I'm curious why you believe different blade profiles are more or less suited to MPPT.
Well, MPPT is not a magic thing. It does is allow your turbine rotor to run at optimum efficiency, and to operate the turbine at very high voltages to improve power transmission efficiency. A fixed pitch turbine rotor has a Cp curve. If the blades are designed to run at 6.5 TSR so their efficiency is 35% (meaning they can capture 35% of the total kinetic energy flowing thru the swept area), both above and below that tip speed ratio, the Cp will drop and you will capture less than 35%. So if you run the blades too fast you'll get less power. If you run too slow you'll get less power.
So to get the most "bang for the buck" from MPPT it's important to have blades (and a blade profile) that will track the wind speed. And this means from cut-in all the way to full rated power. If you run your rotor excessively fast right at cut-in, as is the normal thing to do with a direct hooked machine, you will make less power in low winds than you will if you run the rotor at the proper (most efficient) tip speed ratio.
So let's say the rotor is running at optimum TSR at 8 m/s wind speed, and suddenly there's a gust to 10 m/s. The TSR of the rotor drops immediately when that gust hits it and it must accelerate immediately (gain rpm) to get the TSR back to optimum. Blades that have a lot of "meat" out near the tips and outer blade stations do not accelerate well. They're generating too much drag. Those blades might work well for low wind cut-in, and they might generate the torque required to lean into a "stiff" generator that "stalls" the rotor as wind speed picks up. But they are not good for MPPT because it's impossible to make them track the wind speed. Their tip drag eats up a good chunk their power at higher rotational speeds. And if you can't turn the rpm, you can't get the volts required to make MPPT work.
One of the things that blew me right out of the water was the fact that I am getting better performance from this turbine from cut-in all the way to 12 m/s, and it beats my bigger direct hooked machines every single day in total energy production, even in lighter winds. For a long time I argued with Ryan and boB, and whoever else, believing that was not possible. Well, turns out I was WRONG, and it IS possible - if you tune the turbine for it. The key to improved low wind performance is not running the rotor too fast. Forget everything you thought you knew about how wind turbines are "supposed" to work, and throw it out the door. Then look at how your blades really like to run. All the homebrew book recipes turn these machines at very high TSR at cut-in - dead WRONG with MPPT. I'm cutting this little 3.2 meter rotor in at only 111 rpm. The Otherpower 10 usually cuts in around 145-150. So the Otherpower machine does not have enough copper in it to make the higher voltage required for peak performance on the top end, and it's running WAAAY to fast on the bottom end.
To make the Otherpower 10 work good on 24 volt with MPPT - put a 48 volt stator in it.
Edit: I figured out how to get this off my computer screen using my Picasa program. For some reason, when the Classic resets its daily logs it sometimes disconnects from my Local Status Panel on my computer. I noticed a bit ago that it disconnected and reset its daily kWh counter. So I had to restart the Local Status Panel to get it come back up. The turbine is putting out about 500 watts this morning. But what I wanted you to see, VF, is that at only 500 watts output the input voltage is already at 66 on a 24 volt system.
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This is how you make MPPT work for you. If you run it at only 40 volts or something, you're not going to get the most you can get from your MPPT turbine. I could pull out the logs and take a look at the CSV, but I'll bet the generator is only putting out like 8 amps or so @ 500 watts.
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Chris