Understanding Home Batteries
Learn how home batteries work, different types available, and whether a battery is right for your home.
How Home Batteries Work
Step 1:Excess Solar Charges Battery
During the day, when your solar panels produce more than you use, the excess energy charges your battery instead of being exported to the grid.
Step 2:Battery Stores Energy
The battery stores this energy as chemical energy in lithium-ion cells. Modern batteries can store this energy for days if needed.
Step 3:Evening Use
In the evening when the sun goes down, the battery automatically supplies power to your home instead of drawing from the grid.
Step 4:Grid Backup
If the battery runs low, your home seamlessly switches to grid power. With backup capability, you can also run during blackouts.
Key Terms Explained
Capacity (kWh)
How much energy the battery can store. A 10kWh battery can store 10 kilowatt-hours of electricity.
Power (kW)
How fast the battery can charge or discharge. A 5kW battery can deliver 5 kilowatts at any moment.
Depth of Discharge (DoD)
How much of the battery capacity you can actually use. Most modern batteries allow 90-100% DoD.
Cycle
One full charge and discharge. Most batteries are rated for 6,000-10,000 cycles.
Round-trip Efficiency
How much energy you get back vs what you put in. Typically 85-95% for lithium batteries.
AC vs DC Coupled
How the battery connects to your system. AC-coupled is more flexible; DC-coupled is more efficient.
Battery Types
Lithium Iron Phosphate (LFP)
Pros
- checkLongest lifespan (6,000+ cycles)
- checkSafest chemistry
- checkBetter in hot climates
- checkNo thermal runaway risk
Cons
- removeSlightly larger/heavier
- removeLower energy density
Nickel Manganese Cobalt (NMC)
Pros
- checkHigher energy density
- checkMore compact
- checkGood performance
Cons
- removeShorter lifespan (4,000-6,000 cycles)
- removeMore sensitive to heat
- removeHigher fire risk
Do You Need a Battery?
High evening usage
If you use most power in the evening, a battery lets you use your own solar instead of buying from the grid.
Good feed-in tariff (10c+ per kWh)
If your retailer pays well for exports, the financial case for batteries is weaker. Do the maths first.
Frequent blackouts
Batteries with backup capability keep your essential circuits running during outages.
Time-of-use tariffs
Charge from solar/cheap rates, use during expensive peak periods. Can significantly boost savings.
Environmental priority
Maximise self-consumption of your clean solar energy instead of relying on grid power.
Tight budget
Solar alone has better ROI. Batteries are getting cheaper — you can always add one later.
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