Energy self-consumption is defined as the use of energy generated by oneself through an installation – for example a photovoltaic one – for own consumption.

Photovoltaic solar energy installations are usually divided into two types: installations connected to the grid and isolated installations (without connection to the grid). Although technically both can be self-consumption, since they can serve to cover, partially or totally, our electricity consumption, we usually call self-consumption installations to those connected to the grid that serve to reduce our electricity bill.

In Spain there are some charges on self-consumed energy that we know as “sun tax”. This tax only affects facilities connected to the network. The isolated photovoltaic installations of the network do not have any type of tax or charge.

Self-consumption installations connected to the grid are connected inside a consumer electrical installation (the electrical installation of our facility, home, office or warehouse).

Normally we will not use energy storage by batteries in this type of installations, since it is possible to take electricity from the electrical grid in the cases of low or no generation of energy by solar panels.

Batteries can be used to store part, or all, of the energy coming from the solar installation during the day and use it afterwards when the the sun has gone. This will happen when our electricity needs during sun hours are covered and the solar installation is able to supply us with more energy. With this we will be able to increase the percentage of our demand covered with solar energy, with respect to a battery-free installation, although the overall economic profitability of the project, taking into account the costs of current batteries, will decrease.

Self-consumption is regulated in Spain by Royal Decree 900/2015. This RD distinguishes two types of self-consumption:

Type 1

It is the modality in which the majority of small consumers meet. These are self-consumption installations intended for own consumption, which surplus energy is discharged to the network without compensation. In installations less than 10kW the “sun tax” does not apply.

Type 2

These are medium or large installations, usually of companies, intended for own consumption and which sell the surplus generated energy to the grid. In this modality there are two subjects, the consumer and the producer. They must be registered in the RIPRE (administrative register of electric power production installations). This implies a series of administrative obligations such as registration in the CAE (activity code), quarterly VAT tax declaration, 7% generation tax payment, etc.

Other advantages:

Besides being a good investment, solar photovoltaic installations have these other advantages:

  • Take care of the environment. The use of renewable energy is one of the basic tools against climate change.
  • Image. Nowadays it is a good marketing tool saying that our company uses renewable energy.
  • Helps to maintain a fixed electricity cost. With the solar installation we know what the kWh we consume will cost us, while the consumed energy from the grid has a variable value, nowadays with significant increases.
  • Increase the value of our house, building or facility. It is an infrastructure that makes the value of the building increase up to 3-4%.
  • Create jobs and help the local economy.