Solar Panel Output: What's the Average, and How Do They Differ?

Among the top ten manufacturers, the average watts per panel is about 200…. but what’s a watt?

The (technical) basics: what’s a watt?

Wattage (the amount of electric power) is calculated by multiplying a solar panel’s voltage by the amps of current it produces. Each solar cell will produce a voltage of about 0.5 volts, whether it’s big or small. By attaching single cells together in a series, you can create a higher voltage. Amps, on the other hand, do vary based on size, so the bigger the cell, the more amps you’ll get. Connecting cells in parallel also creates more amps of current.

What’s a watt-peak (Wp)?

This number represents the maximum amount of energy the panel can pump out on an ideal day, i.e., early afternoon on a sunny summer day. The actual wattage the panels produce on an ordinary day will vary depending on how much sunshine is reaching your roof. Cloudiness or fogginess is one factor, the season is another factor (since it affects the height of the sun in the sky and the number of daylight hours), and the time of day also matters. The angle of the panels also affects how much sun they get, and how much power they can produce. The watt-peak is just a reference point you can use to compare various solar panels. It’s calculated in solar panel manufacturing facilities using industry standards.

What are typical wattages?

The average solar panels have watt-peaks ranging from about 175 W to about 235 W, with an exceptionally powerful solar panel measuring 315 W. Among the top ten manufacturers, the average wattage of a panel is about 200 W.

Does it matter which brand of solar panel you choose?

Brand name doesn’t matter too much. All of the solar installers that 1BOG chooses through our careful vetting process use high quality solar panels from a variety of manufacturers. As one installer said in the Wall Street Journal, “Because Suntech, Sharp and all these panel manufacturers have such great technology and the quality is superb, it doesn’t really matter which module you use.” But even if brand doesn’t matter, a particular type of panel might be better suited for your roof. If your roof is partially shaded, a certain type of panel will be best for you. The type of roof you have and the amount of space are also issues that can help your installer decide which solar panels to recommend.

Which solar panels are used in 1BOG campaigns?

The installers we work with will choose the solar panels they think are best. In most campaigns, a few different choices of solar panels are available. Installers often offer SunPower panels as an option for roofs with less space. SunPower panels are more expensive, but they’re also much more efficient, meaning they can provide more power in a smaller area.

Learn more

Find out more about how solar panels work. Interested in getting affordable solar power for your home? Sign up for 1BOG (it’s free!) and we’ll help you find out if solar power is right for you.

By Dave Llorens

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