What Size Solar Bore Pump Do I Need?
Solar bore pump sizing comes down to three numbers. Most people only know one of them.
What size solar bore pump you need is set by three things: the inside diameter of your bore casing, the total head the pump has to lift against, and how many litres a day you need in winter. Get those three and the right pump is usually obvious. For a typical 4 inch stock and house bore with water at 40 to 60 metres, that lands on a 1000W helical rotor kit like the Tuhorse 4S1000 with 1600W of panels at $4,993.
Skip any of the three and you end up with one of the two phone calls we get every week. The pump that does not fit down the hole. Or the pump that fits, runs all day, and fills the trough with a trickle.
Already know your numbers? Jump to the sizing chart, see the Tuhorse 4S1000 kit and the 3 inch Tuhorse 3S500 kit, or browse every solar pump we sell.
Step 1: measure the bore casing
A solar bore pump must have a smaller outside diameter than the inside diameter of the bore casing, so the casing decides which pumps are even on the list.
A 4 inch pump needs a 4 inch or larger casing. A 3 inch pump needs 3 inch or larger. A 2 inch casing rules out almost every solar kit on the market except a narrow pump like the Tuhorse 2S370.
Measure it. Drop a tape inside the casing at the bore head, or dig out the bore completion report from the driller. Do not go off what the previous owner remembers. We have had more than one 4 inch bore turn out to be 100mm PVC with a joint that a 4 inch pump will not pass.
Step 2: work out the total head
Total head for a solar bore pump is the pumping water level, plus the height from the bore head to the top of the tank, plus friction loss in the pipe, all in metres.
Pumping water level, not standing water level
The pumping water level is how far down the water sits while the pump is running, and it is always deeper than the standing water level you measure at rest. A bore that rests at 30 metres can draw down to 40 metres or more under pumping. The driller's report usually lists both. If it does not, assume at least 10 metres of drawdown on a modest stock bore and size for that.
Lift to the tank
Lift to the tank is the vertical height from the bore head to the inlet at the top of the tank. A 2 metre tank on a 4 metre stand is 6 metres. A tank on a hill 25 metres above the bore is 25 metres, and that one catches people out all the time.
Pipe friction
Pipe friction is the head lost pushing water along the poly, and it grows quickly with flow and with smaller pipe. At around 20 L/min, 300 metres of 32mm poly costs roughly 5 to 6 metres of head. The same run in 40mm poly costs under 2 metres. Upsizing the pipe is usually cheaper than buying a bigger pump.
Add the three together. That is the number you read the pump curve at, not the headline "max head" on the box.
Step 3: work out winter daily litres
Winter daily litres from a solar bore pump are roughly the pump's flow at your head multiplied by about 6 hours of useful sun, which is 360 minutes.
So a pump giving 20 L/min at your head moves about 7,200 litres a day in winter, and a lot more in January. Size for June, not January. The tank carries you through cloudy days, because the tank is the battery in a solar pumping system.
Daily demand, as rules of thumb only:
| Use | Litres per day (rule of thumb) |
|---|---|
| Cattle, per head in summer | 50 to 100 |
| Sheep, per head | 5 to 10 |
| Household, per person | About 200 to 300 including garden |
Check stock figures with your local agronomist or vet for your breed and climate. Lactating cows in a hot spell drink a lot more than the low end of that range.
Solar bore pump sizing chart
The sizing chart below matches casing size, total head and winter daily litres to a live solar bore pump kit, using flow figures from each product's spec sheet.
| Casing | Total head | Winter litres a day | Kit that fits | Flow at that head | Price |
|---|---|---|---|---|---|
| 2 inch | 10 to 60m | Up to about 9,000 | Tuhorse 2S370 + 800W panels | 25 L/min at 40m, 18 L/min at 60m | $3,448 |
| 3 inch | Up to about 40m | Small house or a few troughs | Outback Joey 1-60 DC | Up to 18 L/min, 60m max head | $1,992 |
| 3 inch | 20 to 60m | 5,000 to 8,500 | Tuhorse 3S500 + 800W panels | 24 L/min at 40m, 16 L/min at 60m | $3,448 |
| 3 inch | 60 to 100m, cloudy climate | Steady supply with backup | Outback Nomad 1.5-110 AC/DC | Up to 26 L/min, 110m max head | $4,292 |
| 3 inch | 100 to 170m | Deep bore, modest demand | REEFE RS3S2.2-180.SP | Up to 37 L/min, 180m max head | $7,572.85 |
| 4 inch | 40 to 100m | 8,000 to 16,000 | Tuhorse 4S1000 + 1600W panels | 45 L/min at 40m, 30 L/min at 80m, 23 L/min at 100m | $4,993 |
| 4 inch | 10 to 40m | 20,000 plus | Tuhorse 4S1000C + 1600W panels | 80 L/min at 10m, 62 L/min at 40m | $4,993 |
| 4 inch | Up to about 90m | Irrigation, big mobs | REEFE RS4C7.5-101.SP | Up to 125 L/min, 100m max head | $9,458.92 |
Prices current as of November 2026, AUD including GST. Winter litres assume about 6 hours of useful sun. Flow falls towards zero at each pump's maximum head, so do not size a pump to work at its maximum.
A worked example: 60 cattle and a house
A property running 60 cattle plus a house, with water pumping at 45 metres, needs a solar bore pump delivering about 17 L/min at 57 metres of head, which is a 4 inch Tuhorse 4S1000 kit.
Here are the numbers:
- Demand: 60 cattle at 80 litres is 4,800 litres, plus about 1,200 litres for the house. Call it 6,000 litres a day.
- Pumping water level: 45 metres.
- Lift to the tank: 2 metre tank on a 4 metre stand, so 6 metres.
- Friction: 300 metres of 32mm poly at about 20 L/min, roughly 6 metres.
- Total head: 45 + 6 + 6 = 57 metres.
- Flow needed: 6,000 litres over 360 minutes of winter sun is about 17 L/min.
The Tuhorse 3S500 gives 16 L/min at 60 metres. Right on the edge, with nothing spare for a hot week. The Tuhorse 4S1000 with 1600W of panels gives about 40 L/min at 60 metres, which is around 14,000 litres on a winter day. That is the one we would put in, provided the casing is 4 inch.
Stuck with a 3 inch casing? Swap the 32mm poly for 40mm to drop the friction to under 2 metres, and look at the Outback Nomad AC/DC hybrid so a generator or mains can top up in a run of grey days. Or send us the numbers and we will check it properly.
View the Tuhorse 4S1000 + 1600W package →
Panel watts versus pump watts
A solar bore pump needs more panel watts than its motor rating, typically about 1.5 to 1.6 times, because panels rarely produce their full rating and winter sun is weak.
That is why the Tuhorse 4S1000 kit pairs a 1000W pump with 1600W of panels, and the 3S500 pairs a 500W pump with 800W. The 4S1000 with only 800W of panels is $1,095 cheaper at $3,898 and pumps fine at noon in summer. In June it runs far fewer hours. Spend the extra on panels before you spend it on a bigger pump.
Helical rotor or centrifugal
A helical rotor solar bore pump suits deep bores and modest flow, and a centrifugal solar bore pump suits shallow bores and high flow.
Same 1000W motor, same price, very different results. The helical Tuhorse 4S1000 still gives 12 L/min at 120 metres. The centrifugal Tuhorse 4S1000C gives 80 L/min at 10 metres but drops to 15 L/min by 100 metres. Shallow bore and thirsty paddock: centrifugal. Deep bore: helical. That is the whole rule.
Signs a solar bore pump is the wrong size
A solar bore pump that is too small runs all day and never fills the tank, and one that is too big for the bore pumps the bore dry and trips on low water.
Too small is the common one. Usually it is because someone sized on standing water level, or read the flow at 10 metres off a pump working at 70. Too big happens on low yielding bores: the pump outruns the aquifer, the controller trips on dry run, and you get stop start pumping all afternoon. If your bore yield test says 15 L/min, a 60 L/min pump does not get you more water. It gets you more trips.
Already have panels? Buy the pump only
If you already have suitable panels, a pump with controller only is the cheapest way to size up correctly, starting at $1,131.19 for the REEFE RS3S1.7-120, a 3 inch, 500W helical rotor pump rated to 120 metres and 28 L/min.
Match the panel voltage and wattage to the controller, and have a licensed electrician make the connection. For the full shortlist of complete kits, see our best solar bore pumps in Australia guide, and for an honest look at the brand behind most of the kits above, read the Tuhorse solar pumps review. Got mains power at the bore? A 240V pump is often cheaper, and our bore pump sizing guide covers that.
Frequently asked questions
What size solar bore pump do I need for a house?
A house on bore water usually needs a solar bore pump delivering 1,000 to 1,500 litres a day into a header tank, which a 3 inch 500W kit such as the Tuhorse 3S500 with 800W of panels covers at depths up to about 60 metres. Deeper bores, or a house plus stock, usually step up to a 4 inch 1000W kit.
How many solar panels do I need for a bore pump?
A solar bore pump needs about 1.5 to 1.6 times its motor wattage in panels, so a 500W pump wants about 800W of panels and a 1000W pump about 1600W. Extra panel capacity mainly buys more pumping hours in winter.
How do I work out the head for a solar bore pump?
Total head for a solar bore pump is the pumping water level plus the height from the bore head to the top of the tank plus pipe friction, in metres. For example, water pumping at 45 metres, a tank top 6 metres above the bore head and 6 metres of friction is 57 metres of total head.
What size solar pump do I need for cattle in Australia?
For cattle in Australia, size a solar pump for about 50 to 100 litres per head per day in summer, delivered in about 6 hours of winter sun. Sixty cattle at 80 litres need around 4,800 litres a day, roughly 13 L/min at your total head before adding any household use.
Can a solar bore pump be too big for my bore?
A solar bore pump can be too big if it pumps faster than the bore can recharge, which draws the water down, triggers the dry run protection and causes stop start pumping. Match the pump's flow to the yield on your bore test, not to the biggest kit you can afford.
Send us your numbers and we will size it
Send us your casing size, standing and pumping water level, tank height, distance from bore to tank, pipe size and how many litres a day you need. We will match the pump and the panel array, and tell you plainly if a kit will not do the job.
This guide is general information for Australian property owners and is not a substitute for advice on your specific bore and site. Electrical work must be done by a licensed electrician, and bore work by a licensed driller where your state requires it. Stock water figures are rules of thumb only. Confirm final sizing with us before you buy.