What is solar irradiance?
Solar irradiance simply refers to the amount of electromagnetic energy/solar radiation that can reach the Earth's surface, meaning how much sunlight we can receive.
Why is knowing the irradiance level helpful?
If we know the irradiance level of a particular area, we can determine the size of solar collector we need. Generally speaking, areas with high irradiance levels will require fewer collectors than areas with low irradiance levels. Knowing your area's irradiance level allows you to calculate the collector size and energy output more accurately.
What units are used to express irradiance levels?
Different countries use different units to express irradiance levels. However, the most common unit is kWh/m2/day, which represents the amount of solar energy a square meter of the Earth's surface can absorb in a single day. This number is an average value for temperature variations over the length of the day.
Other surface-based unit conversions are:
1 kWh/m2/day = 317.1 Btu or ft2 or day = 3.6 MJ/m2/day
The original energy conversion is:
1 kWh = 3412 Btu = 3.6 MJ = 859.8 kcal
Is my Earth's insolation level low, moderate, or high?
The following examples show how Earth's insolation level is calculated. The average annual value is considered very high, even though it isn't considered very high during the summer months. This is because in some hot, sunny places, such as central Australia, the annual average insolation is only 5.89. The average sunbathing level is 5.89.
Comparing the two extreme locations below, you can determine the sunbathing level for your location.
The average annual sunbathing level is:
Central Australia = 5.89 kWh/m2/day - very high
Helsinki, Finland = 2.41 kWh/m2/day - very low
How do I calculate my collector size? Now that I know my sunbathing level, how do I calculate my collector size?
Click here to visit the collector setup page.
Click the link below to view the sunbathing level for your area.
You can find the sunbathing level for your area by visiting the NASA website below.
Latitude and longitude are the basic information for finding your local sunbathing level, but you must first register for a free site.
