Energy saving

Check a recent electricity bill. Are you being penalised for “excess reactive energy”?
You can easily put an end to these charges!
To eliminate the cost, what you need to do is to install equipment known as “condenser batteries”.

  • With the support and experience of your Fenie Energía Agent and our engineering team, we will draw up a technical study to establish which model of condenser battery is right for your installation.
  • In most cases, the product will pay for itself in under two years, making for a very swift return on your investment.
  • You can apply to pay in 24 instalments, which we will include with your electricity bill if your electricity is supplied by Fenie Energía, giving you savings from the very first day.

Case studies about Compensation of reactive energy

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    Did you know? about Compensation of reactive energy

    1. What is reactive energy?

    Many electrical devices, such as fluorescent light fittings, motors, air conditioning units, lifts, etc., generate a flow of energy that circulates from one side of the electrical network to the other without being consumed, while causing losses and problems in the electricity distribution grid. This energy is known as “Reactive Energy”.

    In addition to losses through the transformation of energy, the energy distribution companies have to make a greater investment to install oversized distribution lines and transformers for the transmission and transformation of this reactive energy. This causes costs for the electrical system that are passed on to customers in the form of a reactive energy penalty on their electricity bill, wherever this exceeds certain limits published by the government in the Official State Gazette, in ITC/3519/2009.

    2. What is a condenser battery?

    Condenser batteries are devices that, when connected to an electrical installation, can detect the presence of inductive reactive energy, and by connecting their condenser units, achieve the required capacitive reactive energy to compensate it. Following on from the above explanation, reactive energy comes and goes without being consumed, between the customer’s apparatus and the condenser battery. This means that the reactive energy does not flow through distribution networks external to the customer’s installation, eliminating the transmission losses and hence the penalty on the customer’s bill.

    3. Why did I not pay a penalty in the past, but do now?

    This could be the result of various circumstances:
    1. It may be that you already have a condenser battery connected to your installation, but for some reason it is faulty or is disconnected and does not perform its function properly.
    2. It may also be that you have at some point extended your installation by incorporating new consumption equipment, or some of the apparatus you already have installed is faulty, leading to an increase in reactive energy consumption, thereby surpassing the limit beyond which a penalty is charged on your electricity bill.
    3. Lastly, it could be the result of the implementation of the new smart meters for tariffs 2.0 and 2.1, which incorporate in one single device active and reactive energy readings. These meters must be installed for new supply contracts, and are progressively replacing the former mechanical meters, most of which did not give a reactive energy reading for many low-level consumption supply contracts.

    4. What is the standard service life of a condenser battery?

    The life of a condenser battery is a parameter that must be estimated by means of indirect trials and tests. The average life of a condenser battery is typically estimated as between 10 and 12 years.
    However, in order for this estimate to be fulfilled, a number of fundamental conditions must be met:
    – The ambient conditions of the condenser battery must be the most appropriate. According to standard CEI 60831:

    Air temperature


    Highest average during a period of


    1 year





    – The voltage and current levels of the installation must be constant. Consideration must be given to the limits established for overvoltage in accordance with standard CEI 60831.
    • 10% overvoltage: up to 8 hours in 24 hours.
    • 15% overvoltage: up to 15 minutes in 24 hours.
    • 20% overvoltage: up to 5 minutes in 24 hours.
    • 30% overvoltage: up to 1 minute in 24 hours.

    – The level of harmonic distortion for the voltage and current must not exceed the following levels:
    2 % THD (V)
    20% THD (I)

    – Basic maintenance must be performed to guarantee proper functioning of the battery.

    5. Will it also reduce my electricity consumption?

    The reduction in consumption will not normally be noticeable. It would only be noticed if the customer has their own transformation centre and a medium voltage meter. By eliminating the reactive energy reaching the transformer, it will enjoy better operating conditions and be more efficient. It is very common to eliminate reactive energy when transformers are saturated or at the limit of their power.

    6. What is the difference between buying a condenser battery on the market and the service provided by Fenie Energía?

    Fenie Energía performs a personalised study of each case. Our network of Energy Agents will, only if it is cost-effective for you, recommend the installation of a condenser battery to eliminate or considerably reduce the penalty applied to your bill.

    In order for you to save money from the very first day without the need to make any investment, we offer you the option of paying for the battery in 24 instalments via your electricity bill (replacing the excess reactive energy that you are currently paying with smaller instalments). After 24 months, you will no longer be paying either excess charges or the instalments.

    Meanwhile, for your own peace of mind, if you have an electricity contract and install a battery with Fenie Energía, we will perform monthly monitoring of your bill to ensure that there is no repeat of the reactive energy penalty. If it does recur, we will immediately notify your Energy Agent to visit your installation and ascertain what could have happened (triggering of protective breakers, new equipment installed, some kind of fault, etc.). Without this kind of control, there are customers who don’t realise that their condenser battery has been disconnected for months.