Wells  are drilled and cased respective sealed to remain septic during the operation. The case runs up to the surface of the water table . The casing it is mainly made of clay , bentonite clay or concrete. The deep well continue from the water table level with a 15" in diameter drilled hole up to the cofined aqufer level. For very deep drills the electric motor it is placed at the surface on the top of the well shaft for easy maintenance purpose.

Pumping system characteristics

1. Resistance of the system: head 

Pressure is needed to pump the liquid through the system at a certain rate. This pressure has to be high enough to overcome the resistance of the system, which is also called “head”. The total head is the sum of static head and friction head:

Static head

Static head is the difference in height between the source and destination of the pumped liquid. Static  head is independent of flow. The static head at a certain pressure depends on the weight of the liquid and can be calculated with this equation:

Head (in feet) =  Pressure (psi) X 2.31 / Specific gravity(SG) = hs + hd
or
H = [Pd-Ps] x 2.31 / SG  

Static head consists of:   Static suction head (hS): resulting from lifting the liquid relative to the pump center line. The hS is positive if the liquid level is above pump centerline, and negative if the liquid level is below pump centerline (also called “suction lift).  Static discharge head (hd): the vertical distance between the pump centerline and the surface of the liquid in the destination tank.

Friction head (hf)

This is the loss needed to overcome that is caused by the resistance to flow in the pipe and fittings. It is dependent on size, condition and type of pipe, number and type of pipe fittings, flow rate, and nature of the liquid. The friction head is proportional to the square of the flow rate.  A closed loop circulating system only exhibits friction head (i.e. not static head).

Pump performance curve 
The head and flow rate determine the performance of a pump, which is graphically shown as theperformance curve or pump characteristic curve. The figure shows a typical curve of a centrifugal pump where the head gradually decreases with increasing flow. As the resistance of a system increases, the head will also increase. This in turn causes the flow rate to decrease and will eventually reach zero. A zero flow rate is only acceptable for a short period without causing to the pump to burn out.

How to calculate pump performance
The work performed by a pump is a function of the total head and of the weight of the liquid pumped in a given time period. Pump shaft power (Ps) is the actual horsepower delivered to the pump shaft, and can be calculated as follows:

Pump shaft power Ps = Hydraulic power hp / Pump efficiency ηpump
or:

Pump efficiency ηpump = Hydraulic power hp / Pump shaft power

Pump output, water horsepower or hydraulic horsepower (hp) is the liquid horsepower delivered by the pump, and can be calculated as follows:

Hydraulic power hp = Q (m3/s) x (hd - hs in m) x ρ (kg/m3) x g (m/s2) / 1000

Where: 

Q = flow rate

hd = discharge head

hs = suction head

ρ = density of the fluid

g = acceleration due to gravity

Type of solar pump applications 

Array-Direct to Elevated Storage.
The most efficient solar water-pumping systems are PV-direct without batteries. This classic off-grid pumping solution connects a DC submersible pump directly to the PV array. One additional component, either a controller or linear current booster (LCB) wired between the PV array and the pump, optimizes the relationship between array voltage and current to maximize the amount of water pumped under varying sunlight conditions. When the sun is shining, the pump moves water to a tank located above the water’s point of use. (For potable water, use only drinking-water-grade tanks.) For each 2.31 feet of elevation, there will be 1 psi of water pressure. Many household water supplies operate at about 40 psi (though down to 20 psi can often work), so locating the storage tank about 100 feet higher than the point of use will provide adequate water pressure.

Array-Direct to Storage Tank with Pressure Pump.

If you like the efficiency of DC pumping and want stored water at your disposal, but don’t have enough of an elevation change on your property for a gravity system, there are still options.  A PV-direct DC pump can be configured to fill a storage tank near its point of use, and an additional DC or AC booster pump can be installed at the tank to pressurize the water. This solution gets the heavy lifting (from the well to the storage tank) done whenever the sun’s shining, and limits energy use during cloudy periods to a smaller pressure pump that activates via a pressure switch when water is used. While this configuration gives you more flexibility to choose when you consume the energy required to pump well water, the up-front costs of the storage tank and additional pressure 

pump add to overall system cost and installation complexity.