How can i run a 1/2 HP AC submersible pump by solar energy

[malijanjua]

Hi ,
I have just joined this forum. it seems very useful. please keep it up.

I am interested in running a 1/2 HP power AC submersible pump through solar energy.
the bore size is 4 inches wide
water head 70 feet
can i get some guide lines on;
how many watts of solar pannels
charge controller
battery
Invertor
do i need

Regards

malijanjua

[lile001]

Hi ,
I have just joined this forum. it seems very useful. please keep it up.

I am interested in running a 1/2 HP power AC submersible pump through solar energy.
the bore size is 4 inches wide
water head 70 feet
can i get some guide lines on;
how many watts of solar pannels
charge controller
battery
Invertor
do i need

Regards

malijanjua

Well, what are the specs on the pump? 120VAC? Maybe 5 or 6 amps? Can you switch to a DC pump, which will make a more efficient system overall?

How long does this pump run? An hour a day? 24 hours? and where are you located?

Let's pretend it runs an hour a day, and you are located in the Midwest, where you can count on maybe 5-6 hours of sun per day.

120V * 6 amps = 720 watts * 1 hr = .72 KWHR per day

.72 KWHR / 6 hrs sun = .12 or 120 watts of solar panels

Considering the inefficiency of small inverters and batteries, say you'll need more like 240W of panels.

You might need more than that, if your location has a week of cloudy weather several times a year like it does here. Or uyou might have to tolerate an outage on this pump if the weather is cloudy for a while. Is that OK, or does it need to be totally reliable?

Your inverter needs to be large enough to start the motor - probably a minimum of 1200 watts, likely more. The inverter mfr will have specs on motor starting capacity.

Batteries - well, lets get answers to the first questions above before we go that far.

[Mike90250]

Is it a well, with a pressure storage tank, or an above ground tank, where hight develops the pressure?
If you can get away with an elevated tank for pressure, you can use a solar power DC pump to raise the water up. If you use a pressure tank, and the pump comes on every 3rd time you use the water in the house, you will have to stay with the AC well pump, and use an inverter & battery to power it.
Is this existing or a new install ? Is the existing pump 120V or 240V ? Do you already have power to the pump? Do you need it to work in power outages ?

[malijanjua]

My Dear Mike
Thank you very much for yr reply.
I will go through the details one by one;

I am located in Pakistan (south Asia).
We have sufficient sunlight available during summer days (more than 8 hours/day) and winters with more than 6 hours. It is close to the warm areas of California.
We don’t have electricity connection available at this site.
At present we are using diesel generator to run the pump which is very expensive.
We have an overhead tank of 1000 gallons. We use the tank for drip irrigation and livestock watering purposes. The height of tank is 30 feet.
DC pumps are very expensive here and with no back support from any vendor.AC pumps and investors are cheaper and easily available in the market.
The submersible pump we are using has wattage written on its label (350 watts)
Our voltage is 220Volts AC.
Our requirement is at least 4-5 hours in summers and 3 hours in winters.

[Mike90250]

Great, useable details.

So, I'll figure the pump consumes 400W, with starting loads, and will run close to that anyway, better to have a little extra power, then to not have enough.

5 hours summer, 3 in winter tracks the sun availability well, not counting for cloudy days. I'll plan for no clouds, and that the generator will be run in cloudy weather.

Summer, 5 h x 400W = 2Kwh consumed (Kwh = Killowatt hours)
Winter 3 x .4Kw = 1.2Kwh consumed

Assume 6 hours sun summer 9am - 3pm and 10am -2pm winter
(The sun is up more hours, but does not provide much usable charging power at those times)

Battery charging, inverter and storage losses = about 50%, so summers, need to collect / harvest 4Kwh and winter 2.4Kwh.

Battery size - for longer battery life, you only want 30% draw off the battery, so 4Kwh use needs a 15Kwh battery bank.
A standard golf cart 6V battery is about 200Ah, or 1.2Kwh
That would require 12batteries. Ouch. how to reduce this, we are pumping in daytime, while panels are creating power, so maybe it's not all coming out of the batteries.
So lets see, If we reduce to 2 batteries, 2 in series, for a small 12V bank that's more manageable, and works if you only run daytimes.

How much solar PV is needed. Well, trading off to a small battery bank, means the solar needs to handle the load. between 500 and 600W of solar panels will be needed.
You will need a charge controller, that can handle 40A of 12V power, I'd suggest the Trace/Xantrex C-60 ($200 US) or the Morningstar TriStar 60 amp PWM controller ($220US)

And you need a Pure Sine Wave inverter, for at least 400W, 600W preferable
I don't know if you are 50Hz or 60Hz ac for the pump.
http://www.behlman.com/pdf/s600.pdf Expect to pay about $500us for the inverter. Modified sine wave inverters are much less expensive, but cause motors to run hot, and consume more power (more PV and batteries needed) and can damage some motors.

http://www.freesunpower.com/battery_designer.php is great to get sizes and configurations, but has poor wire techniques.
Smart gauge site has better wire techniques, and assumes you know how to create a bank. http://www.smartgauge.co.uk/batt_con.html

Hope this helps
Mike

[MarineLiner]

[QUOTE=malijanjua;7981].....
We don

[malijanjua]

about 6000-8000 gallons per day.

[MarineLiner]

If we can pumping the 8,000 gallons in 6 hours good sunlight time,
and have 8,000 gallons tanks,
then we do not need many batteries to store electricity. (Only for some lamps at night).

[Mike90250]

Agreed, best way is to avoid batteries, and pump with direct sunlight. If you are managing with 350watt pump now, we may still have to use inverter and minimal battery bank - only pump daylight, and battery is for 10 second cloud shadow.

The submersible pump we are using has wattage written on its label (350 watts)
Our voltage is 220Volts AC.
Our requirement is at least 4-5 hours in summers and 3 hours in winters.

So all we need is inverter to start the pump. Can you give us all the info on the pump label, that you can find:
Volts
Watts
PF (power factor)
Capacitor
Starting current
RPM
and any other stuff printed there.

I'd suggest a 24V system (4 small, 6V batteries in series) Charge controller, and 24VDC inverter. This might run the pump for 5 or 10 minutes off battery, but the intent is to only run when the sun is up, to keep the batteries charged. And about 800W of solar, on a pole mount, to keep the panels off the ground. 800W @ 24V is about 33 amps of controller needed.