how to compare solar panel kits for sale

Solar panel kits for sale: how much will they cost and how to compare them

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Most home solar panel systems are installed by a qualified solar installer, but more DIY-minded homeowners are exploring options like solar panels for sale online and solar panel kits for home available for purchase in hardware stores. If you’re one of the millions of Americans considering solar, you’ve probably come across some of the DIY solar products available – but do you know how to choose the best product out of all the solar panels for sale? Here’s your complete guide to finding the right option for your home.

How to compare solar power kits for your home

Not all solar panels are created equal. Solar installers select the equipment for their installations based on their technical specifications and the needs of the job, and homeowners shopping for solar panel kits should do the same.

EnergySage has developed a system that rates solar panels based on three key criteria: efficiency, performance, and warranties. You can use the same criteria to compare your solar equipment options. (We’ve also conducted a complete review of Grape Solar panels, one of the most common solar panel kits available for sale. If you’re considering Grape Solar for your DIY solar installation, be sure to read our review first.)


Solar panel efficiency is one of the most important indicators of a solar panel’s quality. It refers to how well a solar photovoltaic (PV) cell can convert sunlight into electricity, and is presented as a percentage. Panel efficiency is particularly important if you have limited space to install a system and you want to maximize your electricity production.

For solar panel efficiency, a higher percentage is better. The best solar panels currently available on the market have an efficiency rating of approximately 22 percent.

Performance (Temperature Coefficient)

A solar panel’s temperature coefficient rating is a simple way to understand how well a solar panel will perform in less-than-ideal conditions. Like any other electronic device, solar panels work best when they are kept reasonably cool (ideally around 25° C/77° F), and their performance can suffer if they overheat. The temperature coefficient can tell you how your panel’s performance will decline during hot summer days. For every degree above 25° C (77° F), your solar panel’s electricity production will decrease by the temperature coefficient.

For example, Grape Solar’s GS-S-160-Fab8 panel has a temperature coefficient of -0.5%/°C. This means that, if the temperature of your solar panel increases from 25° C (77° F) to 26° C (79° F), its electricity production will decrease by -0.5%. If the temperature of your solar panel increases all the way to 35° C (95° F), its electricity production will decrease by 5%.

As you compare solar panels for sale, remember that a lower temperature coefficient is better. The best solar panels available on the market have a temperature coefficient of -0.25.


Every high-quality electronics manufacturer will offer a warranty to show that they stand behind their products, and solar panels are no different. Aside from the technical aspects of the equipment in your solar panel kit, look for a strong materials warranty (sometimes referred to as a product or equipment warranty). The materials warranty guarantees against equipment failures resulting from manufacturing defects or environmental issues. Most manufacturers of solar panels for sale will offer at least a 10-year materials warranty. The best manufacturers will offer materials warranties of 12, 15, or even 25 years.


When to buy (or not buy) a solar power kit

The solar panels for sale online and residential solar panel kits available in hardware stores can be the ideal solution for some situations. If you’re not trying to power your entire home, but rather are looking to add solar electricity generation to your RV, boat, or “tiny house,” then shopping for small solar panel kits and installing them yourself makes sense.

Similarly, solar panel kits are a good solution if you’re trying to power an area of your property that isn’t connected to an electric line. This is one of the top ways that DIY solar can save you money – running a new electric line is costly, and because powering a barn or toolshed typically doesn’t require a huge electricity load, a small solar panel kit can provide all the electricity you need.

Off-grid solar kits vs. grid-tied solar kits

In many cases, solar panel kits for sale are meant to be installed as off-grid systems. The primary difference between an off-grid solar kit and a grid-tied system is that an off-grid system must provide all of the energy for your home or property, while a grid-tied system can rely on backup power from the electric grid in times where there’s not enough solar energy to go around. In order to completely rely on an off-grid installation, you will need to install a battery or set of batteries to store excess power, so you can pull energy from them when the sun goes down.

An off-grid DIY solar solution can be a solid way to power a shed or a portion of your home, but it may be difficult to install panels, produce adequate power, and store enough for nighttime with an off-grid installation.

Solar panels for sale: comparing DIY solar energy systems for sale

If you want to install a DIY solar project, compare several options beforehand. Grape Solar and Renogy Solar offer a few different DIY products for both grid-tied and off-grid systems, which you can find more information on below.

Solar panel kits for sale: examples of grid-tied and off-grid options

ProductSystem size (watts)System costDollars per wattRetailer link
Grape Solar grid-tied solar PV system5,300$10,185$1.92Home Depot
Renogy Solar Cabin Kit for Off-Grid Solar System3,600$5,649$1.57Amazon
Grape Solar grid-tied solar PV system3,180$6,433$2.02Home Depot
Grape Solar grid-tied solar PV system2,300$9,238$4.02Amazon
Renogy Solar Premium Kit800$2,624$3.28Amazon
Grape Solar grid-tied solar PV system480$1,049$2.18Amazon

When you buy a solar panel kit and install it yourself, you likely won’t have the benefit of backup power from the grid. If you want to be able to power your home at night or on cloudy days, you’ll sometimes need to install a solar battery as part of your solar energy system. That adds an extra cost and can cut into the savings you gain by shopping for solar panels for sale on your own.

On top of the limitations of off-grid solar, installing solar is a complicated proposition. Most of the solar installers out there have years of experience installing solar energy systems for years. Solar is a worthwhile investment, but it will cost thousands of dollars at the start – not exactly the ideal situation for a trial-and-error DIY installation.

Need another reason to work with a solar installer instead of buying solar panels online? Many of the best solar panels for sale on the market aren’t available for you to purchase directly. To buy them, you have to be a solar installer who has a relationship with a solar equipment distributor. In fact, solar installers often get a better price on solar panels for sale, because they are buying in bulk. If your priority is to build a high-performing residential system for your house, your best bet is to work with a qualified, pre-vetted solar installer like the ones on the EnergySage Solar Marketplace.

There are easier ways to save money on your solar installation

In some cases – like installing a solar panel kit on an RV or toolshed – DIY solar can be a major money saver. However, as you investigate the solar panels for sale online, be sure you’re evaluating all of your solar options. That means getting multiple installation quotes from solar installers in your area, in addition to pricing out your DIY options.

In fact, comparing multiple quotes is one of the easiest (and free) ways to reduce your solar installation costs. EnergySage data shows that solar shoppers who compare their options on the EnergySage Solar Marketplace save 20 percent or more off the costs of installation, as compared to shoppers who don’t compare quotes from multiple installers beforehand. The reason is simple: when solar installers compete for your business, you win!

Ready to see how much you can save? Get started by reviewing an instant solar estimate from our Solar Calculator, or register your property to start receiving no-obligation solar quotes today.


2 thoughts on “Solar panel kits for sale: how much will they cost and how to compare them

  1. Luke Smith

    I like your thoughts about solar panel efficiency being an important indicator of panel quality. My cousin was just looking into buying some solar panels the other day, and wasn’t sure what a good measure of quality would be. I imagine that all else aside, how much energy it gains you is a good place to start (although how durable the materials are would probably play a factor as well). I’ll tell him to give your post a read.

  2. Lee Vogtman

    You address the issues of buying cheaper panels, but don’t provide a source to purchase high quality panels, ie Sunpower. I need 3 each Sunpower SP X22-360 panels for our cruising sailboat, and will have to drive several states away where I know I can purchase them, instead of spending my money here at home in Md.

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