Short answerPlan on 20 gallons a head a day in hot weather. Fifty head need about 1,000 gallons a day, 3.3 gpm over 5 sun hours, a 3,000 gallon tank and about 240 W of panels at 100 ft of total dynamic head; 100 head double every figure.
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Key takeaways
- Plan 20 gallons a head a day for beef cattle in hot weather.
- 50 head: about 1,000 gal a day, 3.3 gpm, a 3,000 gal tank, about 240 W at 100 ft.
- Beyond about 75 head, plan two pumps or a larger one.
By herd size
| Head of beef cattle | Gallons a day | gpm over 5 sun hours | Tank, 3 days (gal) | Panel W at 100 ft TDH | Panel W at 200 ft TDH |
|---|---|---|---|---|---|
| 10 | 200 | 0.7 | 600 | 50 | 100 |
| 25 | 500 | 1.7 | 1,500 | 120 | 240 |
| 50 | 1,000 | 3.3 | 3,000 | 240 | 480 |
| 100 | 2,000 | 6.7 | 6,000 | 480 | 960 |
| 150 | 3,000 | 10.0 | 9,000 | 720 | 1,440 |
| 200 | 4,000 | 13.3 | 12,000 | 960 | 1,920 |
Reading the table
- Gallons use 20 gallons a head, the hot-weather figure for mature and finishing beef cattle from NDSU Extension. Lactating cows in heat can drink more; cool-season use is far less. See livestock watering for other animals.
- Flow assumes the pump runs 5 peak sun hours. In a darker month, divide gallons by your design sun hours x 60.
- Storage is three days of peak demand, the usual floor for a direct-drive system.
- Panel watts are for a pump wired straight to the panels. Add margin for panel ageing and dusty conditions.
Where one small pump stops
The 24V VEVOR pump we list has a merchant-stated rated point of 5.28 gpm at 84 ft. That covers about 75 head at 5 sun hours at modest lift. Beyond that, or at 200 ft, plan two pumps on separate arrays (which also gives redundancy), a larger DC pump, or an AC pump on a solar pump inverter. See DC vs AC solar pumps.
VEVOR 12V DC 120W submersible deep well pump
Low-volume wells: a cabin, a garden or a few head of stock. The deepest submersion rating of the three.
- Voltage
- 12V DC (12 to 14.8V)
- Rated power
- 120 W
- Max flow (zero head)
- 3.2 gpm
- Max head (zero flow)
- 230 ft
- Max submersion
- 98.4 ft
- Outlet
- 1/2 in
- In the box
- Pump only: no panel, controller or pipe
VEVOR 24V DC 277W submersible deep well pump
Stock water and small irrigation where the water level is within about 100 ft.
- Voltage
- 24 to 42V DC (36V rated)
- Rated power
- 277 W
- Max flow (zero head)
- 9.25 gpm
- Rated point
- 5.28 gpm at 84 ft
- Max head (zero flow)
- 272 ft
- Max submersion
- 65.6 ft
- Outlet / cable
- 1 in / 33 ft
- In the box
- Pump only
VEVOR 48V DC 369W submersible deep well pump
Deeper lifts at modest flow. Wants two 36V-class panels in series to reach its voltage.
- Voltage
- 48 to 82V DC (72V rated)
- Rated power
- 369 W
- Max flow (zero head)
- 8.4 gpm
- Rated point
- 1.77 gpm at 167 ft
- Max head (zero flow)
- 273 ft
- Max submersion
- 65.6 ft
- Outlet / cable
- 1 in / 33 ft
- In the box
- Pump only
We have not tested these products; specifications are the merchant's own. Affiliate disclosure.
Rotational grazing
Where cattle move between paddocks, a central well can feed a livestock pipeline to troughs in each paddock, or a trailer-mounted array can move with the herd to surface water. NRCS lists mobile panels as a design consideration for this, and both are common EQIP practices: see EQIP for solar stock water.
Run your own numbers. The sizing calculator shows every step, for your state, lift and pipe.
Open the calculatorQuestions
- How big a solar pump for 100 head of cattle?
- At 20 gallons a head in hot weather, 100 head need 2,000 gallons a day: 6.7 gpm over 5 sun hours. At 100 ft of total dynamic head that is about 480 W of panels on a direct-drive pump, with a 6,000 gallon tank. The flow is beyond most single small DC pumps, so plan two pumps or a larger one.
- How many gallons of water does a cow drink a day?
- NDSU Extension's table gives about 16 to 21 gallons a day for mature and finishing beef cattle at 90F, and 30 to 41 for milking dairy cows. Cool weather cuts intake sharply. We plan on 20 for beef in hot weather.
The calculator opens with a livestock setup; change the head count, state and lift.