Green Electricity: Is the Rooftop Solar System Still Worth It?

Scale can be better for PV modules not installed on rooftops but in walls. It can actually sometimes be found in commercially used buildings. In theory, about 1,000 gigawatts of solar energy could be accumulated on facades in Germany study. This does not include windows; They can also be equipped with transparent or semi-transparent collectors instead of glass, in whole or in part. However, vertical roofs have lower electricity yield than roof decks. Under current financing conditions, they are “not really economic at the moment, at most if there is a high percentage of personal use,” says Stefan Thomas of the Wuppertal Institute for Climate, Environment and Energy.

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What is the contribution of balcony units and mobile systems?

Even small PV modules produce electricity, but whether it really pays off varies from case to case. Installing solar cells in car bodies, for example, does not make sense: “A car is often just standing things,” says Franz Bütter, general manager of the Solar Cluster Association in Baden-Württemberg. And if the car is often parked in the shade or in the garage, then the cost of expensive solar collectors that fit into the design of the car is not worth it.

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Small solar panels fit just about anywhere | Small solar modules can be installed almost anywhere where the sun shines, here is an example from South Korea. The contribution of these solar systems for small balconies should not be underestimated: on sunny days, basic needs in the house can be well covered.

Simple and small PV modules for rental apartments, connector units, aligned with the right direction. Simply placed on the balcony or in the garden, it contains The necessary inverter to convert direct current to alternating current The collected electricity can simply be fed into the socket. Potter says the units with an output of 400 to 600 watts are enough to cover the basic electricity requirements of refrigerators, WLAN routers, and other consumers in the home.

Organization problems with connector units

Connecting PV modules to homes raises regulatory questions in Germany. Conventional fuses do not realize that there could theoretically be more current in the system than they are protecting from current feeding into and consumed from the grid. Therefore, the VDE standard recommends not connecting the units to a regular household socket, but to a Wieland socket installed by an electrician. In Austria, for example, it is allowed to connect to a simple household socket.

If every household in Germany installed such a unit, it would add up to 8000MW Stefan Thomas of the Wuppertal Institute for Climate, Environment and Energy. That represents just four percent of the new federal government’s stated expansion target of 200 gigawatts. “But since this goal is very ambitious, it will help.”

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Are small wind turbines worth it?

Says Klaus-Dieter Balcke, Chairman of the Board of Federal Association of Small Wind Turbines. The government of Lower Saxony has realized this and will exempt systems up to 15 meters in height in commercial and industrial areas from permit requirements from January 2022. An important step, because so far somewhat larger systems with a production capacity of 20-40 kW have been planned in the regions commercial, industrial or on farms, but was then banned by employees of the responsible building authorities. Systems often have to meet the same regulatory requirements as larger systems 150 m in height and more.

Another obstacle is the declaration of conformity, whereby the company uses the CE mark to confirm that its product meets the necessary requirements of the European Union directives and has passed all specified assessment procedures. Such official certificates of the machine quickly cost 120,000 euros and more – but they are not a problem for large factory manufacturers. “In France, a CE declaration of conformity from the manufacturer is sufficient,” says Balcke.

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