Water is the farm load that most often sits where there is no electricity: a trough at the far end of the grazing, a borehole in a field, an irrigation reservoir away from the yard. A solar water pump puts the generation next to the pump, and because grazing and irrigation peak in summer, the demand and the sunshine arrive together. This guide works through the sizing — water first, then energy, then panels and storage — with sourced figures, and sets out the licensing, planning and grant rules.
SolarPanelsForFarms.uk is an independent guide, not an installer or a pump supplier. Checked 6 October 2026.
Step 1: how much water
Start from the animals or the crop, and size for the hot-weather peak, not the average.
| Animal | Average drinking water (litres per day) |
|---|---|
| Dairy cow, milking | 115 |
| Dairy cow, dry | 41 |
| Beef cow with calf | 55 |
| Beef cow, dry / bull | 38 |
| Finishing cattle | 41 |
| Ewe, lactating | 10 |
| Ewe, gestating | 5.25 |
| Lamb (feeder) | 4.4 |
| Sow, lactating | 20 |
| Finishing pig | 9 |
| Horse, medium frame | 32.5 |
| Laying hens | 250 per 1,000 birds |
| Broilers | 280 per 1,000 birds (450 in summer) |
Ontario Ministry of Agriculture, Food and Agribusiness, "Water requirements of livestock" (updated 6 May 2026). Above 30°C, poultry consumption can rise 50% above normal.
Averages hide peaks. Water engineers quoted by Farmers Weekly put the total water need per cow at up to 170 litres a day on a hot summer's day, and note that the milking parlour can use around 70 litres per cow a day. They size troughs at half the one-hour demand — for a 400-cow herd, 5,600 litres an hour, so 2,800 litres of trough capacity in each paddock.
Step 2: the energy sum
Lifting water takes a fixed amount of energy: 1,000 litres raised 1 metre needs 9.81 kJ (about 0.0027 kWh). The pump loses some of its electrical input as heat and friction, so divide by the pump set's "wire-to-water" efficiency from its data sheet. The height to use is the total head: the depth to the water while pumping, plus the rise to the tank, plus pipe friction.
Worked example — a suckler herd at grass
- 100 beef cows with calves × 55 litres = 5.5 m³ a day
- Total head assumed: 25 m (borehole drawdown plus rise to a header tank)
- Lift energy: 9.81 × 5.5 × 25 = 1,349 kJ = 0.37 kWh
- Pump set assumed to convert 40% of electrical input into lift: 0.37 ÷ 0.40 = 0.94 kWh a day of panel output
The head and efficiency are assumptions for the example — use your own borehole log and the pump's curve.
Step 3: how many panels
PVGIS gives the average daily output a 500 W array would produce near Hereford, month by month:
| Month | kWh per day from 500 W | Covers 0.94 kWh? |
|---|---|---|
| Jan | 0.55 | No |
| Feb | 0.91 | No |
| Mar | 1.38 | Yes, on an average day |
| Apr | 1.87 | Yes, on an average day |
| May | 2.02 | Yes, on an average day |
| Jun | 2.07 | Yes, on an average day |
| Jul | 1.99 | Yes, on an average day |
| Aug | 1.76 | Yes, on an average day |
| Sep | 1.54 | Yes, on an average day |
| Oct | 1 | Yes, on an average day |
| Nov | 0.66 | No |
| Dec | 0.49 | No |
PVGIS v5.3, Hereford (52.06°N), south-facing at 30°, 14% losses, queried 6 October 2026.
So 500 W runs this herd's water from March to October on an average day, which covers a grazing season. Dull spells are the problem an average hides, and that is what storage is for. If the stock are housed in winter on a mains supply, there is no need to size the array for December.
Step 4: store water, not electricity
The simplest solar pump runs only while the sun shines and fills a header tank that feeds the troughs by gravity. Three days of storage for the herd above is 16.5 m³. A tank also means the trough refill rate is set by the pipe from the tank, not by the pump. A battery earns its place when water must be pumped at night, at a fixed pressure, or when there is no high ground for a tank. Our farm battery storage guide covers sizing a battery from meter data.
Boreholes
Submersible solar pumps are made for boreholes, and the borehole's own figures drive the size: the pumping water level (not the resting level), the yield it can sustain, and the rise to the tank. In England, if you will need an abstraction licence you must check whether you need consent to investigate a groundwater source first — it covers constructing a well or borehole, extending one, or installing machinery that abstracts additional groundwater (gov.uk). Ask the driller for a pump test before the solar array is sized.
Irrigation
Irrigation moves far more water. Putting 25 mm on one hectare takes 250 m³. Lifted and pressurised through an assumed 40 m of total head by a pump set assumed to be 50% efficient, that is 9.81 × 250 × 40 = 98,100 kJ = 27.3 kWh of lift, or about 54.5 kWh of panel output. Near Norwich a south-facing array at 30° averages about 4.06 kWh per kW per day in July (PVGIS), so delivering that in one day takes around 13.4 kW of panels — a farm-roof or reservoir-scale system, not a pump kit. On a farm with a grid supply, a roof array can run the irrigation pumps in summer and the rest of the farm all year. Where the reservoir is the obvious place for the panels, see floating solar on farm reservoirs. The evidence on whether panels cut reservoir evaporation is summarised in does floating solar reduce evaporation?
Abstraction licences
The licence depends on how much water you take, not on what powers the pump:
- England: above 20 m³ a day you are likely to need an Environment Agency licence; the exemption applies to the combined total if you abstract from the same source at several points.
- Wales: up to 20 m³ a day per source of supply is exempt; above that, a licence from Natural Resources Wales.
- Scotland: under EASR (from November 2025), up to 10 m³ a day follows general binding rules, 10 to 50 needs a one-off registration with SEPA, and above 50 needs a permit.
The suckler herd above (5.5 m³ a day) sits under all three thresholds; the irrigation example (250 m³ a day) is over all of them.
Planning
A small array beside a farm building can be permitted development under Class K of Part 14 of the General Permitted Development Order 2015: one stand-alone array within the building's curtilage, up to 9 m² of panels, no dimension over 3 m, no more than 4 m high, at least 5 m from the curtilage boundary, and not in the curtilage of a listed building. Panels on the building itself fall under Class J. An array out in a field is not within a building's curtilage, so ask the planning authority before installing it.
Grants and tax
- Wales: the Capital Production and Efficiency scheme (open 28 July 2026 to March 2027, 40% of costs, £500 to £15,000) lists a solar-powered livestock water pump and a solar-powered fencing energiser.
- Scotland: the Future Farming Investment Scheme 2025 round excluded solar panels and batteries but accepted solar-powered equipment such as a submersible water pump. The next round is due in winter 2026; its item list is not yet published.
- England: no grant for farm solar is open; the FETF 2026 window closed at midday on 12 May 2026. See the current farm solar grant position.
- Tax: pumps and panels are plant, and most farm businesses can deduct the cost in year one through the £1 million Annual Investment Allowance — see how capital allowances work for farm solar.
What to ask for in a quote
- ✓ The daily volume and total head the system is designed for, and the pump curve showing it delivers both
- ✓ The array size and the month-by-month output it is based on
- ✓ Tank size and how many days' storage it gives
- ✓ Frost protection for exposed pipework and troughs
- ✓ Theft and livestock protection for the panels — a fenced, secure mount
- ✓ Abstraction licence status for the volume involved
Solar water pumps — frequently asked questions
How big a solar panel do I need for a livestock water pump?
Work out the daily water volume and the height it has to be lifted, then the energy: 1,000 litres lifted 1 metre takes 9.81 kJ, about 0.0027 kWh, before pump losses. For 100 suckler cows with calves (about 55 litres a head a day) lifted 25 metres by a pump set that converts 40% of its electrical input into lift, that is about 0.94 kWh a day — which 500 watts of panels near Hereford covers on an average day from March to October, according to PVGIS.
Is a battery or a water tank better for a solar water pump?
For livestock watering, a header tank is usually the simpler store: the pump runs while the sun shines and the tank feeds the troughs by gravity. Three days of storage for 100 suckler cows with calves is about 16.5 cubic metres. A battery makes sense when the pump has to run at night or to a fixed pressure.
Can a solar pump work from a borehole?
Yes — submersible solar pumps are made for boreholes. Size it on the depth to the water level when the pump is running (not the resting level) plus the rise to the tank. In England, if you will need an abstraction licence you must check whether you first need consent to investigate the groundwater source, and that consent covers constructing a borehole.
Do I need an abstraction licence for a solar water pump?
It depends on the volume, not the power source. In England you are likely to need an Environment Agency licence above 20 cubic metres a day; in Wales the exemption is 20 cubic metres a day per source of supply (Natural Resources Wales). In Scotland, under EASR since November 2025, up to 10 cubic metres a day follows general binding rules, 10 to 50 needs a registration with SEPA, and above 50 needs a permit.
Is there a grant for a solar water pump?
In Wales, the Capital Production and Efficiency scheme (open 28 July 2026 to March 2027, 40% of costs, £500 to £15,000) lists a solar-powered livestock water pump. In Scotland, the Future Farming Investment Scheme 2025 round accepted solar-powered equipment such as a submersible water pump; the next round is due in winter 2026 with its item list not yet published. In England the FETF 2026 window closed on 12 May 2026.
Do I need planning permission for a solar pump array?
A small array beside a farm building can be permitted development under Class K: one stand-alone array within the building's curtilage, up to 9 square metres of panels, no dimension over 3 metres, no more than 4 metres high and at least 5 metres from the curtilage boundary. An array out in a field is not within a building's curtilage, so ask the planning authority before installing it.
Sources
- Ontario Ministry of Agriculture, Food and Agribusiness, "Water requirements of livestock" (updated 6 May 2026).
- Farmers Weekly, "Guide to planning water requirements on your dairy farm" (updated 19 January 2021; figures from Penstar water engineers).
- European Commission JRC, PVGIS v5.3 (queried 6 October 2026): Hereford and Norwich, 1 kWp, south-facing, 30°, 14% losses.
- gov.uk, "Check if you need a licence to abstract water" (updated 2 July 2026); Natural Resources Wales, "Find out if you need a water abstraction or impoundment licence"; SEPA, EASR abstraction guidance; Farm Advisory Service, "EASR explained" (9 February 2026).
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 14, Class K (legislation.gov.uk).
- Welsh Government Capital Production and Efficiency scheme; Scottish Government Future Farming Investment Scheme 2025; Defra FETF 2026 (as cited on our grants page).