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Solar thermal energy is worth it in 2021

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Will solar thermal be worthwhile in 2021?

The sun is the only energy source for generating renewable heat that delivers energy free of charge to your front door or to the roof. With a solar heating system (solar thermal system) you can convert the solar heat into usable heat in order to provide hot water and heating water in the household. The technology has proven itself in practice: At the end of 2019, around 2.4 million systems were in operation in Germany. Here we answer the question: Is solar thermal energy worthwhile in 2021?

Similar to the question “Is photovoltaics worthwhile in 2021”, which we answered with a “yes” in our guide, the same applies to the question of whether solar thermal energy is worthwhile in 2021: Those who focus on ecological aspects can do solar thermal energy only rate it as worthwhile. Those who, on the other hand, approach the answer economically must calculate the acquisition costs and operating costs of the system against the savings in alternative heating energy and the resulting savings in heating costs. In the following, we will do both in order to answer the initial question.

Will solar thermal systems pay off in 2021?

Whether solar thermal energy pays off (keyword: financial amortization), i.e. is economical, is decided by the ratio of income and expenditure that it causes. On the expenditure side are:

The Investment costs of the solar thermal system, which includes the following costs for the individual components of the system:

  • Costs for solar thermal collectors
  • Solar storage costs
  • Cost of the solar pump
  • Costs for the heat meter
  • Solar piping costs
  • Solar control costs
  • Expansions for the expansion tank
  • Solar fluid costs

Today you have the choice of buying the listed components either individually or as a complete package. The latter has the advantage that all components are optimally matched to one another so that the system generates the highest possible yield.

The two big items on the bill are the cost of the collectors and the storage. With the collectors, the technology determines the price:

  • Those who rely on flat-plate collectors (around 250 euros per square meter) save up to two-thirds of money on purchase compared to vacuum tube collectors (around 750 euros per square meter), but they do not benefit from their performance. As a rule of thumb, you can remember that you need about a third more collector surface with flat-plate collectors in order to achieve the same performance as with vacuum tube collectors.
  • The price of the solar storage tank, which buffers the solar heat so that you have hot water and heating water even when the sun does not shine (at night) or does not shine sufficiently, is determined by its capacity and technical structure.

We provide detailed information on the costs of individual system components in our article "Solar thermal acquisition costs".

The bottom line for the total costs on the expenditure side and income side is how the solar thermal system is dimensioned. That in turn depends on what purpose - domestic water and / or heating water heating - the system is used.

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From an economic point of view, the two types of systems are to be assessed as follows:

Solar thermal energy for hot water production (price around 3,500 to 5,000 euros) - worthwhile?

For the provision of warm water, the systems are often dimensioned specifically for a solar coverage. 60 percent solar coverage is common with such system types and means that your solar heating system provides you with 60 percent of your hot water requirements - and thus saves 60 percent in energy and energy costs. At the same time, your heating is relieved: In the seasonal transition times it has to cycle less and in summer it can even be completely off for a long time. An average four-person household saves around 2,000 kilowatt hours of heat over the year, which corresponds to 140 (heating gas) to 220 (heating oil) euros, depending on the type of heating used in the household and the associated fuel. After comparing costs and savings, the payback period for such systems is around 15 years.

Solar thermal for heating support (price around 8,000 euros) - worthwhile?

Systems that support solar heating usually cover up to a third of the heat requirement. The annual savings of a single-family house with four heat consumers can be up to 400 euros. That would mean an amortization period of a good 20 years if you do not take advantage of federal, state or local government funding.

Tip: Anyone who heats their pool with the sun can say with certainty that solar thermal energy will be worthwhile in 2021 as well, because because of the continuity with which the pool draws heat, the heat generation costs are very low here.

Interim conclusion: The economic feasibility study of solar thermal 2021 leads to the result that solar thermal systems for hot water preparation have shorter amortization times than systems for heating support. The initial question of whether solar thermal energy is worthwhile in 2021 must be answered individually in view of the amortization times mentioned. Keep in mind that energy prices have risen steadily in recent years, which means that you also increase the energy and energy cost savings that solar thermal energy will bring you in the future.

In addition, you can count on minimal energy costs from the time the system is amortized, because the running costs (electricity costs, inspection costs, maintenance costs and insurance costs of a solar thermal system) are low. Since the manufacturers often guarantee their products for up to 20 years, you do not have to worry about additional costs for repairs - this also makes solar thermal energy worthwhile in the long run.


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Subsidies make solar thermal energy worthwhile in 2021 (more)

The subsidies that the state provides for heating modernization with heating technology for renewable energies - and sometimes also the manufacturers of the technology - will make the use of solar thermal systems lucrative in 2021 as well. The Federal Office of Economics and Export Control BAFA focuses on economic development and thus the implementation of programs for the increased use of renewable energies and for energy saving. Among other things, BAFA promotes solar thermal systems,

  • that only provide hot water,
  • that only generate heat for space heating
  • and that provide both hot water and room heating (keyword: combined systems).

You can find an overview of the BAFA subsidies for solar thermal energy 2021 on the BAFA website

Ecological consideration

From an energetic point of view (keyword: energetic amortization), the solar thermal system pays for itself after just a few years. Because they quickly brought in the energy that was necessary for their production.

A critical look at the emissions that the solar thermal system causes during operation speaks in favor of renewable heat generation technology. Only the operating current of the system, for example for the integrated solar pump and the solar control system, has a negative impact here. In return, solar thermal energy saves fuel that would otherwise be used to generate heat.

From an ecological point of view, solar thermal energy is definitely worthwhile for you for the reasons mentioned. Your use is just as noticeable on the heating bill as it is on the climate account of your household.


From an ecological point of view, solar thermal energy is always worthwhile. From an economic point of view, you have to reckon with amortization times of between 15 and 20 years in 2021 - depending on the purpose of your system and how much energy and energy costs it will save. The more precisely you adapt the solar thermal system to the local conditions and your heating requirements, the more it is worth using it. You can also be sure that solar thermal energy will become more profitable from year to year, because the prices for alternative energies for heat generation are rising steadily (at least in the past) - while the sun doesn't send you a bill.

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Tags:Solar thermal economy