Solar pumps can be used in many different ways. Their mode of operation in mini ponds, streams or as fountains reflects only a fraction of their field of application. They are not only a good choice visually, but also in terms of sustainability and cost.
Unlike electricity- or battery-powered alternatives, you don't need a power connection and long cables that spoil the look.
With our solar pump test 2021 we would like to help you find the best solar pump for your purposes. We have compared solar pumps for water and heating as well as for projects with decorative purposes and listed the advantages and disadvantages. In this way, we would like to accompany you in your purchase decision and make it as pleasant as possible for you.
- 1 Weekly newsletter with the best personal finance tips
- 2 Summary
- 3 The Best Solar Pump: Our Choices
- 4 Solar pumps: buying and evaluation criteria
- 5 Solar pumps: Frequently asked questions and answers
- 6 Conclusion
- A solar pump uses solar energy to serve a variety of purposes. They are often used in the garden as an aeration pump, water feature in the pond or as a stream pump. A decisive advantage of this technology is that no electricity connection is required.
- Basically, a distinction is made between solar pumps for irrigation, decorative purposes and heating. Each of these variants is available in different price ranges and with different add-ons.
- All solar pumps are easy to use, but you should know beforehand what you want to use your solar pump for, so that the functionality is not impaired and you benefit from your solar pump for a long time.
The Best Solar Pump: Our Choices
Solar pumps: buying and evaluation criteria
A solar pump that fully meets your needs and requirements is something you will enjoy every day. Before you decide on a solar pump, you should therefore consider the following features of a solar pump:
The intended use is the starting point for every consideration. In the following paragraphs we will explain to you what is important in the individual criteria.
Power consumption refers to the electrical power of a device and is expressed in watts. This unit of measurement is the product of voltage (volts) and current (amperes). In the case of a solar pump, this indicates the energy output of the solar panel. The power consumption of the different types of solar pumps varies between 3 and 25 watts.
Solar pumps used for heating in buildings require about 10 watts. For an ornamental fountain, mini pond or water spout, it is best to choose a solar pump with a power consumption of about 5 watts.
For larger ponds or pools, a higher power consumption is required. The approximate power consumption that you should use for a pond, for example, can be determined with the following rule of thumb: Power consumption ≈ length * width * (depth / 2).
The required pressure in the solar pump system is called delivery head and describes the power of a pump. The delivery head does not refer to the system height, as is often erroneously assumed.
Different delivery heads are required depending on the area of application. For a small garden pond, a delivery head of 50 cm is sufficient. In comparison, a watercourse pump has a delivery height of about 2.2 metres.
For larger bodies of water with fish, solar pumps are usually not suitable due to their comparatively lower pumping capacity. The water cannot be sufficiently cleaned and circulated by the solar pump.
According to a rule of thumb, a pump should completely circulate the water in a pond within two hours.
Circulation means that the water is constantly circulating. This enriches the water with oxygen, which is vital for fish.
The flow rate significantly determines the efficiency of your solar pump. This parameter is also called flow rate or volume flow and describes how much volume of the solar fluid flows through a defined cross-section per period of time.
The flow rate of a solar pump depends on the type of system. In low-flow systems, the flow rate is often less than 10 litres per hour and per square metre of the solar panel. The solar fluid consequently flows slowly through the solar panel and thus absorbs a lot of heat.
As a result, a good output of your system can already be generated at low solar irradiation. In high-flow systems, a higher volume flow of about 40 to 50 litres per hour and per square metre is possible.
The solar fluid only remains in the solar panel for a short time and heats up less, so that the heat can be transported to the heat storage tank more quickly and evenly. This storage tank is used to store excess heat and is only present in solar systems that are used for heating.
Otherwise, it is possible to feed the surplus energy into a battery as electricity. Matched-flow systems control the flow rate dynamically to always achieve an optimal volume flow.
Put simply, a matched-flow system behaves like a low-flow system when solar radiation is low and like a high-flow system when solar radiation is high. This is to avoid the comparatively sluggish functioning of high-flow systems at low temperatures.
On days with plenty of sunlight, a solar pump with rechargeable battery feeds the unused energy into the battery. On cloudy days, the solar pump switches to battery operation - you can use the solar pump even when there is little sunlight.
A battery storage is also useful if you want to use the solar pump after sunset. The battery is especially important for a solar pump that you want to use for a pond with fish or an aquarium. Without a battery, the pump would not guarantee a sufficient oxygen content in this case.
When setting up the solar panel, make sure that it gets enough sunlight. If the solar panel is in partial shade, for example, the pump may switch off. This means that the battery can no longer charge and the water cascades or the water spout cannot be operated by the pump after sunset.
The seasons influence not only the duration but also the angles at which the earth is irradiated by sunlight. In summer, you can orient the solar panel almost horizontally to the ground (0 to 27°); in winter, 54 to 75° will result in adequate performance of the solar pump.
If you want more colour in your solar-powered fountain, for example, LED lighting is just what you need. The lighting makes the purchase price a little higher, but it's worth it if you spend a lot of time in your garden in the evenings. An illuminated solar fountain for your garden or outdoor pool is a real eye-catcher.
If you want to use lighting, you should also choose a solar pump with a rechargeable battery, as lighting is usually desired after sunset. This is not possible without a battery.
Most solar pumps offer a choice of white, single-colour or multi-colour lighting. You can choose to have the multicoloured light flash or to have all the colours appear at the same time, like a rainbow. For automatic switch-off, you can often select a timer function between 2 and 6 hours.
A timer is a clock that switches an electrical contact on or off at set times. The switching times can be set individually. With the help of a timer, the pump then only runs at certain times once set. In this way, you do not have to switch the solar pump on and off manually every time.
In the case of a solar pump with rechargeable battery, you use the timer to determine the time period in which the pump switches to battery operation. You can determine when the solar pump should feed energy into the battery and when the battery should operate the solar pump as an energy source. You can also use the timer to control the lighting and set different operating times for different time periods (weeks, months).
Both types have advantages and disadvantages - which one is best for you depends on your preferences. Analogue timers have a lower energy consumption. Typically, they consume about one watt per hour. These timers are much easier to programme and have a lower purchase price.
However, they tick audibly, which is often perceived as annoying. In addition, analogue timers can usually only be programmed for intervals of at least a quarter of an hour. The advantage of digital timers is that you can set many more times and also times that change daily.
Digital models are much quieter and it is possible to control them via your mobile phone. However, they are more expensive to buy and consume about 6 watts per hour. Digital timers are more difficult to set than analogue models.
Solar pumps: Frequently asked questions and answers
Now that you know what to look for when buying, here is a compilation of questions that are important for your understanding of solar pumps.
What is a solar pump?
To ensure that your solar pump also works when there is little sunshine, many models have a rechargeable battery or storage unit. There are no energy costs after the purchase of your solar pump.
The solar panel generates energy through solar radiation, which is necessary to operate the solar pump. This electricity drives the pump motor, which sucks in water and returns it to the pond, for example in the form of a fountain.
The water is thus circulated and enriched with oxygen. Solar pumps are not only popular because they are cost-neutral to operate, but also because they are easy to install and handle. Solar pumps are often offered as complete sets that are ready for operation after a few simple steps.
The complete solar pump set consists of the actual solar pump, which is usually installed in the water. In addition, there is a solar panel that is fixed near the solar pump with a ground spike and connected to the pump via a short cable. The complete set usually also includes various fountain attachments for the pump or a rechargeable battery.
What types of solar pumps are there?
|Solar pumps for bodies of water||There does not have to be a power connection and there is no annoying, loud operating noise||The use is sunlight-dependent. The sunlight must fall as unhindered as possible on the solar panel.|
|Decorative solar pumps||There are no electricity costs due to operation||Usually higher purchase price than conventional models.|
|Solar pumps for heating||Solar-powered heating is more environmentally friendly than a traditional heating pump and saves costs||Solar panels can be damaged by hail or storms.|
Solar pumps for water are used, for example, in garden ponds, pools, swimming pools, streams and aquariums, but also for rain barrels. For decorative purposes, they can be found, for example, in spring stones, waterfalls and water spouts.
Solar pumps can also be used in the home. Here they are used to heat the shower and tap water as well as to heat the living rooms.
What does a solar pump cost?
|Solar pond pump||20 to 80 euros|
|Solar stream set||180 to 230 euros|
|Solar heating pump||50 to 200 euros|
|Solar well pump||20 to 120 euros|
When assessing the purchase price, you should always bear in mind that solar pumps do not incur running costs. Even if your solar pump is a little more expensive to buy, solar pump use is much cheaper over the years than conventional pump systems.
What alternatives are there to a solar pump?
|Pump powered by an electricity generator||Electricity generators can run on petrol, diesel or gas.|
|Battery pumps||Battery pumps are operated without a cable, but the battery must be charged. You cannot use the pump during this time.|
|Pump powered by fuel cells (rare application)||fuel cells are often powered by hydrogen and oxygen.|
Compared to the alternatives mentioned above, a solar pump has some key advantages: No electricity or fuel is needed to operate solar pumps. They are environmentally friendly and easy to handle. Moreover, they do not cause any running costs.
When does a solar pump switch on?
The solar pump switches on when the temperature in the solar collector (solar panel) is higher than a reference temperature set by you and switches off again when the temperature in the solar collector falls below the reference temperature.
With modern pumps, you can also set how strong the circulation should be. This means that the pump only works as hard as it needs to. This avoids too heavy an operating load, saves energy and prevents unnecessary wear.
How can the flow rate be adjusted on a solar pump?
After a constant flow rate has been established, you can now reduce the flow rate as needed. Once you have set the flow rate, you can check from time to time whether the flow rate still meets your requirements.
Can a solar pump be used in winter?
With a circulating solar pump, there is a mixing of the water layers. In winter, the lower, warmer water layer of the pond should not mix with the colder layer at the water surface, as some animals overwinter in the warmer water layers.
Depending on the manufacturer's instructions, you must either store the solar pump in a bucket of water or dry it after cleaning. As soon as it is warm enough in spring that your pond no longer freezes over, you can use the pump again.
Some solar pumps have frost protection built in from the start. They do not require any special attention in winter. You can also operate a solar-powered pump indoors in winter. In this case, however, the insulation of the pipes is important.
With the help of a solar pump, you can transform your home and garden into a place of well-being. Unlike other pumps, you don't need a power cable, no fuel and you act in an environmentally friendly way.
When you buy a solar pump, you decide whether you want to use it for a decorative project or for a practical purpose such as irrigation or heating. A decorative use enhances the appearance of your garden and creates a feel-good atmosphere.
Irrigation and heating can be used efficiently, environmentally friendly and cost-saving thanks to the solar pump. Once you have decided on a solar pump, all you have to do is sit back and let things take their course.
Photo source: Michele Ursi / 123rf