Puerto Rico and other islands in the vicinity, like the US Virgin Islands, has unique conditions that differ from those in the continental US and Canada. They include:
- High solar radiation, relatively stable water mains temperature, and no freezing conditions.
- Significantly lower domestic water consumption per capita than the continental US, on average.
- High incidence of hurricanes leading to grid reliability challenges.
- Common use of solar water heaters without gas or electric backup water heater.
As a result, solar water heating is very cost-effective and widely used in the region. But the lower daily per capita water usage makes the standard 64.3 gallon per day hot water load pattern used by OG-300 less applicable. Therefore, SRCC makes available performance ratings using a number of hot water loads to allow the most applicable to be selected.
The widespread use of solar water heaters as the sole source of domestic hot water (no gas or electric backup) means that added information is needed. Where the manufacturer offers a solar-only system configuration, the supplement includes the revised schematic and information on the percentage of hot water loads it can meet in the area.