question

Solution number 2 is the best, although I'd use a resistor divider and a voltage comparator or opamp which can also offer the ability easily implement and adjustment pot for finer control. The opamp will drive a MOSFET to turn on a big dump resistor.
It would be good to include some hysteresis to prevent the setup from oscillating, the dump resistor remains turned on for a few seconds until the MPPT has taken hold.

It seems that I have under estimated, what it means to "burn" 250 Watts.

I do not get enough of the heat away from the diode bridge and to throw it into the river to cool is no real option ;o)

I now connected a BIG Power Resistor in parallel and this seems to be my final solution, as the Power loss at full load is below 100Watts.

I will live with that.

You can read about this project in a near future blog from John Rushworth.

Thanks,

Markus

After final optimizations and nozzle setup, I do have 341Volt oc :o/

Lessions learned. First do complete nozzle set up, then calculate and buy brake resistors. :o)))

So I have to actually "waste" 900Watts.

I found the perfect device for that:

Solved generator Voc and heating the site in one solution :o)

I now have 1500W of continuous Hydro Power from MPPT or 900W of heating power.

Maybe I consider some downsizing, fo my next Hydro Installation ;o)

I have to replace the Amperemeter, to match the brake load...

Regards,

Markus

Cool stuff. I have a similar install underway by the means of in river hydro and have to convert 220vac to 200+vdc for a similar controller circuit.

My rated output is 2000w at 220vac.

Hello @samin8r,

thanks. It would be very interesting, to read more of your installation.

Do you have 2 Phase AC or 3 Phase AC generated by your hydro generator?

You have to be very careful, not to exceed Open Circuit Voltage of the charger.

For AC to DC rectification calculations regarding open circuit voltage, I would just use AC*SQRT2 for DC Open Circuit Voltage calculation.

Be aware that rectification of 220V AC, result in over 310V DC, but as you said it is producing 2KW at 220V. The unloaded AC voltage of the generator will likely be much higher.

In this dimensions (2KW and over 310V), I would not prefer to choose a MPPT DC charger based on what I have learned.

I would chose a PV inverter, capable of handling those high Voltages and feed this AC to a Multi. But this is only a suggestion and choosing the right solution depends on many things.

But it is also important to have some braking, in case of an unloaded situation of the wheel. Your bearings will be thankful. And an unloaded waterwheel spinning at very high speeds, sounds like a siren.

But this is a very interesting theme and also funny to build, to have and to maintain. :o)

If you have further questions, I would be glad to help.

You can get a bridge rectifiers really cheap, on common online trading platforms ;o)

And I hope it is clear to everyone that playing around with those high voltages is very dangerous and you should only work with those voltages if you know exactly what you are doing.

PS.: Dont make the same mistake I did and make calculations and buying hardware before you have set up your hydro generator with the right sized nozzles... ;o)

Best Regards,

Markus

Thanks for the response. The units are quite well finished machines from China. They are a 48DC which then is put through an Inverter to make 220VAC. I have quite a cable run and need to keep the voltage up for loss's. I did plan to use a bridge rec to swap back to DC but was trying to work out capacitor sizing? But if putting this through an Inverter the need to smooth out the wave form may not be an issue? The turbines have a braked system built into the controller hardware which is great.

I am utilizing a Quattro which has the two AC In terminals which would be ok for an Inverter hook up. Though I'm not sure if AC load is larger than AC2 Input whether it starts to stall the input? I have been running on solar for a year now and am keen to get this going as a supplement during adverse weather.

You are probably correct? I was thinking about putting it through an MPPT and it could supplement the other MPPT's?

My only concern was whether the Quattro would stall AC load In 2 connection if the load was larger? It shouldn't and with Generator Input 1 it has never before?

I was informed by a person within the industry it may stall the Hydro but I think that may be false?

Why don't u use a transformer? A 3 phase 400v-230v transformer should work. If you place it close to the battery it also saves a bit on wire losses, and gives you galvanic isolation.

other option is of course to lower the rpm (bigger wheel?) but that would mean a lot of work I guess.

This device is already set up with a governor from the factory. It is a run of river generator and thus the rpm is quite low and more linear.

It is 48vdc from the generator and the factory controller steps it up to 220vac. '

Thanks for the ideas though.

Markus. I have discovered your hydro story and found it excellent. I have similar plans, although with less head and more flow. I’m also looking to use an existing under utilised 250/100 Victron MPPT (secondary solar array, in winter shade). Firstly, I’m interested in your hydro units. They look very robust and well made. Could you provide a supplier? Regards

Enda

Ahoj Markusi, nemůžu tě zastihnout. Dělám něco špatně?