⚡ System Design
How to Size and Plan a Solar Power System
1. Determine Your Energy Needs
This is the foundation of system design.
Step A — List your appliances
Example table:
ApplianceWattsHours/dayWh/dayLight bulb10W5h50WhFan40W6h240WhTV80W3h240Wh
Step B — Add them up
Total Daily Consumption = Sum of all Wh/day
Example: 50 + 240 + 240 = 530 Wh/day
2. Size the Solar Panels
Use this formula:
Panel Watts Needed=Daily WhSun Hours
If you have 5 sun hours:
5305=106W
Round up → 150W panel.
3. Size the Battery Bank
Use:
Battery Ah=Daily WhBattery Voltage
For 12V:
53012=44Ah
Add 2 days backup → 90Ah battery.
4. Size the Charge Controller
Use:
Controller Amps=Panel WattsBattery Voltage
Example:
15012=12.5A
Choose a 20A MPPT.
5. Size the Inverter
Inverter must handle:
- Total watts of appliances
- Surge watts (motors, pumps, fridges)
If your highest load is 300W:
- Choose 600W pure sine wave for safety.
