Working from home and solar savings in Perth: what changes when you're home all day

When you work from an office, your home consumes very little electricity between 9am and 5pm — lighting, fridge, and standby loads only. Solar panels generate most of their energy during exactly that window. The energy pours into the grid at the Synergy DEBS rate of 10 cents/kWh, rather than offsetting your own use at 33.26c/kWh (A1 rate as of July 2026).

Working from home changes this equation significantly.

Why WFH shifts the solar maths

Self-consumption is what makes solar pay. Every kilowatt-hour your household uses during the day avoids buying from the grid at 33.26c/kWh. Every kilowatt-hour you export earns only 10c/kWh. The difference — 23.26 cents — is the per-kWh premium of self-consuming vs exporting.

For a household where only one person works from home full-time, typical daytime consumption on a workday increases by around 3–6 kWh compared to a fully-absent household. For two people working from home, the increase is larger.

Rough numbers for a WFH day (Mon–Fri):

• Dual screens + laptop: 0.1–0.2 kWh per 8-hour work session
• Monitor + desktop workstation: 0.3–0.5 kWh per 8-hour session
• Home office lights (LED): 0.02–0.05 kWh per hour (8-hour day = 0.16–0.4 kWh)
• One extra kettle boil + lunch preparation: 0.5–1.0 kWh
• Air conditioning for home office comfort (Perth summer): 1.5–3.5 kWh per session

Total additional WFH consumption (daytime, workday): 2–5 kWh per person per day, of which the air conditioning is the dominant variable.

Estimated savings for a WFH household in Perth

| Household profile | Additional WFH daytime load | Solar self-consumed that was previously exported | Annual additional saving | |---|---|---|---| | 1 person WFH, moderate AC use | ~3 kWh/day × 250 work days | ~750 kWh/yr | ~$174/yr | | 1 person WFH, heavy AC use (Perth summer) | ~5 kWh/day × 250 work days | ~1,250 kWh/yr | ~$291/yr | | 2 people WFH, moderate AC | ~6 kWh/day × 250 work days | ~1,500 kWh/yr | ~$349/yr | | 2 people WFH, heavy AC | ~10 kWh/day × 250 work days | ~2,500 kWh/yr | ~$581/yr |

Saving calculated as: additional self-consumed kWh × (33.26c import rate - 10c DEBS rate) = additional kWh × 23.26c/kWh. Assumes solar covers the WFH load during working hours.

These are additional savings on top of what the solar system was already saving. A household that previously had 35% self-consumption may see self-consumption rise to 55–70% with full-time WFH — a meaningful difference in payback period and annual savings.

Perth air conditioning is the big variable

Perth's summers are hot. A home office without cooling is uncomfortable from October through April. The air conditioning choice for a WFH home office determines whether solar is a good match.

Reverse-cycle split system for home office:

• A 2.5kW split system draws 0.6–0.9kW running
• On a hot Perth summer day (38°C+), it may need to run continuously from 9am–5pm: 5–7 kWh/day
• A 6.6kW solar system generates 26–32 kWh on a summer day — more than enough to cover this load

Pre-cooling strategy on Midday Saver: If you're on the Synergy Midday Saver tariff (off-peak 24.34c/kWh in shoulder, super-off-peak 8.85c/kWh 10am–3pm), pre-cooling the home office between 10am–2pm uses the cheapest solar or grid power, then the space stays comfortable through the work afternoon.

Does WFH affect solar sizing decisions?

If you're pre-solar: A WFH household should size their solar system larger than a household where everyone is away during the day. The conventional rule of thumb for away-all-day households was "size to roughly 1 kW per person." For WFH households, sizing 30–50% larger captures the additional daytime load without oversizing to the point of generating large amounts of export.

Example: A 2-person away-all-day household might size at 6.6kW. The same household fully WFH could justify 8–10kW — the additional panels pay for themselves faster because the output is consumed rather than exported at 10c.

Battery storage for WFH: WFH households that consume heavily in the day typically have lower battery payback than evening-peak households — they're already self-consuming solar during the day. A battery is most valuable for the evening peak. WFH doesn't particularly increase the case for a battery unless evening peak loads are high.

What changes on the Midday Saver tariff with WFH

Midday Saver has three pricing periods:

• Super-off-peak (10am–3pm): 8.85c/kWh — cheapest grid electricity in Perth
• Off-peak (3pm–9pm and shoulder hours): 24.34c/kWh
• Peak: 55.33c/kWh

For a WFH household with solar:

• Between 10am–3pm, solar covers most or all of the WFH load at zero cost
• On overcast days, Midday Saver's 8.85c rate means you're drawing from the grid at 8.85c rather than 33.26c — a significant backup buffer
• The 55.33c peak applies mainly in the evening, which solar (without battery) doesn't cover

WFH + solar + Midday Saver is typically the most favourable combination for Perth households.

Checking your WFH impact with your actual data

If you have solar monitoring already, pull your Synergy Smart Meter half-hourly data (download via Synergy's online portal) and compare consumption patterns on WFH days vs office days. The difference in daytime consumption is visible in the half-hourly intervals — look for higher consumption blocks between 9am and 4pm on WFH days.

This actual consumption data is also what BillWise uses to model your solar scenario — if you upload a bill with recent consumption, the analysis reflects your actual usage pattern rather than generic estimates.

WFH households in Perth typically see 20–40% higher solar self-consumption than fully-absent households, translating to meaningfully better payback. Air conditioning for the home office is the largest variable. If you're pre-solar and WFH full-time, size your system 30–50% larger than the conventional away-all-day estimate to reflect actual daytime load.