Solar Panel Power Calculator

Thinking about solar panels? You may ask, “How much power can they really make?” That’s where our solar panel power calculator comes in. It’s built to give you a fast answer. You’ll see power in watts and energy in kWh, so you can plan your solar setup with ease.

How the Solar Panel Power Calculator Works

The calculator uses two proven methods.

Nameplate Method

This one is simple. It starts with the rated power of your panel. You’ll see this number on the datasheet, often written as PSTC (Standard Test Conditions). Then it adjusts for sun strength, panel heat, tilt, and system losses.

The formula looks like this:

P = PSTC × (G / 1000) × [1 + γ (Tcell − 25)] × cos(θ) × PR

Where:

• G is sunlight (W/m²)
• γ is the temperature factor from the datasheet
• Tcell is cell temperature (°C)
• cos(θ) is the tilt factor
• PR is the performance ratio (system losses)

Detailed Method

This option is more physical. It uses the actual area of the panel and its efficiency.

P = G × A × η × [1 + γ (Tcell − 25)] × cos(θ) × PR

Where:

• A is panel area (m²)
• η is efficiency (decimal form)

Both methods give you panel power. Then the calculator multiplies by the number of panels to get your full array power.

How to Use the Calculator

Using the calculator is easy. Enter:

• Number of panels you plan to use
• Sunlight (irradiance) in W/m²
• Cell temperature
• Panel rating or size
• Performance ratio (usually 0.75–0.85)

Press calculate. The tool shows you step by step power output. If you tick “energy,” you’ll also see the kWh output for daily, monthly, or yearly periods.

It’s like having your own PVWatts calculator, but in a much simpler way.

Final Verdict

The solar panel power calculator is your quick helper. You don’t need to guess. You don’t need complex math. Just plug in your numbers, and you’ll know how much power your panels can give. This makes planning your solar array stress-free.

FAQs

How do you calculate how much solar panels you need?

Divide your daily energy use (kWh) by the daily output per panel. The calculator gives that value.

What is the 120% rule for solar panels?

It’s a code rule in the US. It says solar circuits must not exceed 120% of the busbar rating of your electrical panel.

Will a 200W solar panel run a fridge?

Not on its own. Most fridges need more power, and they run all day. You’d need several panels and a battery.

How much power does a 400W solar panel produce?

At full sun, it makes 400 watts. Over a sunny day, it can make about 1.6 to 2 kWh, depending on conditions.