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Easily find the solar panel wattage you need with our Solar Panel Wattage Calculator. Simple, fast, and accurate results for home or business use.
Thinking about solar power? You’ll want to know how many panels you need. That’s where our Solar Panel Wattage Calculator comes in handy. We built it so anyone can use it no tricky math or confusing charts. Just enter a few details, and you’ll get the answer right away.
The math is simple. First, you find your daily energy use in watt-hours. Then, you divide it by the number of peak sun hours in your area. Finally, you adjust for system losses with a factor called the performance ratio.
Here’s the formula in plain text:
Array Wattage = Daily Energy (Wh) ÷ (Peak Sun Hours × Performance Ratio)
Let’s say you use 10,000 Wh a day. Your area gets 5 peak sun hours. Your performance ratio is 0.8.
The math looks like this:
10,000 ÷ (5 × 0.8) = 2,500 Wp
That means you’ll need about 2.5 kW of panels. If your panels are 400W each, you’ll divide 2,500 by 400. That gives you 6.25, which means you’ll need 7 panels.
The 20% rule is a safety margin. It means you add about 20% more capacity than your base need. Why? Because real life isn’t perfect. Clouds, dust, and heat reduce output. Adding a small margin keeps your system reliable even when conditions aren’t ideal.
The number in the panel’s name is its rated wattage. A 400W solar panel can produce up to 400 watts in full sun. But remember, that’s under test conditions. In real life, output can be a bit lower. Think of it like a car’s fuel rating it shows potential, not always what you’ll see every day.
A 200W panel can power small gadgets, lights, or even a fan. But a fridge is a heavy user. A standard fridge often needs 100–200 watts when running. But fridges don’t run all the time they cycle on and off.
Still, a single 200W panel won’t be enough for daily fridge use. You’d need more panels and likely a battery system to store extra energy.
Using our tool is simple.
The calculator shows your needed array size, number of panels, and even roof area. It also gives you an idea of daily, monthly, and yearly production.
Switching to solar doesn’t have to feel like rocket science. Our Solar Panel Wattage Calculator makes the process quick, clear, and stress-free. You’ll know how many panels you need, how much space they take, and what to expect in return.
If you’re serious about cutting bills and going green, this tool is the first step toward making that dream a reality.
Divide 1,000 kWh by 30 to get about 33 kWh/day. Using the formula, you’ll need around 8–10 kW of panels depending on sun hours.
It’s possible, but not ideal. For best results, stick with panels of the same size and brand.
Yes. Most panels lose about 0.5% efficiency per year. A 25-year warranty is common.
Both can work. If you’ve got space, more panels are fine. If space is tight, go for higher wattage panels.