Numerical weather forecasts supporting the Renewable Energy Sector (RES) in Poland

The climate and energy crises are going hand in hand. The need to adapt to the excess heat and the energy demand - especially for cooling - will increase. The biggest relative change in Cooling Degrees Days will particularly affect the population of Central and Northern Europe. Thus, a good plan is needed to organise the energy system, preferably designing the use of RES resources as adopted by the European Commission in the 'fit for 55' package. Poland's gross domestic consumption still falls short of achieving a 20% share of green energy in the energy mix. The share of RES in domestic production is steadily increasing, especially in the prosumer installations segment. Due to local problems with energy connections and storage, one of the key issues remains maximising self-consumption from in-house installations. On an annual basis, it can be approximated that wind turbines will operate at rated capacity for an average of 25% of hours per year, and photovoltaic installations will average about 12% of hours per year. However, the expected energy yields can be realistically assessed only by taking into account the synoptic variability of cloud cover, irradiation, and airflow conditions. As well as their variation in neighbouring locations or on consecutive dates for the same location. 
In October 2023, the - first in this part of Europe – public free-of-charge RES forecast service for micro-installations in Poland was launched. Constant and averaged solar irradiance values and wind speed generated from the ECMWF HRES 0.1° model fields were assumed in hourly intervals. The forecast values were expressed as a percentage [%] of the rated power yield of a wind or photovoltaic installation according to the assumed installation parameters: a wind turbine with a diameter of 1 m², an installed rated capacity of 8.2 kW, and a threshold value of useful wind speed of 3 ms^-1. As a model, the photovoltaic installation was one PV module of southern exposure, the slope of the unit 30% from the ground, and the power generated under standard conditions of 1 kW, where the maximum daily intensity of solar radiation under standard conditions was set at 1000 Wm^-2. The module operating temperature under real conditions was set at 50°C, and the overall system efficiency, considering losses on the inverter, cabling, or module dirt, was set at 80%.