a PWM controller (like the C40) you're going to be forcing the panels to work at battery bank voltage instead of at Vmp (max-power voltage) so you won't see maximum possible power from the panels.  They are a current source, so will only put out their rated current (Imp) whatever the voltage.  As the voltage drops the total wattage drops.

To get the most power from a given set of panels, you can use an MPPT charge controller, which lets the panels run at Vmp but of course they cost more than a PWM controller.

[xboxman]

Hi
 and thanks for the info
 sorry for the delay in getting back to this
i am not offended at all just forgot about getting the manual from the website

here's the info from my panels
the Open Circuit Voltage is 36.80 Volts
the MPP Voltage is 30.00 Volts
and the MPP Current is 8.00 Amps
i am going to hook 2 panels up to double the amps and run a sundanzer freezer and maybe some solar lights
the pros told me i would be better off with a outback or midnight solar classic charge controller .. which i could add on to the size of the system later with a good controller

thanks

[SparWeb]

I would agree with the others you were talking to:  The C40 is a bit outdated, is only PWM operated, and even the ratings are a bit confusing (C40 = 40 amps solar, but only 32 amps wind diversion, shucks).

But the MPPT Tristar and Outback definitely cost more.  Decide now: either you are committed to expanding your system in the future, or this is just for fun and tinkering and you don't need the max of the maximum to be satisfied.  Depends on what you want out of the system.

For my example, I have a Tristar TS-60 for wind, a C40 for solar, just the PWM models.  My batteries are for backup, not really for daily power, so they're always at float, and the solar I have is enough to maintain float charge sun or cloud.  Getting a MPPT controller wouldn't do any good for me.  If I changed the purpose of my system, then these needs would change too.