What are the different types of solar panels?
Almost all solar panels use silicon semiconductor material that makes up the solar cells. There are two primary types of solar panels: polycrystalline and monocrystalline.
Polycrystalline Panels
Poly Crystalline panels are made from silicon material that has a heterogeneous crystal structure that’s created by melting together many specially treated or “doped” crystals. The solid that’s produce is sliced into thin wafers or cells that are then mounted on a flat substrate or backsheet and electrically connected into a series circuit. Polycrystalline solar panels have a distinct flecked appearance and tend to have a bluish hue to them—which are sometimes considerations for customers.
Monocrystalline Panels
Unlike polycrystalline solar panels, monocrystalline panels are made from silicon material that is a single homogeneous crystal. Manufacturing this single crystal structure is a more expensive process but makes monocrystalline solar panels more effcient in transforming solar irradiation into electrical energy than polycrystaline panels. Monocrystalline solar panels also have a more consistent coloration and appear a as darker black—which is more desirable to some customers.
What size and wattage panel do I need?
Solar panels are made in many diffent sizes and power ratings. The wattage of a panel is directly related to the total area of the solar cells in the panel—the larger the panel, the higher the power output.
The typical full-size residential solar panel measures roughly 40 inches wide by 66 inches long and is often composed of 60 solar cells per module. Power ratings for panels of this size range from 300 watts to 350 watts or more. Panels below 300 watts are manufactured in much smaller numbers and are usually more expensive, or a higher price per watt. For a standard off-grid or grid tied system, the full-size 300 watt or larger panel is recommended. Smaller size panels have a place in RV and mobile applications where the size and shape of available array space is at a premium and in remote low-power systems like electric gate operators, scientific monitor equipment and the like.
Higher wattage panels (350-400 watts or more) are more usually used in the higher-voltage residential grid-tied and commercial power generation systems. These panels consist of 72, 96 or even 120 cell modules. Other panels in this class are called bi-facial. Bi-facial panels are essentially two-sided panels with a second layer of solar cells on what would be the bottom side of the module. These panels produce extra power and energy from reflected light that bounces off light-colored roof surfaces.
What voltage should my panel be?
Solar panels are sometimes classified by voltage, such as 12 or 24V. Certain solar charge controllers require the panel voltage to match the voltage of the battery that is being charged. But for the more common charge controllers and high-voltage string inverters or micro-inverters, matching the voltage of the panel is less important since they’re usually wired in strings of multiple panels. Typical residential solar panels have an open circuit voltage of around 38-45V DC.
How do I attach my solar panels?
Solar panels require a safe and secure method of mounting so they can harvest power and energy from solar radiation and with stand environmental conditions like high winds and heavy snow loads. The selection of a mounting system takes into account available southern-facing roof or ground space.
Roof Mounts
A common way to mount solar panels is on the flat surface of a building’s roof. Roof mounts use parallel rails secured to the roof system with feet secured to roof trusses or cross members with the solar panels set on top of these rails and secured with a clamp-type system. Roof mounting solar panels has the advantage of using existing flat roof area. But, they may not optimize the panel angle in relation to the southern horizon, thus reducing the potential energy production of the array.
Ballasted Mounts
Solar panels can be mounted on flat roofs in a less permanent manner by using a ballasted mount. This type of mount uses a weighted row-and-column-style lattice instead of fastening the mounts with screws or bolts to the roof system. The ballast can be sandbags or cinder blocks. Their weight holds the panels to the roof.
Pole Mounts
There are essentially two types of pole mounts. Both involve steel poles, usually made of schedule 40 steel pipe. Top-of-pole mounts use a gimbal that is attached to the top of a vertical steel pipe. The solar panels are then secured to several rails that are attached to the gimbal. Top-of-pole mounts can attach one panel to as many as 12 solar panels on a single pole. These mounts have a lot of flexibility to be tilted to where the sun is—from completely horizontal to 45 degrees. They’re also easy to clean without the need to climb a roof and shed snow very effctively. Side-pole mounts utilize a vertical steel pipe or pole as well and are most often used to mount smaller-wattage panels or as many as three full-size residential panels. However, they aren’t equipped to handle large solar arrays.
Linear Ground Mounts
Linear ground mounts involve a lattice of vertical and horizontal steel poles with solar panels secured to parallel rails that are usually aluminum. The panels are arranged row-and-column style and the entire array can be angled towards the southern horizon—optimizing energy production. Linear ground mounts share the same easy maintenance as top-of-pole mounts when it comes to cleaning and snow removal. Large solar arrays work well with linear ground mounts, with the only limitation being the available ground space.
RV and Mobile Mounts
The most common way to mount solar panels on an RV is to use metal Z-brackets. These brackets are essentially a set of feet that attach with nut and bolt fasteners to holes that are pre-drilled in the bottom edge of the solar panel frame. These feet are then attached to the RV roof with a self-leveling adhesive sealer and mechanical fasteners like stainless steel screws. There are also RV tilt mounts available for 26-inch and 40-inch wide panels.
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