PV array as voltage clamp with Hydro/MX60.

[serapheim]

Hi all.

I am wondering if someone can help me here.

I would like to wire my Stream Engine in parallel with my MX60 / PV array.  The PV array is made up of 3 X 3 Sharp NUS030E panels - specs -

Pm    180w

Voc    30

Vpm    23.7

Isc    8.37

Ipm    7.6

aVoc    -104

Since their connected 3 X 3 - that gives an Voc of 90 vDC with Vpm of 71 vDC and PM of 1620 watts (if my maths are ok).

My battery bank is 24 vDC, 3300 Ah/100.

The stream engine has 2 nozzles and is wired parallel delta.  I have access to 2 water sources, that run mainly at nights but sometimes during the day.

The first water source is 1 l/s.  The penstock is 40 mill and 250 meters approx.  When working the pressure gauge shows 200 PSI! The supplied power at the batterys is 525w as measured by an Outback FNDC battery monitor / shunt.  

The other water source is 2 l/s.  The penstock length is 100 meters of 50 mill and 150 of 40 mill.  I dont have a pressure gauge on this line but the battery monitor shows about 250 watts when charging.

At the moment the stream engines rotor is quite a distance from the stator - tuned to provide the most power with our first water source.

What do I need to do to safely connect the turbine to the mx60 without damaging my PV array? I would like to use the mx60 mppt function for the turbine.. what would happen when the mx60 does its sweep though?    What else should I do to protect the turbine/mx / pv array.

Sorry for the long winded question and for any errors... im still on the lower end of the learning curve.

Thanks

serapheim

[dave ames]

someone did a nice job matching up the pv array with the mx60 in that setup, can't get much better use of equipment than that. probably only goes into current limit a few times a year! so no room there even if we could mix.

best bet (imho) would be to feed the rectified hydro right into the battery bank and run a controller on the bank. you could do another mx60/fm60 for the hydro and set it to hydro function (parked mppt) but that's an expensive option.

that stream engine sounds neat, and the brief read i just did looks like there would not be very much gain to be had with an mppt controller...if you have a very long run might set it up as 48vdc and do the step down thing when we get to the 24vdc bank.

wish i had one of those....and a fast flowing river..and..

[serapheim]

Hi dave and others...

thanks for your comments.  

Actually, the hydro usually runs only at nights so the PV would  not be producing much .  

I would really like to use the MPPT in its normal mode (eg sweep every 10 minutes)  simply because we have access to 2 water supplys that run at differing times which are not in our control and I can only tune the Stream Engine (ie rotor/stator gap) for 1 of the streams.  

I was hoping that if I could connect to the PV array to clamp the voltage each time it sweeps I could simply make the air gap as small as possible on the Stream Engine and let the MX60 do its thing for max output.  

Well thats the theory anyway... I only know enough to be dangerous    I guess I really need someone to tell me if I have to look out for something if I am planning on doing this and if its feasible.  (Feasible meaning something want go bang  ).  

The matching of the MX and panels was mine... a bit of neophyte luck!

Thanks for comments.

[Flux]

This is something I have no experience of but I hoped you would get more replies.

I am sure you are right that you can use pV panels to clamp the voltage. What I don't know is how far you can go with this. Clamping within the short circuit current of the panels should not be any problem, beyond this I am not sure, instinct tells me that you can probably go way beyond this but thermal limitations and failure of the bonds will eventually take place and you had better find more accurate advice rather than make a very expensive mistake but if your hydro doesn't produce much more than the short circuit current of the panels I suspect it is ok.

If this is at night when the panels are not receiving solar heat then thermal limits are unlikely but connection failure is still a worry.

There are other ways of clamping the voltage but they are not so simple and it becomes something of a project. If you can safely do as you suggest it would be a good way forward.

Flux

[serapheim]

Flux, thanks for the reply and thoughts.

Actually I was hoping to get more replies too ..  I had read on the forum I think it was hydrosun that actually had done this successfully.  I was hoping he or anyone else who has tried this could join in and perhaps give some more details what I should / need to look out for and its feasible for my site.   It just seems like a really easy way to use the charge controllers MPPT and battery charging functions with hydro without the extra cost - thats if it works safely that is!  Your quite right, I dont want to make an expensive mistake...  

Thanks again..

serapheim  

[serapheim]

For anyone interested there was some good information over at the microhydro group on the same topic.

Thanks.

serapheim

[dave ames]

serapheim,

 this is an interesting topic and have been looking for that "microhydro group" for more information without any luck. can you point the way to that discussion?

best regards, dave

[serapheim]

Dave,

you can try the following link - http://tech.groups.yahoo.com/group/microhydro/message/12599.  

The responces I received varied widely.  A few were all against it stating that it would eventual strain and cause damage to the panels.  From what I have concluded however from the remarks/ input of the more knowledgeable is that using this method definitely has worked for others. You simply have to be carefull of not going over the max current of your PV.

Ill post back with my own results if I go ahead...

best regards,

serapheim