How to Read Your Electricity Bill to Size a Solar Battery
Learn to decode your electricity bill in 10 minutes. Find the kWh number that drives every battery sizing calculation and avoid the most common mistake.
BatteryBlueprint Editorial Team
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Most people have never actually read their electricity bill. They glance at the total, wince, and pay it. But if you want to size a solar battery correctly, your electricity bill contains the single most important number in the entire calculation: your daily energy consumption in kilowatt-hours (kWh).
Get this number wrong and every other calculation falls apart. Overestimate and you'll spend thousands on capacity you'll never use. Underestimate and you'll run out of power at 9pm on a cold Tuesday.
This guide walks you through finding that number on any bill format — US, UK, or Australian — in under 10 minutes.
What You're Looking For: The kWh Number
Your electricity bill charges you for energy in kilowatt-hours (kWh). One kWh is the amount of energy used by a 1,000-watt appliance running for one hour. A typical electric kettle uses about 0.1 kWh per boil. A tumble dryer uses about 2.5 kWh per cycle.
Your bill will show your total kWh consumed over the billing period. This is the number you need.
Do not use the dollar/pound/dollar amount. Electricity prices vary wildly by location, time of day, and tariff type. The currency figure tells you what you paid, not how much energy you used. Battery sizing is about energy, not cost.
Where to Find It
On most bills, look for a section called:
- "Energy Usage Summary"
- "Electricity Consumption"
- "Usage Details"
- "Meter Reading Summary"
It will show something like: "Usage: 847 kWh" or "Units used: 847"
That's your billing period total. Now you need to convert it to a daily average.