If you still buy a lot of electricity during daylight hours, more solar may be the first thing to investigate. If you already export plenty of solar and then buy expensive electricity later, a battery may be the better comparison. Some customers need both—and some need neither.
Start by finding the energy gap
The answer comes from understanding when your existing solar is falling short. Are you still buying power while the sun is up, or are you exporting during the day and buying it back later?
When more solar may come first
- Your existing system is relatively small
- You still import significant electricity during daylight hours
- Your household or business energy use has grown
- You are adding an EV, heat pump, air conditioning or machinery
- You have suitable roof space and network capacity
When a battery may come first
- You already have useful surplus solar
- You export during the day at relatively low value
- You buy meaningful grid power later
- Peak electricity is expensive
- Backup has real value to you
When both may be worth comparing
If your solar system is too small to cover current daytime use and also charge the battery you want, a combined solar expansion and battery option may be more logical than storage alone.
Why I do not start with battery size
A battery capacity should come from available charging energy and later demand. Choosing 20 kWh, 30 kWh or more before looking at the load profile can create an expensive system that is not used effectively.
Two simple examples
Home A: 6.6 kW solar, high daytime imports because of an EV and pool, small exports. I would investigate more solar before assuming a large battery.
Home B: 10 kW solar, strong midday exports, high evening imports. A battery is worth modelling against the current system.
The best answer may be no change
If the existing solar system already performs well and the extra investment produces weak savings, leaving the system alone can be the right recommendation. The goal is not to add equipment; it is to improve the customer's result.
Solar and battery performance and savings are estimates that depend on the individual site, electricity use, tariffs, equipment, installation and assumptions used. Current incentives and network requirements should be checked for the specific project before a proposal is finalised.
Want to look at your actual situation?
You do not need to know the system size first. Start with your electricity use, existing system and what you want to achieve.