Combining 3 renewable energy sources

[dannn]

Hi guys, I am working on a project to bring 3 different renewable energy sources (hydro, wind, and solar) into charging a single 12V 9 AH battery.
The wind will turn a 12V 3W DC motor.
The hydro will turn a 12V 8W DC motor.
And I have 3 solar panels rated 6V 6.5W each.

I think I have to connect them in parallel, but I have found out that connecting power sources of different voltage is “finding trouble”.
The voltage generated is naturally lower than the rated one.
What should I use/do to make the power generated stay at a voltage high enough to charge the battery?
On a note, I did not use a linear regulator because the efficiency is too low, and I am not very limited on money.

Many thanks in advance!!

 

[Nigel Goodwin]

Simply 'AND' them together with diodes, and monitor the charging current over a decent time - you might not need a regulator?.

 

[dannn]

Thanks for the reply Nigel,

I know of "AND gate" IC chips, but i have only used them in digital electronics classes almost 2 years ago.

Will look into it.

 

[ronv]

Charger

Something like this might work. The diodes are Nigel's big AND block.
Any 3 amp Schottky diode is OK.
Set the output to the battery to 14.1 volts.
Pololu Adjustable Boost Regulator 4-25V

 

[4pyros]

Not AND gates, diodes. You can use two or three cheep diodes in parallel for each sorce to isolate them from each other. Andy

 

[JimB]

RonV's drawing is correct, this is a common way of connecting power supplies.

Nigel made a slip of the fingers, he should have said OR gate rather than AND gate.

JimB

 

[Nigel Goodwin]

RonV's drawing is correct, this is a common way of connecting power supplies.

Nigel made a slip of the fingers, he should have said OR gate rather than AND gate.

True - or perhaps I meant NAND gate?

 

[engineernate2782]

Why not wire the three PV's together to get 18V and run a DC-DC converter like this one: **broken link removed** to get a 12V output and then connect all three in parallel?

 

[4pyros]

Why not wire the three PV's together to get 18V and run a DC-DC converter like this one: 711XBXCL-24D to get a 12V output and then connect all three in parallel

Thay need to be isolated because none of them are stable power sources. Once again all you need is regular diodes. Andy

 

[engineernate2782]

Thay need to be isolated because none of them are stable power sources. Once again all you need is regular diodes. Andy

They do need to be isolated with diodes but you can't charge a 12 volt system with 6 volt PV cells.

 

[4pyros]

He will have to put the three solar panels in series. Andy

 

[engineernate2782]

Fair enough Andy,
but just diodes does leave the potential for un-regulated 18Vdc power to cook the battery if all three sources are operating at their rated max ouputs, maybe a simple inline voltage regulator to keep everything below 13.1 max?

 

[4pyros]

Maybe but not necessarly. None of these power sources run at thare rated max. Thay are all small so the potential of over charging is small. The OP should log thare outputs to determan if reguashoin is needed. Andy

 

[ronv]

The only source with the capability to overcharge the battery would be the solar panels. My bet is the 3 in series will be just right when you consider the diode drops specs vs actual etc. But if it is a problem you can just use 2 in series and they will only play when the other sources 2 bog down.