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Samstag, 27. Juni 2020

What contribution do "small power plants" in private residential construction make to the desired energy- and heat-transition?

On the weekend I had another nice conversation with someone who was interested in installing a solar system on his roof. A conversation which animated me to this article.
In the course of the conversation, a question was asked again and again: "What is the point of my small system, if we strive for a global energy- and heat- transition?"
Well, the answer should be simple. Any system that ensures that we do not need a combustion process to generate heat or electricity is an asset.
To put it in rough figures, let's say 1 million roofs are equipped with a 3 kWp PV system and a 5 m² solar thermal system.
With PV this would be about 3 million KWp or 3 GWp of power that would be installed, which corresponds to an annual output of about 3 TWh of electricity that would be generated.
Yes, I estimated 1000 kWh/KWp. In the south it will be a little more, in the north less. It is a milkmaid's bill, no question, but not far from reality.
And if you now add to this the fact that a solar thermal system in summer can help to avoid burning oil or gas to generate hot water, I would say that this, taken as a whole, is no small contribution to the energy- and heat-transition.
But I have now focused only on solar. If we spin this idea further, then we come to heat pumps that can convert electricity into heat many times over. Depending on the type of system, it is possible to turn 1kWh electric power in up to 4 kWh of heat. How nice if most of the electricity or additional heat would now also come from the roof. ?!
Unfortunately, in such conversations, you come across a factor that is at the forefront of such considerations. "What does such a system cost me and when will my investment pay off?" A perfectly understandable question. But even here, just pull out the calculator and think about what e.g. the electricity from the grid costs and what e.g. the electricity generated by my PV system costs. Especially with regard to the low-interest loans that are currently granted for the construction of such a system.
And if you now add the subsidy programs for the use of "renewables" in general, the answer should not be difficult.
Here is an additional example from the past: "What, 10,000 EUR for a solar thermal plant, that's too expensive for me..." A few months later it sounded like this: " What 12,000 for a solar thermal plant with a subsidy of 2,000 EUR, ... I am interested".  Well, everybody can think about that on his own...
Another sentence that got stuck in my memory: "The energy-transition is more likely to be achieved with large solar and wind parks. Well, of course, a large plant concentrated on one area is able to generate more power than a plant on a private roof. BUT, on the one hand, such plants are more reserved for investors who want to generate a quick profit.
On the other hand, we have to ask ourselves to what extent a large plant, for which forests are cleared, agricultural areas are sealed, or natural areas destroyed, can still be called "sustainable".
It is not about demonizing these plants, whether wind or solar parks, but about not losing sight of the thoughts "environmentally friendly, nature conserving, real sustainable etc.", just because one concentrates on the fast profit.
Especially in regard to the fact, that there are already applications in the solar sector available that allow the occupied area to be used in a multiple way. Keyword "Agro-PV", here an agricultural area is used to generate electricity, but is still available for the cultivation of agricultural products. In combination with e.g. semi-transparent modules in the field of PV, even the cultivation of sun-sensitive agricultural products is possible.
In addition, even a reduction in water consumption can be achieved through partial shading.

Picture: Solidenergie GmbH -

We have to start looking a little bit more beyond the horizon. On the one hand, with regard to the effect of "many small systems from the field of renewables" in private or small commercial applications and, on the other hand, with a view towards "real sustainability" instead of "quick profitability", at least if we want to implement a truly environmentally friendly energy and heat turnaround in a globally sensible way. And this NOW!
Just a simple thought.


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