Offline testing of the optimization of Power Purchase Agreements between RES Operators and Electricity Retailers, towards Greening Electricity Supply and reducing associated tariffs and costs.


Demo case 9 aims to promote the retailing and supply of green electricity, enabling the retailers’ transition to a Sustainable Energy commercialisation, whilst optimising the users’ tariff. The demo case, led by CUERVA (Electricity Retailer) and COBRA (RES Plant Operator), could be used as a tool for feasibility assessments for PPAs, defining the optimal PV power and users’ tariff in the long-term, prior to the signature of the PPA itself. For such purposes, the tool will use energy generation profiles and energy demand profiles for a certain study area.  Current details on tariff price information, hourly tariff periods and wholesale electricity market prices were used to guarantee an accurate representation of the situation.

Cuerva and Cobra have defined all the requirements and confirmed the work plan for a successful deployment of this demo case, firstly carrying out an offline test of the tools used in this demo case. This demo case offline test consisted of:

  1. A long-term climatic characterisation using 25 years of data records of the location where the PV plant would be located. This dataset contained several climatic variables to estimate the PV generation profile in the long-term per unit power.
  2. Long-term generation profile prediction per kWp. The results of this simulation can be seen in Figure 1 below on a daily basis.
  3. 2-year tariff-divided electricity consumption profile in kWh, a part of which is shown in Figure 2 below, also on a monthly basis. Additionally, information on tariff prices and hourly periods are used to calculate the total electricity expenditure.
  4. Projections of demand increase/decrease over the period, yearly CPI and panel degradation are used to create a full-period demand-generation coupling.
  5. Solar PV CAPEX and OPEX curves information are used to correctly size the required power plant that will minimize the cost for the consumer while guaranteeing a certain return on investment.
  6. The process is repeated several times with small parameter variations to obtain confidence intervals for the PV plant capacity size

This demo case allows showcasing the benefits that could be achieved between an energy community stakeholders and renewable energy investors, managing projects that benefit all parties involved. The use of real-life climatic information and consumption profiles ensures the viability of the tool for future projects, while the open-to-user definition of tariff periods and prices allows the tool to be used in almost any combination of circumstances and countries.