Should you buy Grape Solar panels from Costco or Home Depot?

Grape Solar panel kit review EnergySage

Installing solar panels is fast becoming a home improvement project that any homeowner can take on. Now that you can buy solar panels at Costco and Home Depot, you may even be considering installing a home solar energy system yourself. One of the most popular DIY options is to purchase a solar panel kit from Grape Solar, an Oregon-based solar panel manufacturer whose products are for sale at Costco and Home Depot. But before you make a Costco solar purchase, we recommend you learn more about how Grape Solar panels compare to other solar panel brands.

How Grape Solar reviews compare to other panel manufacturers

There are four key metrics to consider when evaluating solar panel quality: (1) panel efficiency, (2) warranty, (3) performance, and (4) price. To help you understand Grape Solar panel quality, we’ve analyzed the technical specs of their panels and compared them to other leading panel manufacturers offered on the EnergySage Solar Marketplace.

1. Efficiency

Solar panel efficiency refers to how well your solar panel can convert sunlight into usable electricity. A higher efficiency rating is better, because it means that your solar panel is able to convert more of the sunlight it captures into electricity. The best solar panels available on the market today operate at approximately 22 percent efficiency.

The graph below shows how Grape Solar panels measure up when compared to 24 of the most popular solar panel brands offered to solar shoppers on the EnergySage Solar Marketplace. As you can see, the most common solar panels out there fall between 14 and 18 percent panel efficiency, and Grape Solar panels fit comfortably within that range. Our review of Grape Solar panels found that they have an efficiency rating of anywhere from 16 to 17.5 percent.

Grape Solar panel efficiency

2. Temperature Coefficient (Performance)

The temperature coefficient tells you how well your solar panels will perform in less-than-ideal conditions. Solar panels are like any other kind of electronic equipment: they operate most efficiently when they are kept cool (ideally around 25° C or 77° F). The temperature coefficient gives you a sense of how your panel’s performance will degrade during hot summer days. For every degree above 25° C, your solar panel’s electricity production will decrease by the temperature coefficient.

For example, Grape Solar’s GS-S-160-Fab8 model has a temperature coefficient of -0.5. This means that if your solar panel’s temperature increases by one degree (from 25° C to 26° C), its electricity production will fall by 0.5%. If the temperature increases to 35° C (or 95° F), Grape Solar panels will produce five percent less electricity. While 95° F might seem high to you, remember that the surface of your roof can get much hotter than the air around it when the sun is beating down on it.

A lower temperature coefficient is better, and the best solar panels available on the market have a temperature coefficient of -0.25. Grape Solar panels have a temperature coefficient that ranges from -0.4 to -0.5, which is slightly less competitive than the mid-range seen in the EnergySage Solar Marketplace.

Grape Solar panels performance


3. Warranty

Whether you’re buying a new TV, a car, or solar panels for your roof, you should expect that the manufacturer will stand behind their product with a strong warranty. A solar panel’s materials warranty (sometimes referred to as the product or equipment warranty) protects you against equipment failures due to manufacturing defects or environmental issues. Most companies, including Grape Solar, offer a 10-year materials warranty, but the best solar panel manufacturers will guarantee against equipment failures for 15 or even 25 years. For example, on EnergySage approximately a third of the panels offered by our top 25 manufacturers come with a 25-year warranty. Grape Solar’s warranty is right in the middle range of the marketplace, at 10 years.

Grape Solar materials warranty

4. Price

Perhaps the most important question of all – are you going to save money when you buy solar panels at Costco or Home Depot? How does the cost of Grape Solar panels compare to other panel brands?

As of January 2018, buying a 5,300-watt (5.3 kilowatt) solar panel system at Home Depot will cost you $10,499 before any tax credits or other financial incentives. Subtract the 30 percent federal tax credit for solar, and you reduce your equipment costs to $7,350. However, these off-the-shelf prices for Grape Solar panels don’t include installation costs, and not every state allows you to connect DIY solar installations to the grid. By comparison, on EnergySage, a fully installed and grid-connected 5 kW solar panel system can cost as little as $8,500 (depending on where you live).

Don’t need a 5 kW system? Home Depot also offers a 3,180-watt (3.18 kW) solar panel system for $6,657. Again, subtract the 30 percent federal tax credit – your equipment costs are now $4,660. By comparison, you can get a fully installed and grid-connected 3.5 kW solar panel system on EnergySage for as little as $5,950 – just a few hundred dollars more for the installation labor.

Of course, the price that you end up paying for your solar panel system depends on the equipment that you choose. Grape Solar manufactures mid-tier panels for a reasonable price, but they are not the cheapest solar panel prices we’ve seen offered. As with any major home improvement decision, you should always compare prices and reviews for multiple products before you make your purchase. You can easily evaluate solar panel quotes from qualified solar installers side-by-side on the EnergySage Solar Marketplace to see how a Grape Solar panel kit stacks up against the competition.

Grape Solar panel reviews compared to competitors

Grape Solar Panels 25th Percentile 50th Percentile 75th Percentile
Efficiency (%)  16.2 – 17.4%  15.7% 16.2% 16.8%
Temperature Coefficient  -0.4 – -0.5  -0.45 -0.43 -0.41
Warranty (Years)  10 10 12 25
Price ($/Watt)  $1.98 – $3.01  $3.25 $3.50 $3.75

Should you buy solar panels at Home Depot or Costco?

If you’re looking at Costco or Home Depot solar panels, Grape Solar will be one of your only options. Why is this? Most solar panel manufacturers don’t sell directly to consumers, but instead sell their products to solar installation companies via distributors. This means that many of the industry-leading solar panel brands, like SunPower and Panasonic, just aren’t available for you to buy directly at the hardware store – you need to work with a local solar installer that offers those products.

Finding someone who knows what they’re doing can actually save you both time and money. Some of the best solar installers have been installing solar energy systems for decades – experience that no amount of online research or DIY guides can replace.

Your solar installer will also help you complete and file the permits and applications that you’ll need to submit to get your solar energy system up and running. Even if you’re ready and able to do all of the installation work yourself, you’ll still need to find a certified electrician to sign off on your work before your utility will allow you to connect your new solar panel system to the grid.

In the end, there are still some cases where DIY solar makes sense. If you’re looking to install a small PV system, and comfortable doing your own electrical work, and not prohibited from installing your own system, then buying your solar equipment online might be just what you need. In these situations, buying Grape Solar panels can be a reliable, no frills option. Compare several options beforehand, and click the retailer link on the table below once ready.

Product System Size (Watts) System Cost Dollars per Watt Retailer Link
Grape Solar grid-tied solar PV system 5,300 $12,009 $2.26 Home Depot
Grape Solar grid-tied solar PV system 3,180 $7,332 $2.30 Home Depot
Grape Solar grid-tied solar PV system 2,300 $9,238 $4.02 Amazon
Grape Solar off-grid solar PV system 480 $1,199 $2.50 Amazon

Note: This post contains affiliate links. We only link to products that we think are great.

One thought on “Should you buy Grape Solar panels from Costco or Home Depot?

  1. Nelson Gibson

    Oh, wow! Where do I begin? Who pays your salary? There is an obvious bias in the article. The graphs in the first two sections on efficiency and performance do not support your claims. You include the graph lines from other manufacturers lumped together as a whole and compare them to a Grape Solar Panel from Cost Co or Home Depot. One panel might have high efficiency specs and poor performance or vice versa. I could comment further, but that should be enough for you to rethink the article.
    However, I tend to agree with your conclusion. Buying panels at Cost Co or Home Depot piece by piece is not a wise investment.
    I am a retired electrical engineer. I plan to start a DIY 4.5 kW solar panel installation maybe the end of this year or next year. I am doing my research now.
    This year I am taking a 40 day Australian cruise and a month travel vacation traveling in the USA. That is in addition to two months vacation in the Bahamas. And, yes, I do have my priorities in the correct order. (Smile.)
    Happy New Year to you. May all your resolutions for 2018 come true.


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