Running your Perth pool on solar: pumps, heating, and timing

A standard 0.75kW pool pump running 8 hours per day costs approximately $730/year at Synergy's A1 tariff (33.26c/kWh). The same pump, timed to run entirely during solar generation hours (9am–4pm), can reduce that electricity cost to near zero for an owner-occupier with solar — or to ~$64/year at Midday Saver's super off-peak rate if you import from the grid during that window.

How pool electricity breaks down

A typical Perth home with a pool uses electricity for:

Pool pump (filtration):

• Variable speed pump (VS): 0.2–0.5kW typically
• Fixed speed pump: 0.55–1.1kW typically
• Running 6–10 hours/day in summer, 3–5 hours in winter

Pool heating (if applicable):

• Gas heater: no electricity (apart from controls)
• Heat pump: 1.5–4kW (significant load)
• Solar thermal: near zero electricity (small circulation pump only)

Pool lights:

• LED: 12–50W (minimal)

The pump is by far the dominant electrical load.

The pool pump timing strategy

A timer on your pool pump is the single most impactful pool-related energy decision. Timing the pump to run during solar generation hours means your solar system — which is generating during the day — offsets the pump's electricity consumption directly.

Optimal window with solar:

• 9:30am to 4:00pm — this covers Perth's solar peak generation window
• A variable-speed pump running at 50% speed can often run 8–10 hours within this window and still complete the required daily filtration volume
• Running within Midday Saver super off-peak (9am–3pm) also means any grid-imported pool electricity costs only 8.85c/kWh instead of up to 55.33c/kWh peak

What filtration time does a Perth pool need? The general rule is to turn over the pool's water volume once per day. For a 45,000L pool and a 150L/minute pump, that's 5 hours of filtration. In summer, you may want 6–8 hours; in winter, 3–4 hours is typically sufficient. A variable-speed pump at reduced speed can achieve the same daily filtration volume over a longer window at lower power draw.

Variable speed pumps: the upgrade that pays for itself

Older single-speed pool pumps run at full power or off — no middle setting. A variable speed (VS) pump can run at 30–60% speed for the filtration cycle (consuming 0.2–0.4kW instead of 0.75–1.1kW) and ramp up briefly for backwashing or features.

Cost comparison (per year, 8 hours/day, summer season):

| Setup | Daily kWh | Annual energy (summer 6mo) | Cost at A1 | |---|---|---|---| | Fixed 1.0kW, peak hours | 8 kWh | 1,460 kWh | $486 | | Fixed 1.0kW, solar hours | 8 kWh | 1,460 kWh | ~$0 (solar) | | VS 0.35kW, solar hours | 2.8 kWh | 511 kWh | ~$0 (solar) |

The VS pump on solar hours uses 65% less electricity than a fixed pump on solar hours — but either way the cost is near zero if you're on solar. The VS pump's value is that it draws less during the hours solar can't fully cover (winter, cloudy days).

VS pump cost: typically $1,200–$2,000 installed in Perth. Payback on electricity savings alone: 2–4 years. With solar timing, the payback is on total consumption reduction if the pump ever runs during non-solar hours.

Pool heat pumps and solar

A pool heat pump (1.5–4kW) is a significant electrical load. Running one on solar requires planning:

Best approach with solar: Set the heat pump timer to run 10am–2pm — the peak solar generation window. A 3kW heat pump running 3 hours uses 9kWh, which a 6.6kW+ solar system can produce during peak generation hours on a sunny day.

Midday Saver super off-peak as backup: On cloudy days or in winter when solar doesn't fully cover heat pump demand, Midday Saver's 8.85c/kWh super off-peak (9am–3pm) means the worst-case cost for grid-imported heat pump electricity is 8.85c/kWh × 9kWh = 79c/day — still cheap compared to running at peak (55.33c × 9kWh = $4.98/day).

Pool and battery: does it make sense?

Using battery storage to power a pool pump is rarely the most efficient use of battery capacity. The pump is best run during the day (solar hours), not at night (when battery would be needed). If you have a battery, the priority should be offsetting evening household load (lights, cooking, entertainment) at peak rates, not storing solar to run a daytime pump.

The exception: if your pool has features that run in the evening (waterfall, lights, spa jets), those make more sense to power from battery storage.

Steps to optimise your pool's electricity cost with solar

1. Install a timer (if you don't have one): a basic 24-hour timer costs $40–80 and allows scheduling pump operation within solar generation hours
2. Set the timer to 9:30am–4:00pm (or 9am–3pm for Midday Saver super off-peak guarantee)
3. Reduce winter filtration time: 3–4 hours/day is sufficient for most Perth pools in June–August
4. Consider a VS pump upgrade at your next pump replacement: VS pumps significantly reduce draw during non-solar hours
5. Check your current pump speed: many VS pumps are installed at 100% speed by default — ask your pool technician to set it to 50–70% for filtration cycles

Pool pump electricity savings depend on pump age, speed, daily run time, and whether you're on a flat or time-of-use tariff. Check your Synergy bill for your current tariff type.