# waterpump Helllllllllpppppp!!!!!



## jjh81 (Aug 17, 2010)

OK so I'm totally lost so bear with me. I have a 275 gal water tank I want to plumb to my house. I will be using a 12volt on demand sure flow water pump to pump to the house. It uses a max of 9.6 amps and I want to be able to run it for 4 ours off and on for showers dishes toilet ext.. I can't figure what I need and I'm so confused. If someone could please help me on this I need to figure out how many batt's and how much solar I'm going to need? Any help would be appreciated.


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## Harry Chickpea (Dec 19, 2008)

Playtime. Just some top-o-the-head stuff-

Call it 10 amps at 12 volts. Volts x amps = watts 120 watts
120 watts over an hours time converts to .12 KWH
4 hours of it converts to .48 KWH
In theory...
Battery capacity is commonly measured in Amp hours. Multiply the amp-hours by battery voltage to get watt-hours. Divide by 1000 for kWh.

So, if you are only running the pump and need .5 KWH per day, you need a lead acid cell array with a capacity of 5 KWH if you plan on only using 10% of battery cycle to make the batteries last. 5,000 divided by 12 volts = 425 Amp Hour capacity +-

To recharge the battery daily, you'll need at least 8,000 watt hours to account for losses, and you'll have to figure on the least sunny day OR increase your battery capacity so that it can coast over a few cloudy days. That is a LOT of solar panels. 

However... 275 gallons is much more water than you would use for showers and dishwashing and washing on a daily basis AND the pump will only be running intermittently, so your real needs are _far_ less.

A simpler setup might depend upon avoiding large (and lossy) storage of electric power. A tank 30' above the spigot (vertically) will automatically give you 15 pounds of water pressure. Full house pressure is commonly around 40 PSI.

You COULD stick the tank on a 70' tall tower or hill and only have to pump the water to that tank, which could be done only while the sun shines - eliminating the need for all but a small battery to even out the voltage while filling the tank. That might be impractical, but if the tank is even at a second story or attic level, you can use a couple of pumps and split the load. One (low wattage) pump pumps the water up to the tank during sunny periods (primarily using immediate solar power), another pump takes the partly pressurized water and finishes the pressurization for your shower and so on, using power from a battery. In essence, the water tank acts as an energy battery, just not in electric units. The higher it is, the more energy is stored.

The full tank of water weighs maybe 2500 lbs, so any structure holding it has to be sturdy and wind braced. You also have to mitigate freezing issues with insulation and solar heating of the water.


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## 12vman (Feb 17, 2004)

jjh81 said:


> OK so I'm totally lost so bear with me. I have a 275 gal water tank I want to plumb to my house. I will be using a 12volt on demand sure flow water pump to pump to the house. It uses a max of 9.6 amps and I want to be able to run it for 4 ours off and on for showers dishes toilet ext.. I can't figure what I need and I'm so confused. If someone could please help me on this I need to figure out how many batt's and how much solar I'm going to need? Any help would be appreciated.


 Figure 10 amps @ 4 hrs. (40 aHr.) Multiply b 17.. 680 watts. Divide by 4.. 170 watts.. (Figuring a 4 hr. charge time/day) Round up to 200 watts of panel..

Battery.. 40 aHr. Times 4.. 160 aHr. of battery. Round to ~200.. (25% discharge rate) A large 12 volt deep cycle marine battery is at around 60 aHr. reserve. 3 connected in parallel would be close enough..

The pump uses it's max current when you shut the water off, while it's pressuring up. As you free flow, (shower, toilet filling, rinsing dishes) it may only use 2-4 amps..

Don't forget a charge controller..


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## jjh81 (Aug 17, 2010)

I'm kinda lost I got two totally diff numbers like way diff one at 8000 w 1 at 200 w now I'm really lost


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## wy_white_wolf (Oct 14, 2004)

Your location is needed as that will determine the solar insolation available (sun hours). Then I can run some numbers. I'd guess 12Vmans numbers are close but feel he might be a little undersized as the US average for winter is on 2.5 hours of solar insolation.

WWW


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## K.B. (Sep 7, 2012)

I think Harry got an extra zero on there, somehow


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## farminghandyman (Mar 4, 2005)

a small pressure tank will make the pump last longer,


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## idahodave (Jan 20, 2005)

First you need to know how much water gets used each day. Then work from the pump gpm and current draw to determine energy use. That will give battery and solar panel needs. Otherwise it's just a guess.

I use a RV pump to fill a 120 gal bladder tank from a cistern. The tank can supply about 18 gallons with a 20/30 psi switch setting between pump runs. The pump takes about 5 minutes to refill the tank. On some days the pump never runs.


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## 12vman (Feb 17, 2004)

idahodave said:


> First you need to know how much water gets used each day. Then work from the pump gpm and current draw to determine energy use. That will give battery and solar panel needs. Otherwise it's just a guess.
> 
> I use a RV pump to fill a 120 gal bladder tank from a cistern. The tank can supply about 18 gallons with a 20/30 psi switch setting between pump runs. The pump takes about 5 minutes to refill the tank. On some days the pump never runs.


 I pondered a pressure tank myself but figured it wasn't worth it. For the time it takes the pump to pressure the tank back up, about the same amount of energy would be used. (or more) They really suck power when they are making pressure, especially for a longer period than needed..

I use a short length of garden hose between the pump and the hard plumbing. The hose expands just enough to make the pressure switch work without stuttering and blocks noise from traveling down the pipes. Turn on a spigot, the pump runs as long as the spigot is open and shuts down shortly after the spigot is closed. The current demand of the pump at free flow is low and it will build up pressure fast and shut down quickly. The flow is limited to the output of the pump but mine puts out enough for a shower.. (~1.5 gal/ min.) That's all the restrictor in the shower head will let through anyway.. Just my thoughts..


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## Jim-mi (May 15, 2002)

I have wanted to add a second big bladder tank to my system. That way I could draw down 40 -50 gallons before the pressure pump even comes on.


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## idahodave (Jan 20, 2005)

The tank can deliver water faster than the pump, so when the washer fills or if I need 20 gallons for the sprayer I don't have to wait for the pump.

I think that long run times are easier on the pump. It's pumped the 2000 gal cistern many times and still works, although the time to fill the tank seems to be increasing.


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## jjh81 (Aug 17, 2010)

Sorry haven't been near a inet connection I'm in northern Nevada winnemucca to be exact. I really can't tell you how much water is run a day. But I'm going to use a sure flow pump diafram type on demand. I dont know what else I can tell u to help that's why I said it would run about 4 hrs thanks


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## wy_white_wolf (Oct 14, 2004)

Winnemucca is pretty good for solar. According to PVwatts it has a low of @3.5 hours solar insolation in December.

So 12v * 10amp * 4 hours = 480WH daily usage.

For a PWM controller 480WH * 1.5 = 720WH that you'll need to produce and store.

720WH / 3.5 Hours = 205 watt array and a 20A controller

720Wh * 5days / 12volts = 300AH battery bank at 12V
150AH battery bank at 24V


For an MPPT controller 480WH * 1.25 = 600WH that you'll need to produce and store.

600WH / 3.5 Hours = 175 watt array, while a 15 amp controller should handle it I'd go with a 20 amp just to be safe.

600Wh * 5days / 12volts = 250AH battery bank at 12V
125AH battery bank at 24V

I think the cost of a good MPPT controller is not justified as the system is just too small. It'll cost less for the larger array and battery than the increase in controller cost.

WWW


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## jjh81 (Aug 17, 2010)

Thanks wolf I appreciate you time and knowledge now to start getting parts. Does anyone recommend anywhere imperticular. There are so many online retailers that I don't quite know who to go through.


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## wy_white_wolf (Oct 14, 2004)

One thing to pay attention to with a PWM controller is the panel voltage. Keep the VMP to between 17 to 19 Volts. If you go with a MPPT then panel voltage can be higher.

WWW


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## idahodave (Jan 20, 2005)

I think if you use the 4 hour a day figure you'll have excess capacity in the solar system. 4 hours will drain the tank every day, I use about 300 gallons in a week. Do you plan on refilling the tank each day?


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## Bellyman (Jul 6, 2013)

I'm with IdahoDave. Start with the amount of water you need and go from there. You may not need as much as you think. 

You may want to look at ways to use less water, too.

As fulltime rvers, my wife and I probably use about 200 to 250 gallons of water a week, total, and that includes laundry. Granted, we have some unique fixtures. Our toilet flushes with just a few cups of water, not a gallon or more. And our shower head has a knob to shut the water off when we don't need it to be spraying water. (Navy showers.) 

If you have the capacity to pump into a reserve tank that gives you even a little pressure in the house, that can give you something to rely upon in the event that you have problems with the pump or the solar setup or have a few days when the sun doesn't shine much, provided the tank is large enough. Batteries are expensive and they don't last forever. Our Amish neighbors had a railroad car tank that they placed on a high spot in one of their fields and had a windmill that would pump water for it. It supplied their household and barn with water. I don't imagine that they had a lot of pressure but it didn't take batteries and didn't care whether it was night or day. They did have a gas motor that would run it if they needed more than the windmill could keep up with.

More than one way to do it... and more than one way to do it well. It will be interesting to hear what you decide upon and how it works out for you.


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## jjh81 (Aug 17, 2010)

No I dont plan on refilling everyday but I also dont want to short myself if I do end up using it all.


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