How Many Solar Panels Do I Need? 2025 Calculator | SolarTech
How many solar panels do I need? Use our 2025 calculator to size your system by home size, kWh usage, and location. Get panel count, roof space, and kW—free from SolarTech.
Solar panel power ratings range from 250W to 450W. Based on solar.com sales data, 400W is the most popular power rating and provides a great balance of output and Price Per Watt (PPW). If you have limited roof space, you may consider a higher power rating to use fewer panels. If you want to spend less per panel, you may consider a lower wattage.
The goal for any solar project should be 100% electricity offset and maximum savings — not necessarily to cram as many panels on a roof as possible. So, the number of panels you need to power a house varies based on three main factors: In this article, we'll show you how to manually calculate how many panels you'll need to power your home.
An average 400-watt monocrystalline solar panel will produce 2 kWh of energy per day. Solar panels with higher efficiency ratings will generally have higher wattages and are best for homes with limited roof space. The table below outlines how much energy different types of solar panels produce per month:
Look at different panels and see what the wattages are. The solar panel wattage is also known as the power rating, and it's a panel's electrical output under ideal conditions. This is measured in watts (W). A panel will usually produce between 250 and 400 watts of power. For the equation later on, assume an average of 320 W per panel.
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