## 1 Introduction
### Climatology and Microgrid Architectures at the Three Locations
#### SkyImager at San Antonio, TX, USA  
Texas produces more electricity than any of the other 49 states, and as a result has its own interconnect ERCOT. In 2017, power statewide was generated by a variety of sources: natural gas (45%), coal (30%), wind (15%), and nuclear (9%). In 2014, wind replaced nuclear as the third-largest source of power and Texas now produces more wind power than any other state. Solar generation is increasing, but still relatively small for a state with abundant annual sunshine. Located in central Texas some 200 miles from the Gulf of Mexico, San Antonio is home to almost 1.5 million people and several military bases. CPS Energy serves San Antonio and is the nation's largest public power, natural gas and electric company. They are committed to renewables, funding a 400 MWac project with multiple PV plants (Alamo 1-7) close to San Antonio, and wind farms in West and South Texas. CPS Energy is among the top public power wind energy buyers in the nation and number one in Texas for solar  
Figure 6: Microgrid at NREL ESIF Building where the first SkyImager was deployed in 2015.  
generation. In keeping with this commitment, TSERI was formed in 2001 as an alliance between CPS Energy and UTSA. For San Antonio, the most significant local weather issue is low-level Gulf stratus [44]. Elevations of the terrain increase from sea level at the Gulf coast to almost 800 ft at San Antonio, and a moist air mass over the Gulf of Mexico will cool adiabatically to saturation as it moves upslope. Nocturnal radiational cooling causes cloud formation before midnight, resulting in a ceiling of 500-1000 feet. A solid cloud deck will cover much of central Texas and remain in place until late morning when the sun burns off the stratus and cumulus clouds begin to form. Forecasting Gulf stratus is an important problem for aviation; it is a matter of accurately predicting low-level wind flow (<5000 ft) with the most favored wind direction for stratus formation from 90\({}^{\circ}\) to 180\({}^{\circ}\). It is important to address these local weather conditions that occur below the spatial and temporal resolution of NWP, but are crucial for both inter-hour and day-ahead irradiance forecasts. Use of machine learning using local datasets and climatology will allow the information and intelligence of a study such as [44] to be incorporated in site-specific irradiance forecasts. The Fort Sam Houston Library location at JBSA presented several unique challenges for the deployment of the UTSA hardware and software, challenges that provide valuable insights for other researchers. Many of the issues that arose were heavily dependent on the specific location. At JBSA, the Sky Imager was deployed using an edge-computing configuration with a wired Ethernet connection for cyber security. The JBSA microgrid is shown in Figure 7 and includes the Base Library building, solar arrays, inverters, and the pod housing the battery energy storage system (ESS). The need for accurate on-site meteorological observations necessitated installation of a complete MET Station atop a 10m antenna tower. A Campbell Scientific weatherproof instrument box at the tower base contained a National Instruments MyRio computer, a transformer, backup battery, and an Odroid C2 single board computer (SBC) for calculating the day-ahead load/PV forecasts. Atop the tower sat the SkyImager, a WXT520 Vaisala weather transmitter, and a pyranometer. Figure 7: The Microgrid at Joint Base San Antonio, TX, USA. In July of 2018 another Skylmager was deployed in San Antonio at the location of a university PV generation project. Funded by a DOE-SECO grant [45] in 2014, solar panels were installed on the Engineering Building, HEB University Center III, and Durango buildings at UTSA. In addition, equipment was installed to record measurements from 4 Combiners, 4 Inverters, 2 Kipp & Zonen CMP11 pyranometers, and a WXT520 Vaisala Weather Transmitter at the UCIII. Figure 8 displays the Skylmager and PV panels and Figure 8 shows combiners/inverters atop the Engineering Building.