Solar water heater STC calculator

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Calculate the number small-scale technology certificates (STCs) for solar water heater or air source heat pump systems

Please note that STCs can only be created within 12 months of the installation of an eligible system. See creating small-scale technology certificates for more information.


The solar water heater calculator is designed to assist members of the public to determine the approximate number of small-scale technology certificates (STCs) that may be created under the Small-scale Renewable Energy Scheme (SRES) in relation to an installation. The calculator is designed as an approximate guide only, and does not provide an accurate assessment of the number of STCs that can be created for an installation.

You should be aware that:

  • the calculator does not take into account all of the variables which may affect the calculation of the STCs for an installation, and
  • the calculator is based on data which may be updated from time to time and therefore results using the calculator may vary over time.

In order to accurately calculate the number of STCs that can be created for an installation, you will need to consult the Renewable Energy (Electricity) Act 2000 and the Renewable Energy (Electricity) Regulations.