How do solar pool covers work?

Solar pool covers retain heat and minimize evaporation. They contain small air pockets that capture heat from the sun, which they then transfer to the water in the pool. Solar covers also act as insulators, so heat can't escape the water. Solar covers are great ways to reduce pool heating costs, as they use heat from the sun to insulate and minimize evaporation as opposed to a traditional pool heater , which requires electricity.

Are solar pool covers effective?

Solar pool covers are effective as long as you use them consistently. Using one overnight can reduce heat loss and make the water warm enough to swim in the next day.

Do solar pool covers cause algae?

Although it could be argued that higher temperatures in pool water may cause algae to grow, solar pool covers alone don't typically cause this. A number of factors can cause algae growth, including the presence of nitrates, very warm temperatures, rain water, and imbalanced chemicals. Having low chlorine levels in your pool can cause algae to grow very rapidly. Also, make sure rain water doesn't get stuck on top of your solar pool cover, as this can increase the risk of algae growth as well. As long as you clean and care for your cover and pool regularly, you shouldn't have any problems.

The 7 Best Solar Pool Covers of 2022

The 8 Best Solar Pool Covers of 2022 — The Spruce / Chloe Jeong

A solar pool cover provides many benefits—raising water temperature using solar energy, preventing heat loss through evaporation, and shielding the water from UV exposure that can impact chlorine levels. We spent hours researching the top solar pool covers available online, considering ease of installation and use, durability, and overall value.

Our favorite, the Sun2Solar 1200 Series Rectangle Solar Pool Cover, keeps pool water at a comfortable temperature, is up to 95% effective at preventing evaporation, and can be cut to fit most pool shapes.

Here are the best solar pool covers.

Our Top Picks

Best Overall:

Sun2Solar 1200 Series Rectangle Solar Pool Cover at Amazon

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Best Budget:

Sun2Solar 800 Series Solar Pool Cover at Walmart

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Best for In-Ground Pools:

Pool Supply World Velox Silver Solar Cover at Poolsupplyworld.com

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Best for Above-Ground Pools:

Summer Waves Adjustable Round Solar Pool Cover at Amazon

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Best Round:

Midwest Canvas Space Age Solar Blanket at Amazon

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Best Oval:

Midwest Canvas Supreme Solar Cover at Poolsupplyunlimited.com

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Best for Hot Tubs:

Spa Depot Thermo-Float Spa Blanket at Amazon

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Best for Heat Retention:

In the Swim Premium Plus Solar Blanket at Amazon

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In This Article

Our Picks
What to Look for
Why Trust The Spruce

4.7

Courtesy of Amazon.

View On Amazon

What We Like

Minimizes changes in water chemistry
Easy to roll
Trim to fit

What We Don't Like

Not available in round or oval shape

What do buyers say? 77% of 6,300+ Amazon reviewers rated this product 4 stars or above.

This pool cover from Sun2Solar is our top pick because it is available in a variety of sizes and it keeps your pool warm after a long day in the sun. Made of a flexible resin, this cover is durable enough to withstand the elements yet thin enough to transmit solar heat. However, this cover can be prone to rip because of its thin construction, so always be cautious when rolling it up and storing it during the off-seasons.

Air bubbles cover the bottom of the Sun2Solar pool cover; place them face down in the water, leaving the smooth side facing up. The surface of the light blue cover absorbs UV rays from the sun, while the bubbles transmit the absorbed energy into the water. Although clear solar pool covers transmit more of the sun’s energy into the water, they also let in more UV rays that cause significant changes to pool water chemistry—requiring more chemicals to avoid algae and maintain ideal water conditions.

This light blue cover is a more versatile option for homeowners that are looking for a pool cover to keep out debris, lock in heat at night, and absorb the sun’s energy during the day. It can even be trimmed to better fit your pool, if it’s between sizes.

Size: 15 x 30 feet | Shape: Rectangle | Thickness: not listed | Material: Plastic | Weight: Approx. 30 pounds

Courtesy of Walmart

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What We Like

Blue resin blocks UV rays
Trim to fit

What We Don't Like

More prone to tearing

A pool cover is a smart way to save time and money, since it can protect your pool from debris, heat loss, and minimize the effect of UV rays on your chlorine levels. If you’re also looking to minimize your spending on the pool cover itself, then this option from Sun2Solar is an affordable solution.

Made of 8 mil thick resin, this is not the thickest solar pool cover on the market but it gets the job done. Be sure to pull gently when setting up or removing the cover from your pool. It’s available for small to large swimming pools and can be trimmed to fit your pool specifically. The light blue color of this solar cover absorbs the sun’s energy while reducing its effects on your pool’s chlorine levels.

Size: 18 x 38 feet | Shape: Rectangle | Thickness: 8 mil | Material: Not Listed | Weight: Not Listed

Pool Supply World Velox Silver Solar Cover

Courtesy of Pool Supply World

View On Poolsupplyworld.com

What We Like

Protects against UV rays
Extra durability from 16 mil thickness

What We Don't Like

Heavier to fold or roll

Whether you plan to use your solar cover during the day or at night to prevent a steep drop in your in-ground pool's water temperatures, this Velox Silver Solar Cover has your pool covered. It’s available in various sizes ranging from 12 x 20 feet to 25 x 50 feet.

The UV-resistant silver-colored material allows the sun’s energy to pass through to the water below but also protects against some of the effects of UV exposure on pool chemicals. A thickness of 16 mil means extra durability, which is handy if you plan to use a pool cover reel to easily store your in-ground pool solar cover.

Size: 16 x 32 feet | Shape: Rectangle | Thickness: 16 mil | Material: UV Resistant | Weight: Not Listed

Summer Waves Adjustable Round Solar Pool Cover

Courtesy of Amazon

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What We Like

Drawstring adjusts for various pool sizes
Made of durable PVC

What We Don't Like

May be loose on smaller pools
Only fits pools up to 15 feet in diameter

In-ground pools benefit from ground insulation, but above-ground pools have to contend with ambient temperature loss through the pool sides. Plus, these pools are still subject to heat loss through evaporation. A solar cover for above-ground pools solves these problems while minimizing the time you need to spend skimming your pool of leaves, bugs, and pollen.

The Summer Waves Adjustable Round Pool Cover is sized for above-ground pools with a diameter of 10 to 15 feet. A drawstring cord allows you to pull the cover snugly around the pool perimeter. Keep in mind that smaller pools don’t have as tight a fit, but this cover does provide a solid surface to keep debris from falling into your pool. It’s made of a thick, durable PVC that is also opaque for UV resistance.

Size: 10-15 feet | Shape: Round | Thickness: Not Listed | Material: PVC | Weight: 9.3 pounds

The 7 Best Above-Ground Pools of 2022

Courtesy of Pool Supplies

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What We Like

Silver bubbles to transfer heat
10 year limited warranty

What We Don't Like

Expensive

For a round solar pool cover, consider this option from Midwest Canvas. The Space Age Solar Blanket is a 12 mil thick solar pool cover, thick enough to withstand frequent setup and removal. It fits pools of various diameters, depending on which option you select. (You can always trim the cover if it’s a little too large.) This version stands out for its "space age" silver air bubbles, which transfer the sun’s energy but minimize the effect of UV exposure on chlorine levels in your pool.

Size: 16 feet | Shape: Round | Thickness: 12 mil | Material: Resin | Weight: Not Listed

Midwest Canvas Supreme Solar Cover for Oval Pools

Courtesy of Pool Supply Unlimited

View On Poolsupplyunlimited.com

What We Like

Clear for better heat absorption
5-year warranty

What We Don't Like

Above-ground pools only

If you have an oval-shaped pool, shop for a solar cover that matches your pool’s shape and dimensions. Round pool covers may leave the end of an oval pool exposed, while rectangular solar pool covers may have too much overhang.

The Supreme Solar Cover from Midwest Canvas is made to match the shape of oval pools and comes in seven sizes. Like many other top solar pool covers, this one is also 12 mil thick. It’s clear, so it allows most of the sun’s energy to pass through and heat the water. Keep in mind, though, that this may also mean you need to add more chlorine to the water.

Size: 16 x 32 feet | Shape: Oval | Thickness: 12 mil | Material: Not Listed | Weight: Not Listed

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Courtesy of Amazon

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What We Like

16 mil thick material
Reduces heat loss up to 95 percent

What We Don't Like

Only available in one size

A hot tub solar cover keeps out debris but also conserves energy. A spa blanket, as they’re sometimes referred to, reduces heat loss—keeping your hot tub warmer and ready to go with less energy usage. This option from Thermo-Float is made of thick 16 mil material that is durable and energy-efficient. Unlike thinner solar pool covers that are 8 or 12 mil thick, this version prevents up to 95 percent of evaporative heat loss.

It measures 8 x 8 feet, but the manufacturer advises you to trim it to fit your spa, with an overhang of about 2 inches. Place the plastic bubbles facedown; they absorb solar energy and transfer it into your hot tub water.

Size: 8 x 8 feet | Shape: Square | Thickness: 16 mil | Material: Not Listed | Weight: Not Listed

The 8 Best Hot Tubs of 2022 for Relaxation and Style

Courtesy of In the Swim

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What We Like

Aluminized cover to transfer heat
Blocks UV rays
7-year limited warranty

What We Don't Like

Heavy to move

If your primary purpose for a solar cover is to maintain your pool’s temperature, then shop for a dark-colored solar blanket. This blue-black version from In the Swim is designed to retain heat and prevent evaporation. The solar cover is 12 mil thick and features an aluminized bottom to boost heat transfer from the sun’s rays to the pool water. It can raise water temperatures up to 15 degrees while at the same time reducing the amount of debris that lands in your pool.

Size: 16 x 32 feet | Shape: Rectangle | Thickness: 12 mil | Material: Not Listed | Weight: Not Listed

The 9 Best Pool Cleaners of 2022

Final Verdict

The Sun2Solar 1200 Series Rectangle Solar Pool Cover (view at Amazon) is our top choice. This rectangular cover features thick plastic construction, which makes it excellent at retaining heat and preventing evaporation. For a budget-friendly choice, we recommend the Sun2Solar 800 Series cover (view at Walmart). Made of 8 mil thick resin, this is not the thickest solar pool cover on the market but it gets the job done.

Size

Choose a solar pool cover that approximately matches the dimensions of your pool. However, know that you can trim most pool covers to fit your pool's specific size and shape without voiding the manufacturer’s warranty. If you’re in between solar pool cover sizes, go with the larger size. You may also need to trim a pool solar cover for a uniquely shaped pool such as a kidney pool.

Thickness

Thickness is an important consideration when buying a pool cover since it impacts how heavy the pool cover is along with its durability. Thicker pool covers are less likely to tear or rip when putting the cover on your pool or removing it. Additionally, thinner pool covers typically allow more of the sun’s energy to reach the water below the cover—but also may allow for more heat loss during the night. The thickness of a solar pool cover is measured in millimeters. Typically, you find 8, 12, or 16 mil options, though other thicknesses (like 14 mil) are sometimes seen, as well.

Material

There are three primary materials for solar pool covers: vinyl, polyethylene, and polypropylene. Vinyl pool covers are very durable but can be heavy. Polyethylene and polypropylene covers are very common; choose a thicker cover if you want one that is more tear-resistant.

You also have choices regarding the color of the solar cover. Opaque (or solid color) pool covers block UV rays that impact pool chemistry but also result in less passive heating from solar energy. Clear solar covers allow the sun’s rays to pass through to the water below and can result in the largest temperature rise, but also frequently cause an increased need for chlorine. Silver or light blue covers, that fall in between opaque and transparent, are often a good compromise. Solar covers made of these materials block some UV radiation while still allowing for solar heating.

FAQ

How do solar pool covers work?

Solar pool covers retain heat and minimize evaporation. They contain small air pockets that capture heat from the sun, which they then transfer to the water in the pool. Solar covers also act as insulators, so heat can't escape the water. Solar covers are great ways to reduce pool heating costs, as they use heat from the sun to insulate and minimize evaporation as opposed to a traditional pool heater, which requires electricity.
Are solar pool covers effective?

Solar pool covers are effective as long as you use them consistently. Using one overnight can reduce heat loss and make the water warm enough to swim in the next day.
Do solar pool covers cause algae?

Although it could be argued that higher temperatures in pool water may cause algae to grow, solar pool covers alone don't typically cause this. A number of factors can cause algae growth, including the presence of nitrates, very warm temperatures, rain water, and imbalanced chemicals. Having low chlorine levels in your pool can cause algae to grow very rapidly. Also, make sure rain water doesn't get stuck on top of your solar pool cover, as this can increase the risk of algae growth as well. As long as you clean and care for your cover and pool regularly, you shouldn't have any problems.

Erica Puisis has been covering the best products for outdoor and indoor living at The Spruce since 2017. Her research and areas of expertise have included pool heaters, cleaners, and water testing equipment. To find the best options for this essential pool accessory, she considered the thickness of each solar cover, its ability to retain heat, block UV rays, or provide passive heating for pool water, and the length of any warranty periods.