A solar pool cover mostly keeps the heat your pool already has, while a solar pool heater adds new heat. Per the U.S. Department of Energy, a cover can raise water temperature by roughly 5-15°F, and a properly sized heater typically adds a similar amount on top of what the sun does alone. They solve different problems, and most pools do best with both.
Quick answer
Buy a cover first. It costs far less per degree gained and cuts the evaporation that drives most heat loss. Add a solar heater when you want controllable, reliable warmth and a longer season. Pairing them keeps the heat the collectors make.
- Best for tight budgets: a solar cover, about $50-$600
- Best for longer seasons: a heater plus a cover
- Best for cool, shady yards: a cover plus a heat pump
- Covers retain and capture passive heat. Heaters add heat on demand. They are not like-for-like substitutes.
- The Department of Energy says covers can cut pool heating costs 50-70% by reducing evaporation.
- Collector area should be about 50-100% of the pool’s surface area, per the Department of Energy.
- Heater payback runs roughly 1.5-7 years. Covers usually last about 2-6 years.
- Neither option is a safety cover. A cover will not prevent drowning.
- Is a solar pool cover or a solar heater better for my pool?
- Why do pools lose heat?
- How many degrees does a solar pool cover raise pool temperature?
- How many degrees can a solar pool heater add?
- How big does a solar heater need to be?
- How much does each option cost?
- Can I use a solar cover and a solar heater together?
- How does solar compare with a heat pump or gas heater?
- What are the practical downsides?
- Which setup fits your pool?
- What do owners say?
- Frequently Asked Questions
Is a solar pool cover or a solar heater better for my pool?
Neither wins on every count. A cover wins on price and on cost per degree. A heater wins on control, reliability and swim-season length. Here is the quick comparison.
| Factor | Solar cover | Solar heater | Both |
|---|---|---|---|
| Upfront cost | About $50-$600 | About $3,000-$6,000+ | Heater cost plus cover |
| Typical gain | About 5-15°F over uncovered | About 5-15°F, sun and size dependent | Highest and steadiest |
| Season extension | Days to a few weeks | Several weeks | Longest of the three |
| Daily effort | High: on and off, store | Low once installed | Moderate |
| Lifespan | About 2-6 years | 10-20 years for unglazed collectors (DOE) | Mixed |
| Payback | Often within a season or two | About 1.5-7 years (DOE) | Faster than heater alone |
| Best for | Small budgets, small pools | Sunny sites, frequent swimmers | Most owners who want warm water |
One caution on all the numbers in this article. Gains depend on a baseline: the uncovered pool, air temperature, hours covered, and cover type. A “10 degrees” claim means little without those details.
Why do pools lose heat, and how much of the loss is evaporation?
Evaporation is the main culprit. It is commonly cited as around 70% or more of heat loss from an uncovered outdoor pool, and the Department of Energy calls it the main source of loss. Each pound of water that evaporates carries a lot of heat away with it.
The rest leaves in three other ways:
- Convection: wind pulls warm air off the surface and replaces it with cooler air.
- Radiation: the water gives off heat to a clear night sky.
- Conduction: small losses through the walls and floor, larger on above-ground pools.
Night is where most heat disappears. The sun is gone, the air is cooler, and the water is still warm. That is why covering the pool overnight pays off, even if you never cover it by day.
How many degrees does a solar pool cover raise pool temperature?
The Department of Energy and Energy Saver guidance puts the gain at roughly 5-15°F (about 3-8°C) over an uncovered pool. The wide range comes from climate, wind, how many hours the cover stays on, and the cover’s quality.
A cover does two jobs. It absorbs sunlight and passes some of it to the water. More importantly, it blocks evaporation. The Department of Energy says a cover can reduce pool heating costs by 50-70% for this reason.
Cover types
- Bubble (solar blanket): the common choice. Air cells float on the water and trap heat. Blue covers absorb more sun. Clear ones pass more sunlight into the water.
- Liquid covers: a thin chemical film that slows evaporation. They are easy to use but weaker than a physical cover, and they do not absorb sun.
- Solid or reflective covers: often used for heat retention and debris control rather than sun capture.
Does a solar cover work in cool or cloudy weather, and does it heat at night?
It holds heat at night and on cloudy days, but it cannot make heat without sun. On a cold, gray day the cover mainly slows the loss. It does not warm the water. At night it works as an insulating lid, and that is where it earns most of its value.
How many degrees can a solar pool heater add, and what does it depend on?
A properly sized heater typically adds about 5-15°F. The result depends on collector area, sun exposure, air temperature, wind, and how many hours the pump runs.
Here is how the system works. The pool pump sends water through the collectors on a roof or rack. The sun warms the water, and it flows back to the pool. A controller and diverter valve send water to the roof only when the collectors are warmer than the pool.
- Unglazed collectors: black polypropylene panels with no glass. The Department of Energy says these are commonly used for pools. They suit warm weather and moderate climates.
- Glazed collectors: glass-covered panels that hold heat better in cool or windy weather. They cost more and are less common for pools.
A heater needs real sun. The Department of Energy notes that it only works well with adequate sun exposure, and that many owners pair it with a backup heater for cool or cloudy periods.
How big does a solar heater need to be for my pool (collector area vs pool surface area)?
The Department of Energy advises collector area of about 50-100% of the pool’s surface area. Sunnier, warmer climates sit near 50%. Cooler, shadier or windier sites need closer to 100%.
Worked example: 16×32 ft pool
The surface area is 16 x 32 = 512 sq ft. Assumptions: a south-facing roof with little shade, and roughly 4-6 peak sun hours depending on region. Costs are rough planning ranges based on the typical $3,000-$6,000+ system range. Get local quotes, since installers price differently.
| Collector share | Collector area | Rough cost range | Likely gain |
|---|---|---|---|
| 50% | 256 sq ft | Low end, about $3,000-$4,000 | Lower end of 5-15°F, sunny climates |
| 75% | 384 sq ft | Middle, about $4,000-$5,000 | Mid-range, most climates |
| 100% | 512 sq ft | Upper end, about $5,000-$6,000+ | Upper end, cooler or partly shaded sites |
Adjust for your site. Add area if the roof tilts away from the sun, if trees shade it for part of the day, or if wind is common. In the Northern Hemisphere, south-facing surfaces are best. Tilt close to your latitude works well for year-round use, and a flatter tilt favors summer.
How much does each option cost to buy, install and run?
A cover costs about $50-$600, with no running cost. A solar heater typically costs $3,000-$6,000+ installed, and the Department of Energy says it usually costs less to run than gas or heat pump systems. The only running cost is the pump, which you probably run already.
- Cover extras: a reel can add to the budget. Plan on replacing the cover every 2-6 years.
- Heater payback: the Department of Energy gives roughly 1.5-7 years. Small or rarely used pools sit at the slow end.
- Heater life: unglazed collectors can last 10-20 years.
Cost per degree favors the cover almost every time. A $300 cover that adds even 5°F beats a $4,500 system on that measure. The heater justifies itself with control, reliability and a longer season.
Can I use a solar cover and a solar heater together, and is it worth it?
Yes, and it is the standard efficiency recommendation. The heater makes heat during the day. The cover stops that heat escaping overnight. Without the cover, a large share of the heat the collectors produce leaves through evaporation.
Owners who combine them report that overnight temperatures stay up. A cover can also let you size the collectors toward the lower end of the 50-100% range, since less heat is lost.
How does solar compare with a heat pump or gas heater for running cost and speed?
Solar is cheapest to run but slowest and weather dependent. Heat pumps and gas heaters work on demand, so they are faster and more predictable.
Here is a rough energy example. Assumptions: a 16×32 ft pool averaging 4 ft deep holds about 15,300 gallons. At 8.34 lb per gallon, raising it 10°F takes about 1.28 million BTU, or roughly 375 kWh of heat. At the national average near 17 cents per kWh, a heat pump with an assumed coefficient of performance of 5 uses about 75 kWh, or around $13. Electric resistance would use all 375 kWh, about $64. This covers only the first warm-up. Ongoing losses to evaporation and night cooling are larger, which is why the cover matters.
| Option | Speed | Running cost | Works in cool weather |
|---|---|---|---|
| Solar cover | Slow, passive | None | Retains heat only |
| Solar heater | Slow to moderate | Low, pump only | Weak without sun |
| Heat pump | Moderate to fast | Moderate, varies by your rate | Good, down to cool air limits |
| Gas heater | Fast | Highest per degree | Yes |
Electricity prices run from roughly 12 to 40 cents per kWh across the U.S., based on state averages from the U.S. Energy Information Administration. Check your own rate before comparing.
- If you only swim in peak summer, buy a cover and skip the heater.
- If you want a longer season and have unshaded roof space, add a heater and a cover.
- If you already own a heat pump or gas heater, add a cover first. It cuts your heater’s run time.
- If your yard is mostly shaded, pick a cover plus a heat pump.
What are the practical downsides: storage, handling, reel, chemical wear, roof space, freeze protection?
Covers are the hands-on option. Heaters need space and some planning.
Cover downsides
- Handling: a large wet cover is heavy and awkward without a reel.
- Wear: chlorine and sun break covers down. Owners report creasing, shrinking, residue and discoloration within a few seasons.
- Not a safety cover: the Department of Energy states solar covers do not prevent drowning. Never let anyone walk on one, and remove it fully before swimming.
Heater downsides
- Roof or ground space: you need a sunny area roughly half to all of the pool’s surface area.
- Freeze protection: in cold regions, drain the collectors or use a system designed for freeze conditions.
- Poor sites: cold, shaded or windy locations underperform.
From the Shop
Based on patterns in owner reviews, the most common regret is not the price. It is a heater bought for a lightly used pool, or a cover that nobody wants to pull off every day. Match the gear to how you actually swim.
Which setup fits your pool?
Use this checklist: sun hours, roof or ground space, shading, pool size, budget, any existing heater, and whether you will handle a cover daily. Then match your case below.
| Scenario | Recommended setup | Why |
|---|---|---|
| Cool-climate small pool | Cover first, then a heat pump if needed | Low sun limits solar collectors; the cover cuts losses cheaply |
| Sunny-climate large pool | Heater at 50-75% of surface area plus a cover | Strong sun lets collectors do most of the work |
| Pool already on a heat pump | Add a cover | Lower run time and lower bills with little spend |
What do owners say?
Owners like
- Covers are cheap, noticeably warm the pool, and reduce chemical and water loss.
- Heaters have free running costs after install and extend the swim season by weeks.
- Heater systems are quiet and low-maintenance once installed.
- A cover with a heater keeps overnight temperatures up.
Common complaints
- Covers are awkward to remove and store without a reel.
- Covers degrade, crease or shrink within a few seasons and can leave residue or discoloration.
- Heaters perform poorly in cloudy, cool or shaded conditions and need roof space.
- Installation cost is high, and payback is slower than expected for small or little-used pools.
- Covers can overheat water in hot summers if left on all day.
Summarised from owner reviews and long-term user reports; individual experiences vary.
Frequently Asked Questions
Solar pool cover vs solar heater: which should I buy first?
Buy the cover first. It costs a fraction of a heater, needs no installation, and cuts the evaporation that causes most heat loss. If you still want warmer water or a longer season after a full season with a cover, a heater is the next step.
How many degrees does a solar pool cover raise pool temperature?
Roughly 5-15°F (about 3-8°C) over an uncovered pool, according to Department of Energy and Energy Saver guidance. Results depend on the cover type, wind, climate and hours it stays on. The cover retains heat rather than creating it, so gains shrink in cold, cloudy weather.
Can a solar cover replace a solar heater?
Only partly. A cover helps the pool hold and collect passive heat. It cannot add heat on demand. If you just want a few extra degrees in summer, it may be enough. For a longer season, you will likely want a heater too.
Does a solar heater work without a cover?
Yes, but it works less efficiently. A large share of the heat it makes escapes through evaporation overnight. Adding a cover keeps more of that heat in the water.
Is a solar pool cover safe to leave on when kids are around?
No. The Department of Energy notes solar covers are not safety covers and do not prevent drowning. Remove the cover completely before anyone swims, and use a certified safety cover or other barriers where required by local rules.
