How Fast Does a Solar Cover Heat a Pool?

Pool water feels really refreshing on a hot summer day, but many people underestimate just how cold they can get after spending some time in the pool. Water is extremely effective at conducting heat away from the human body, causing our core temperature to drop rapidly. For some people, the pool water is just a little bit too cold for comfort, so it’d be beneficial to heat it up slightly.

A very effective and affordable way to do so is to place a solar cover over their pool. That way, you don’t need to install expensive gas or electric pool heaters or anything fancy like that. However, when something sounds too good to be true, people reasonably have questions like how effective are solar covers really? How long does it take to heat a pool with a solar cover?

On average, you can expect a fully covered swimming pool to increase in temperature by 10-15°F. This is assuming that the pool was covered up for at least 3 consecutive sunny days. You can reasonably expect to heat a pool up by 2-5°F every 8-12 hours. In order to retain the heat stored in the pool, you must also leave the solar cover on the pool at night.

Are you confused at all about how this works? Keep reading on to learn the benefits of using a solar cover, how it works, and the recommended practices for it to achieve the best heating results.

What does a solar cover do?

A solar cover will help your pool get a bit warmer and retain that heat for as long as possible. They work best when used in conjunction with a heat pump or pool heater because as the heater is working, the solar cover will ensure minimal heat loss to keep your pool warmer for longer.

In addition to its thermal benefits, it also does what a regular pool cover does as well. Solar covers can keep insects and debris out, reduce water evaporation, and help you save on your water and hydro bill.

How does a solar pool cover work?

Now that you know what a solar cover does, you might be confused about how it’s doing it. A misconception people often have is that the solar cover can make their pool really warm as a heater can. As mentioned, you can expect around a 10-15°F increase in temperature after 3 consecutive days of sunlight, and no other sources of heat.

That said, solar covers are designed to maintain heat. If used in combination with an external pool heater, it can help the pool heat up much faster since heat will not continuously be lost to evaporation or wind. Solar covers themselves are not a source of heating power.

Since evaporation is the primary cause of heat loss, a solar cover plays a crucial role in acting as a barrier between the pool water and air. It is at its most effective at night when temperatures drop because the solar cover will help the pool retain the heat that was absorbed during the day and prevent evaporation.

Solar covers will help your pool warm up faster in the spring and fall when it’s still a bit chilly, but another misconception is that it will keep your pool warm in the dead of winter. Again, solar covers are not a source of heat. You’d need a heater to keep your pool warm during winter.

Should you leave the pool pump on/off with a solar cover?

You should definitely keep your pool pump on if you want your pool to heat up faster and stay at a consistent temperature.

With a pool pump off, you will notice that the water is warmer by the surface and colder below that. The pool pump will help circulate the water so that it’s evenly warm throughout, rather than warmer in some parts and colder in others. This makes the water feel more stable and pleasant to swim or lounge in.

What are the best solar cover colors?

You can get solar covers in different colors, but the most common ones are black, blue, and white.

Black solar covers are the most effective at trapping heat. The color black absorbs the most light, so in milder climates where you want the maximum amount of warmth, look for black pool covers to heat your pool up faster.

Blue solar covers are the most aesthetically pleasing since it blends in with the water. However, in terms of heat retention, it loses out to a black solar cover.

White solar covers don’t absorb much heat and will prevent your pool from overheating if you live in a sunny and hot climate.

Downsides of solar covers

Solar covers are most effective at heating smaller pools, and will have diminishing effectiveness the larger your pool is. If your pool is deep, solar covers will probably not be that effective at heating your pool up unless you are using the pool heater to help out.

Furthermore, since solar covers only work if your pool is covered by them, this can be inconvenient for you. You may want to use the pool frequently during the summer, and having to cover it up and uncover it so often can be annoying.

Additionally, without a pool heater, it can take a long time for the solar cover to trap enough heat to cause your pool to feel noticeably warmer. Ideally, you’d need 3 consecutive days of sunny weather for your pool to warm up.

Therefore, you are at the mercy of the weather. If there are cloudy or rainy days interspersed, then that can undo all the heat that the solar cover trapped the day(s) before.

Don’t expect miracles

Solar covers are a highly versatile and useful piece of pool equipment that you should probably own. However, you must keep your expectations in check.

I have to reiterate that solar covers do NOT heat pools. There must be an external heat source such as a pool heater or clear skies for the sun’s rays to reach the pool. Solar covers merely trap heat; it does not generate any on its own.

If you want to rely entirely on the sun to heat your pool, understand that it becomes less feasible of an option the larger your pool is. It could literally take days before your pool is only a few degrees warmer. That said, if you live in a hot climate, then this may be a possible option.

Solar covers are most effective when used in combination with a pool heater. Without a solar cover, much of that heat will be lost at night due to the cold air and evaporation. Solar covers can help you save money on water and energy bills, but they aren’t going to magically make your pool warm in the winter.