How Many Solar Panels Does It Take to Run a Pool Pump?
A variable-speed pump needs about two panels; an old single-speed pump needs about six. Here are the sums, the datasheet that backs the cube law, and what happens when the sun is not out.
The short answer
A variable-speed pool pump needs very little: on our assumptions it uses about 2.6kWh a day through a May to September season, which about two 400W panels generate on an average day. An old single-speed pump drawing around 1.1kW for eight hours uses about 8.8kWh a day, which takes roughly six panels to match. The bigger lesson is in the table: swapping the pump moves the answer by a factor of three or more, so the question to ask first is which pump you are powering.
| Pump set-up | Energy per day | Per May–Sept season | Cost at 26.32p | Array to match on paper | 400W panels | Note |
|---|---|---|---|---|---|---|
| Single-speed pump, about 1.1kW, 8 hours a day | 8.8 kWh | 1346 kWh | £354 | 2.4 kWp | 6 | Our worked-example assumption; one European datasheet gives 0.99kW at full speed. |
| Variable-speed pump, worked-example assumption (70% saving) | 2.6 kWh | 400 kWh | £105 | 0.7 kWp | 2 | Inside the 50–90% range US research reports. |
| Variable-speed pump at 1,000rpm, same water moved (datasheet) | 1.6 kWh | 242 kWh | £64 | 0.4 kWp | 1 | Runs about 23 hours a day at 0.07kW; flow is roughly 35% of full speed. |
How the sum works
Start with the pump's power in kilowatts and the hours it runs, and multiply to get kilowatt-hours a day. Then divide by what a kilowatt of panels produces on an average day in the swimming season. PVGIS, the European Commission's solar-yield tool, gives about 981kWh per kWp a year for a south-facing 35° array near Leicester, and 56–58% of the year's output arrives between May and September across the UK locations we checked, which is about 560kWh per kWp over 153 days, or 3.7kWh per kWp per day. For a 400W panel that is about 1.5kWh a day on an average swimming-season day, a little more in June and a little less in September. Leeds gives about 3.5kWh per kWp per day and Exeter about 3.8.
Why the pump type matters more than the panels
Pump power falls with the cube of the speed, which is a standard affinity law for centrifugal pumps. A real datasheet shows it: Speck's BADU SuperPro Eco Touch-Pro II is rated at 0.99kW input at 2,830rpm and 0.07kW at 1,000rpm. At 1,000rpm the pump moves roughly a third as much water per hour, so it must run about 2.8 times as long to move the same volume, and 2.8 hours at 0.07kW is about a fifth of the energy of one hour at 0.99kW. US research reports variable-speed savings of 50% to 90% depending on how the pump is set, and the ENERGY STAR page for pool pumps is more modest about certified models, so treat anything above 70% as a best case and check your own pump's datasheet. The worked running-cost example on this site assumes 70%, which is cautious against the datasheet. If you are choosing between spending on a variable-speed pump and spending on panels to feed an old one, the pump wins on cost every time; the covers and efficiency page puts the pump in its place in the efficiency order.
Running the pump directly from the panels, or through the grid
Almost every UK installation is grid-connected: the pump runs from the house supply and the panels offset it. You do not need the array to match the pump at every moment. A variable-speed pump running slowly for most of the day will draw power at night as well as in the daytime, and the daytime share is covered by the panels while the night-time share comes from the grid at the electricity price cap of 26.32p per kWh (Ofgem, October to December 2026, GB average). At 0.07kW the night-time share of a slow-running pump is small money: eleven hours is under a kilowatt-hour, about 20p. If you want the pump itself to run only on sunshine, set its schedule to daytime and let it run faster for fewer hours, which gives up some of the cube-law saving.
What about a dedicated solar pool pump kit?
Direct-current solar pool pumps that run straight from panels without the grid exist. An Australian supplier lists 200W and 500W DC pumps with panels and frames, and a Spanish supplier lists kits for pools of 65,000 to 75,000 litres with five 480W panels and a 1.5CV pump at about €1,763. We did not find a UK retailer with a clear price for a pool-pump-sized kit, and both overseas suppliers say the pumps should be connected by a qualified electrician. For most UK pools a normal variable-speed pump on a grid-connected array, or on the house supply with panels on the house roof, is simpler and covers evenings and dull days.
The heat pump is the bigger load
If you are sizing panels for a pool and the pump is the whole story, the sum above is all you need. If the pool also has a heat pump, that is usually the larger load: in our 8×4m worked example the heat pump takes 1,320–1,650kWh a season against about 400kWh for the variable-speed pump. Size the array for both, and put the controls so that the heating window sits in daylight: the heat pump and PV page explains the sizing and the controls, and the worked example prices the whole sequence. Pricing for the panels themselves, at the DESNZ median of £1,595 per kW for small installs, is on the costs page.
Sources and how the numbers were built
- European Commission JRC, PVGIS v5.3 (SARAH3, 35° tilt, due south, 14% losses), queried 20 October 2026: Leicester 981, Leeds 947, Exeter 1,052 kWh/kWp/year; May–September 56–58% of the year.
- Speck, BADU SuperPro Eco Touch-Pro II installation manual (04/2025), poolsana.de: 0.99kW input at 2,830rpm; 0.07kW at 1,000rpm; 230V 50Hz.
- Pacific Northwest National Laboratory / US DOE Building America, Variable-speed pool pumps (updated 16 July 2018): 50–90% savings depending on settings. ENERGY STAR, pool pumps: certified pumps use about 20% less energy than standard.
- Ofgem, price cap 1 October to 31 December 2026 (published 26 August 2026): electricity 26.32p/kWh, no VAT.
- Overseas solar pump kits: Solazone (Australia); Suministros del Sol (Spain). Neither is a UK price.
- Our assumptions: a 1.1kW single-speed pump for 8 hours a day over a 153-day season; variable-speed pump energy about 400kWh a season (70% saving); a 400W panel.
Questions people ask
How many solar panels do I need to run a pool pump?
For a variable-speed pump set to run slowly, about two 400W panels match its average energy use in the swimming season on our assumptions; an old 1.1kW single-speed pump running eight hours a day needs about six. These are on-paper matches that ignore timing; on a grid-connected system the grid covers any gap.
Can I run a pool pump straight off solar panels without the grid?
You can with a dedicated DC solar pump kit, but we found no UK retailer with a clear price for a pool-sized kit, and installation should be by a qualified electrician. Most UK pools use a normal pump on the house supply with panels on the roof.
Is a variable-speed pool pump worth it?
Usually yes. The same datasheet pump uses about a fifth of the energy when run slowly for longer, and US research reports savings of 50% to 90% depending on settings. On our worked example the saving is about £250 a season for a £600–£900 fitted planning cost.
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