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Solar without a battery saves money by reducing daytime grid purchases and exporting excess energy at a low feed-in tariff. Adding a battery allows you to store that excess energy and use it at night, avoiding expensive grid rates. This can significantly increase self-consumption and reduce bills, but the upfront cost means batteries usually have a longer payback period than solar panels alone.
How Does Solar Save Money Without a Battery?
A standard solar system saves money in two ways: self-consumption and exports.
Self-consumption is the most valuable part. When your home uses solar power at the same time it is being generated, you avoid buying electricity from the grid. If your electricity rate is 35 cents per kilowatt-hour, every kilowatt-hour you use directly from your panels saves you that full amount.
Any excess energy you do not use is exported to the grid. For this, you receive a feed-in tariff, which may only be 5 to 8 cents per kilowatt-hour. This large gap between what you pay and what you earn is the key reason batteries change the financial equation.
What Changes When You Add a Battery?
A battery stores excess solar energy instead of exporting it at a low feed-in tariff. During the day, your solar system powers your home first. Any surplus charges the battery.
In the evening, when solar production stops, your home draws power from the battery instead of buying electricity from the grid. Each kilowatt-hour you use from the battery avoids paying the full retail rate, which is often 30 to 45 cents per kilowatt-hour.
In simple terms, a battery time-shifts cheap solar energy from midday to the evening, when electricity is most expensive.
What Does the Real-World Difference Look Like?
Consider a home using 20 kilowatt-hours per day, with 8 used during daylight hours and 12 used in the evening.
Without a battery:
• 8 kilowatt-hours are self-consumed during the day.
• The remaining solar energy is exported for a low feed-in tariff.
• All 12 evening kilowatt-hours are purchased from the grid at the full retail rate.
With a 10 kilowatt-hour battery:
• 8 kilowatt-hours are still used directly during the day.
• 10 kilowatt-hours charge the battery instead of being exported.
• In the evening, 10 kilowatt-hours are supplied from the battery.
• Only 2 kilowatt-hours are purchased from the grid.
The result is significantly lower evening grid imports and higher overall self-consumption, often increasing total solar usage from around 40 percent to 80 percent or more.
Is a Battery Always Worth It Financially?
While a battery increases savings, it also adds a substantial upfront cost. Solar panels typically have a faster payback period than batteries.
Battery payback depends on:
• The gap between your retail electricity rate and feed-in tariff.
• How much of your electricity is used after sunset.
• Available government incentives.
If you use most of your energy in the evening and your feed-in tariff is low, a battery can make strong financial sense. However, payback periods are generally longer than for solar alone.
