Xantrex C60 PWM CC input voltage up to 55V?

[Gundam1s]

I have a Xantrex C60 and just learned that PWM CCs drop the voltage down instead of converting it and wastes power. For example I have 600W's coming in at 39V and about 16A peak, but the CC just drops it down to 14V at 16A giving me only 224W's. So my question is why does the C60 accept up to 55 volts? even if it was a 24V system it wouldn't be able to utilize the extra voltage headroom. A 48V system on the other hand would but is only available on the C40 which has an accepted input voltage up to 125V?. Anyways, just wanted to know if I was missing something.

I will be rewiring my panels down to 18V at 30A to maximize my system. If I had known this I would have gotten a MPPT. Oh well, live and learn.

Thanks,
Jimmie

[Sunking]

Well first if you have 600 watts of panel power you should be using MPPT. Once you get above about 200 watt panel power MPPT is less expensive.

To answer your question a PWM does not lower the voltage directly, the battery does that. A PWM controller is nothing more than a on/ff switch,. OK with any PWM controller input current = output current.

So with that same panel with a Vmp = 39 volts and Imp = 16 amps on the output to the battery is only 12 volts x 16 amps = 192 watts.

A MPPT is a power converter from one voltage to another. With MPPT Input Power = Output Power - conversion loss of about 2 or 3%. So So that same panel produces a maximum of 50 amps @ 12 volts. You can also use another formula to determine output. Output Current = Panel Watts / Battery Voltage. So 600 watts / 12 volts = 50 amps.

So here is the boat that you missed. When using PWM controllers, you have to use more expensive battery panels. A battery panel Vmp = 18 volts for each 12 volt of battery. But even with that said a 100 watt at best will only deliver 66 watts out of 100.

[inetdog]

So my question is why does the C60 accept up to 55 volts?

For a 36 volt battery system?
Or to give some headroom for low temperature Voc increase in a nominally 24V panel?
Or to allow you to use (although inefficiently) a grid-tie panel instead of a battery panel?
Only the manufacturer knows for sure.

[Gundam1s]

Thanks for the reply guys.
I'm going to save up for an outback fm60.

[Sunking]

I'm going to save up for an outback fm60.

Skip that, you can get much better for about the same price and it will grow nicely to 80 amps. The Midnite Solar Classic 150. Blows Outback and MorningStar off the map. They both run from $500 to $600. Check it out.

[Gundam1s]

My options seem to have come down to $609 Midnight Classic 150 with display or a $464 Outback FM60 with display. I think for my setup I will never be fully utilizing 100% of either the Midnight or Outback capabilities. My goals are about 1.5KW worth of panels so I'm leaning towards the Outback. There is also the $509 Midnight classic lite 150 without display but I'm not considering it because I will eventually get a display so might as well get it upfront.

Thanks
Jimmie

[KEN_KACEL]

C40 with a 55V input same results

I called up Xantrex and got tech support. I stated that my output was extremly low for a 120watt panel. He said my voltage was to high for a C40 , 55 volts, with a 12 volt system. I stated that the manual will allow a 125 volt input. The manual never states that your Input voltage and output need to be fairly close and the closer the better. If they would address this in the manual it would make sense . I read the manual several before I purchased 4 C40s for my system.... Stung big time.... He asked if I consulted an expert ... I told him I consulted the manual.

Disappointed in Xantrex C40 manual .... Buyer beware!!!

[Naptown]

Almost every manual I have ever seen with solar equipment is not geared toward the novice but a pro with knowledge of the physics and constraints of the piece of equipment and its proper use.
If you hook up a 55 V mp panel to a charge controller that is rated for a max of 55 volts you have missed a huge part of solar design namely Voc and temperature compensation.
That controller will last less than a week.
It is not a single component manual that can be expected to teach all aspects of solar design and install.
You need to look at the entire picture

[Sunking]

Disappointed in Xantrex C40 manual .... Buyer beware!!!

Sorry to bust your chops, but your ignorance did you in. Not Outback. If you knew what the simple formula for PWM meant you would know you were making a huge mistake.

Input Current = Output Current.

It is simple 5th grade math. A 120 watt panel with 55 volts has a Imp of 2.2 amps. That means at best your panel panel will deliver 12 volts x 2.2 amps = 27 watts.

Not Outbacks fault you do not know what you are doing.

[KEN_KACEL]

Busting my chops

I took the advice of the guy I bought the solar panels from .... and I have been running PWM systems without fail since 1986 . Stuffed my own boards. Thanks for the encouragement you are no help as Xantrex was no help. Their documentation does not indicate any Vin -Vout max. It only states 125V max . Read it for yourself and see what conclusion you draw. And about the 5th grade slam...I never let school interfere with my education.

[Naptown]

Best thing you could do is return or sell them on eBay
That's about all the help we can give you.
And next time get the mppt ones

[Gundam1s]

yes yes yes its unfortunate for guys like us to lose money but it is because of our ignorance. But lets take these lemons and turn them into lemonade I went for the OB FM60.

At least we can use our xantrexs for load controllers.

[Sunking]

I took the advice of the guy I bought the solar panels from ....

Unfortunately he did not know what he was talking about.

I have been running PWM systems without fail since 1986

Then after 27 years of experience you should know better.

Their documentation does not indicate any Vin -Vout max. It only states 125V max . Read it for yourself and see what conclusion you draw.

That is all any PWM controller is going to state. What you haved missed for 27 years is Input Current = Output current which is clearly indicated in the documentation. With PWM controllers YOU MUST USE BATTERY PANELS PERIOD. At best using PWM maximum efficiency is 66% meaning for every 100 watt panel input you get 66 watts out. Use a 55 volt Grid Tied Panel on a 12 volt battery and will only get 22% efficiency plain and simple.

[inetdog]

Unfortunately he did not know what he was talking about.


Then after 27 years of experience you should know better.

That is all any PWM controller is going to state. What you haved missed for 27 years is Input Current = Output current which is clearly indicated in the documentation. With PWM controllers YOU MUST USE BATTERY PANELS PERIOD. At best using PWM maximum efficiency is 66% meaning for every 100 watt panel input you get 66 watts out. Use a 55 volt Grid Tied Panel on a 12 volt battery and will only get 22% efficiency plain and simple.

And a 125 volt panel or panel string would be next to useless for PWM, even in a 48 volt system, but the controller would not complain. On a 12V system you would have ~10% efficiency if that.

[Sunking]

, but the controller would not complain. .

It would get a little hot under the collar.