Simple, Accurate Sizing for Your Home or Business Solar Setup.
This easy-to-use calculator helps you determine the right size for your solar panel system by considering your daily electricity needs and real-world conditions that affect solar performance.
What This Calculator Determines
- Your Daily Electricity Need (Watt-hours per day – Wh/day)
- The total power your appliances use each day.
- *Example: If a 50W bulb runs for 5 hours, it uses 250 Wh/day.
- Adjusted Power Need (With Safety Buffer + Losses)
- Adds extra power (30% safety margin) to cover unexpected usage.
- Includes losses from heat, dust, wiring, and other real-world factors.
- Solar Panel Size (Watts – W)
- How much solar power you need based on sunlight hours in your area.
- *Example: If you need 2000 Wh/day and get 5 sun hours, you need ~400W of solar panels.*
- Battery Bank Size (Amp-hours – Ah)
- How much battery storage you need for nights or cloudy days.
- Accounts for energy lost when charging/discharging batteries.
- Inverter Size (Watts – W)
- The device that converts solar power (DC) to usable home electricity (AC).
- Sized to handle your highest possible power demand at once.
- Charge Controller Size (Amps – A)
- Protects your batteries by regulating solar power flow.
- Ensures panels charge batteries efficiently.
Real-World Factors Included (Why Solar Doesn’t Always Perform at 100%).
| Factor | What It Means | Default Adjustment |
|---|---|---|
| Heat Loss | Solar panels work worse in hot weather. | +8% more panels needed |
| Inverter Loss | Some power is lost when converting DC to AC. | +5% extra capacity |
| Wire Loss | Long or thin wires waste some electricity. | +3% compensation |
| Dust/Dirt | Dirty panels produce less power. | +5% extra needed |
| Shading | Trees or buildings blocking sunlight. | +5% safety margin |
| Battery Loss | Energy lost when storing/using battery power. | +15% more capacity |
| Controller Loss | Small loss in the charge regulator. | +2% adjustment |
| Panel Aging | Panels slowly lose efficiency over years. | +3% future-proofing |
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Why This Calculator is Better
✅ Made for real-world conditions – Not just “perfect lab” numbers.
✅ Easy to use – Just enter your appliances and local weather.
✅ Explains every step – No confusing tech jargon.
✅ Customizable – Adjust losses if your situation is different.
How to Use It
- List your appliances (lights, TV, fridge, etc.) + how many hours they run.
- Enter your location’s average sunlight hours (e.g., 5 hours in Kenya).
- Get your perfect solar system size – with all losses already included!
For Non-Technical Users:
- W (Watts) = Power an appliance uses (like a lightbulb’s brightness).
- Wh (Watt-hours) = Total energy used over time (like a car’s fuel consumption).
- Ah (Amp-hours) = Battery storage capacity (like a fuel tank’s size).
This calculator does all the hard math for you – just plug in your numbers and get a reliable solar setup!