Solar Irradiance

Solar Irradiance is a measure of how much solar power you are getting at your location. This irradiance varies throughout the year depending on the seasons. It also varies throughout the day, depending on the position of the sun in the sky, and the weather.

Solar insolation is a measure of solar irradiance over of period of time - typically over the period of a single day.

This irradiance calculator takes data collated over a 22 year period to provide monthly average insolation figures. This information is then used to calculate the average daily power generation a photovoltaic system will produce in any given month.

How to use the
irradiance calculator:

• Select your country from the list.
• If you have selected America or Canada, select your state or province.
• Select the town or city nearest where you live.
• The irradiance calculator will then show monthly figures showing the average kWh per square meter per day for energy at your location.
• You can multiply this irradiance figure by the wattage of your photovoltaic panels to give you an average daily amount of energy you can expect to generate with your system, measured in watt-hours.