Heating with solar energy for the pool: this is how you get the most out of the sun’s heat
The trend towards having your own pool in the garden continues. Usually the pool heating the pool with solar energy is part of it, so that you can swim on cooler days. Modern pool heaters use solar energy and score with their efficiency and environmental friendliness. Read the following article to find out which system is right for you.
Pool Heating With Solar Energy
The Federal Association of Swimming Pools and Wellness eV counted over 700,000 private swimming pools in Germany in 2018, and the trend is rising. The weather in Central Europe doesn’t always play along, even in summer. A water temperature between 26 ° C and 29 ° C is ideal for paddling and swimming. After several cooler days, jumping into the private bathing oasis is sometimes uncomfortable even in July. One remedy is pool heaters that keep the water at a constant temperature.
Scheme: use solar thermal energy for pool heating © arahan, fotolia.com
The energy of the sun to heat your swimming pool to use an excellent idea for several reasons:
- The sun exposure is most intense in summer when you use the pool the most.
- Compared to electricity-operated pool heating systems such as heat pumps and heat exchangers, there are hardly any electricity costs.
- The heating system can be expanded as required by purchasing more modules.
- The construction is simple and can usually be done on your own.
Solar absorbers and solar collectors – an overview
The simplest and cheapest way to heat a pool are solar absorbers for heating pool with solar energy. Both are made of UV and heat-resistant plastic, which is also resistant to salt and chemicals. Inside there are pipes through which the pool water flows. However, there are differences between the two systems. Solar collectors have a hard structure and glazing, while solar absorbers are manufactured as soft rubber mats without a cover.
The principle remains the same. In both cases, the sun heats the material. The pool water, which has already been filtered, is pumped through the hot pipes and absorbs its heat before it flows back into the pool.
However, the two types of pool heaters differ in terms of their structure:
- Solar collectors are more space-saving than absorbers. Due to the construction, they are usually set up under the water level or near the pool. Solar absorbers require more space, but are also suitable for mounting on the roof.
- Solar collectors are an optimal solution for small and medium-sized pools, while absorbers deliver a higher energy yield and are also suitable for large pools.
Plus and minus points of solar absorbers and solar collectors
Where can I install the solar heating for the pool?
Depending on the model, the mats or collectors can be set up vertically or horizontally. For a maximum yield, a south orientation and an inclined installation is recommended. Mounting on the garage or pool roof is also popular . This variant has the advantage that you do not need any additional space in the garden.
How big should my pool heater be?
At night, the water of an outdoor pool with a cover cools down by 0.5 to 2 degrees, depending on the starting temperature. Much more heat is lost without bubble wrap. In this case, the temperature difference the next morning can be up to 10 degrees.
The values listed above apply to in-ground swimming pools. In pools with steel walls or flex pools, the heat loss is even higher because the walls give off heat to the cool air at night. You should also keep in mind that bad weather fronts can cause temperature fluctuations even in summer.
As a rule of thumb, the total area of your absorbers or collectors should be 60 to 80 percent of the pool area. If you want to feel like you are in the tropics on cloudy days, however, you should expect 100 to 120 percent of the pool area. Conversely, you can get by with a space utilization of 40 to 50 percent if 23 ° C is enough for bathing and your pool is well covered.
How much does pool heating with solar energy cost compared to other types of heating?
Example calculation for a heat pump
In comparison, you need a heat pump with an output of at least 12 kW for your 40 square meter sample pool. You have to reckon with around 2,500 euros for the purchase alone, roughly the same as for the solar collectors.
Added to this are the electricity costs, which depend on the efficiency of the heat pump and the temperature drop overnight. 46 kWh are required to heat 40 square meters of water by one degree. With an efficiency of the heat pump of 5 results from June to September (120 days) an electricity consumption of:
Example calculation for a heat exchanger
Heat exchangers are inexpensive to purchase. A heating heat exchanger with an output of 70 kW is sufficient for a 40 square meter pool and is available for around 500 euros. However, it uses the heat from the heating circuit, so there are heating costs. With a total energy requirement of 5,520 kWh for the entire bathing season, the following results for gas heating:
Thus, viewed over time, a heat exchanger is somewhat more expensive than a heat pump.
Heat the pool with solar thermal energy
Solar absorbers and collectors are an inexpensive solution for your pool heating that does not require a lot of effort. However, if you already have a solar thermal system for heating and drinking water, you can also use your energy for the pool.
The difference to the solar absorbers is that in this case the pool water is not heated directly, but by the heat transfer fluid of the solar thermal system. There are two ways to heat a swimming pool using solar thermal energy:
- The pool is connected to the heating circuit . A heat exchanger ensures the exchange of energy between the warm heating water and the cold pool water. This solution is easy to build, but the heating circuit gets an additional consumer.
- Alternatively, you can have a separate circuit laid between the solar absorbers in the system and the pool. A built-in control then decides whether the heat transfer medium flows into the heating or the pool circuit. This solution is particularly advantageous in summer, when your solar thermal system is already producing excess heat.
Two ways to heat the pool using solar energy
Can my pool be heated with solar energy even in winter?
The radiation output of the sun is already decreasing at the end of summer. If it is an average of 1000 W / m 2 on a clear summer day in June , it drops to 500 W / m 2 and below on a foggy October day . At the same time, the water cools down more and more. From the end of September it is therefore hardly possible to heat the pool with solar energy alone.
If you want to use your outdoor pool in winter too, you need to install an additional heating system. A modern heat pump delivers constant output even at low outside temperatures and remains the cheapest solution. Heat exchangers connected to the heating circuit also provide warm water in the cold months. Alternatively, an electric pool heater provides the required heat, but this increases your electricity costs considerably.
With solar absorbers and solar collectors, you can use the radiant power of the sun to heat your pool free with solar energy of charge and in an environmentally friendly manner. The space-saving modules can be mounted on the roof or set up in the garden. A south orientation ensures a high energy yield and warm water in the pool.
During the summer months, solar heating is superior to other types of pool heating and alone can provide the required heat output. If you would like to use your swimming pool in winter as well, you will need an additional heating system. In order to keep your electricity and heating costs as low as possible, you should think about a combination of a modern heat pump and solar collectors .