All About Solar Panel Sizes and Wattage

Panel Type

There are three types of solar panels: polycrystalline, monocrystalline, and thin-film. They all have their own advantages and disadvantages.

Residential vs. Commercial Panels

Most home solar power dimensions are 65 inches by 39 inches per panel. Panels are made up of small photovoltaic (PV) solar cells that are always the same size: roughly six inches long by six inches wide. Most residential solar systems have up to 60 PV cells.

Commercial solar power dimensions are larger, typically 78 inches by 39 inches per panel. They usually contain 72 PV cells but can have up to 98.

A third category of solar panel size, the “portable” 100 Watt solar panel is the smallest at around 40 inches by 20 inches. These are typically used to power small appliances when camping or for emergency power.

Material

Monocrystalline cells are made from a single silicon crystal. In contrast, polycrystalline cells are composed of small fragments of silicon crystals that are melted together before being cut into wafers. Even though their makeup doesn’t affect their size, monocrystalline cells are more efficient, so fewer will be needed.

Wattage

Each solar panel consists of many individual solar cells connected in parallel circuits. The higher the solar panel wattage, the more solar cells are needed, and the bigger the panel will be. Solar panels that are used on homes are typically in the 300-400 Watt range. Panels of this size are great for home installations due to their size, weight and cost. While larger, 500 Watt solar panels do exist on the market, the larger size doesn’t necessarily translate to greater benefits.

Watt Usage & Daily Sunlight

To determine how many solar panels your home needs, the first thing you need to do is to calculate your home’s average daily watt usage. Take a look at your electric bills for the kWh that you tend to use in 30 days. Divide that number by 30 to get your daily average. An average home in the United States will use 900 kWh in a month, averaging about 30 kWh per day. Next, figure out the number of daily peak sunlight hours that your location gets. For instance, because of the difference in latitude, this number will be a lot lower for someone who lives in New York than it will be for someone in Los Angeles. Multiply your daily usage by 1,000 to convert it to watts, and then divide that by the number of peak sunlight hours your home gets. Assuming an average consumption of 30 kWh per day and five peak sunlight hours a day, then your home would require 6,000 watts each day.

Solar Power Output Efficiency

Output efficiency is another significant factor in the size and wattage of your solar panel system. Not all solar panels are the same and can range in wattage from around 150 watts to 370 watts per panel, depending on the solar panel size and the manufacturer. However, the more efficient your solar panels are, the more wattage they can produce. With efficient panels, you’ll be able to install fewer panels on your roof to get the same output.

Though there are variations in efficiency, standard-size solar panels typically produce around 250 watts. To determine how many solar panels you need, divide your daily wattage requirement by the panel’s wattage. Using the typical watt amount and the numbers we calculated above, the equation would be

6,000 / 250 = 24 panels