Solar panels are manufactured in a wide range of sizes, adapting to multiple applications. For example, weather monitoring devices in remote locations often use miniature solar panels to replenish their batteries. However, when dealing with solar systems for homes and businesses, two types of solar panels are the most common: 60-cell modules and 72-cell modules.
You have surely noticed how the surface of solar panels has a grid-like appearance. Each space in the grid contains a separate solar cell, and they are wired together in series to add up their voltages. The rated voltage is typically 20V for 60-cell modules, and 24V for 72-cell modules. Smaller solar panels with 36 cells and a 12V rating are also common, but they are not normally used in rooftop solar systems. Solar cells with a blue color are composed of multiple silicon crystals (polycrystalline), while black solar cells are formed from a single crystal (monocrystalline).
Normally, 60-cell solar panels are described as residential and 72-cell panels are described as commercial. However, this does not limit their use in buildings: you can assemble a residential solar system with 72-cell modules and it will work normally, just like you can use 60-cell solar panels in a commercial building.
Both types of solar modules have their cells arranged in rows of 6, which means their width is the same. The difference lies in the number of rows: 60-cell modules have 10, while 72-cell modules have 12, which makes them taller.
Weight also varies depending on the solar panel model and manufacturer. Most 60-cell solar panels weight around 40 pounds, while 72-cell panels weight around 50 pounds. The extra weight and length of 72-cell solar panels makes them more difficult to handle by a single person, but this is not an issue considering that solar installers work in teams.
Since 72-cell modules have 12 additional cells, they normally have a higher wattage than their 60-cell counterparts. Most 72-cell solar panels are rated above 300 watts, while 60-cell solar panels are below that value. Some of the most efficient 60-cell panels are slightly above 300 watts, but on average they are still below the output of 72-cell panels.
There is a common misconception that 60-cell modules are exclusively for homes while 72-cell modules are exclusively for commercial buildings. However, this is just a naming convention and not a technical limitation. Ideally, you should select the option that will result in the lowest cost per kilowatt of capacity. In medium- and large-scale applications, 72-cell solar panels are almost always the best option:
Of course, every project is unique and you can only determine the best option with a professional assessment of your site. Based on the dimensions of the available area, there may be cases where 60-cell modules allow a more efficient use of space than 72-cell modules. If you plan to use micro-inverters instead of conventional string inverters, 60-cell modules tend to be the best option. Many 72-cell modules exceed the wattage of commercial micro-inverters, and the surplus power output is wasted.
Since residential solar power systems are smaller, the racking and labor savings of 72-cell solar panels are less noticeable, and 60-cell panels may be the best option if some cases. Like with commercial systems, a professional assessment is recommended to determine the most suitable system configuration.
Assume you have space for 20 solar panels of either type. You have a technical proposal with 60-cell modules rated at 290 watts, and another with 72-cell modules rated at 330 watts. The installed capacity is 5.8 kW DC with 60-cell modules, and 6.6 kW DC with 72-cell modules.
Two important factors to consider here are the cost of each system and surplus generation. Remember that you save the full price of each kilowatt-hour when consuming the output of your solar array, but only get a small feed-in tariff for surplus generation exported to the grid.
Solar system providers normally calculate financial performance metrics for their technical proposals. Ideally, you should go for the option that yields the highest return on each dollar spent.
In this example we assumed that space is not an issue, but it becomes an important design consideration in some projects. For instance, a smaller rooftop may have enough space for two rows of 60-cell modules, but only one row of 72-cell modules. In this case, the 60-cell modules still allow a capacity of 5.8 kW, but the larger 72-cell modules limit system size to only 3.3 kW.