How Much Does Panel Wattage Matter?


Many manufacturers or installers tout their panels as best because they're “the most powerful”, etc. This can make it hard to determine which equipment is right for you, especially when there are so many  options. 

High wattage panels have gained a lot of popularity as of late, but they can often come with a high price tag. This article will discuss panel wattage, its importance, and Project Solar’s policies/recommendations.


Breaking down panel wattage - what does it mean?

Solar panels use sunlight to produce energy, but each panel has a limit to how much energy it can produce at a given time.

Conveniently, solar panels typically include this information in the module name: the wattage.

For example: our Q-CELLS 400W panels have a wattage of 400. This means that, in ideal conditions, these panels can produce 400 watts of power.

Adding the wattage of each panel in a solar system is how we get the system size–12 400W panels, for instance, would add up to 4,800 total watts, or 4.8 kilowatts (kW). Thus, we have a 4.8kW system.

Conversely, 16 300W panels also add up to 4,800 total watts, which means a 4.8kW system could have various configurations.

Tip: Confused about the difference between kilowatts (kW) and kilowatt-hours (kWh)? Check out our article on the subject here! 


Considering the positives and negatives of different modules

When deciding which panels you want on your roof, it’s important to remember a few factors:

  1. 1. Efficiency
    Most residential solar panels have between 15-22% efficiency. However, efficiency can be deceptive--since larger panels have a greater area, they often have a lower efficiency.

    Additionally, panels in the 22-23% efficiency range can be much more expensive, and the significantly higher cost doesn't always justify the extra 1-2% efficiency.
  2.  Panel Size
    High wattage panels are usually physically larger than lower wattage panels, which can be good and bad. The good news is that less panels are required for each system, but the bad news is that larger panels may not be as maneuverable as their smaller peers.

    For example: the below roof has pipes and fire restrictions that limit the number of panels. A smaller, lower-wattage panel is able to provide a larger configuration & system size on Roof A than the higher wattage panels on Roof B:Panel_Wattage_Graphic.png
  3.  Price Per Watt

    Newly developed products typically cost more, and high wattage panels follow this trend–especially over 400W.

    Imagine a 400W panel costs about $400, and a 420W panel costs about $500. The price for each watt of power--price per watt--can be found by dividing the cost by the panel wattage. So:

    $500 / 420W = $1.19 per watt

    $400 / 400W = $1 per watt

    Even though the 420W panel can produce slightly more energy, it would still be more cost effective to build an 8.4kW system by purchasing 21 400W panels than 20 420W panels, because the 400W panels have a lower price per watt:

    20 x $500 = $10,000

    21 x $400 = $8,400

Project Solar's Guidelines

At Project Solar, we've optimized our panel options to get you the highest quality equipment at the lowest possible price. 

Panel wattage is an important factor when designing a solar system, but it shouldn't always be the highest priority; build quality, warranty, and manufacturer reputation are just as important--if not more.

We recommend going with a trusted, Tier 1 panel manufacturer with options rated to IEC 61215. These factors help determine higher quality equipment. 

Furthermore, high quality panels should include a 25-30 year linear performance warranty. When you're comparing quotes and panel options, be sure to review the price per watt.

For a list of the equipment we offer, check out our Equipment Specifications Page.

Was this article helpful?
0 out of 0 found this helpful



Please sign in to leave a comment.

Articles in this section

See more
Browse the Project Solar store.
Get a quote
See your salesman-free system pricing with our online calculator.
Chat with us
Our agents are available Mon-Fri, 9am-5pm Mountain Time.
Check out our Youtube channel
Learn more about solar.