SOLAR PANELS

Solar panels are the most recognizable component of a solar power system. Solar panels convert sunlight into electricity through a process called the photovoltaic effect.

Individual panels are made of up several solar cells, which are silicon wafers that are wired together and held in place by the backsheet, frame, and a pane of glass.

A panel string is a group of (typically 4-10) panels wired together in series, which then plugs into an input on a string inverter.

Your solar array refers to all the panels that make up your system. An array may contain one or more panel strings wired into a string inverter, or any number of panels individually paired with microinverters.

When you’re browsing solar panels, you’ll come across two types: monocrystalline or polycrystalline, and two different sizes.

Monocrystalline vs. polycrystalline

Monocrystalline (mono) solar panels contain solar cells which are cut from a single source of silicon. Polycrystalline (poly) solar panels are created by melting smaller silicon fragments and blending them to create solar cells. The blended nature of poly cells makes them slightly less efficient than mono cells, which means mono panels allow you to fit more solar in a smaller space.

While mono panels used to carry a higher price tag due to their increased efficiency, that is no longer the case. As companies have geared their production lines to focus on mono panels, more efficient manufacturing processes have brought the cost of mono and poly panels right in line with each other. Mono cells now represent about 75% of the panels on the market.

60 / 120-cell vs 72 / 144-cell

Full-sized solar panels come in two standardized sizes:

60-cell and 120-cell panels are about 40” by 66”, give or take an inch depending on the manufacturer. 60-cell panels contain 10 rows of 6 cells each. 120-cell panels are the same size and configuration, but the cells are cut in half, which boosts panel efficiency slightly.

72-cell and 144-cell panels are about 40” by 78”, again with small variations depending on the manufacturer. 72-cell panels contain 12 rows of 6 cells each. 144-cell panels are the same form factor, but with half-cut cells.

Larger solar panels are about a foot taller and 8 pounds heavier, which can make them a bit harder to carry during installation, especially if you are installing a system on your roof. Regardless, it should be easily doable with 2+ people assisting the install.

Larger panels can be slightly more cost effective, however your choice often comes down to whichever one will fit best on your rooftop. If you have a tall roof, you may be able to fit two rows of 60-cell panels, whereas a smaller roof may need 72-cell panels to fit as much solar as possible into a limited space.