Solar energy is on everyone's lips. With a solar energy system, you can convert this energy into electricity or heat. A distinction is made between photovoltaic and solar thermal systems. In this article, we explain the advantages and disadvantages of both types.
Advantages and disadvantages of solar systems and solar energy for power generation
Solar energy is usable energy that is generated with the help of solar radiation. This energy can be generated in the form of electricity (photovoltaics) or heat (solar thermal energy).
We have listed the advantages and disadvantages of both forms for you in our "Solar energy pros and cons table".
| Advantages | Disadvantages |
|---|---|
| Green energy generation | Weather dependency |
| Independence from the grid provider | High initial costs |
| Savings in electricity and heating costs | Bureaucratic effort |
| Protection against rising energy prices for the next 25 to 40 years | Low energy production in winter |
| Electricity and heat are produced at the consumption location, i.e., no energy transport | Less environmentally friendly if modules have long transport distances |
| Solar cells can be disposed of and recycled for free | Tax-related effort |
| Low maintenance costs | Requires sufficient roof space |
| Electric car can be charged for free | |
Advantages of solar systems and solar energy for generating electricity
The advantage of solar energy, apart from the green generation of electricity and heat, is the reliability of energy production for the next 25 to 40 years. A solar system also has the advantage of saving money on electricity and heating costs, with relatively low maintenance costs. At the same time, there is independence from rising energy prices.
Solar energy is green, emission-free and environmentally friendly
In contrast to electricity production using coal and gas, no fossil fuels are required when using solar energy. This means that no CO₂ is emitted during electricity production. The CO₂ balance for photovoltaics is 50 g per kWh of electricity, which is very good.
In comparison, the CO₂ emissions for electricity production with lignite are over 1,000 g per kWh. For hard coal it is over 800 g/kWh and for natural gas it is still 500 g/kWh.
For this reason, solar cells pay for themselves energetically after one to three years, depending on the type of cell. In other words, the solar system will have generated more electricity in one to three years than was used in the production of the solar cells.
A solar system makes you independent of the grid operator and rising prices
With your own solar system, you become less dependent on the grid operator. This means that you are no longer at the mercy of constantly rising electricity prices and, in some cases, power cuts. Fossil fuels are not available indefinitely, which is why electricity prices are rising. They account for more than 70 % of electricity production in the USA.
Solar energy, on the other hand, is unlimited and free. With a solar system, you can generate your own electricity every day at a fixed price.
With the combination of a solar system and electricity storage, you become even more independent. The solar power you generate yourself is stored and is therefore also available to you in the evening and at night. This means you have to buy even less electricity from the public grid. The solar system can now cover up to 80% of your electricity requirements.
Electricity costs are permanently reduced
Producing electricity with photovoltaics is free, but you first have to buy or rent a PV system. However, if you calculate the acquisition costs over a period of 20 to 25 years, one kilowatt hour of electricity costs just under 11 cents. At the current electricity price of around 36 cents (as of November 2022), you therefore save up to 25 cents per kWh.
Electricity production is guaranteed for at least 25 years
The service life of a good photovoltaic system is at least 25 years. In reality, the service life is much longer. With regular cleaning, maintenance and occasional repairs, a service life of 30 to 40 years is possible. During this period, you will significantly reduce your electricity costs.
E-car can be charged free of charge.
The best thing about photovoltaics is that the more electricity you use yourself, the more profitable your own solar system is. If you combine your PV system with a wallbox, you can easily charge an electric car. This means you can charge your e-car for free and at the same time increase your own consumption and thus the profitability of your solar system.
Disadvantages of solar systems and solar energy for power generation
The cost of a solar system for private households is between ＄7,000 and ＄20,000. The costs are even higher for PV systems with an electricity storage system. It takes around 10 to 15 years for them to pay for themselves through the electricity cost savings.
Would you like to save on the purchase costs and not have to worry about anything else? Some providers offer solar systems with no purchase costs. With this model, you rent the solar system permanently and pay a monthly installment of a previously agreed amount. The provider also takes care of the maintenance and insurance of the PV system.
Solar energy is dependent on the weather
Although electricity production with photovoltaics also works in bad weather and in the shade, the yield is significantly lower in this case. Even in light cloud cover, the electricity yield is reduced by up to 60 %. In the rain, the power loss is as high as 95 %. A full solar power yield is therefore only achieved on completely sunny days.
As a solution, you can install an electricity storage system. This stores the surplus electricity on sunny days. This means you can use it at night or on days with bad weather.
Less solar power is generated in winter
As the sun moves not only throughout the day, but also throughout the year, electricity generation is significantly lower in winter than in summer. A photovoltaic system generates around 70% of the annual electricity yield from April to September. In the winter months, the yield is therefore significantly lower. This means that more grid electricity has to be purchased to cover the daily electricity demand.
A solar system entails tax and bureaucratic costs
You must register your own solar system with the tax office, the Federal Network Agency and the grid operator. In addition, operating a photovoltaic system is considered a commercial activity, which is why taxes are incurred. In some cases, you even have to register a business. However, as a private operator of a small system under 10 kWp, you can make use of the hobby rule. In the latter case, your solar system will be exempt from tax by the tax office.
Solar modules from Asia are less environmentally friendly
PV modules from China are generally cheaper. This is because they can be produced on a large scale and labor wages are lower.
Fraunhofer ISE examined the CO2 footprint of various photovoltaic module production locations. China comes off worst with 750 kilograms of CO₂ per kWp. In the USA, the average was 520 kg CO₂ per kWp.
Solar thermal energy: advantages and disadvantages of solar energy for heat generation
In addition to generating electricity, solar energy can also be used to generate heat. Instead of photovoltaics, a solar thermal system is used for this purpose.
Advantages of solar thermal energy
The advantages of using solar energy to generate heat are as follows:
Free energy generation for 20-30 years
A solar thermal system generates heat free of charge for 20 to 30 years. The maintenance and cleaning costs are lower than for photovoltaics. If you take the acquisition costs as the basis for the heat price, one kilowatt hour costs between ＄0.10 and ＄0.20. The price remains constant, while fossil fuels such as oil and gas become more expensive every year.
Surplus energy can be stored in the buffer storage tank
Solar thermal systems always use a heat storage tank. If the heat generated is not used directly for heating or hot water, it is fed into a buffer storage tank. It can then be used at a later time. This means that no generated heat remains unused.
A solar thermal system is CO₂-free and climate-friendly
Just like photovoltaics, a solar thermal system is emission-free and climate-neutral. The energy payback period is two to four years. After this time, the system will have generated the amount of energy required for production and transportation. It then generates climate-neutral heat for the next 20 to 30 years.
Direct subsidies for solar thermal systems
The Federal Office of Economics (BAFA) grants subsidies for solar thermal systems. You can receive direct payments of up to 30% of the investment costs.
Solar thermal energy can also be installed on the house wall
Solar thermal panels can be easily installed on the wall of the house. Thanks to this type of installation, the roof can remain free for an additional photovoltaic system. In addition, the steeply mounted solar collectors achieve a better yield in winter, i.e. when heating is also required. This is because the sun has a shallow angle in winter. This also prevents excess heat in the summer.
Disadvantages of solar thermal energy
In addition to the advantages, solar thermal energy also has a few disadvantages.
High acquisition costs
As with photovoltaics, solar thermal systems also have high acquisition costs. On average, these amount to just under ＄10,000 for a detached house. In many cases, the purchase of a solar thermal system is also associated with a boiler modernization. Here you may incur further costs of up to ＄10,000.
However, you can also receive subsidies for solar thermal energy in the form of direct payments. BAFA will pay you up to 30% of the purchase price. This reduces the purchase costs to just ＄7,000.
Unused heat in summer
Especially in summer, when there is no heating, there is a surplus of heat. If the buffer tank is full, the heat usually remains unused. One option is to heat the water in your own pool - if you have one.
Another solution is to install the collectors on the wall of the house instead of the roof. Here, the angle of the sun's rays is less favorable in summer and therefore heat production is also lower. However, the angle is perfect for winter. The solar thermal system generates more heat, which you can use for heating.
Dependence on the weather
Solar energy is always dependent on the weather. In contrast to photovoltaics, however, solar thermal energy is less dependent on solar radiation. Even in Diffuse radiation conditions, a solar thermal system still performs well. In winter, however, the output is up to 30% lower. This is due to the lower temperatures and the lower number of hours of sunshine per day.
Generates only heat and no electricity
Photovoltaics are used to generate electricity. Electricity is versatile and can also generate hot water for consumption or heating. Unfortunately, a solar thermal system is less flexible. If you want both, a combination system of solar thermal energy and photovoltaics may be worthwhile for you. Alternatively, you can opt for the use of hybrid modules. These combine photovoltaics and solar thermal energy in one.
Conclusion
Whether solar thermal or photovoltaic, the use of solar energy has many advantages. They generate electricity and heat emission-free and also free of charge for the next 30 to 40 years. Subsidies in the form of direct payments and favorable loans help to reduce the purchase price. Once the purchase costs have been financed, you are reliably independent of rising energy prices.
Correct planning and installation are important to ensure that your solar system really does generate electricity or heat reliably for such a long time. It is therefore essential that you seek advice from a specialist solar installer.