1. Deciding the Direction and Angle of Installation.

The angle and direction of installation is of great importance as it will affect the efficiency of the solar collector. Naturally, you want the collector to receive the maximum amount of sunlight each day and throughout the year. If you are in the Northern Hemisphere then the collector should face South and if you are in the Southern Hemisphere then the collector should face North. See diagram below.

Insolation diagram


The angle at which you mount the collector should roughly correspond to the latitude of your location.

If your roof angle is within +/-10°of your desired angle, you can just mount the solar collector flush against the roof surface without it affecting the efficiency of your unit.

How to prevent excessive summer heat output:

Adjusting the angle of the collector can help to reduce summer heat output. By increasing the vertical angle of the collector by about 15 to 20 o more than the location's latitude (i.e. 45o instead of 30o), greater winter performance will be experienced. This is because the collector is "facing" the sun as the sun is lower in the winter and higher in the summer. During the summer months, the collector will be slightly less efficient and as such, heat output will be reduced as the collector is not "facing" the sun. This simple solution alone can reduce peak summer output considerably, thus reducing problems associated with excessive summer heat production. 

Please note: For the RUNSUN solar collectors, optimal heat pipe performance is achieved in the angle range of 20-70o. Although your location may have a latitude of less than 20o, this basic installation guidelines should be followed.  Horizontal angles of +5o are acceptable and may be appropriate.

2. What is Solar Insolation?

What is solar insolation?
The amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Basically that means how much sunlight is shining down on us.

Why is knowing the insolation level useful?
By knowing the insolation levels of a particular region we can determine the size of solar collector that is required. An area with poor insolation levels will need a larger collector than an area with high insolation levels. Once you know your region's insolation level you can more accurately calculate collector size and energy output.

What units are used to express Insolation levels?
The values are generally expressed in kWh/m2/day. This is the amount of solar energy that strikes a square metre of the earth's surface in a single day. Of course this value is averaged to account for differences in the days' length. There are several units that are used throughout the world.

The conversions based on surface area as follows:
1 kWh/m2/day = 317.1 btu/ft2/day = 3.6MJ/m2/day

The raw energy conversions are:
1kWh = 3412 Btu = 3.6MJ = 859.8kcal

Is my region's insolation level low, moderate or high?
The following scale is a basic guide for insolation levels. Although a value of 5 is not considered very high during the summer months, as an average annual value this is very high. You will see that in central Australia, which is a hot, sunny place, the annual average insolation is 5.89.

You may compare you location to the following two extreme locations.
Average annual insolation levels:
Central Australia = 5.89 kWh/m2/day - Very High
Helsinki, Finland = 2.41 kWh/m2/day - Very Low

Now I know my insolation level, how do I calculate my collector's size?
Please click here to visit the collector sizing page.

Click on the links below to view insolation levels for your region.

Apricus Solar Distributors - Central & South America Apricus Solar Distributors - Asia & South Pacific Apricus Solar Distributors - Europe Apricus Solar Distributors - USA & Canada

If you would like to find the insolation levels for your area, please visit the NASA website below.
You just need to know your latitude and longitude. Free registration at the site is required for access.

Nasa Surface meteorology and Solar Energy Data Set