Final answer:
The Southwest desert of the United States, particularly the Mojave Desert in California, experiences the most intense insolation. Insolation values across the U.S. vary, but generally not by more than a factor of two, even in very different environments. The standard unit of insolation is W/m², easily convertible from kWh/m²/day.
Step-by-step explanation:
The region of the United States with the most intense insolation is the Southwest desert, particularly around areas like the Mojave Desert in California. According to the information provided, this region receives the highest levels of solar potential, with insolation values not varying by more than a factor of two even in contrasting environments such as the rainy Olympic Peninsula in Washington. The measurement of insolation can be expressed in units of kWh/m²/day or W/m², and the average amount of power from sunlight reaching the ground is typically about 200 W/m².
To convert from kWh/m²/day to W/m², you can multiply the insolation value in kWh/m²/day by 1,000 to get Wh/m²/day, and then divide by 24, the number of hours in a day. For example, if the insolation is given as 5 kWh/m²/day, the conversion to W/m² would be (5 kWh/m²/day × 1,000) / 24 = 208.33 W/m². This indicates the average power from sunlight that falls onto a square meter of a horizontal surface.