Good afternoon..

To all the electricians and solar fundies out there, I need some advise, help with a diy off the grid power project for our home

I am planning to build an off the grid electrical system using a home made water turbine which will be running on a river using a treadmill motor as a generator / alternator and up gearing to achieve the rpm needed to output anything from 12 to 24 volts DC.

From this it will go to a charge controller and charge the battery bank of say 2 x 12v 105 ah deep cycle battries..

I want to then run a 5kva pure sine wave inverter to supply us our electricity for our home.

This system is very much a like a solar panel set up, however it will not need solar panels to charge the batteries and unlike solar where it's dependant on the sun it will be charging the batteries 24 hours a day.

I have been doing alot of research on the internet on diy projects making off the grid diy waterwheels and wind turbines.

So I've got a good idea how I want to go about seting up this system, but need advise from someone who works with solar systems, electricians that have better experiance knowledge on the electrical side as in will I need to have a big battery bank?

Or any ideas or suggestions that may help me get this system running as well as possible.
 
Thanks

The nice thing about a water turbine is that it should run 24 7 so batteries may be less of an issue than you think, I presume this is for a perennial water source?

Yes 24/7 fast flowing private riverfront 

Its like any solar installation, you need to figure out what your power needs are, and size the system appropriately. Solar panels are easy as the power production is known. How much power will you get from the water turbine? Once that is known, you can figure out how much you will need to suppliment with solar or generator, and how much battery storage you will need for peak loads.

Thank you for the info, much appriciated. I am looking at getting around 14 to 24v from the turbine.

3 hours ago, Shaun0007 said:

I am looking at getting around 14 to 24v from the turbine.

Yes, but at what current? And hence what power, and like a PV panel, the voltage will probably sag with load, so there will be a maximum power point. Even at 24 V, it's probably not going to be like a truck battery.

I think you'll need some sort of boosting MPPT converter to charge a 24 V or 48 V battery. Do you have a suitable charge controller in mind?

2 hours ago, Coulomb said:

I think you'll need some sort of boosting MPPT converter to charge a 24 V or 48 V battery. Do you have a suitable charge controller in mind?

According to a guy on youtube that I follow, this is a boost converter that is actually not the worst thing in the world... 🙂

 

I am not sure of the current at this stage, hence i am doing research..

My water turbine is based on a wind turbine as there is not much info in SA on water turbines..

Using a tredmill motor this is what the minimum rrquirements are.

Mnimum Volts to RPM ratio of 0.035

Minimum amperage rating of 5amp

Min 100v @2500 rpm

Will output around 14.4v at 450 rpm

Obviously this is going on the 100v @2500rpm giving 14.4v at 450rpm minimum.

If i can get higher voltage amperage motor at not to high rpm it will be easier to obtain the right volts at maybe lower rpm or even get higher voltage.

Start with this, the electrical parameters will follow on from the energy available:

https://www.renewablesfirst.co.uk/hydropower/hydropower-learning-centre/how-much-power-could-i-generate-from-a-hydro-turbine/

I nearly bought a property on the Lions River and was keen on hydro generation and found these guys.

https://www.zmsa.co.za/en/categories/water-energy

Maybe you can get some tips from them?

 

Thank you will contact them.. I have seen some of these systems and the cost is crazy.. and support and on site help more money... But for sure maybe they can advise... So far seams i must do this myself.. very little advise help on diy projects everyone wants money..

If a wind turbine using a treadmill motor can be sufficient at random rpm and no wind at all.. I am sure my water turbine running 24/7 using same concept can do better. 

Build it first, and the you will know! Odds are you won't get it right the first time, and then tweak and rebuild the turbine. As long as you post some pics 😀

7 hours ago, Shaun0007 said:

Minimum amperage rating of 5amp
Will output around 14.4v at 450 rpm

Trouble is, 5 A at 14.4 V is a whopping 72 W. Granted, it runs 24/7, but it would not run my house's fixed loads (fridge, freezer, computers).

You might be able to mechanically gear up the speed, so the motor generates more like its rated voltage, so you get more like its rated power. With 100 V @ up to 5 A, you at least have some 500 W. That's like 3000 watts of PV as far as energy is concerned, and hopefully no intermittency due to rainy or cloudy days (only due to the hopefully occasional drought).

Probably you need to build a bigger turbine than you thought. What design are you using? One that runs in a sluice, or a falling water one? You should get more speed from the falling water designs as the water in the sluice limits the max speed of the turbine.

Thank you for the advise. Ok so maybe i need to look at a car alternator i have seen some that are 24v @ 110a thats 2640 watts.

I can gear up to get a higher rpm but what is the minimum rpm that the alternator will produce that power.

 

On 2019/05/19 at 3:08 PM, Shaun0007 said:

Yes 24/7 fast flowing private riverfront 

I quite enjoyed this video a few years back.

There is a few vids like this where guys took a normal Alternator and had a permanent magnet rotor installed. Seems like all of them had pretty good results. Maybe something to keep in mind. 

 

 

No, that won't work. I've tried that with wind power and you need a lot of speed on the alternator to produce anything. If you think about the pully sizes on a car, if the engin is only idling at 1000rpm, the alternator will be at 3000rpm already.

You need a permanent magnet alternator/generator or build one yourself. either you need a few magnets rotating very fast, or a large diameter rotor with lots of magnets on which can rotate more slowly (probably better suited to water power). What is the water velocity you have, also what is the elevation drop across the property? If you have a good slope you can catch the water in a weir, and pipe it to somewhere where you have a good drop and generate a lot of pressure. 

I am looking at one that will run on the water.. still need to calculate the flow rate.. but its fast flowing water.. im also looking at width about a meter or meter and a half.. i should get a decent rpm and enough torque to pull a cow lol hopefully.

8 minutes ago, Jaco de Jongh said:

I quite enjoyed this video a few years back.

There is a few vids like this where guys took a normal Alternator and had a permanent magnet rotor installed. Seems like all of them had pretty good results. Maybe something to keep in mind. 

 

 

That looks like the idea, that guy has the potential to get a much larger water drop if he catches the water further upstream.

Notice he gears it up twice, once with what looks like a bicycle chain, and then again with what looks like a washing machine belt and pully. I love it, power created from junk.

With the bicycle chain you could use a bicycle gearset to play around with the gearing to get the right velocity/ gearing balance.

Edited May 21, 20197 yr by DeepBass9

That is a awesome idea.. however my river flows so im looking at harnessing the power... Im looking at two bicycle rims 1.5 neters apart with stainless steel blades.. This should give mr loads of torque..

Lets say i get 50rpm from the turbine i can gear up 4.1 three times so 50 x 4 x 4 x 4 thats 3200rpm 

OK, I would think it would be an idea to try and confine the water somehow, if you put your water wheel in the river and then the water simply flows around it, then that won't work. If you elevate and drop the water, or confine to a sluice you will direct the water onto the turbine better.

Bear in mind that you may gear it up so much that the water can't move it. I played around with a vertical axis wind turbine on an alternator, and getting enough speed was the problem. If you gear it up too much then you basically stall it, too little and it will spin merrily but never get to the point of making usable power. What I also learnt is that chains and sprockets have less power losses than belts and pulleys. I think belts are mainly used in cars because they are quieter.

Edited May 21, 20197 yr by DeepBass9

Thank you for all the info.. I will set up a basic solar system 2 x 400 watt solar panels a 5kv inverter and 2 x 12v 105 ah and charge controller to have some power on the property.. i will then experiment and play around with the water turbine and hopefully i can get something decent out of it and add it to the existing system.

Would these maybe work?

https://talontools.co.za/2-pole-alternators/

Thanks for that link. I have a lister engine driving an ancient hoffberg generator that I would like to replace with a more modern brushless generator at some point. Those look like they will do the trick.

Edited May 21, 20197 yr by DeepBass9