How Much Solar Power Can My Roof Generate?

Power output or wattage is a highly relevant factor to consider when you compare solar panel options. Some examples of what you may be told by one of our installers at Hot Solar Solutions are “it’s a 255 Watt panel” or “a panel we recommend carries a wattage of 300.” You could also read on your Hot Solar Solutions quote the following:  245W, 300W, or 345W next to the name of the panel. They all relate to a solar panel’s wattage, capacity, and power output. 

Let’s find out how much power your roof can possibly generate when you go solar. 

A General Solar Equation

There are several equations for determining how many solar panels and the amount of power is necessary for a household. An example is the following:  

The average energy needs of a U.S. household is a 6.62-kW solar system to match the 9000 kWh of average usage by U.S. households annually. What’s more, it is typical that a solar panel makes 320 watts of electricity in ideal sunny conditions. Use the following formula to calculate how many solar panels that equals:  Divide 6.62 kW (the system size) by .320 kW (the wattage per panel) = 20.69 – rounded up that is 21 panels. While your home may not be average, this is how you calculate your own estimate. 

How Much Energy Does a Solar Panel Produce?

As an example, if you are getting five hours of direct sunlight each day in a sunny area like the Tri-Cities you can calculate your solar panel output this way: 
5 hours x 290 watts (an example wattage of a premium solar panel) = 1,450 watts-hours, or approximately 1.5 kilowatt-hours (kwh).  As a result, each solar panel would produce about 500-550 kWh of energy every year. 

How Solar Panels Are Rated

Solar panels are rated by the amount of DC (direct current) power they generate under standard test conditions.  Solar panel output is measured in units of watts (W) and reflects the panel’s theoretical power production under ideal sunlight and temperature conditions.  The majority of home solar panels on the market currently have power output ratings ranging from 250 to 400 watts, with higher power ratings usually considered preferable to lower power ratings. Pricing in solar is normally established in dollars per watt ($/W), and the total wattage of your solar panels plays an important role in the cost of your solar system. 

Size vs. Quantity:  Typical Solar Panel Ratings and Capacity

Power output by itself is not a reliable indicator of a panel’s quality and performance characteristics.  For certain panels, their high power output rating is the result of their larger physical size instead of their higher efficiency or technological superiority. 

For instance, if two solar panels each have 15 percent efficiency ratings, however one has a power output rating of 250 watts and the other is rated at 300 watts, this means that the 300-watt panel is about 20 percent physically larger than the 250-watt panel. EnergySage and other industry experts look at panel efficiency as being a more accurate criterion of solar panel performance strength than solar capacity alone. 

Another way to think about it is a solar panel rated capacity of 5kW (kilowatts) could be comprised of either 20 250-Watt panels or 16 300-Watt panels. Both systems will produce the identical amount of power in the same geographic location. Although a 5kW system is likely to generate 6,000 kilowatt-hours (kWh) of electricity annually in Boston or Seattle, that same system will generate 8,000 kWh yearly in Los Angeles or the Tri-Cities because of the amount of sun each location gets annually. 

Which Solar Panels Produce the Most Electricity?

Solar panels typically vary in wattage output from approximately 250 watts to 400 watts, however some panels surpass the 400 watt mark. The solar panel with the highest watt is the SunPower E-Series, a commercial solar panel line. The premium panel in the E-Series generates as much as 435 watts. As for residential solar panels, the top wattage panel available is the SunPower A-Series AC Module – the top panel in the A-Series line generates an impressive wattage of 425 watts. 

Hot Solar Solutions 🡪 Your Local, Expert Solution for All Things Solar

If you are in the market to purchase solar panels for your business, look no further than Hot Solar Solutions in Kennewick.  With more than 300 days of sunshine in the Mid-Columbia area, solar not only makes sense, it makes dollars and cents!

Energy rates through local Public Utility Districts continue to soar. In 2015 Franklin PUD Rates increased 3% for their customers and Benton PUD customers saw a rate increase of nearly 5 percent.

Now is the perfect time to invest in solar energy for your home or business. 

Hot Solar Solutions is a local company, with deep roots in the Tri-Cities area, and we are committed to helping our customers save money, be more self-sufficient, and make a positive impact in our community by reducing their carbon footprint.

If you are interested in exploring solar power, we invite you to contact Hot Solar Solutions, your complete solar solutions company, at (509) 539 6140!