Where each kilowatt-hour goes
In a well-configured paired system the priority order is usually: serve the house, then charge the battery, then export the remainder.
That order flips under a time-of-use tariff. In the expensive evening window the system discharges the battery to the house instead of drawing from the grid, and it may deliberately hold charge through the afternoon to be ready for it.
None of this happens by accident. It is configuration, and it should be set against your actual tariff rather than left at the factory default.
AC coupling and DC coupling
In a DC-coupled system the panels and the battery share one inverter, so solar electricity charging the battery is converted once. Less is lost, but the architecture has to be planned from the start.
In an AC-coupled system the battery has its own inverter. Solar electricity is converted to AC, then back to DC to charge, then to AC again to use. That is a round trip more, and in exchange it retrofits onto almost any existing solar system.
If you are adding storage to solar you already own, AC coupling is usually the practical answer. If you are buying both at once, ask why the designer chose what they chose.
What pairing gives you that neither gives alone
Two capabilities only exist when both are present.
- Recharging during an outage. A battery paired with solar refills the next day. A battery alone runs down and stays down until the grid returns.
- Self-consumption under poor export rates. Where the utility pays little for exports, storing surplus and using it in the evening converts a low-value export into a high-value offset.
Backup reserve, and why people think their battery is broken
Most systems let you hold back a percentage of the battery that is never used for daily cycling and is kept for outages.
Set it high and you get excellent outage protection and disappointing bill savings, because most of the battery is untouchable. Set it to zero and you maximise savings and may face an outage with an empty battery.
Neither is wrong. Knowing the setting exists, and that it is yours to choose, is what stops it feeling like a fault.
How the work runs
- Establish the tariffFlat rate, time-of-use, or net billing. This determines what the system should optimise for and there is no sensible design without it.
- Choose the couplingDC if designing both together and efficiency is the priority; AC if retrofitting to existing solar.
- Size the pairArray sized to consumption, battery sized to the evening gap you are trying to cover.
- Design the backup scopeWhich circuits survive an outage, and whether the power rating supports them.
- Permit and interconnectPaired systems are usually one interconnection application, but storage may add its own inspection.
- Commission the logicTime-of-use schedule, backup reserve, and export behaviour configured against your real tariff — not the default.
What moves the price
We do not publish a national average and present it as your price. These are the variables that separate two quotes for the same job — run your own numbers with the cost guides and calculators, and check what incentives you actually qualify for.
| Factor | Why it moves the number |
|---|---|
| Coupling architecture | A hybrid inverter that handles both is priced differently from two separate inverters. |
| Battery capacity and power | The same two numbers that drive any storage decision. |
| Backup scope | Critical circuits against whole-home is the largest single swing. |
| Retrofit penalty | Adding storage later may mean replacing a working inverter, which is cost you would not have paid installing both at once. |
| Tariff complexity | Nothing about your tariff changes the hardware price, but it changes whether the hardware pays for itself. |
What to ask before you commit
Take this list to the conversation. A professional who answers these directly is telling you a lot; one who deflects is telling you more.
- Is this AC-coupled or DC-coupled, and why did you choose that?
- What tariff have you designed this against, and have you seen my actual bill?
- What backup reserve will it ship with, and can I change it myself?
- Will the battery recharge from solar during a multi-day outage?
- If I add more panels in five years, does this inverter accommodate them?
Common questions
Is it cheaper to install solar and a battery together?
Usually, yes. A single design, one permit process, one mobilisation, and no risk of replacing an inverter that is only three years old. The trade-off is a larger upfront commitment.
Will my battery recharge during a power outage?
If it is paired with solar and configured for it, yes — the array recharges it the following day. A battery with no solar cannot refill until the grid returns.
Should I set the backup reserve high or low?
It depends what you bought it for. High reserve favours outage protection; low reserve favours bill savings. Most people want something in between, and it is adjustable.
Does adding a battery increase my solar production?
No. It changes what happens to the electricity the panels already make — storing it instead of exporting it. Production is set by the array.