21.1.3
measuring the power consumed from the grid, the other measuring energy delivered to the
grid) or one smart meter are required. We distinguish between two kinds of feed-in tariffs,
gross and net. In the system of gross feed-in tariffs, all the electricity produced by the
system is sold to the grid utility and all the electricity consumed by the household is
bought from the grid. In contrast, for net feed-in tariffs the actual power consumption is
subtracted from the PV power generation and only the surplus electricity is sold to the
grid.
Feed-in tariffs stimulate the installation of renewable electricity technologies such as
PV, if the feed-in tariffs are above the electricity price. On the other hand, if they are set
(slightly) below the electricity price, self consumption can be stimulated, as discussed
below.
Self consumption
Self consumption is an important aspect of PV systems. It is defined by the European
Photovoltaic Industry Association as the possibility for any kind of electricity consumer to
connect a PV system, with a capacity corresponding to their consumption, to their system
for on-site consumption, while receiving for non-consumed electricity [135]. In practice
this refers to policies that allow a consumer to install a PV system without being charged a
premium for connection to the grid.
As PV systems are penetrating the electricity grid power more and more, certain
issues start to arise. Figure 21.1 shows how a household with a PV system interacts with
the grid. Because of the unpredictable nature of PV electricity generation, the peaks and
troughs on this system will be very difficult for utility companies that manage the
electricity grids to predict. The grid injection levels may exceed the current demand of a
grid well before the PV penetration reaches 100%. This means that there are reasons to
encourage prosumers to directly consume the energy they produce in order to avoid grid
instability issues. Utilizing the generated PV electricity on site, rather than injecting it into
the grid is known as direct consumption.
measuring the power consumed from the grid, the other measuring energy delivered to the
grid) or one smart meter are required. We distinguish between two kinds of feed-in tariffs,
gross and net. In the system of gross feed-in tariffs, all the electricity produced by the
system is sold to the grid utility and all the electricity consumed by the household is
bought from the grid. In contrast, for net feed-in tariffs the actual power consumption is
subtracted from the PV power generation and only the surplus electricity is sold to the
grid.
Feed-in tariffs stimulate the installation of renewable electricity technologies such as
PV, if the feed-in tariffs are above the electricity price. On the other hand, if they are set
(slightly) below the electricity price, self consumption can be stimulated, as discussed
below.
Self consumption
Self consumption is an important aspect of PV systems. It is defined by the European
Photovoltaic Industry Association as the possibility for any kind of electricity consumer to
connect a PV system, with a capacity corresponding to their consumption, to their system
for on-site consumption, while receiving for non-consumed electricity [135]. In practice
this refers to policies that allow a consumer to install a PV system without being charged a
premium for connection to the grid.
As PV systems are penetrating the electricity grid power more and more, certain
issues start to arise. Figure 21.1 shows how a household with a PV system interacts with
the grid. Because of the unpredictable nature of PV electricity generation, the peaks and
troughs on this system will be very difficult for utility companies that manage the
electricity grids to predict. The grid injection levels may exceed the current demand of a
grid well before the PV penetration reaches 100%. This means that there are reasons to
encourage prosumers to directly consume the energy they produce in order to avoid grid
instability issues. Utilizing the generated PV electricity on site, rather than injecting it into
the grid is known as direct consumption.