Solar for Perth FIFO households: sizing for two-week on/off cycles

Perth has one of Australia's largest FIFO (fly-in fly-out) workforces, with a significant portion of the population working rotations to WA's remote mining and resources regions. If your household includes a FIFO worker, your electricity usage pattern differs significantly from a standard residential household — and this affects solar sizing and tariff selection.

The FIFO electricity pattern

A standard FIFO rotation is two weeks away, two weeks home — but variations are common (4:1, 3:1, 8:6). For solar and tariff planning purposes, the key is the occupancy swing:

• Roster home (2 weeks): Full household — the FIFO worker is home, all appliances and living spaces are in use, usage may be highest
• Roster away (2 weeks): Reduced household — typically a partner and children (if any) remain, or the home may be near-empty for single workers without family

Typical consumption swing: In a FIFO household with one away partner:

• Roster home: 25–40 kWh/day (summer, with air conditioning)
• Roster away: 15–25 kWh/day

For single FIFO workers without family:

• Roster home: 10–20 kWh/day
• Roster away: 0.5–3 kWh/day (base load only — refrigerator, hot water on timer, standby appliances)

How the swing affects solar sizing

Standard solar sizing uses average annual consumption divided by 365 to estimate daily consumption, then multiplies by 0.7–0.8 as a self-consumption ratio target. For FIFO households, the oscillation between high and low periods means:

During the roster-away (low occupancy) period: If the household is at minimal occupancy, solar generation significantly exceeds consumption. Most generation exports to the grid at DEBS rates (10c super off-peak, 2c otherwise). Export is valuable but less so than self-consumption.

During the roster-home (high occupancy) period: Higher consumption means better self-consumption of solar generation. The high-occupancy weeks benefit more from the solar system.

Implication for sizing: For FIFO households with a near-empty away period, a very large system (13kW+) will generate significant surplus during the empty weeks that mostly exports at 10c — good, but not as valuable as self-consumed savings at 33c. A mid-size system (6.6–10kW) may have a higher self-consumption ratio on average, making it a better economic fit per kilowatt installed.

Exception: If battery storage is included, the away-period surplus can be stored for the sparse evening draw of the stay-at-home occupant, improving the economics.

Tariff considerations for FIFO households

Midday Saver suitability: Midday Saver's 3pm–9pm peak rate (53.58c/kWh) is punishing for households with high evening loads. In a FIFO roster-home period, evening loads are high (family cooking, entertainment, air conditioning). During the roster-away period, evening loads may be much lower.

For a FIFO household:

• With family remaining during away period: Midday Saver may still be attractive if the family can time loads and has battery storage to avoid the 3pm–9pm peak
• Solo FIFO worker (home is empty during away period): Midday Saver can be extremely advantageous — during the empty away period, evening consumption is near zero (the high peak rate barely applies), and during the home period, you can consciously avoid the peak window
• A1 tariff is safer for FIFO households who can't confidently avoid the 3pm–9pm window during roster-home periods

Hot water system strategy for FIFO households

A near-empty home during roster-away periods still consumes hot water for showers and any household members remaining. This has two implications:

1. Heat pump hot water for FIFO: A heat pump set to heat during Midday Saver super off-peak hours (9am–3pm, 8.8511c/kWh) or during solar generation hours is very efficient during roster-away periods when the hot water demand is lower — the tank stays warm with minimal reheating.

2. Electric resistance hot water on a timer: If you have an electric resistance hot water system, set it to heat during solar hours rather than overnight. During the roster-away period, the reduced demand means the tank may stay warm for 24+ hours — the resistance element barely activates.

Pool pump and FIFO households

Many Perth properties have a pool pump — often the largest continuous electrical load after air conditioning. During the FIFO roster-away period when the pool isn't being actively used:

• Reduce pump run time during the away period (minimum required for sanitation is typically 4–6 hours/day in winter, 8+ hours/day in summer, but less than the default timer setting for many households)
• Ensure the timer is set to run during solar generation hours (9am–3pm) regardless of occupancy
• A pool pump drawing 0.8–1.2kW running from solar costs nothing; running from grid at peak rate costs $0.43–$0.64/hour

Battery storage for FIFO households

A battery is particularly useful for FIFO households with family remaining during the away period:

• The family benefits from stored solar during evenings without the FIFO worker's higher consumption patterns
• The battery provides resilience during outages — a concern for a household where one partner is away and managing alone

Battery sizing for a FIFO roster-away period typically requires 5–10kWh to cover an evening of modest consumption (lighting, one split system, TV, cooking). A 10kWh battery in a near-empty home during the roster-away period may only cycle to 30–50% capacity daily — low cycling extends battery life.

Smart home automation for remote management

Perth FIFO workers often value smart home automation to manage energy during their away periods:

• Smart plugs/powerpoints: Turn off non-essential standby loads remotely
• Smart thermostats: Adjust cooling setpoints for unoccupied home vs occupied home periods
• Inverter monitoring apps: Check solar generation and export remotely to confirm the system is working correctly
• Pool pump smart timers: Adjust run time remotely based on weather and season

These don't require a smart home system — a handful of individual smart devices can manage the key energy loads from Perth or a remote site.

Perth FIFO households benefit from solar but should size based on the roster-home consumption period (not the average of both), recognise that the roster-away period will export more than self-consume, and consider whether Midday Saver's 3pm–9pm peak rate is manageable in the roster-home period before switching from A1.