Analysis
Solar with battery vs solar without
An honest look at what a battery adds — and when it might not be worth it. What it means for your home depends on your usage pattern, and costs are confirmed on your written quote.
A battery lets you use more of your own solar electricity and can store cheaper overnight electricity. It also adds to the system cost, which is confirmed on your written quote. Whether it’s worth it depends on how you use electricity.
| Metric | With battery | Without battery |
|---|---|---|
| Self-consumption | Higher — more of your own solar used at home | Lower — more surplus sent to the grid |
| Evening solar use | Yes — stored from daytime | None — exported to grid |
| Overnight cheap tariff | Yes — charge on a cheaper off-peak rate | No — pay the standard rate |
| Cost | Priced at survey | Priced at survey |
| Grid independence | Partial — reduced import | Low — still importing evenings |
| SEG export income | Lower (you use more yourself) | Higher (more surplus exported) |
How a battery changes the picture
Without a battery, a typical household uses part of its solar generation directly during the day and exports the rest to the grid, where it may earn SEG export income.
With a battery, more of that daytime generation is stored and used in the evening instead of importing from the grid. You export less, so SEG income is usually lower, but you rely less on grid electricity.
A battery adds to the upfront cost. A time-of-use tariff, charging overnight and using that stored electricity at peak times, can make it more worthwhile. Costs are confirmed on your written quote after a survey.
The seasonal argument: Perth daylight
Perth sits at 56°N. In summer (May–Jul) you get an average of 16.8 hours of daylight per day — a 4kWp system can generate far more than most households use during the day. That surplus is where the battery earns its keep: it stores what would otherwise be exported at a low SEG rate.
In winter (Nov–Jan), daylight drops to 7.2 hours on average. Generation falls sharply. A battery still helps by storing cheap overnight electricity (on a time-of-use tariff) to offset peak-rate imports during the evening.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7h 13m | 9h 13m | 11h 26m | 13h 55m | 16h 06m | 17h 23m | 16h 51m | 14h 53m | 12h 26m | 10h 02m | 7h 48m | 6h 36m |
When a battery makes sense
You are out during the day and use most electricity in the evening. Your energy supplier offers a time-of-use tariff with cheap overnight rates. You want to reduce grid dependence as far as a domestic system allows.
When it might not
You work from home and use electricity during the day when panels are generating. You are on a flat-rate tariff with no overnight discount. You want to keep the upfront cost as low as possible and are comfortable exporting surplus to the grid at the SEG rate.
Off-peak and export: unlocked with a battery
A battery unlocks two revenue streams that solar-only cannot access. First, overnight charging on a cheaper off-peak tariff lets you offset peak-rate imports. Second, some tariffs pay more for exports during peak hours — a battery lets you time your exports. Neither is available without storage.
Answers
Battery questions
Ready to see what solar could do for your Perth home?
Tell us about your property and we will arrange a survey and a written quote. We install through MCS-certified partners.