The solar panels used in residential projects are generally rated at around 300 Watts.
Over the past few years, however, higher-wattage panels have begun to hit the market. There are currently at least seven commercially available models rated at 500 watts or higher.
Now, a 500-watt panel can generate more power than a 300-watt panel—that's just true by definition. Which makes it natural to think that using larger panels will get you more solar energy.
But, as widespread as that assumption may be, it isn't true.
When determining how much power you're going to get from a solar system, the wattage of each individual panel is actually irrelevant.
And it turns out that, when it comes to residential solar projects, despite all the high-wattage hype, smaller-wattage panels will almost always deliver more bang for your buck.
Higher wattage = bigger & heavier
In fact, though it may sound impressive, there's really nothing particularly innovative about producing higher-wattage solar panels.
A solar panel is just a bunch of individual solar cells wired together in series. Its overall wattage is just the sum of the wattage of each of its individual cells.
So, to create higher-wattage solar panels, all you've got to do is add more cells.
But that means that increasing the wattage comes at the cost of also increasing the panel's physical size and weight.
60 vs 72-cell panels
Even before the recent advent of 500-watt-plus panels, commercially available solar panels typically came in one of two different sizes.
60-cell panels, which fall between 260–330 watts.
72-cell panels, which fall between 360–400 watts.
72-cell panels have been standard for large-scale industrial installations. Because of the extra wattage, fewer panels need to be used.
Importantly, however, the economic benefit of having to transport and install fewer panels isn't offset by any substantial increase in labor costs since large-scale projects use heavy machinery to get everything where it needs to go anyway.
The smaller-wattage advantage
But the size of 72-cell panels turns out to create a number of huge and costly headaches for residential installations.
- 60-cell panels are smaller and lighter, making them easier to install and resulting in much lower labor costs.
60-cell panels are typically around 66” x 40” and weigh around 40 pounds. Whereas 72-cell panels tend to be around the same width but an extra foot in length. They weigh in at around 48 pounds.
These differences may not sound like much. But if you’re employing a crew to carry solar panels up to someone's roof, they're likely to become quite costly.
A 72-cell panel will probably turn out to be taller than your biggest crew member. So, lugging them up to a roof that may be two or more stories off the ground will be very labor intensive and, hence, lead to significantly higher installation costs.
- 60-cell panels provide greater design flexibility.
One great challenge in designing a solar installation is often maximizing the amount of power produced so that it meets all of the homeowner’s energy needs.
Roof space is always limited, so the design flexibility provided by smaller 60-cell panels can turn out to be a huge advantage. Even more so given that many states and localities have fire access codes that put major additional constraints on panel placement.
Using 60 as opposed to 72-cell panels frequently allows for one or more extra rows, translating into a larger system able to meet all the homeowner’s energy needs.
To be perfectly honest, shipping companies aren’t even terribly fond of the non-standard-sized pallets required for the 60-cell panels which are the solar industry norm. But 72-cell panels create even bigger headaches.
A 78” long pallet is too big to be turned inside a freight truck. And anyone who’s ever worked a forklift will tell you that balancing a 78” pallet along its length is going to be inordinately challenging.
60-Cell Panels Make Sense
And there you have it.
Despite the hype, the size of each individual panel is completely irrelevant to meeting your energy needs. All that matters is the total size of your overall system.
As a result, because they lower labor and transportation costs as well as offer better design flexibility, 60-cell panels are likely to remain the industry standard for residential projects.