Confused on which Pump & specs

Re: Confused on which Pump & specs

You may end up with two pumps (or more)... Leave the well pump filling your tank/cistern/pond. And install (one or more) above ground pumps from the tank to pressurize the drip system.

There are different types of water pumps. Those that are "positive displacement type" (think pistons/diaphragms that move xx volume of water per stroke--and if the water valve is turned off, the pump can actually stall/not turn because of the back pressure) and those that are (usually) centrifugal pumps--Sort of like fans in the air or a vacuum cleaner. They move water when the back pressure is below the pump's output pressure, or just spin when the back pressure is high.

Many shallow well pumps are centrifugal type pumps. As the pressure increases, the flow reduces, and (to a degree) the electrical power use of the pump drops too. Very easy to connect to a variable flow system, not very expensive type of pump, can usually tolerate sand/dirt a bit better, but can be a waste of electricity (bigger pump than you need turned on when you need "any" water flow).

With positive displacement pumps, they tend to be more efficient but usually need an electrical pressure switch and a water pressure tank to provide variable flow loads.

I am guessing, but perhaps a "mixed" system would work well for you.

Keep your well pump pumping to a tank/cistern (make the water storage tank larger, if needed, and keep tank/water level above ground level). Use a water level switch to control the well pump. Set up the tank so that sand/dirt settles out on one side of the tank and you have a good area to pick up clear water.

Install one or more smaller pumps (probably positive displacement) so that the pump is below water level with a screen on the pump input (sucking up water above the water level or through a dirty/fine mesh screen can cause all sorts of pumping problems. Water pumps with positive water pressure on the inlet are much more efficient and much less chances to have problems with pulling air into the system and problems with cavitation--creating "vacuum" bubbles that stop pumps from pulling up water and/or collapse and cause excessive wear around the valves and pumping surfaces).

Depending on the pump, if centrifugal you can just connect the output of the surface pump(s) to your plumbing with a timer/etc. as needed.

If positive displacement, you can add a pressure tank and pressure control switch to control the motor. Then pipe out to the field.

If your storage tank is "below ground level"--Then you may have to make a pit to install the surface pumps. Will work fine, but you probably have to install a sump pump and an alarm to ensure that any water leaks/rains do not flood the pit and the pumps.

Note--You are "paying" for the privilege of pumping to 40 PSI or so for the water. It costs you energy. If you could find a drip irrigation system that runs on 15 psi--you can save some power costs... But, "do the math" first (a paper design with several pumping options/configurations). In your case, the extra power costs may not be a big issue verses the ability to use standard irrigation equipment.

This is a very complex subject. You have water, pump specifications, AC vs DC questions, pumping during sunlight and/or battery or generator backup, one pump vs two pump solutions, etc. If doing AC, there are electronic devices (VFDs; variable frequency drives) that can allow you to match pump RPM to flow/pressure needs and reduced the surge current during starting (soft start).

The whole question of trying to do a system that is "solar panel+pump" only vs a solar panel+battery+inverter(maybe)+pump+generator backup+etc... If you can do a "solar+pump" only system--That can cut the cost of your "power equipment" by 3/4's... (when you add batteries, you need more solar panels, charge controllers, possibly AC inverter, backup genset, replace the batteries every 3-5 years, etc...).

And, you have a different selection of equipment 1/2 a world away from us--So what we suggest may be too expensive/too difficult to obtain anyway.

I would focus on understanding the pumps available to you (AC, DC, centrifugal/positive displacement, etc.) and see what would be an "ideal" setup for you--Then look at what it takes to power the configuration (solar, batteries, inverter, etc.).

Using above ground pump(s) that are installed below the water level of the storage tank can really save energy and maintenance issues. However, replacing the well pump with a higher pressure version that can pump direct to field may keep the system much simpler and less costs over all (but may hurt you when looking at costs to power the pump).

-Bill