Solar energy is a sustainable way for private individuals and companies to power buildings independently. Solar modules on the roof of the house, the carport, the open space and even on the wall of the building generate electricity from this renewable source. With around 66 gigawatts of installed capacity, photovoltaics are already making a significant contribution to the energy supply.
By 2035, Germany wants to be able to obtain all the electricity it needs from renewable sources. By then, 215 gigawatts of photovoltaic capacity alone will have been installed. And with the amendment to the Building Energy Act (GEG), retrofitting is almost inevitable.
However, questions about safety, feed-in tariffs and profitability make companies and private individuals reluctant to invest in clean energy generation, despite comprehensive subsidy programs. Here you will find answers to the most important questions about photovoltaic systems.
What is photovoltaics and how does it work?
A photovoltaic or solar system is the technology used to capture energy from the sun's rays and other light sources and convert it into electricity.
Photovoltaic systems are constructed from:
- Solar cells that are combined in solar modules.
- a mounting system with which the solar modules are installed on the roof or the area used.
- Inverters that convert the direct current generated from light into alternating current that our electricity grids can use.
- a storage system so that you can use the electricity when you need it.
- Bidirectional meters that measure electricity consumption.
- Management software with which the system is set and controlled.
A solar cell consists of silicon layers. When light hits these layers, silicon electrons - to put it simply - start to move and migrate from one layer to the next. This creates an electric field whose current we can use.
The characteristic value kilowatt peak (kWp) is used for the output of a solar module. This value indicates the output of the system under optimum conditions. The real output is made up of several factors:
- the light actually captured: How much light a solar cell absorbs depends on the time of day and season, cloud cover, air pollution and soiling of the modules, the location and the angle of incidence of the light.
- the temperature: solar modules may generate less electricity in hot weather.
- the wind: Wind has an effect on the module temperature.
The Helmholz Center Berlin explains exactly how this works on its YouTube channel.
Good to know: While photovoltaics converts light into electricity, solar thermal energy generates heat from light!
Advantages of photovoltaic systems
Solar energy is environmentally friendly
Solar, wind and hydropower are ways of generating electricity without burning or otherwise destroying our planet's resources. For this reason alone, photovoltaic systems are among the most environmentally friendly solutions for generating energy. Much of the land that is suitable for harvesting solar power currently remains unused, e.g:
- Roofs
- Parking lots
- Carports
- Fallow land
With a photovoltaic system, you can turn your unused areas into sun tanks, make an important contribution to the energy transition and supply your buildings independently.
Many areas such as agricultural land and farmland are suitable for dual use. In this way, a solar system can even be used to provide shade and shelter for plants, animals and aquacultures. Building integrations, installations on artificial lakes or traffic routes are also possible. According to Fraunhofer ISE's "Facts on photovoltaics in Germany", there are sufficient areas for photovoltaics in Germany without any significant conflicts with agriculture or nature conservation.
What about theCO2 balance including manufacturing costs? Fraunhofer ISE calculates the greenhouse gas potential of a PV system at 56 gCO2-eq./kWh, whereCO2-eq. stands forCO2 and equivalent substances. By way of comparison: electricity generated from coal has aCO2-eq./kWh of over 1000 g, while natural gas has around 400 gCO2-eq./kWh.
According to the latest data from the scientists, it only takes 1.3 years for a plant to recoup the energy used to produce it.
Independence from energy suppliers
If you generate your own electricity, you become independent of energy suppliers. Generating and consuming electricity yourself with a photovoltaic system is therefore also financially worthwhile. The more of your self-generated electricity you consume directly, the less dependent you are on market fluctuations.
With the amendments to the Building Energy Act, new buildings must be built from January 1, 2024 (outside of new development areas from 2026/28) in such a way that 65% of the heating energy comes from renewable sources. The heating energy supply for existing buildings is also to be freed from fossil fuels in the future. An electricity-based heating system in combination with a PV system represents a sustainable solution here.
Increase in the value of the building
With every construction measure you take to optimize the energy efficiency of a property, you also increase its value. With a view to a possible sale, a solar installation not only brings plus points as a technical facility, it also increases the rating in the energy performance certificate and thus the overall value.
The installation of photovoltaic systems
The costs of a solar system
To be able to use green energy, you still have to invest first. The costs of a solar system depend on the area used and the defined target output, among other things. Advice portals such as the consumer advice center give 1600 euros/kWp as a guideline. The experts recommend making maximum use of the available area. The surplus electricity can be fed into the grid and used as an additional source of income. A study by HTW Berlin showed that small systems optimized solely for self-consumption are often associated with comparatively higher overall costs.
However, the total costs are influenced by more factors than just the number of modules installed. Maintenance costs, inspection costs, insurance and the costs of the storage solution must be taken into account. Maintenance should be carried out annually in consultation with your specialist company. The system should be inspected again every four years. However, the maintenance costs are quite low compared to other energy generators.
Do you have a specific project? Please contact us.
How the solar modules get onto the roof
A solar module weighs around 20 kilograms on average. A roof must be able to support a corresponding amount of weight. This is where our mounting system comes into play. A good substructure distributes the load perfectly on the roof, so that virtually any roof is suitable for a solar installation today. Additional loads such as snow and wind are included in the calculation.
In order to operate the solar system efficiently, it must be optimally aligned to the incidence of light. You can find out how solar energy systems are aligned in our article "The basics of aligning a solar energy system".
Today, you can expect an average service life of 20 years for solar energy systems. However, if the system is well maintained, it may well run for longer. Alternatively, you can equip the mounting system with newer modules.
The calculation and installation of a solar system should be carried out by a specialist company. Errors during installation can lead to short circuits and fires.
Promotion of photovoltaic systems
The current version of the Building Energy Act (GEG), which was passed in September 2023, also includes a new funding catalog. Implementing a building's heat and power supply in tandem is therefore a way of making buildings future-proof and securing up to 50 percent of the eligible costs.
For private individuals, companies, associations, farms and other target groups, the KfW Bank's "Renewable Energies - Standard" promotional loan also offers attractive support for the construction and expansion of photovoltaic systems and battery storage systems. Loans of up to EUR 50 million are available for each project, which can be combined with other promotional instruments. For private individuals, the granting of loans is linked to the obligation to feed in or sell part of the electricity produced.
System concepts such as Floating-PV and Agri-PV are now also integrated into subsidy programs, which offers interesting prospects for ground-mounted systems.
Yield and profitability
The amendment to the German Renewable Energy Sources Act (EEG) for 2023 has also made some changes for photovoltaics. Every year, operators can decide whether they want to feed all of the electricity they generate into the grid or consume some of it themselves. Feed-in was previously capped, so it was hardly attractive for operators to invest in a large solar system with little or no self-consumption. This has also changed with the amendment.
Savings through self-consumption
For small systems in particular, it is still worth consuming most of the electricity yourself. All the more so now that the EEG levy for self-consumption and direct deliveries of energy for photovoltaics and heat pumps have been abolished. Developments in the battery sector are also making it possible to store more solar power and use it flexibly. E-mobility can now also be easily combined with solar technology.
Income from the sale of surplus electricity
By selling the surplus PV electricity, you can amortize part of the investment costs. A new feature of the EEG amendment is that you can also decide to feed all of the electricity into the grid. Those who feed in all of their electricity receive a higher payment per kilowatt hour. For large systems in particular, it can be more profitable to feed all of the electricity into the grid. Incentives are also created for private individuals to equip their entire roof area with a high-performance system.
Conclusion: Is photovoltaics worth it?
We can answer this question with a resounding yes. Solar energy is one of the main pillars of the future energy supply. Converting at an early stage will give you energy independence, long-term financial benefits and a contribution to environmental protection. With the German government's goal of making buildings fossil-free by 2045, it is all the more advisable to act quickly. Our experts will be happy to advise you on whether and how your area/property/project is suitable.
FAQ:
Do small PV systems also generate attractive returns?
According to Fraunhofer ISE, every system can generate returns. If all of the electricity generated is fed into the grid, the feed-in tariff per kilowatt hour is higher. If the electricity is used to cover self-consumption, the yield depends on the difference between the electricity procurement costs and the electricity generation costs. The expected yield depends on several factors such as the solar radiation at the installation site and must be calculated individually.
Are PV systems destroying ecologically valuable areas?
However, the studies conducted by Fraunhofer ISE clearly show that this is not true. Planned and implemented ground-mounted systems with a view to biodiversity actually promote the renaturation of the areas used. When used in moorland areas, the PV modules with their shading effect ensure that moorland areas do not dry out any further.
Do PV modules dazzle?
The glass surface of the modules can cause glare. The cover glasses of the solar modules usually have a light texture and are provided with anti-reflective layers. In critical environments such as airports, modules with heavily textured cover glass are used to minimize glare. PV modules therefore do not generally pose a danger.
Do PV systems pose a fire risk?
Like all electrical systems, photovoltaic systems can also cause short circuits if they are defective or have been installed incorrectly. Regular maintenance by a specialist company is therefore essential.
