Yield. Own-Consumption. Self-Sufficiency.


Commonly PV, stands for the generation of electricity from solar energy. The photoelectric, especially: the internal photoelectric effect in semiconductors (such as silicon) is applied. Photovoltaics is a relatively easy way to generate your own electricity.

With 2Degrees you can compare different combinations and locations, PV sets and other energy systems based on these factors.See how a battery storage impacts on the 3 characteristics of self-sufficiency, own-consumption and economics in our free PV-Calculator.

Photovoltaic systems for your home

With a PV-system on the roof of your home, today we can economically produce our own electricity. Power from the roof is even cheaper than the electricity supplied by your utility at your socket. We currently have to pay between 25 and 28 cents per kWh to the electricity supplier, including taxes, levies and the EEG surcharge. At the same time, solar power can be produced by ourselves for plants between 2 and 10 kilowatts of installed capacity (kWp) for costs between 9 and 11 cents per kWh. Therefore, investing in your own photovoltaic system by saving electricity from the grid and using the feed-in tariff is a profitable option.

Cost-effectiveness of photovoltaic systems.

Your own photovoltaic system achieves an appreciable economic efficiency in two ways today. On the one hand, the owners can use the generated electricity themselves. Each kilowatt-hour of the roof’s own use saves at least 14 cents per kWh compared to electricity from the grid. On the other hand, owners of a photovoltaic system with electricity that they do not use themselves and therefore feed into the grid can earn between one and three cents per kWh through the feed-in tariff. For systems below 10 kWp of installed capacity, the feed-in tariff is 12.20 cents per kWh (as of January 2018). Thus, both self-consumption and feed-in tariff contribute to the profitability of photovoltaic systems.

Economics, own-consumption and self-sufficiency can be individually calculated for your location & consumption in our  PV-Calculator.

How to increase the Own-Consumption share from your Photovoltaic System.

Der höhere Gewinn durch die Photovoltaik-Anlage auf dem Dach liegt beim Eigenverbrauchs-Anteil. Daher sollte möglichst viel selbst erzeugter PV-Strom im Haus selbst verbraucht werden. Bei Anlagen bis 10 kWp Leistung muss keine EEG-Umlage auf den selbst erzeugten Strom gezahlt werden. Die gesamte Differenz zwischen Stromgestehungskosten aus der eigenen Photovoltaik-Anlage und Kosten für Strom aus dem Netz kommen dem Anlagenbesitzer zugute. Daher verbessert ein hoher Eigenverbrauch des Stroms aus der Photovoltaik-Anlage die Wirtschaftlichkeit.

Solar power for hot water, heating & more self-sufficiency!

Eine weitere Möglichkeit, den Eigenverbrauchs-Anteil zu erhöhen, ist die Nutzung des Solarstroms für die Warmwasserbereitung und für die Heizung. Die einfachste und kostengünstigste Möglichkeit ist eine direkte Erwärmung des Wassers in einem Speicher mit Heizstab. Effektiver ist jedoch der Einsatz einer Wärmepumpe, für welche die Photovoltaik-Anlage einen Teil der Stromversorgung übernimmt. Diese kann die Energie für die Warmwasserbereitung und eventuell auch für die Heizung in einem Pufferspeicher lagern.

Wie hoch der Eigenverbrauch des Solarstroms vom Dach ist, hängt im wesentlichen von der Größe der Photovoltaik-Anlage und den Maßnahmen zur Optimierung des Eigenverbrauchs ab. Grob gesagt können rund 25 bis 35 Prozent des Solarstroms selbst genutzt werden. Je nach Speicher-Kapazität lässt sich dieser Wert mit einem Batteriespeicher auf 50 bis 70 Prozent steigern.

Heat Pump with PV & Battery Online Calculator

Battery Storage increases the Own-Consumption share and Self-Sufficiency of your PV system.

In order to consume even more electricity from the photovoltaic system itself and to increase the own-consumption share, an electricity storage can make sense. Batteries store the electricity generated during the day so that it can be used in the evening and at night when the sun is no longer shining. The own use of the electricity is much more attractive than to feed the power generated into the grid.

For the purchase of a battery storage homeowners can apply for a grant from KfW Bank in the programme „renewable energy storage“. See also our Subsidy-Tool.

Energy management increases the Own-consumption share with simple means.

Owners of a photovoltaic system should, if possible, switch on electrical devices to increase own-consumption if the solar radiation is high. These include in particular large consumers, such as washing machines, dryers and dishwashers. Energy consumption management systems or smart home solutions can be used to support consumption cost optimization, especially if you cannot be at home during the day to turn on these devices. Such systems are e.g. offered by inverter manufacturers and start the devices even in the absence of users – if they are filled and ready for use – depending on the sunlight and the weather forecast. In addition, they provide a convenient overview of your own power generation and own-consumption.

Smart meters from innovative providers offer a variety of visualization options. Further advantages of smart meters you will find here.(German)

How to achieve Self-Sufficiency through Solar Power?

A frequent motive for the investment in a photovoltaic system and possibly in a battery storage is the independence from the electricity supplier and market-dependent price developments. This makes the self-sufficiency rate interesting. This indicates the proportion to which you can provide yourself with electricity. A degree of self-sufficiency of 100 percent would mean that you are completely self-sufficient.

The degree of self-sufficiency depends on your own total electricity consumption; it will be increased if you manage to reduce overall power consumption. The other way is to increase the own-consumption share from the photovoltaic system. The less electricity you need to purchase from an external utility beyond self-generation, the higher the degree of self-sufficiency. In contrast, the own-consumption rate indicates the share of self-generated electricity, which is also consumed itself or could be consumed due to the performance of their own photovoltaic system.

You can find more information about our PV sets and the yield calculators here.

We are at your disposal for all questions concerning photovoltaics, battery storage and the combination with heat pumps and fuel cells.

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