Classic 150 For Hydro

[wildblue]

Hi all! I've been using my Classic 150 with a PV setup for a few months and am quite pleased with it's performance so far, but now I'm going to try it with a hydro system and have a few questions. ( I'm still pretty new at this and would prefer to avoid the smoking box of electronics. ) I have an LV-750 DC turbine and a C-40 for a diversion controller. What I want to know is:
1. How exactly does the Classic work with hydro? Will it brake the turbine?
2. How do I wire the Classic and the C-40 into the system so they don't interfere with each other?
Pretty basic questions I know, but everybody's got to start somewhere. I'm researching it, but there doesn't seem to be a lot of info out there about hydro/MPPT setups, so I figured I'd ask the experts. Any help would be greatly appreciated.

[boB]

Hi all! I've been using my Classic 150 with a PV setup for a few months and am quite pleased with it's performance so far, but now I'm going to try it with a hydro system and have a few questions. ( I'm still pretty new at this and would prefer to avoid the smoking box of electronics. ) I have an LV-750 DC turbine and a C-40 for a diversion controller. What I want to know is:
1. How exactly does the Classic work with hydro? Will it brake the turbine?

There is a special "Hydro" mode in the Classic.  This mode is very similar to the "Legacy P&O" mppt mode
which, in one case, every so often, rocks the input voltage around the last measured max power point (MPP)
voltage found.  How far it rocks around this last power point voltage is determined by the "Sweep Depth"
adjustment.  Sweep Depth, in percent, is basically how far the Classic will drop its power output level
before it either goes back to the MPP voltage found or rises again to find another drop off in output
power determined by the Sweep Depth.

So if the MPP V was sitting at 100 volts and 500 watts and the Sweep Depth was set to 10% and the Classic
did a sweep, the input voltage would first drop down to whatever happened to make it 450 watts (500W - 10%)
and then it would raise the input voltage until the power dropped down to 450 watts again, assuming that the
MPP voltage was still sitting at 100V and the max output power was still 500 watts.

If the power kept rising when it was doing this sweep, either down or up in input voltage, the Classic will continue
to change the power until the power drops by 10% from this newly found MPP.

That method holds for either 2 minute sweep time and greater and also what is called "Twiddle Dither" mode.
Twiddle Dither is  the same thing as the sweep interval set by the minutes between sweep except that it
sweeps up and down continuously.  Twiddle Dither still uses the Sweep Depth to determine how far it sweeps
away from the MPP voltage last found.  This TD mode was handy if the hydro was moving around a lot.
We have had hydro installs where the flow rate was basically moving around quite often.

TD can be real handy if you have a power source that you want to adjust mechanically and
you want the Classic to dynamically find its MPP voltage as you are adjusting the flow or
nozzles or whatever.  It's not necessarily limited to hydro per se' of course.

The next hydro mode that can be real useful is just manual MPP V mode.  This is where
you set the Classic's input voltage and just let it stay there.

Having said all this, there is another great way to run hydro, especially if the flow changes
often or on a daily basis.  Wind mode.   Wind mode requires a power curve to be entered
but a power curve can usually be found fairly simply and quickly by using hydro mode
in manual MPP or twiddle dither and seeing what input voltages correspond to the highest
amount of output power and then creating a power curve from that information.

We are working on "wind learn" which will find a good power curve over time but this
should also work great for hydro too.  Hydro should learn pretty quick too since it doesn't
move around as fast as wind does.

2. How do I wire the Classic and the C-40 into the system so they don't interfere with each other?
Pretty basic questions I know, but everybody's got to start somewhere. I'm researching it, but there doesn't seem to be a lot of info out there about hydro/MPPT setups, so I figured I'd ask the experts. Any help would be greatly appreciated.

The C-40 will just connect up to the battery side to load the output down when the battery voltage exceeds
the C-40 diversion set point.  Problem is though that if the C-40 is controlling the battery voltage,
and the Classic cannot bring the battery voltage up to Absorb voltage (or Float V or EQ V), then those
charge stages may not complete and your batteries may suffer.

You might want to see if you can get the Classic's Aux 1 or Aux 2 output to control the diversion controller
settings.  I don't think you can drive the C-40 from an external Aux output but that would be ideal, then
you could use the C-40's power section to handle that higher current but controlled by the Classic
and then the voltages could be coordinated.  For instance, by using the "Waste Not" Aux mode in
the Classic.

boB

[wildblue]

Ok, thanks for the explanation. My water supply is very stable (much more than this turbine can use) so I'll probably use manual, but twiddle dither mode (who came up with that one?  ) sounds useful for getting the system up and running.

"Problem is though that if the C-40 is controlling the battery voltage,
and the Classic cannot bring the battery voltage up to Absorb voltage (or Float V or EQ V), then those
charge stages may not complete and your batteries may suffer."

I'm charging a 48V battery bank so if I set the Classic's bulk voltage to something like 65V and the C-40's to 57.6V shouldn't the Classic just stay permanently in bulk and let the C-40 control the charge cycle?

[boB]

Ok, thanks for the explanation. My water supply is very stable (much more than this turbine can use) so I'll probably use manual, but twiddle dither mode (who came up with that one?  ) sounds useful for getting the system up and running.

"Problem is though that if the C-40 is controlling the battery voltage,
and the Classic cannot bring the battery voltage up to Absorb voltage (or Float V or EQ V), then those
charge stages may not complete and your batteries may suffer."

I'm charging a 48V battery bank so if I set the Classic's bulk voltage to something like 65V and the C-40's to 57.6V shouldn't the Classic just stay permanently in bulk and let the C-40 control the charge cycle?

Yes on that last sentence about Classic being set for 65V and staying in Bulk.  Just make sure that the C-40
goes to Float after a while or the batteries might stay at Absorb too long.

Sounds like you know what you are doing so no problem.

boB

[wildblue]

I'll do that and hopefully it'll work. Thanks for the help!

Sounds like you know what you are doing so no problem.

boB

Thanks for the vote of confidence but we'll see.