October 31, 2019
◼ 3 years "cables instead of pipes" in residential construction
A builder takes stock.
Three years ago, Paul Langmann, owner and energy expert, opted for a purely electrical building technology concept in the course of the general renovation of his multi-party house in Styria. Since then, photovoltaic hot water generation with solutions from my-PV has been an essential part of this concept. Now he takes stock.
Left: Exterior view with PV facade
On the right: the "heating house".
Since 2016, eight residential units and one commercial unit have been largely supplied with clean energy from a 30 kWp photovoltaic system. Missing energy is purchased as green electricity, and any surpluses are fed into the public grid.
While the infrared panels for the room heating are still switched by thermostats, the hot water preparation was already implemented at that time with infinitely variable heat generators from my-PV. Today, this would also be the case for space heating, because this precise controllability is the foundation stone for heat with photovoltaics and thus contributes to the highest degree to energy savings and sustainability of the building.
How did the decision for this concept come about?
Paul Langmann: For me, the cheapest and simplest storage medium was water. If it is then heated in smaller boilers in the residential units in a decentralised manner, then all pipe and distribution losses are avoided from the start. Solar energy is converted into heat exactly where it is needed, and the legionella issue is also suddenly off the table.
Isn't that very expensive to buy?
Paul Langmann: The investment costs for building services were in any case much lower than for conventional water-guided heating systems due to "cables instead of pipes" and the associated lower use of materials. In addition to complex piping and expensive boilers, the chimney is also eliminated. In addition, the classic boiler house was not even necessary, just one control cabinet covers the entire control technology and the space thus gained in turn offers other benefits.
What is the summary after three years?
Paul Langmann: After three years of operation, I particularly enjoy the low operating costs. Thanks to my-PV's infinitely variable hot water heating devices, the rate of PV self-consumption is over 60 percent every year. This means that 45 percent of the energy required for hot water, space heating and community electricity (staircase, outdoor lighting) can be covered. The remaining residual energy comes from the electricity grid and (after deduction of the proceeds from feeding in surpluses) causes average monthly energy costs of only 260 euros for the entire building. On top of that, my system, which does not need any moving parts, is not only low-maintenance but also low-noise.