The biggest mistake homeowners make is “under-paneling.” If you have a large battery but too few panels, your battery will never reach 100% charge during the day, leaving you in the dark when load-shedding hits at night.

The Golden Rule: The 5-Hour Window

In South Africa, we get an average of 5 hours of “Peak Sun” per day. You need to produce enough energy in those 5 hours to cover your daytime usage AND refill your batteries.

Step 1: Know Your Battery Capacity

Check your battery’s kWh (Kilowatt-hour) rating.

• Standard Lithium Battery: 5.12kWh
• Large Lithium Battery: 10kWh

Step 2: The Calculation

To find the required solar wattage, use this formula:

(Battery Size ÷ 5 Hours) x 1.25 (Efficiency Buffer) = Required Solar kW

Example for a 5kWh Battery:

1. 5kWh ÷ 5 hours = 1kW of solar production needed per hour.
2. Multiply by 1.25 (to account for heat and clouds) = 1.25kW (1250W) of solar panels.
3. If you use 550W Tier 1 Panels, you would need: 1250W ÷ 550W = 2.27 (So, 3 Panels minimum).

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Quick Reference Guide

Battery Size	Min. Panels (550W)	Recommended Panels (For Load-Shedding)
5kWh Battery	3 Panels	4 – 6 Panels (Gives you extra power for the house)
10kWh Battery	6 Panels	8 – 10 Panels (Full energy independence)
15kWh+ Bank	9 Panels	12+ Panels (Ideal for large homes/offices)

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Pro-Tip: Don’t Forget the Daytime Load!

Remember, while your panels are charging your battery, they also need to power your fridge, Wi-Fi, and TV. We always recommend adding 2 extra panels to your minimum calculation to ensure your home runs on “Live Solar” during the day while the battery stays reserved for the night.

Ready to Go Solar with Confidence?

Don’t guess when it comes to your solar system – let Smartechs design the perfect setup for your home and battery needs. Get a free personalised quote today!

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