How To Size Your Solar Battery Bank.

Sizing Your Solar Battery Bank. Quickly find the battery and solar panel size you need based on your daily power usage. Get results showing how many Amp-hours (Ah) of battery you need and how many Watts (W) of solar panels are required.

Example: 1,000W × 10 hrs = 10 kWh/day. Get results in Amp-hours (Ah) (battery) and W (solar).

How to Size Your Solar Battery System.

When choosing solar batteries, it’s important to match the size of your battery bank to how much electricity you use daily — and the type of battery you’ll be using.

Let’s break it down simply:

Example: You Use 10 Units (kWh) of Power Per Day

Depending on the battery type, here’s what that means:

Lead-Acid Batteries.

These can only use about 50% of their capacity (to avoid damage). So:

• 10 kWh x 2 = 20 kWh.
• Add 20% to cover system losses: 20 kWh x 1.2 = 24 kWh battery needed.

Lithium Batteries.

Lithium batteries are more efficient and can use up to 80% of their capacity:

• 10 kWh ÷ 0.8 = 12.5 kWh.
• Add 5% for system losses: 12.5 kWh x 1.05 = 13.1 kWh battery needed.

🔢 What Is Battery Capacity?

Battery capacity tells you how much energy it can store. It’s usually measured in:

• Kilowatt-hours (kWh) – like “units” on your electricity bill.
• Or Amp-hours (Ah) – often used for solar batteries.

Example:

If you need 24 kWh and your system is 48 volts:

• 24,000 Wh ÷ 48V = 500 Ah.

It’s a good idea to round up your battery size slightly — to cover for things like inverter loss, voltage drop, or cloudy days. So instead of 500Ah, you may want 600–800Ah depending on your needs.

How to Calculate the Right Battery Size.

You don’t need to be an expert. Just follow these three steps — or use our free calculator to do it for you!

Step 1: Know Your Daily Energy Use

• Check your electricity bill to see how many units (kWh) you use in a month
• Divide that by 30 to get your daily use in kWh

Step 2: Think About Cloudy Days

• If your area has days without sunshine (like during the rainy season), you’ll need more battery storage.
• More cloudy days = bigger battery needed.

Step 3: Check Your Local Temperatures

• Batteries don’t perform as well in very cold areas like Limuru during cold seasons.
• Knowing your lowest average temperature helps you choose the right size and type of battery.

Need Help?

Use our Solar Energy Calculator to:

• Estimate your daily usage.
• Calculate your battery bank size.
• Get suggestions for solar panel wattage and charge controller.