Table of contents:
- Is wind power worth it?
- Solar cells for the monument:
- Test operation for the pioneer:
- Electricity and heat at the same time:
Video: Generating electricity: top examples: we are independent
There are various technical options for harvesting and using electricity yourself: photovoltaics, wind power, cogeneration, fuel cells. Here are a few examples.
Because electricity is becoming increasingly expensive, many homeowners are looking for ways to make themselves independent of electricity providers - and thus save. The federal government has also been talking about how necessary the energy transition is for a long time - and yet it gets caught up in political quarrels with the federal states. The most recent point of controversy was a power line intended to transport wind energy from the north to the south.
Actually, the Renewable Energy Sources Act (EEG) is supposed to help convert the energy supply and use more regenerative technology to generate electricity. The first version came into force on August 1, 2004 and has since been revised several times, most recently in 2014. The EEG regulates the remuneration for every kilowatt of electricity that comes from plants for wind, water, solar, geothermal energy or biomass - and is fed into the grid. The remuneration is set at 20 years from the moment of commissioning. Network operators are obliged to purchase green electricity - this has priority over fossil-generated electricity. In order to bridge the difference to the electricity price on the electricity exchanges, there is the EEG surcharge. Every consumer pays this with the electricity price. The 2014 EEG reform should also burden the electricity consumption of new PV systems with the EEG surcharge. Small systems with an output of up to 10 kW (typical for a family home) are not currently affected - the bureaucratic effort seems too great. But that can change.
Preliminary work: With the appropriate software (E.ON and Sungevity) you can determine in advance whether solar cells are worthwhile at the location. Online and without an on-site appointment. The expected yield can be calculated from energy consumption, hours of sunshine, aerial photos, photos of the house, information on roof pitch, sun orientation and roof area.
Photo: E.ON / Markus Traub
Photo: imago / sven lambert.
Is wind power worth it?
For a small rotor to use the wind effectively, it needs an average wind speed of twelve meters per second. This pace arises, for example, on the coast. In the low-wind inland, you can look forward to five to eight meters per second. The masts often have to reach very great heights in order to collect sufficient strength. Before you decide: Check the wind conditions at the desired location - over a longer period.
Solar cells for the monument:
Sometimes you have to be patient until dreams come true. Petra Fritsch and Gerhard Greiner lived in the spacious attic apartment in a Kassel town house, renovating here and there. Greiner had been thinking about expanding the storage for some time. An important point in his conversion plans: he wanted to use solar energy. Because the architect is co-owner of the HHS Planer + Architekten office, which is famous for energy-efficient buildings. As the building is a listed building, every change to the roof and facades had to be coordinated with the monument conservationist. “The office of head of the building department was newly appointed in 2012. He demanded that historic preservation and energy efficiency should no longer be seen as irreconcilable opposites,”says the client. So he planned the roof conversion together with the young colleague Lukas Droste. Photovoltaic system, skylights and contour were coordinated, the technology was integrated harmoniously and all conversions were coordinated with the monument authority in several appointments. "The plant generates about three times the amount of energy we consume." The inverter shows a harvest of 5418 kWh. The two consume 1400 kWh, feed 4784 kWh into the network. "The heating requirement is also covered in the balance sheet, " says Greiner.
Here's how it works:
Solar cells convert sunlight into direct current. The inverter turns it into alternating current. This is fed into the grid, consumed in the house or stored in the power store.
Test operation for the pioneer:
The Schmitt family had the gas boiler in their two-family house replaced by a wall-mounted, innovative fuel cell heater (from Vaillant and EnBW) last year. The property is taking part in a practical test that has been running since 2008 (carried out by Callux). Schmitts wanted to contribute to climate protection and reduce their CO2 emissions. “We easily get the heating that is needed for the house. We feed the electricity completely into the grid.”The amount generated can be checked on the system controller of the system. On average, the technology creates an electricity yield of 5200 kWh per year. Monitoring and control are carried out by remote diagnosis. “We know that someone is taking care of the system. And the operators always have an insight into the technology and can adapt everything - even when we're not there.”More information on the practical test at www.callux.net
Here's how it works:
Fuel cells work with natural gas. It mainly consists of methane and is easily converted into a hydrogen-rich gas - technicians call this reforming. Hydrogen serves as fuel for the fuel cells. It is converted into heat and electricity through a controlled chemical reaction. The first devices were brought onto the market this year, with more to follow soon.
Satisfied: The Schmitts wanted to reduce CO2 with the regenerative heating - and are testing the latest technology.
Photo: Callux / EnbW / Vaillantt
Electricity and heat at the same time:
When the Zieglers bought the 280 square meter 80s building, they were looking for an efficient energy system. Because the two work at home - and operate a large office with computers, scanners, printers. "We wanted a future-oriented and climate-friendly technology." They chose a Dachs SE G5.5 with an additional 750 liter buffer tank (both from SenerTec). The combined heat and power plant (CHP) generates around 13, 300 kWh of electricity per year. Zieglers use about a fifth (around 1800 kWh) of the electricity generated directly. They feed in the rest and receive remuneration for it. The combined heat and power plant (CHP) completely covers the heating needs of the house of 35, 000 kWh. More: www.senertec.de
Here's how it works
An Otto or Stirling engine burns natural gas, biogas, oil, rapeseed oil or biodiesel, generates kinetic energy and thus produces electricity. The engine heats up considerably. This "waste heat" is used for heating by means of a heat exchanger. The principle of combined heat and power (CHP) has meanwhile been better adapted to the electricity and heat requirements of private one- and two-family houses. Mini combined heat and power plants generate an average of 5-6 kilowatts of electricity and 10-14 kW of heat. The smaller micro combined heat and power plants produce around 1 kW of electricity and 6 kW of heat.
Double: Zieglers feed the solar electricity into the grid, they use the yield of the combined heat and power plant themselves.