Self-consumption (solar power)

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Internal consumption of solar power means that by solar panels produced even electricity used locally by the operator and not to the public electricity grid is fed. While in the past was the supply of self-generated solar power into the public grid the rule, important against a backdrop of declining feed-in tariff of own consumption in importance. Self-consumption can be increased through intelligent power consumption if consumers are switched on specifically during the day or even at particularly sunny times. The use of battery storage systems can also be used to buffer the time lag between power generation and power consumption, thus increasing the proportion of self-consumption.

Regulation by the Renewable Energy Sources Act

The legislator has steadily reduced the remuneration under the Renewable Energy Sources Act (EEG) over the past few years. The EEG has so far also regulated the promotion of self-consumption. With the last revision of the feed-in tariff on April 1, 2012, the framework conditions have fundamentally changed. The additional remuneration granted up to then for self-consumed solar power was abolished. Operators of systems with an output of more than ten kilowatts now have to consume ten percent of the electricity they generate themselves or market it in some other way.

As part of the 2014 EEG reform, it is planned to charge self-consumption with the EEG remuneration. The Federal Association for Renewable Energy fears that this will result in less electricity being used and more being fed into the grid, which would lead to a higher EEG surcharge.

Situation in Switzerland

According to Article 17 of the Swiss Energy Act (EnG 730.0), several landowners and end users can join forces for joint self-consumption, provided that the total production output is significant in relation to the connected load at the measuring point.

Grid parity

The grid parity - that is, that the self-consumption is cheaper than buying from the current provider - is the German energy market for new plants now reality. The average kilowatt hour (kWh) from the self-consumption system only costs 8-14 cents (2013, see electricity generation costs ), while the average kWh for German energy providers is already 26 (as of January 2013) cents and higher. This is why the installation of a PV system is already worthwhile for private households and businesses today (as of January 2013). In order to achieve a high proportion of self-consumption, the system must be designed correctly and the consumption behavior adapted accordingly.

economics

So- called solar batteries can be installed to increase the proportion of self-consumption . Despite the additional costs, the operation of photovoltaics becomes more economical.

By leasing parts of the system, tenants can also use the inexpensive self-consumption electricity from the apartment building.

There are now service providers z. B. in Munich, who help with the bureaucracy when apartment buildings want to obtain electricity from their own roof or from the neighborhood. The potential for solar power in cities is great. Purchasing electricity from your own roof lowers electricity costs by 25 to 40 percent, as there are no costs for network charges and electricity tax compared to mains electricity.

Some energy providers already offer a mixture of solar power from the roof and green power from the grid. The electricity tariff achieved in this way is well below the other network tariff. This is of particular interest to tenants who tend to be limited when it comes to inexpensive self-consumption of solar power.

Citizens' energy cooperatives and bioenergy villages operate on a somewhat larger scale, but with the purpose of self-consumption .

In Bavaria there is an electricity tariff (so-called eco-regional electricity tariff) in cooperation with an energy cooperative, which markets the solar electricity generated in the region on site. The solar power is bought directly from the operators of solar systems at a higher price than the feed-in tariff. The feed-in tariff does not apply. This electricity is then sold directly to local consumers. The electricity stays in the local electricity network, which means that there are no network charges and the electricity tariff is therefore cheap.

The Nuremberg company ikratos offers the Tesla Powerwall (7 kWh) together with an inverter, solar modules and installation for 9,999 euros. The 30 m² photovoltaic system is supposed to deliver 3000 kWh per year. Assuming an electricity price of 30 cents per kWh for the next ten years, this system will have amortized itself after 11 to 12 years.

Tenant electricity

Some homeowners in Germany install solar systems on the roof of an apartment building as well as block-type thermal power stations and sell the self-generated electricity to their tenants or hire a company to install the systems and sell the electricity. The self-generated electricity is cheaper than electricity from the grid, because u. a. There are no transport costs for electricity through the power grid, as well as some taxes. Participation is voluntary for tenants. The electricity gaps are filled with electricity from the grid. With tenant electricity , property owners increase the attractiveness of their own property because the ancillary costs decrease. The potential in Germany is around 1.5 million apartments.

Components of a self-consumption system

A photovoltaic system for self-consumption consists of several components. On the one hand you need the photovoltaic modules on the roof, garages or on facades. In addition, inverter , solar load control, solar batteries of lithium ion and an energy management system is required. An intelligent electricity meter can optionally be used. Optionally, a combined heat and power unit can be used to avoid having to draw electricity from the grid in unfavorable weather conditions. A heat pump can optionally be used to transfer excess solar power to the hot water system or heating system.

Solar energy is used and direct current is generated via the PV modules. The inverter converts this into alternating current and feeds it into the house electricity network. An energy management system controls the consumption of the individual devices and coordinates the feed into the battery system. Solar charge regulators ensure that the battery is charged with the correct current and absorb excessively high or low charging voltages or currents. The billing of self-consumption with the public energy supplier takes place via a special arrangement of the electricity meters.

Existing PV systems can be retrofitted with the solar charge controller, energy management system and battery. For new systems there are products that combine inverters, solar charge controllers and intelligent energy management systems in one device. This makes the installation quick and easy (complete system within one day) and easy to operate for the owner.

Storage of energy

An energy management system stores excess solar energy, which is produced but not immediately consumed, in its own solar batteries . Electricity from the public grid is usually not used to charge the battery. The exception is e.g. B. the integration of the solar battery in a swarm storage for network services. With battery storage systems, power failures can be bridged or unstable grids protected. Rising electricity prices, on the one hand, and falling prices for inverters and batteries, on the other, mean that stored solar electricity is cheaper than grid electricity. In the meantime (2/2014) the prices for batteries have fallen sharply. The electricity production costs for solar systems have also fallen sharply, so that despite storage they remain well below the costs for grid electricity.

In addition to storing electrical energy, other forms of storage can also be used to a limited extent:

  • Cold storage, e.g. E.g. by charging freezers to −32 ° C during the day using solar power, increasing to −18 ° C at night
  • Heat storage in geothermal heat pump systems by reversing the heat flow or by preferential charging of the buffer storage

Solutions have also been implemented in Germany in which a homeowner with a solar system uses the battery of his electric car to store electricity.

Since the end of 2014, electricity storage systems and battery cabinets have been used in German private households and by companies for energy storage and their own use. In interaction with other self-generated energies such as B. with combined heat and power plants , a degree of self-sufficiency of 100% can be achieved with these systems. In many households, however, only solar batteries are used to store energy from photovoltaics or wind power and make this available for their own use. If you also use part of the stored energy to provide hot water and heating, a degree of self-sufficiency of up to 80% can be achieved. Such storage systems are funded by KfW funding with KfW program 275 .

Heating with solar power

An alternative to storing solar power in accumulators is to store the energy in thermal storage . For this purpose z. B. used with a heat pump solar power to heat domestic water or heating water, which is then stored in a thermal store (similar to a vacuum jug ). The thermal energy is then not converted back into electrical energy, but fed into the heating system. The costs for useful heat can thus be reduced from around 8 cents / kWh to around 2 cents / kWh compared to oil and gas heating (see operating costs of heat pump heating systems ).

Income surpluses can also be converted directly into heat. Photovoltaic heat generation is much less complex than with heat pumps, and the excess energy in typical small systems in summer is usually sufficient for hot water preparation. This means that conventional heat generators can be switched off outside the heating season.

Billing with the network operator

In order to bill the energy supplier for self- consumption , the electricity meters in the PV system must record the electricity generated on the one hand, and the consumption of public electricity and the feed into the public grid on the other. Self-consumption is calculated from the difference between energy generated (PV meter) and energy fed in (feed-in meter). The network operator creates a credit note based on the feed-in and self-consumption values , on the basis of which the down payments to the PV system operator are calculated.

Participation in the network costs

The profitability of self-consumption of solar electricity results from the fact that the costs of electricity purchase represent full costs ( i.e. include the costs of the electricity grid and taxes in addition to the costs of electricity generation ), while the costs of the end consumer only represent partial costs . Currently, the amount of self-consumed solar power is still low. Due to the rising electricity prices (among other things due to the EEG surcharge), an increasing proportion of self-consumed solar electricity (and other types of generation) is expected, which in turn leads to an increase in the electricity price, since the fixed costs of the network fall to a lower number of transported kWh must be allocated. In order to avoid this and to achieve a polluter-based allocation of the network costs, a network usage fee and an increased fee are proposed for those who both feed in and withdraw electricity.

Solar tariff

In the Swiss Energy Act (EnG 730.0) there is only one indication that the Federal Council can issue provisions in the ordinance to protect tenants and lessees from abuse.

In the energy ordinance, two points of orientation for solar power are then defined in order to prevent unfair prices:

·       Production costs : The price for solar power should be based on the investment in the solar system.

·       External reference : The internal solar power should not be more expensive than the related from the public mains.

The income from feeding solar power into the public grid must be deducted from the internal solar tariff. There is also a specific tenant protection provision. If the client invests in a solar system, half of the actual profit has to be distributed to the tenants. This provision does not therefore apply to building cooperatives or condominiums.

Web links

Individual evidence

  1. ↑ Renewable Energies Act on solarwirtschaft.de
  2. ^ Agency for Renewable Energies: Own consumption and regional direct marketing. Opportunities and challenges. Background paper, 2014
  3. ↑ a b SR 730.0 Energy Act of September 30, 2016 (EnG). Retrieved April 13, 2020 .
  4. ↑ Grid parity from when the self-consumption of solar power is worthwhile at ratgeber.immowelt.de
  5. ↑ orf.at ( Memento of the original from January 31, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. "New storage for solar power" accessed on January 24, 2016  @1@ 2Template: Webachiv / IABot / noe.orf.at
  6. ↑ taz.de "A Munich service provider helps with the bureaucracy when apartment buildings want electricity from their own roof or from the neighborhood." and "A feasibility study on behalf of the Munich City Council showed that of the total of 42 million square meters of roof area in the city, around 15 million are suitable for generating solar power." and "Schütze speaks of savings of 50 to 100 euros per household per year, because the electricity consumption from the expensive grid is reduced by 25 to 40 percent through photovoltaics." and "Since the users of the locally generated electricity are usually not the owners of the power plants, the EEG surcharge for the promotion of renewable energies is due on the local electricity sold. But at least there is no electricity on the way from the roof to the house network public network is used, which is why network fees are saved. There is also no electricity tax. "
  7. ↑ pv-magazine.de "In Berlin Hellersdorf, since the beginning of the month, tenants have been able to obtain“ home electricity ”- which is a combination of locally generated solar power from the roof and green electricity from the grid. It is the largest commercial project to directly supply tenants with renewable energies, said Lichtblick. The aim behind this is to equate tenants with homeowners, who have long been able to use solar power from the roof themselves. "
  8. ↑ pv-magazine.de "In a pilot project, tenants of the Wohnbauten-Gesellschaft Stadt und Land in the Yellow Quarter in Berlin Hellersdorf are supposed to be able to use electricity directly from solar systems, which is generated by photovoltaic systems on the roofs of 50 apartment buildings. This is produced on site Solar power combined with certified green power from Lichtblick and bundled into what is known as a home power tariff. Supply to households is to begin in March 2014. According to Lichtblick, this model has two advantages for tenants. On the one hand, the electricity generated on site is cheaper than with conventional electricity tariffs Secondly, the general public will also be financially relieved because the electricity consumed locally no longer has to be fed into the grid. Therefore, no pay-as-you-go subsidies under the Renewable Energy Sources Act have to be paid. "
  9. ↑ pv-magazine.de "The Japanese electronics company wants to implement photovoltaic systems for apartment buildings in Baden-Württemberg. The solar power should then be sold to tenants at low cost. In the event of bottlenecks, Toshiba wants to buy electricity at the wholesale market. The model should go beyond photovoltaic feed-in tariffs of the EEG work. "
  10. ↑ Energiegenossenschaft and Grünstromwerk bring Bavaria's first eco-regional electricity tariff to market, including 25% solar electricity ( Memento from May 24, 2014 in the Internet Archive )
  11. ↑ SunPower and Tesla in a package for every roof
  12. ↑ The 99 roofs campaign .. for 9,999 ( memento of the original from March 31, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.ikratos.de
  13. ↑ 3000 kWh * 30 cents / kWh * 11 years = 9900 euros
  14. ↑ sueddeutsche.de "Tenant electricity: From the roof to the socket" from March 17, 2016, accessed on March 18, 2016
  15. ↑ manager-magazin.de electric car rebel Karabag: "Our electric car concept is cheaper than a conventional car"
  16. ↑ KfW Renewable Energy Program “Storage” (PDF) KfW. May 25, 2018. Retrieved March 22, 2019.
  17. ↑ Photovoltaics and thermal energy storage: Energiebau includes Junkers heat pumps in its product range ( Memento from April 14, 2014 in the Internet Archive )
  18. ↑ Bosch presents innovative solutions for photovoltaic systems in combination with electricity storage and heat pumps at Intersolar Europe 2014 ( Memento from May 24, 2014 in the Internet Archive )
  19. ↑ Archived copy ( Memento of the original from December 4, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.dena.de
  20. ↑ http://www.wienerzeitung.at/nachrichten/oesterreich/politik/743100_Schatten-ueber-dem-Solarstrom.html
  21. ^ Andreas Mihm: Network users have to pay; in: FAZ of June 14, 2013, p. 11
  22. ↑ What is a fair solar tariff? In: Zevvy Helpcenter. March 18, 2020, accessed April 13, 2020 .