Solar Panel Array Sizing Calculator
Number of solar panels needed for a daily energy target.
Enter your values
Enter the daily energy need in kWh.
Enter the panel wattage in W.
Enter the peak sun hours in hours/day.
Enter the system efficiency in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Panels needed
- 7 panels
- Array capacity
- 2800 W
- Daily energy from array
- 11.2 kWh
Quick answer
Panels needed = daily energy demand / (panel wattage x peak sun hours x system efficiency).
N = Ed / (W x PSH x eff)
At a glance
| What it does | Number of solar panels needed for a daily energy target. |
|---|---|
| Category | Engineering |
| Inputs needed | Daily energy need, Panel wattage, Peak sun hours, System efficiency |
| Main output | Panels needed |
| Formula | N = Ed / (W x PSH x eff) |
| Cost | Free — no sign-up, no download |
How to use the Solar Panel Array Sizing Calculator
- 1Enter your daily energy requirement in kWh.
- 2Enter the wattage of the panels you plan to use and your location's peak sun hours.
- 3Apply a system efficiency factor for inverter and wiring losses, then round up to whole panels.
Inputs explained
- Daily energy need(kWh)
- Enter the daily energy need in kWh.
- Panel wattage(W)
- Enter the panel wattage in W.
- Peak sun hours(hours/day)
- Enter the peak sun hours in hours/day.
- System efficiency(%)
- Enter the system efficiency in %.
Worked example
Using the values the calculator loads with:
Inputs
- Daily energy need10 kWh
- Panel wattage400 W
- Peak sun hours5 hours/day
- System efficiency80 %
Results
- Panels needed7 panels
- Array capacity2800 W
- Daily energy from array11.2 kWh
Frequently asked questions
What are peak sun hours?
The equivalent hours per day of sunlight at 1000 W/m² intensity; check local solar irradiance maps.
Why include system efficiency?
Inverters, wiring, dust and temperature all reduce real-world output below the panel's rated wattage.
What do I need to enter into the Solar Panel Array Sizing Calculator?
Just 4 values: daily energy need, panel wattage, peak sun hours, system efficiency. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Solar Panel Array Sizing Calculator work out the answer?
Panels needed = daily energy demand / (panel wattage x peak sun hours x system efficiency). It applies the formula N = Ed / (W x PSH x eff) and shows the working so you can check each step by hand.
Is the Solar Panel Array Sizing Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.