Solar panel buyer’s guide
04 Feb 2024
There are thousands of solar panels available – how do you know which ones to use for your installation? Some important aspects to consider when comparing your options include panel type, cost, wattage, efficiency, and warranty offering. All of these aspects plus more are considered in each panels' quality rating.
Types of solar panels
Solar panels are generally broken into two groups by cell type: monocrystalline and polycrystalline. While there are other types of solar technologies that exist (like thin-film cells), the majority of photovoltaic solar panels available for installation are either monocrystalline or polycrystalline, and are made out of silicon.
The main advantage of installing a solar plus storage energy system is that it gives you the ability to use solar electricity even when the sun isn’t shining. When you install a solar panel system without a battery, excess electricity that your system generates is sent back to the grid. With a solar battery, that energy can be stored and drawn on when the sun goes down, and you’ll only need to draw and pay for energy from the grid when your battery is depleted.
Monocrystalline solar panels are thought of as a premium solar product and are made with silicon wafers cut from a single crystal, hence the name "monocrystalline". In general, monocrystalline panels are capable of higher efficiencies than polycrystalline panels.
Polycrystalline solar panels are also made from silicon, but their cells are made by melting together many fragments of silicon rather than from a single silicon crystal. While polycrystalline panels usually have lower efficiencies than their monocrystalline counterparts, they often have a lower price point.
Solar panel efficiency
What does it mean for a solar panel to have a higher or lower efficiency than another panel? Simply put, solar panel efficiency is a measure of a solar panel's ability to convert incoming sunlight into usable electricity. This is important because higher efficiency panels produce more energy with less space than lower efficiency models. Most solar panels today have efficiencies ranging from 15% to 20%, but some manufacturers sell panels that exceed 20% efficiency ratings.
Solar panel cost
The cost of a solar panel installation varies by location, property type, and, of course, the panels used for the installation. Premium solar panel products with high efficiencies and advantageous warranties usually cost more money upfront but can offer higher potential long-term savings. The best way to evaluate the price of a solar panel installation is in dollars per watt ($/W). Similar to comparing dollars per square foot when shopping for a home, $/W helps standardize the cost of solar by showing the cost of solar on a per watt basis. Currently, the average price of a solar panel system install in the U.S. is $2.91/W.
The best way to estimate how much a solar installation will cost you is with EnergySage’s Solar Calculator. Our tool takes into account how much sunlight you’ll get, local electricity rates, as well as any state and federal solar incentives like rebates and tax credits.
How do solar panel warranties work?
There are two types of solar panel warranties to be aware of: the equipment (or materials) warranty and the performance warranty.
Equipment warranties cover the physical integrity of your solar panels. For example, manufacturing defects, premature wear and tear, and environmentally-caused damages are covered by panel equipment warranties. Equipment warranties usually cover any failure due to these factors over a specified time period.
Performance warranties cover the actual production of electricity from solar panels. Photovoltaic panels naturally degrade over time, and a performance warranty protects you against undue degradation rates. Performance warranties guarantee that a certain level of electricity production will be maintained over a specified time period.
The EnergySage solar panel rating system
The EnergySage classification system incorporates technical specifications for solar panels to compare their performance, durability, warranty and overall quality. By assessing each product across a range of metrics, the EnergySage rating system groups equipment into five different classifications: Poor, Fair, Good, Very Good and Excellent.
Products rated as Poor or Fair are at the low end of what is currently available in the market, or may be outdated models no longer produced by manufacturers and rarely stocked by solar installation companies. Equipment receiving Good, Very Good or Excellent ratings must meet a baseline set of criteria rigorously developed so that you can be confident that your solar energy system will meet your needs.
（source from :energysage.com)
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