Sun Pumps SJT10-120BL - Manual (Page 5)

3.2 System Design Basics (Read carefully before installation)
1. The pump discharge piping should be sized for efficient pump operation. We suggest using the Friction Loss Tables to
calculate the Total Dynamic Head using different pipe sizes. Use no less than a 1 ¼” suction pipe and increase the pipe size if
the run is over 50 feet.
2.
For optimum pump performance make sure that the wire is sized properly for the length of run between the pump and the
solar modules. Wire sized too small will cause a decreased output from the pump. Keep the distance from the solar modules
to the pump as short as possible. Refer to a DC wire loss chart for proper sizing. It is recommended to keep the voltage drop
under 3%.
3. The SJT series shallow well jet pumps have a maximum suction lift capability of 25 feet at sea level. For every 1000 feet
above sea level the suction lift will be decreased by 1 foot.
4. Always use a foot valve on the suction pipe with a negative suction lift. Keep the suction pipe in a straight sloping line
without any loops where air could be trapped. Keep the suction pipe as short as possible. To avoid air pockets, slope the
horizontal pipes continuously upward from the water source by at least 1 inch for every 30 inches of horizontal pipe.
5. Always fill the suction pipe and the pump with water before you turn the pump on. If the pump is operated dry, damage to
the impellers will occur and dry running is not covered under warranty.
6. If pumping from a tank or any source that could run low on water, install a low water float switch to protect the pump from
running dry.
7. If a pressure switch is used in the system, choose one with a Low Pressure Cut-Off. If the pump runs dry the pressure will
drop and the low pressure switch will turn the pump off.
8. Never install the controller in direct sunlight. Direct sunlight on the controller may cause over-heating of the controller.
9. Never lay the controller on the ground or mount the controller in a horizontal position. The controller should be mounted
in a vertical position only. A convenient place to mount the controller is on the north side (shaded side) of the solar module
array.
10. The controller should be grounded to the pump motor housing, the frame of the solar modules and to an 8-foot ground rod. If
the well casing is steel it may be used as the ground rod. Drill and tap a hole in the casing or weld a bolt to the casing for the
ground lug. Use only a copper lug to attach the ground wire. The cemented support structure pole will not provide an
adequate ground. Do not ground the positive or negative electrical wires. Always use a DC surge/lightning arrestor on the
panel side of the controller. (Midnight Solar MN-SPD surge arrestor is recommended)
11. Do not ground the array positive or negative electrical wires.