What is the difference between the self-production rate, also called self-sufficiency rate, and the self-consumption rate?
The self-production rate is the part of a building's total consumption which is self-produced thanks to the panels.
It is therefore the share of solar energy in the total consumption of the building. The excess energy injected into the network is no taken into account.
This rate makes it possible to know its level of energy autonomy and therefore its dependence on the electricity network.
It is different from self-consumption rate, which is the share of panel production that is self-consumed by the building.
Self Consumption : The electricity produced is used by the house. If it produces too much the electricity is rejected to the network.
Self Production : The house uses the electricity from the panels. If it doesn’t produce enough the house takes electricity from the network.
Source : ecologie.gouv.fr
The Ministry of Energy Transition defines the following examples to illustrate this:
Example 1: Small solar installation = 100% self-consumption
If a consumer, in his house, uses a photovoltaic installation of reduced size, the electricity production of this installation will be low.
His house will therefore be able to consume entirely local production: his self-consumption rate will reach 100%. On the other hand, insofar as the size of the installation will not make it possible to produce up to the total consumption of the house, the self-production rate will be very low.
The consumer will therefore use electricity from the traditional network to meet part of his consumption.
Example 2: Large solar installation = 100% self-production
If the consumer uses a larger installation that allows him to produce his electricity up to his total consumption, the self-production rate will be 100%. However, in this case, it is very likely that, to cover its consumption, the installation is oversized and produces in excess at times of low consumption.
In this case, the self-consumer will also need the traditional network to reinject the electricity produced locally and his self-consumption rate will probably be very low (less than 30%).
He can also equip himself with a solar battery to store the electricity produced and consume it later, or adapt his consumption habits to use electricity during periods of sunshine and production of the panels: all this will improve its self-consumption rate.
Thus, insofar as renewable installations are intermittent, they do not produce electricity all the time. They cannot therefore cover the consumption needs of a site at all times, especially during peak consumption in the morning and evening.
In the majority of cases,the site must be connected to the electricity network.