Rednecktek
Solar Wizard
Well, AIO's usually come with 60-80a charge controllers and a Victron gets really expensive really fast to get half that so...
I'm not sure what you mean by double conversion, either way it has to go through an inverter. Separate SCC also divert to load depending on how much the inverter needs depending on where the voltage is lower. Anything left over goes to the batteries. An AIO does not change this, it just puts it in a convenient package.Victron is more efficient at charging the battery.
But when you factor in the double conversion, it's almost a wash. An AIO can take it from the panels to load, in one conversion.
Well, I oversimplified it as "double conversion".I'm not sure what you mean by double conversion, either way it has to go through an inverter. Separate SCC also divert to load depending on how much the inverter needs depending on where the voltage is lower. Anything left over goes to the batteries. An AIO does not change this, it just puts it in a convenient package.
Thats interesting. It would be curious to see how much power is saved skipping the up convert on the DC side. Thanks for clarifying that. Im guessing that is the reason for the low voltage input specs on allot of the AIOs?Well, I oversimplified it as "double conversion".
A Victron charge controller converts the higher PV DC voltage into lower battery voltage. Then it must be converted to the higher DC voltage. And then inverted to AC voltage.
The MPPT in the AIO provides the higher DC voltage directly to the inverter.
ProbablyThats interesting. It would be curious to see how much power is saved skipping the up convert on the DC side. Thanks for clarifying that. Im guessing that is the reason for the low voltage input specs on allot of the AIOs?
Thats the route I have gone and will continue for now. I won't buy another HF inverter ever again if I don't have to. One thing that has been important to me is reliability/redundancy and low power strings. I don't have any strings over 800w. All fully independent to its own charge controller. I have currently 12 strings/SCCs going on two systems and am adding 5 more strings to one of them. Cant do that with an AIO.It will be separate CC's and big honkin' LF inverters for any system I have.
You missed the point.That, combined with the multiple conversions that timselectric did an excellent job of explaining could explain the higher performance of stand-alone SCC's.
not to derail this tread, I shared my ideas here; Feel free to comment on that thread.Why are you concerned about low power strings?
You missed the point.
It was to the exact opposite.
The extra conversions are with separate components.
I believe you are missing the point. The main difference between an MPPT and nonMPPT charge controller is the lack of tracking as conditions change.Do not give up on PWM.
MPPT provides more versatility and allows higher voltage panels or arrays to be used with lower voltage battery. If panel operating voltage is only slightly higher above battery charging voltage, PWM controller will operate in MPP zone.
For example a 12V battery and 18V panel with OC voltage about 21V as shown in picture below. PWM controller does not do DC/DC conversion and is just connecting panel directly to battery. The charging voltage of 12V LA battery is about 15V that is very near MPP in optimal conditions 95W and pretty much dead-on MPP in suboptimal 55W for this panel.
If a 36V panel (42V OC) is used with 12V battery, PWM will perform terribly. But it will work with close to MPP efficiency with 24V battery. It may work even with higher efficiency than MPPT because there are no DC/DC conversion losses. Also less heat burden on the controller = higher reliability.
I believe you are missing the point. The main difference between an MPPT and nonMPPT charge controller is the lack of tracking as conditions change.
When I say tracking, I mean the ability to find and keep the higher output at current conditions. Conditions could be solar irradiance, shading, temperature, etc.... The controller will very the draw down/load on panel in the sweet spot, you cant do that with out an MPPT circuit in the controller.
Most MPPT are PWM on the output side (to regulate charge rate) if memory serves correctly.
Yea, that is interesting. I just check todays output and I was at 50% volts when at 25% amps. So there is some power that would be zero with PWM since voltage would be to low. Maybe not tons of power but over lots of time its good, especially if its a cloudy day. It could just be 15% output for the day but thats better than zero.I agree with what you said except that I missed the point.
Look at graph above. MPP area spans wide voltage range and when comparing optimal 95W and sub-optimal 55W, PV voltage does not change a lot....