Why Bigger is Better
When thinking about battery storage, most people imagine one big bucket of energy. But to truly maximize the return on your battery investment, it’s better to think in sections or use categories. A large-capacity battery gives you the flexibility to divide its energy into specific roles:
• Operational Use (50%)
This is your everyday storage – solar energy captured during the day and used at night to power your home. It’s the foundation of bill savings.
• Electricity Price Arbitrage (20%)
This slice of the battery is used to buy low and sell high, capitalizing on wholesale market spikes and time-of-use pricing. The bigger the slice, the bigger the profit.
• Emergency Backup (20%)
This reserve is kept charged in case of blackouts – ready to run essential loads like fridges, lights, and the internet.
• Safety Buffer or Unusable Capacity (10%)
Most batteries don’t allow full use of their total rated capacity, either to protect battery health or due to system design limits.
With a small battery, you’re forced to choose between these roles — and often sacrifice one for the other. With a larger battery, you can confidently assign energy to all three functions, and still have enough to respond to the grid or handle an outage.
Go Large for Home Battery Storage in SEQ If you’re in South East Queensland and already running a powerful solar system – say, 30 kW – it’s time to think big on storage too. Here’s why larger batteries deliver far better return on investment than smaller ones like the Tesla Powerwall (13.5 kWh).
1. Store More of Your Solar
Avoid Wasting Free Energy A 30 kW solar system can generate around 120 kWh/day in SEQ’s sunshine. Most homes only use ~25 kWh/day.
• Problem with small batteries: A single Powerwall fills up fast and leaves 80+ kWh of solar wasted or exported at low rates.
• Why big batteries win: They store more of that excess for your evening and nighttime use.
Result: Less energy exported at low rates, more energy used by you – higher savings.
2. Beat the High Cost of Electricity
Grid power in SEQ costs ~33¢/kWh. Feed-in tariffs (FiTs) pay just 5–12¢/kWh.
• Use your own solar stored in a battery = 33¢ saved.
• Export it = only 5–12¢ earned.
Big battery = more stored solar = bigger bill savings.
3. Protect Against Grid Outages
SEQ is no stranger to summer storms and blackouts.
• A single Powerwall covers only about 12 hours for an average home.
• Larger batteries (30–40+ kWh) give you 24+ hours of backup for essentials like: • Fridges • Lights • Internet • Some air con
Result: Ride out blackouts in comfort, not darkness.
4. Capture Price Spikes
Get Paid When the Grid Panics Wholesale electricity prices can spike to $19/kWh during extreme events.
• Charge when prices are low or free
• Discharge (or export) when prices spike Small batteries = little capacity to export Large batteries = serious cash in your pocket
Example: Exporting 10 kWh during a spike could earn you $190 in one go.
5. Everyday Arbitrage
Time Your Energy Use Even on normal days, power is cheaper off-peak and expensive in the evening.
• Big batteries let you:
• Charge during low-cost times
• Discharge when prices rise
Result: Daily savings without changing your lifestyle.
6. Avoid Losing Money from Negative Wholesale Prices
If you’re with Amber Electric or another wholesale pass-through retailer, your solar exports are tied to real-time energy market prices – which can sometimes go negative.
• That means you could be charged to export your solar, not paid.
• This often happens midday, especially when there’s lots of solar on the grid and not enough demand.
• A small battery like the Powerwall fills up quickly, forcing the rest of your solar to be exported – possibly at a loss. Larger batteries let you store excess power instead of exporting during negative price periods.
Result: You avoid losing money, keep more of your solar, and wait to use or sell it when prices rebound.
Final Word
A small 15kWh can’t do it all.
A single Powerwall just doesn’t cut it for:
• Capturing big solar output
• Running a house for 24+ hours
• Profiting from price spikes It’s a good start, but it leaves ROI on the table.
Future-Proof Your Energy Setup With power prices rising, solar feed-in rates falling, and energy volatility increasing – a large battery gives you control, security, and financial upside. Think of your battery as your energy bank. The more it can store, the more value you’ll unlock.
Consider a Better Life Batteries system - we offer a 60kWh battery at a similar price point to a single Tesla Powerwall, exceptional value, and a sustainable alternative to tractional battery options. Learn more:
Sam Hamilton-Smith - Director
MDatSc CPEng RPEQ MIEAust
Sam is a charted & registered electrical engineer with over 15 years experience delivering electrical assets for Queensland.