*(a) Data Collection*

At this stage, the main inputs to the design process are gathered: topographic information, renewable resources (with special attention to wind resource, which is usually more difficult to evaluate), consumption characterization (crucial), and technical and economic information of the equipment. In projects of a certain size, it is a common practice to carry out field campaigns for both the wind resource and the consumption characterization [38].

In the case of performing a measuring campaign, in order to summarize the high quality requirements in wind measurement, international standards have been developed, such as the MEASNET guidelines. MEASNET is an international network of measurement institutes, which developed the guideline "Evaluation of site-specific wind conditions". This guideline describes the process of site assessment including data collection, evaluation, and interpretation. The MEASNET guideline refers to IEC 61400-12-1 and focuses on data quality, plausibility, and integrity [39].

Even for SWT there are some guidelines available for site assessment, such as [40], that covers most of the aspects that may apply when considering the inclusion of a SWT in a system. More detailed guidelines for site turbulence influence on the SWT estimated production can be found in dedicated guidelines, such as [15], for example.

However, one of the main limitations for taking into account wind generation in REDPS in the range that is being considered in this work is commonly the lack of reliable wind data necessary to evaluate its convenience. Nowadays, there are both global and local (usually at a national level) wind atlases. In this case, the no-data situation, which was not rare a few years ago, is almost extinguished. However, in order to perform a minimum performance evaluation of wind generation within a REDPS, it is not the case that any wind resource characterization will be valid: characterization needs to include spatial and temporal information in the most detailed possible manner. It should be remembered here that, of course, the best method to achieve this goal is an on-site wind measurement campaign, but it is precisely the case of not having this campaign that it is being covered at this point.

At least hourly average wind speed variation is needed to be able to assess the wind generation in a REDPS in order to evaluate its matching with load and other forms of generation profiles from an energy balance point of view. Other short-term phenomena (dynamics and/or transients) would require even higher time resolutions, but they are out of the scope of this particular application since there is long-term storage.

Global and local wind atlases may only bring information on the overall yearly wind regime [41] or even on the monthly average wind speed [42]. In the latter, some software (such as HOMER Pro) may generate hourly synthetic series from monthly average values of wind speed, so they might be a first approach. For the site assessment, wind direction estimation is also necessary. Global Wind Atlas [41] provides an overall wind rose.

The news on this topic is the availability of reanalysis data derived from satellite observations are described in Section 2.1.3 (a) in this paper, both globally and freely, and provides relatively sufficient time resolution (one hour) wind speed and wind direction data but with an insufficient spatial resolution of several square kilometers. However, there is a possibility to use these data as an input for downscaling (considering also the available information on roughness and DEM, Digital Elevation Models) by generating higher spatial resolutions down to several hundred meters. Although all these sources of information are freely available so that anyone could produce these results (these are good news for SWT), some commercial tools exist that allow performing it in an easier manner. As a reference, EMD in Europe and UL in the US offer different software solutions to obtain hourly wind resource estimation for any point (Windographer and WindNavigator, in the case of UL; WindPro, for EMD) with a reasonable spatial resolution: UL offers a Typical Year Time Series Short term data set using the AWST MASS model and scaled to 200 m resolution to represent a 365 day sample from a 15 year period [22], while with EMD's full windPRO modeling chain, it is possible to downscale the data from the global level to the mesoscale level and, further, to the microscale level (e.g., using the windPRO scaler options) to a 250 m resolution or even 100 m resolution with WAsP [21].

These two software groups also offer two particular applications that are especially suitable for the assessment of SWT in REDPS: myWindTurbine (EMD, [28]) was designed for the evaluation of the influence of obstacles in SWT production which, as it was mentioned in Section 2.1.3 (a), is a key issue for SWT; and HOMER Pro (recently acquired by UL, [29]), which is the reference for REDPS optimization, as it described in Section 2.1.3 (c). In its latest version of HOMER Pro 3.14.2 (10 August 2020), there is a link to WindNavigator ([43], UL software for wind resource estimation) that, while it is not ye<sup>t</sup> available, opens the door to connect both applications.

One estimate of the cost to have a site modeled in the United States in 2016 was approximately \$500. The model utilizes static wind maps, which is a gross approximation using annual average site wind speed and micro-site adjustments [17]. A characterization using myWindTurbine software costs around 60 EUR/site [28]. However, care should be taken with respect to the temporal needs in REDPS previously described, which may not be covered by these solutions.
