A question on how solar dc water pumping works.

[waceycornia]

I have some 12 volt solar panels and want to run some small dc water pumps to irrigate some small pieces of land can i hook the panels up directly to the pumps or will it fry them? Can i run the pumps with a charge controller with a dc outlet?

[Mike90250]

Most simple DC pumps with brushes, will need a "Linear Current Booster" to prevent a stalled rotor from burning when PV is low.
Some electronic DC pumps will have them built in.

[waceycornia]

If i wanted to run a pump like this http://www.amazon.com/dp/B000O8B7LO/...I1SPNRP7Z1RCNF what would i need?

[LETitROLL]

If i wanted to run a pump like this http://www.amazon.com/dp/B000O8B7LO/...I1SPNRP7Z1RCNF what would i need?

Nice looking pump, but not what most would consider small to run off a couple 12v solar panels. Looks like you will need near 200w supply to that pump, so you will need 300-400w minimum worth of solar panels to be assured of having that much "net" power after wiring losses, etc. and even at that it will probably only supply enough during the prime middle portion of bright sunny days. Are you by any chance going to be pushing the water any significant distance and/or uphill at all?

[peakbagger]

My solar hot water system has a PV panel that drives a DC pump. Its been running that way for about 12 years. At some point after the initial install I did install a DC differential pump controller that turns the pump on whenever a temperature sensor on the outlet of the panel exceeds the temperature in the tank. The motor has brushes but I have never needed to change them. This is closed loop system so the actual developed head is quite low which may the reason it seems to run without a LCB. Its centrifugal pump so even at low current the rotor can spin so the rotor is never locked. Many DC water pumps are positive displacement as they are far more efficient. With a positive displacement pump I expect that if the current in not sufficient to move the water in the pipe that the pump could have overheating issues as the power applied would need to be dissipated as heat. During cold winter weather my glycol gets too thick to pump and my centrifugal pump spins and heats up the water on the discharge of the pump. The heat is rapidly dissipated into the air.

So if you are used a positive displacement pump is sound like a LCB is required while using a centrifugal pump it may not be

[Logan005]

If i wanted to run a pump like this http://www.amazon.com/dp/B000O8B7LO/...I1SPNRP7Z1RCNF what would i need?

that pump is not made for solar applications. you may be able to adapt it but would be expensive and likely not last very long. you would be much better off with a pump that is made for solar applications.

[Wy_White_Wolf]

If i wanted to run a pump like this http://www.amazon.com/dp/B000O8B7LO/...I1SPNRP7Z1RCNF what would i need?

You'll have to ask the manufacturer since they don't list the specifications we need to determine if it can run solar direct or if you need a battery to stabilize the power.

I run a shurflo 9300 series well pump off a 120w solar panel thru a LCB. The pump does not need the LCB to work solar direct but will last longer between rebuilds. It fills a cistern that gravity feeds to water my orchard thru a timer.

WWW

[solarix]

Your marine bilge pump is only meant for intermittent operation. Running it for hours on end will kill it in short order.
Even most DC solar pumps don't last long in my experience. They need either close tolerances or seals so that the pump will operate at slow speeds. Seals and close tolerances don't last - especially if you have any sediment etc in your water. Then - when the seal or diaphragm leaks - your submersible motor gets ruined! Ask me how I know.... On the other hand, you basic AC centrifugal pump goes a long time because it has very large tolerances - but, has to run a full speed so needs batteries and an inverter. My recommendation for most well pumping applications is to just use your AC pump and go ahead and get set up with a nice solar system with a big inverter as you can use it for everything else too. Also, none of your solar gain goes to waste that way.

What do I use? I have shallow water full of silt and have a large settling (storage) tank already, so use a Simple Pump brand jack-pump where the 24Vdc motor is up above the well and the whole thing is easily serviced. I get 1500g/day off of two broken (shattered) solar panels.

Want to do what is done throughout South America - google what is called a "rope pump". You can make the whole thing yourself. Not exactly what your local health department would call sanitary though....

[Hop Shepherd]

Need some help with a design of an off-grid farm water pumping set up. I'm transferring water from one pond to another using a Harbor Freight Pacific Hydrostar 12 volt Transfer Pump rated at 5 amps / 50 watts hooked to a 12 volt Exide Stowaway Dual Purpose Marine / RV - Dual Purpose deep cycle battery from Tractor Supply which I have hooked to a Harbor Freight 45 watt Thunderbolt Magnum solar kit. I'm struggling to get this set up to run more than an hour per day. I'm not sure what I need. More solar panels or a 2nd battery? Can you help me figure this out?

[Logan005]

Hop Shepherd, consider starting your own thread.

[Mike90250]

Horrible Fright is the first problem. It's not likely you are going to get 45W out of their panel kit. It's often been said the cardboard box the panels come in, is worth more than the panels.

So your pump is supposed to be 5A @ 12V which would be actually 60 watts. A deep cycle Group 24 (size code) 12V battery is about 80 ah, of which 40ah are usable. so the battery alone should run the pump for 8 hours. The choices are: Pump consumes more than 5A, battery is damaged and not capable of storing 80ah, or was never fully charged.

[Hop Shepherd]

Thank you for the quick reply Mike really appreciate it.