water wheel confusion.

This stuff really is over my head a bit. i am trying to understand it the best i can. I have an area where i feel a water wheel will work to make a small amount of electricity. it has roughly 6ft of possible head, and around 50 to 75 gpm. my math tells me i can only expect around 60 watts. That is with using the calculations i found on another site. now is that 60 watts per day? that isnt hardly worth it is it? am i missing something here? how do people run homes on such small water wheel set ups?

60 watts is the instantaneous power. To convert that into a more common unit of measure multiply it by 24 hours per day, to get 1.4 kW-hr per day. A family member's bill I just checked shows that they use about 10 KWh per day.

60 watts would be enough to power a laptop and a few lights for a few hours per day, or it could power a single smallish refrigerator and little else.

Joseph Lofthouse wrote:
60 watts is the instantaneous power. To convert that into a more common unit of measure multiply it by 24 hours per day, to get 1.4 kW-hr per day. A family member's bill I just checked shows that they use about 10 KWh per day.

60 watts would be enough to power a laptop and a few lights for a few hours per day, or it could power a single smallish refrigerator and little else.

that is what i was hoping to hear. 1400 watts is what i was wanting at a minimum. but wouldn't that allow me to run more than what you mention? if my laptop uses 50 watts an hour, it would use 400 watts in 8 hours right? and i could run 2 cfl lights at 46 watts for 8 hours using under 400 watts. that still leaves over 600 watts. what about a microwave. im a bit confused here. a 1000 watt microwave uses about 120 watts in 5 minutes. so i could run one of those occasionally?

The 60 watts charges a battery. Then you can draw energy out of the battery as needed.

Assume that the laptop and light each use 400 watt hours. A ball park estimate is that batteries lose about 15% of the energy put into them, so around 200 watt-hours is lost, leaving about 400 watts of excess energy, which could run the microwave on average for 24 minutes per day.

Joseph Lofthouse wrote:
The 60 watts charges a battery. Then you can draw energy out of the battery as needed.

Assume that the laptop and light each use 400 watt hours. A ball park estimate is that batteries lose about 15% of the energy put into them, so around 200 watt-hours is lost, leaving about 400 watts of excess energy, which could run the microwave on average for 24 minutes per day.

Thank you for clearing up a few things for me. i greatly appreciate it. I guess ill do a little research to see how to maximize my potential power. There are two small streams. The one i plan on using is fed by water run off from a fish hatchery on top the hill. i may even be under-estimating the water flow and i may be able to gain more head height. the second stream comes through the property at a pretty lazy speed. i MAY be able to get about 3-4 feet of head and add a second smaller wheel.

So if i understand this correctly (and i dont think i do)...for various benefits, id want to go with a 24v battery bank. and if i am making 1400 watts and i want 2 days of storage then id double it and go with 2800 watts. so 2800 watts at 24 volts is 100amps. so id need a 24v battery bank with atleast 100 amp hours? so 2 batteries- 12v at 100amp hours wired in series - gives me that. now ill need a 24v alternator to charge the 24v battery bank correct? and this alternator has to put out atleast 60watts? and a 24v charge controller rated at atleast 60watts? i plan on using a grid tie inverter, so is the charge controller necessary? Even though i am only making 1400w a day, can i still get a 3000w inverter for when/if i begin producing more than 1400w a day? I hope i am making sense and not too far off the mark with my understanding of all this.

- Just trying to put a little spin on a comment about 'little refrigerators'' not trying to highjack this thread ! Please not that those small refrigerators that college students

like to have in their dorm rooms are Generally NOT energy efficient, and often use more Electricity than a full sized Fridge -

The best refrigerators are Chest type refrigerators that open from the top. This has the additional benefit that the cold air doesn't fall out of the fridge as soon as you

open the door. Just my two cents ! Big AL

A grid tie system with a water-wheel is an entirely different application... With a grid-tied system, you are using the grid as a storage battery, so if your in-home use of electricity is less than you are using, you give energy to the grid. If your in-home use is more than your generator is suplying then you take power from the grid. The best form of grid tied inverter for a water wheel is an induction motor running at grid voltages, either 110, or 220 V. The motor only creates electricity when the grid is supplying power to it. The cost of induction motors is perhaps around 1/10th the cost of an inverter. 60 watts is 0.08 horsepower, so you'd want a motor about that size... That's in the range of what fan motors run at... The componenets to store energy at home, and then to dump the excess onto the grid add a lot of complexity to a system... Think of a small grid tied inverter as a metnod of reducing you power bill by the amount it would be reduced if you stopped burning a 60 watt light bulb all day long every day: A savings of around 15 cents per day.

For small stand alone systems not tied to the grid I prefer 12 volt applications, because it is a very common voltage used in the automotive and trucking industries and appliances are readily available in 12 volt configurations. Then you add enough batteries to cover the unevenness of your usages. A simple way to connect a stand-alone system to the grid is to use a battery charger. Whenever grid power is available, and the battery level is too low, power can be grabbed from the grid. Power is not added back to the grid in this scenario, but the amount of grid power is reduced somewhat. And battery chargers are much less expensive than grid-tied inverters.

watts is the instantaneous power being generated. Chargers and inverters are sized to meet the maximum instantaneous power. The time they are operational doesn't matter.

watt-hours is the amount of power generated over time. In other words, watt-hours doesn't apply to chargers and inverters.

The watts stay the same regardless of any changes in voltage. In other words, the amount of water falling doesn't change regardless of the form of the electricty. So you don't double the watts if you double the voltage.

---edited to correct the following---
60 watts equals 5 amps at 12 volts.
60 watts equals 2.5 amps at 24 volts.
So it would take 20 hours to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 hours to charge a 100 amp-hour battery bank at 24 volts.

Joseph Lofthouse wrote:
A grid tie system with a water-wheel is an entirely different application... With a grid-tied system, you are using the grid as a storage battery, so if your in-home use of electricity is less than you are using, you give energy to the grid. If your in-home use is more than your generator is suplying then you take power from the grid. The best form of grid tied inverter for a water wheel is an induction motor running at grid voltages, either 110, or 220 V. The motor only creates electricity when the grid is supplying power to it. The cost of induction motors is perhaps around 1/10th the cost of an inverter. 60 watts is 0.08 horsepower, so you'd want a motor about that size... That's in the range of what fan motors run at... The componenets to store energy at home, and then to dump the excess onto the grid add a lot of complexity to a system... Think of a small grid tied inverter as a metnod of reducing you power bill by the amount it would be reduced if you stopped burning a 60 watt light bulb all day long every day: A savings of around 15 cents per day.

For small stand alone systems not tied to the grid I prefer 12 volt applications, because it is a very common voltage used in the automotive and trucking industries and appliances are readily available in 12 volt configurations. Then you add enough batteries to cover the unevenness of your usages. A simple way to connect a stand-alone system to the grid is to use a battery charger. Whenever grid power is available, and the battery level is too low, power can be grabbed from the grid. Power is not added back to the grid in this scenario, but the amount of grid power is reduced somewhat. And battery chargers are much less expensive than grid-tied inverters.

I agree that a battery bank would be complicating things a bit but i really would like to implement it into the system. while i do have access to the grid, id like to have a battery bank for if the grid ever goes down. I seem to be getting conflicting info from the net on this though. I see it being a small complication but i feel that the ability to be on the grid in case of failure and on the batteries in case of grid failure would be a good thing to have. i dont see it being very much more complicated. So the alternator to the charge controller to the battery bank (of appropriate size) to the inverter. the inverter ties into the main breaker box and then power can be sent to the house or back to the grid.

Joseph Lofthouse wrote:watts is the instantaneous power being generated. Chargers and inverters are sized to meet the maximum instantaneous power. The time they are operational doesn't matter.

watt-hours is the amount of power generated over time. In other words, watt-hours doesn't apply to chargers and inverters.

The watts stay the same regardless of any changes in voltage. In other words, the amount of water falling doesn't change regardless of the form of the electricty. So you don't double the watts if you double the voltage.

60 watts equals 5 amps at 12 volts.
60 watts equals 2.5 amps at 24 volts.
So it would take 20 days to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 days to charge a 100 amp-hour battery bank at 24 volts.

Can you explain how you calculated that? if i am making 60 watts instantaneously and that would be 1.4kw daily wouldnt that be 116ish amps daily.

allen lumley wrote:- Just trying to put a little spin on a comment about 'little refrigerators'' not trying to highjack this thread ! Please not that those small refrigerators that college students

like to have in their dorm rooms are Generally NOT energy efficient, and often use more Electricity than a full sized Fridge -

The best refrigerators are Chest type refrigerators that open from the top. This has the additional benefit that the cold air doesn't fall out of the fridge as soon as you

open the door. Just my two cents ! Big AL

By all means, post what you feel is pertinent! thank you for that post. Chest type refrigerator it is!

Paul Delaet wrote:Can you explain how you calculated that? if i am making 60 watts instantaneously and that would be 1.4kw daily wouldnt that be 116ish amps daily.

Amps is an instantaneous measurement of current. It speaks to how big the wires in your system need to be before they melt.

Amp-hours is a measurement of how much energy can be stored in a battery. For example, a 100 amp-hour battery can deliver 1 amp for 100 hours, or 10 amps for 10 hours.

Watts = Voltage X Amps

So if you have a 60 watt output from your generator, and it is running a 12 volt system, then the system is producing 5 amps (60 watts/12 volts). If the system runs for 24 hours, then it is producing 120 Amp-hours per day. Oops. I sure messed up that calculation from a few posts ago. Sorry about that.

Joseph wrote:So it would take 20 days to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 days to charge a 100 amp-hour battery bank at 24 volts.

What I should have written is:

So it would take 20 hours to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 hours to charge a 100 amp-hour battery bank at 24 volts.

Joseph Lofthouse wrote:

Paul Delaet wrote:Can you explain how you calculated that? if i am making 60 watts instantaneously and that would be 1.4kw daily wouldnt that be 116ish amps daily.

Amps is an instantaneous measurement of current. It speaks to how big the wires in your system need to be before they melt.

Amp-hours is a measurement of how much energy can be stored in a battery. For example, a 100 amp-hour battery can deliver 1 amp for 100 hours, or 10 amps for 10 hours.

Watts = Voltage X Amps

So if you have a 60 watt output from your generator, and it is running a 12 volt system, then the system is producing 5 amps (60 watts/12 volts). If the system runs for 24 hours, then it is producing 120 Amp-hours per day. Oops. I sure messed up that calculation from a few posts ago. Sorry about that.

Joseph wrote:So it would take 20 days to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 days to charge a 100 amp-hour battery bank at 24 volts.

What I should have written is:

So it would take 20 hours to charge a 100 amp-hour battery bank at 12 volts using this generator.
It would take 40 hours to charge a 100 amp-hour battery bank at 24 volts.

oh dont apologize one bit. I should be the one apologizing for bugging you so much =) if i were to use a PMA would my wattage increase enough to justify buying one? and ill have to figure out a few things, but i still want to try to grid tie inverter with a battery bank. Do you have any recommendations on what brands/sizes to go with for the inverter and charge controller?

I am a scientist, so I understand the physics of water and electricity. I'm also a subsistence farmer living under a vow of poverty, so I don't have a clue about what consumer goods are available.

If it were me, and I wanted a grid-tied system. I would build a stand-alone system to power an appliance or two, or one circuit. Then when the battery was full, dump the excess power onto the house mains through one of those micro feed-only grid-tied inverters. And if the system was generating more power than the rest of your house was using then the excess would end up on the grid. If the battery got too low during normal usage, then it could be filled with a battery charger powered by the grid.

60 watts is very low power today, but if the grid went down, it would be a treasure.

Joseph Lofthouse wrote:I am a scientist, so I understand the physics of water and electricity. I'm also a subsistence farmer living under a vow of poverty, so I don't have a clue about what consumer goods are available.

If it were me, and I wanted a grid-tied system. I would build a stand-alone system to power an appliance or two, or one circuit. Then when the battery was full, dump the excess power onto the house mains through one of those micro feed-only grid-tied inverters. And if the system was generating more power than the rest of your house was using then the excess would end up on the grid. If the battery got too low during normal usage, then it could be filled with a battery charger powered by the grid.

60 watts is very low power today, but if the grid went down, it would be a treasure.

I am a high school drop out with a G.E.D. The "stand-alone system" sounds much simpler but sounds like i would need 2 inverters unless i was to run the one circuit as DC. The plan is to "homestead" a 4 acre plot that my fathers house used to sit on when he was a kid. there are no existing or new structures on the land right now. While the property isnt hooked into the utility grid, it isnt far enough out to not have access to it. I will have gas, water, and electricity, but the plan is to supplement my usage with alternative methods to hopefully eventually be totally reliant and use the utility grid as a safety net. What was going to happen first was i was going to set a pole and mount a meter for the power company to hook to and run wire in conduit underground to a small shed by the creek to house the breaker box. To start with i would probably have one outlet and a light in the shed, and run conduit or direct burial cable to 1 weatherproof outlet towards the back of the property on a 4x4 post. this would be a more permanent "temporary service" to aid in building the small 250 square feet cabin i am designing. I currently work as a electricians laborer and put services in daily for residential buildings. but i have no knowledge in low voltage electricity dc and its interaction with high voltage ac. i added some pictures i made in paint real quick. the dual input grid tie would be nice. have the charge controller feed the batteries until they were charged then the controller will flip over to feed the inverter directly. a switch could be integrated into the system (if the inverter doesnt have the option) to choose between battery supply, grid supply, or direct + grid supply so power could be drawn directly and used while also drawing from the grid to supplement power when using demanding power tools.

hydro generator+solar panel>>charge controller>>battery>>inverter>>house/load.
If for whatever reason you can't produce enough electricity you can then plug the grid into the inverter to fill up the battery, or you can use a gas generator, if the grid goes down.

hydro generator=$1,000 aka 1k (1440w per day....60w*24hr)
solar= 1k (4000w per day ......1000w*4hr)
charge controller + inverter =2k
battery = 1k (8kwhr can be 80% discharged vs the usual 50%)
honda gas/propane generator =1k (2000w surge, 1600 rated and 1000w eco/quite mode @only 49 decibel)

S Bengi wrote:hydro generator+solar panel>>charge controller>>battery>>inverter>>house/load.
If for whatever reason you can't produce enough electricity you can then plug the grid into the inverter to fill up the battery, or you can use a gas generator, if the grid goes down.

hydro generator=$1,000 aka 1k (1440w per day....60w*24hr)
solar= 1k (4000w per day ......1000w*4hr)
charge controller + inverter =2k
battery = 1k (8kwhr can be 80% discharged vs the usual 50%)
honda gas/propane generator =1k (2000w surge, 1600 rated and 1000w eco/quite mode @only 49 decibel)

I understood the top portion. but what exactly you mean with the "k" is eluding me. My mind is quite awake this morning. surely you aren't meaning cost of components. $1,000 aka 1k?

everywhere you see 1k substitute it for $1,000.
So the entire setup cost $6,000. $1000 for the gas generator, another $1,000 for the battery, another $2,000 for the charge controller and inverter, another $1000 for the solar panel, etc.

S Bengi wrote:everywhere you see 1k substitute it for $1,000.
So the entire setup cost $6,000. $1000 for the gas generator, another $1,000 for the battery, another $2,000 for the charge controller and inverter, another $1000 for the solar panel, etc.

OR i could spend less than $200 on an alternator, less than $200 on a charge controller, less than $400 for an inverter, about $600 for the battery bank and i dont plan on having a solar panel or a gas generator. Ive been pricing parts on ebay and other sites and i cant see where you are getting such high numbers.

The $1400 price point looks very attractive and will probably do the job that it was created for.
My price of $4000 ($6,000 if I include solar panel and emergency gas generator), is so high because of quality and use case.


Inverter
If all I need to do is power a pump or drill then any cheap inverter will work, but if
I want one what will not damage electronic like laptop, computers, tv, etc, it will have to create a pure sine wave ac
If I only plan on using it once in a while then a cheap one will do, but if I am going to have it on 24/7 year after year, A more expensive one with components rated for 24/7 is needed.
If I only plan on only pulling a max power of 1000watt, I can use a cheap one but if I envision my lights+tv+computer+pump+microwave+fridge+etc all on at the same time. It will then necessitate of 4000watts.
If I am going to have motors/etc running then I have to also worry about surge power(of say 6000w) and not just rated power(of say 4000w).

Battery
You should only discharge a battery to 50% so you really need to double your rated storage capacity.
Once you battery reaches 75% full the efficiency drops and as you approach 99% full more than 50% of the power going into it is wasted, so you really need your battery at 3x your rated storage need.
If you want your battery to store enough power for 3 or so days in case of emergency then you need at least 9x

Hydro-Generator
From flow*head calculation to actual loads in the house the combined efficiency is only 55% or less. So your 1440w per day is now down to only 720w per day or less, so a solar panel actually makes alot of sense.
Even going with a cheap microhydro, there is alot of misc cost such as wire, pcv pipe, bolts, structures, case, possible earthworks, electrician, etc I pretty much included some misc cost into it.

Charge Controller
If one were to supplement the microhyrdo with solar, then a more robust charge controller is needed that can accept power from both hydro and solar. It would also need to be mppt to accommodate constantly changing sunlight condition on each panel.

Solar
Solar Panel are actually pretty cheap at less than $1 per 1watt/hr or $1 for 4watt/day.

Backup Generator
Gas/Propane/LNG generator is only 45lbs so very portable, it is super quite at only 49decibel and with 1gallon lasting 4hr-10hr. It is pretty economical. But why would you need it. So that you can run some tools when you are away from the house, so that you can car camp in real style or power a RV, so that you have a power source if you other options are unavailable, etc

S Bengi wrote:The $1400 price point looks very attractive and will probably do the job that it was created for.
My price of $4000 ($6,000 if I include solar panel and emergency gas generator), is so high because of quality and use case.


Inverter
If all I need to do is power a pump or drill then any cheap inverter will work, but if
I want one what will not damage electronic like laptop, computers, tv, etc, it will have to create a pure sine wave ac
If I only plan on using it once in a while then a cheap one will do, but if I am going to have it on 24/7 year after year, A more expensive one with components rated for 24/7 is needed.
If I only plan on only pulling a max power of 1000watt, I can use a cheap one but if I envision my lights+tv+computer+pump+microwave+fridge+etc all on at the same time. It will then necessitate of 4000watts.
If I am going to have motors/etc running then I have to also worry about surge power(of say 6000w) and not just rated power(of say 4000w).

Battery
You should only discharge a battery to 50% so you really need to double your rated storage capacity.
Once you battery reaches 75% full the efficiency drops and as you approach 99% full more than 50% of the power going into it is wasted, so you really need your battery at 3x your rated storage need.
If you want your battery to store enough power for 3 or so days in case of emergency then you need at least 9x

Hydro-Generator
From flow*head calculation to actual loads in the house the combined efficiency is only 55% or less. So your 1440w per day is now down to only 720w per day or less, so a solar panel actually makes alot of sense.
Even going with a cheap microhydro, there is alot of misc cost such as wire, pcv pipe, bolts, structures, case, possible earthworks, electrician, etc I pretty much included some misc cost into it.

Charge Controller
If one were to supplement the microhyrdo with solar, then a more robust charge controller is needed that can accept power from both hydro and solar. It would also need to be mppt to accommodate constantly changing sunlight condition on each panel.

Solar
Solar Panel are actually pretty cheap at less than $1 per 1watt/hr or $1 for 4watt/day.

Backup Generator
Gas/Propane/LNG generator is only 45lbs so very portable, it is super quite at only 49decibel and with 1gallon lasting 4hr-10hr. It is pretty economical. But why would you need it. So that you can run some tools when you are away from the house, so that you can car camp in real style or power a RV, so that you have a power source if you other options are unavailable, etc

I totally agree that a backup generator is a great thing to have. And i will most likely have one in future years. Its just not on my top list of things to get right away. like the solar panel. i am eventually going to have one, and it will be a great supplemental power source but i question if i have enough sun to justify buying one right off hand. and keep in mind, budget is TIGHT.

I worked as a plumber for a year or so and have access to all sorts of pipe and plumbing supplies, and with my job i have now i have accumulated a large amount of wire and outlets/switches, breakers, conduit, and other stuff. i have a huge amount of lumber going to waste and I have a few deep cell batteries so i wont have to buy too many. basically everything for this system i will try to source for free or dirt cheap. the batteries, inverter and charge controller will be about all i have to buy minus some odds and ends.

since i dont plan on spending any money constructing the water wheel, shed to house the equipment, and ill have VERY little in putting in an electrical service(inspection fee and what ever my boss charges me.. ill be doing the labor so hopefully not much) i could spend more on the inverter and charge controller and batteries like you recommended. then when i do decide to get a solar pv panel ill have the charge controller and inverter that can handle them both plus the battery storage to hold it.

Paul Delaet wrote:This stuff really is over my head a bit. i am trying to understand it the best i can.           I have an area where i feel a water wheel will work to make a small amount of electricity. it has roughly 6ft of possible head, and around 50 to 75 gpm.  my math tells me i can only expect around 60 watts. That is with using the calculations i found on another site.  now is that 60 watts per day? that isnt hardly worth it is it? am i missing something here? how do people run homes on such small water wheel set ups?

To understand Watts better have a look at the Wikipedia explanation: https://en.wikipedia.org/wiki/Watt