Technical Energy Storage Parameters
For the co-located Energy Storage analysis the Pexapark team assumed the following operational parameters for a typical Battery Energy Storage System (BESS) commonly associated with co-located renewable projects:
System Sizing: We assume the system is sized such that it is able to provide ‘Usable’ power & energy in-accordance-with the selected parameters. Thus a 100%, 2-hr battery will have enough ‘Nameplate’ power and energy to overcome the round-trip-efficiency (RTE) losses associated with the system. Thus the BESS will deliver power equivalent to the size of the PV system (100% power ratio) as measured at the boundary meter (also known as the point-of-interconnection meter) for a full 2 hours.
RTE: For Round-Trip-Efficiency we assumed an industry benchmark of 85% commonly identified by leading Independent Engineering (IEs) firms who provide bankability studies for such projects.
Degradation: We have assumed no degradation for the BESS in our analysis. Our analysis looks at the benefit of profile shaping solar generation for a specific historical year and we assume the system operated within the selected parameters for the entire year. Degradation effects should be modeled in-accordance-with the equipment specifications from the BESS supplier.
Cycles: We have assumed a maximum of 2 cycle per day.
Renewable Generation Profiles
For the co-located Energy Storage analysis, the Pexapark team uses ENTSO-E market level generation data for each specific renewable resource we model. For the Historic Co-located BESS Capture Factors, we use actual realized ENTSO-E production data and for the Forward Co-located BESS Capture Curves we use forecasted market level generation of each specific renewable resource based upon projected additions to the system from Bloomberg and ENTSO-E TYNDP scenarios. This has the result of ‘smoothing’ out the type of production volatility that would exist at the project level, and thus our Co-located BESS Capture factors and curves represent conservative estimates of the true benefits co-located energy storage can provide to a specific project.
Optimization Formulas
With hourly prices and hourly volumes (including renewable generation, storage charging and discharging quantities), historical Co-located BESS capture factors chyb are calculated as the ratio of realized effective renewable energy price of the Co-located BESS system phybeff and the baseload price pBL , where pi and qi denote the spot price and the renewable generation quantity for hour
Uncertainty range
Two "forecasting" algorithms are applied to determine realistic upper and lower bounds of the uncertainty range, i.e. the maximum and the minimum values of the Co-located BESS capture factor.
Max Value
Dispatch (i.e. renewable generation, storage charging and discharging) of the Co-located BESS system is optimized considering perfect foresight of the wholesale electricity prices over the simulation period, aiming to maximize the revenue of the Co-located BESS system.
Min Value
To incorporate the impacts of uncertainties, a methodology, which follows the principle of persistence forecast (forecasted hourly prices are equal to realized prices for the previous day) while respecting the weekly pattern of the price curves, has been applied to determine the "Min Value". Any reasonable forecast applied to dispatching the storage asset should be of higher quality.
Remarks
Due to the concern for the data quality of the Netherlands actual solar power production published by ENTSO-E, the solar capture factors and the Co-located BESS solar capture factors for the Netherlands are calculated based on the corresponding day-ahead solar power production data.