Solar Panels: Everything You Need To Know [Mini-Course Part 2/6]
Solar panels are the poster child for solar energy. They are easily the most visible and recognizable part of any solar power system, and therefore attract a lot of attention and questions. In this lesson, we will break down everything you need to know about solar panels for your off grid, DIY, or portable solar solution.
What are Solar Panels and Why Do We Need Them?
For many, the first solar panel they ever used was built in to power a small calculator. In the past 20 years, however, the popularity of solar panels on homes, RV’s, and vans has skyrocketed.
It is important to note that there are two main types of solar collectors: solar thermal and photovoltaic (PV) panels. Solar thermal collectors are mainly used to generate heat for water and usually look like a series of tubes. In this article, we are going to be talking about photovoltaic (PV) solar panels, which are used to generate electricity from sunlight.
In order to create an DIY solar energy system, you will obviously need solar panels. Solar panels are one of the best solutions for off grid power, because they can generate electricity anywhere in the world, so long as the sun is shining. As a global society, the adoption of solar power is extremely beneficial in the pursuit of renewable energy sources and a reduction in carbon emissions.
How Do Solar Panels Work?
Solar panels are made up of individual solar cells. Whenever sunlight hits an individual cell, an electric field is created in between the positive and negative lays of silicon. Silicon acts a semiconductor, and is the second most abundant element in the Earth’s crust, after oxygen. Once the electricity is generated, it is sent through the rest of the system to be used immediately, fed into the utility grid, or stored in a battery. The electricity generated by a solar panel is naturally direct current (DC). Most DIY off grid solar panel systems use an inverter to modify the electricity to alternating current (AC). This makes it usable for most home appliances.
Mono Vs. Poly Solar Panels
If you have been browsing PV solar panels for your off grid system, then surely you have come across the two main types: Monocrystalline (Mono) and Polycrystalline (Poly). The only difference between the two technologies is the amount of silicon in each cell. If you’ve brushed up on your latin, you may be able to guess that monocrystalline solar cells are made up of one single crystal of silicone, whereas polycrystalline solar cells are created by melting many silicon fragments together.
In general, mono panels are seen as the “premium solar panel.” Monocrystalline panels are usually more expensive, but also more efficient than polycrystalline cells. The easiest way to distinguish between the two is the color. For the most part, mono panels are blackish, while poly panels are blue. Depending on your budget and space, both types of solar panel can perform very well in generating plenty of electricity.
Solar Panel Size (Watts)
The power capacity of solar panels is rated in wattage (W). In small, DIY situations, it is common to see panels that are 100W & 200W. Many offgrid homes utilize larger sizes around 300W. The bar is constantly being raised as manufacturers around the globe continue to develop and test even high wattage panels.
Electricity is measured in watt-hours(Wh), so the wattage size of solar panels relates directly to the output potential. Let’s say you have three 100W solar panels (3 x 100W = 300 Watt solar panel) on your portable RV solar system. This means that for every hour your solar panels are working in ideal conditions under direct sunlight, the system should be able to generate a total of 300 watt-hours (Wh). If you receive 5 hours of sunlight, then your 300W solar panel setup will generate 1500Wh or 1.5 kilowatt hours (kWh) that day.
Wiring Solar Panels: Series vs. Parallel
Whenever it comes time to mount and wire your solar panels, there are two distinct methods you can use: series or parallel. In a series connection, all of the solar panels must be the same amp rating and voltage, as they essentially act as one large unit. In a parallel circuit, each panel creates power on its own and sends it through the charge controller with a combined amperage.
There are advantages and disadvantages to both methods. In an offgrid array in which every panels receives nearly the same amount of sunlight through the day, a series connection may be easier and also more efficient. In a portable solar setup, in which panels are more prone to bouts of shade or possible damage, a parallel connection can be better because it relies on individual cell performance, rather than the series as a whole.
It is also possible to wire your solar panels together in a series and parallel manor simultaneously. For more information and diagrams on series and parallel wiring, you can read our article which explains the differences even further.
Rigid vs. Flexible Solar Panels
Within the realms of mono and poly technology, there are two different types of solar panels: rigid and flexible. Rigid PV solar panels are the traditional, flat rectangles that you see on top of homes and in solar gardens. Flexible panels weigh considerably less than their rigid counterparts and can be curved for up to 30 degrees. Each technology has its pros and cons, and rigid or flexible solar panels may suit your individual needs more than the other.
Rigid solar panels are generally more efficient and durable than flexible solar panels. They are also generally warrantied for longer periods of time. Rigid solar panels are recommended for permanent installations.
Flexible solar panels are lightweight and extremely easy to install on a variety of surfaces. In terms of installation drawbacks, rigid solar panels may require you to drill holes in the roof of your cabin or RV. However, flexible solar panels have been known to trap heat and damage the roof an RV.
Folding vs Suitcase (Blanket) Solar Panels
If you’re trying to make your solar energy system as portable as possible, then you are probably interested in a folding or suitcase set of solar panels. Although the terms can be used somewhat interchangeably, suitcase solar panels are essentially a specific type of foldable solar panel. Both folding and suitcase panels can become long lasting, efficient solutions for generating remote solar electricity.
Foldable solar panels have also been referred to as solar “blankets.” These are quick, convenient, roll-out arrays of high powered solar panels that are either flexible or rigid. They are made to be lightweight and durable so that users can set them up wherever they are.
Suitcase solar panels refer to a specific type of folding solar panel. Generally, suitcase solar panels contain two identical, rigid, and high efficiency solar panels that can be folded up and carried with a handle. Suitcase solar panels also usually come with a stand in order to prop them up at the best angle for the sun to hit.
Solar Panels Conclusion:
Depending on what type of system you're building, there are a number of factors that go into choosing the "best" solar panels. Wether you're looking for panels to mount to your roof, open when you get to the campsite or bring along with you on a hike or day at the beach, we always recommend figuring out how and you're planning on using the solar panels for before you start shopping. You can see our complete collection of solar panels here.
If you still have questions, feel free to reach out or give us a call at 877-242-2792.
Also consider our next guide for assembling your own solar power system - How to Use a Solar Panel