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To account the generated energy in the balance the generated energy may not be sold
to a solar stock market or to the special Swiss fund for renewable energy. This Swiss
fund is financed by a premium on electricity in Switzerland and in turn financially
supports the installation of renewable energy sources.
These restrictions require the owner to choose between selling the electricity exported to
the grid with the goal of refinancing the photovoltaic system or getting the Minergie-A
certificate. These restrictions are based on the fact that the solar electricity should only
count one time. Without these restrictions, more Minergie-A buildings would be certified.
The upkeep of this restriction is currently being discussed. One of several issues in this
regard is that ownership, tenancies and contracts change during the times. It’s not
possible for Minergie to track such changes.
Figure 7: On-site generation.
4.3 Grid interaction
Minergie-A buildings are grid connected. Nearly every building has a photovoltaic system
and interacts with the grid: it imports energy if the on-site generation is lower than the
demand and it exports energy otherwise. The grid is used as a kind of storage or credit
item. As the requirement of the net zero energy balance is on an annual basis, Minergie-
A does not rate the time shift between demand and generation or the intensity of grid
use. Figure 8 shows an example of the grid impact of Minergie-A and Net ZEB on a
monthly base for a single family building. To fulfil the net zero energy balance of
Minergie-A, the need of energy production through a photovoltaic system is much lower
than to fulfil the net zero energy balance of Net ZEBs. Therefore, Minergie-A buildings
have a much lower surplus in the summertime and the generation and demand correlate
much better than for Net ZEBs.
To date, due to the low number of Minergie-A buildings and other buildings with
photovoltaic systems, there is no discernible impact on the Swiss electricity grid.
As the political energy target is to cover the operational energy by renewable energy
sources with on-site energy generation, grid control, electricity storage and electricity
transportation for short time and seasonal aspects are major discussion topics. The
reduction of fluctuations by on-site storage e.g. by small batteries in every building,
intelligent control of HVAC and white goods to avoid peak loads and heat storage in the
construction could help increase self-consumption and reduce grid interaction. All these
subjects are current research topics and part of political debate.
